Although the so called Homo naledi find in South-Africa is impossible to
evaluate - due to complete lack of dating, context etc. - it's already
presented as both "important" and dismissed as "Western pseudoscience".
Two years ago, several skeletons belonging to an unknown species of
early human lineage were discovered in the Rising Star Cave near
Johannesburg, South Africa. Now, anthropologist Lee Berger and his team
have presented their findings.
Please see the scientific description furthest down on this post.
Dr. (!) Mathole Motshekga: Science should be spiritual - not Western pseudoscience about evolution.
The presentation of the discovery of Homo naledi in South-Africa wasn't well received by all.
As a lawyer Mathole Motshekga obviously lacks training in science*.
However, that shouldn't spare him from criticism for his crypto-racist
rant against the "Western world".
* In Demand for Resources
(1992:43) Klevius wrote that the only truly all-scientific discipline is
jurisprudence, where axiomatic true statements (the law) are checked
against reality. In other words, the discipline is science. However,
that gives no bearing in disciplines lacking pre-made answers.
Homo nadeli is ‘pseudo science’, according to Motshekga.
Mathole Serofo Motshekga is a South African politician and lawyer who is
a member of South Africa's Parliament. Motshekga holds a leadership
position within the African National Congress as parliamentary chief
whip. He was also the second Premier of Gauteng province. Outside of
politics, he is a lecturer in the department of law at the University of
South Africa.
Homo Naledi critisism and science denialism
On Friday 11th September 2015, the day after the announcements of the
newly discovered hominin species, Homo naledi, during an interview
conducted by eNCA Motshekga espoused a scientific denialist view by
making largely incoherent statements criticizing the findings as
pseudoscientific and as an attempt by the western world to promote the
idea of Africans as subhumans:
"I have no objection to scientists conducting research into the past,
but when I follow these findings historically, they seem to be
calculated to affirm what apartheid and colonialists did to say that we
are subhumans who developed from the animal kingdom and therefore gave
us the status as subhuman beings to justify slavery, colonialism,
oppression and exploitation."
He continued to claim that "...humanity preexisted the universe itself,
so the humanity cannot be the product of the animal kingdom which
emanated much later. So this thing is inconsistent with reality, is
inconsistent with the available African evidence which is being
suppressed by the west to support their story that we are subhuman, and
that we developed from the animal kingdom. And that's why even today no
African is respected anywhere in the world, because of this type of
theories which have no scientific basis."
He allegedly based his views on 36 000 year old African literature: "I
have access to primal African information that you have never seen."
(According to the wikipedia pages on the history of writing and
proto-writing the generally accepted consensus is that the oldest
writing systems date back to 3200BC, while proto-writing systems date
back to 8000BC)
Motshekga elaborated generally on his view of science and evolution by
stating: "Science is first and foremost a spiritual thing. For instance
if you want to talk about evolution, you must start with the law of
squares, which says the mind squared plus the soul squared plus the body
squared is equal to this."
President Thabo Mbeki says Western HIV/AIDS aid is 'poison' while
allowing quack doctors play with the lives of some 400,000
South-Africans
July 10, 2003 PRETORIA, South Africa, July 9— President Bush today
brought the promise of more money for fighting AIDS to South Africa,
which has been slow to attack the disease, and he pressed President
Thabo Mbeki to deal with the epidemic more effectively.
On the second day of his five-day trip to Africa, Mr. Bush urged the
South African leader, who has expressed doubt about the link between HIV
and AIDS and raised questions about the effectiveness of the drug
treatment that has become standard, to come up with a plan that includes
both the drug regimen and prevention efforts.
AIDS was one of two issues in which the two leaders stepped gingerly
around each other during a morning of meetings here. The other was the
future of Zimbabwe, which is becoming unstable under President Robert
Mugabe.
South Africa has 4.7 million people with H.I.V., one of the largest
infected populations in the world, but Mr. Mbeki's government has not
yet made life-prolonging antiretroviral drugs widely available. Advocacy
groups have long demanded that Mr. Mbeki drop what they consider to be
his incomprehensible reluctance to deal aggressively with the problem.
White House officials played down the differences between Mr. Bush and
Mr. Mbeki on AIDS. But they made clear that the United States would use
the leverage of its offer to include South Africa in the first round of
countries to benefit from the $15 billion AIDS-fighting package Mr. Bush
proposed in January to prod Mr. Mbeki to move faster to bring all
available weapons to bear.
''We need a common-sense strategy to make sure that the money is well
spent,'' Mr. Bush said at a news conference with Mr. Mbeki. ''And the
definition of well spent means lives are saved, which means good
treatment programs, good prevention programs, good programs to develop
health infrastructures in remote parts of different countries so that we
can actually get antiretroviral drugs to those who need help.''
Homo naledi description
Average height 1.5 m, weight 45 kg.
Skull: Primitive,
similar to Homo habilis. Between 466 and 560 cc, in comparison to H.
habilis 510 to 700 cc, H. erectus 550 to 1100 cc, H. floresiensis 426
cc.
Dentition: Many teeth representing many ages from young
to old individuals. They look primitive in the increasing size towards
the back of the tooth row, but they look modern in their small size and
they are simplified, set in lightly built jawbones.
Post
cranial: The wrist, hands, legs and feet are similar to those in
neandertals and modern humans. The hands have curved fingerbones,
suggestive of climbing behavior. The legs were made for long distance
walking. The feet reflect effective walking. The body has similarities
to the Dmanisi’s Homo erectus.
H. naledi lacks the
reduced cranial height of Homo floresiensis, and displays a marked
angular torus and parasagittal keeling between bregma and lambda that is
absent in the latter species. H. naledi further has a flat and squared
nasoalveolar clivus, unlike the pronounced maxillary canine juga and
prominent pillars of H. floresiensis. The mandible of H. floresiensis
shows a posteriorly inclined post incisive planum with superior and
inferior transverse tori, differing from the steeply inclined posterior
face of the H. naledi mandibular symphysis, which lacks both a post
incisive planum or a superior transverse torus. Dentally, H. naledi is
distinguishable from H. floresiensis by the mesiodistal elongation and
extensive talonid of the mandibular P4, and the lack of Tomes' root on
the mandibular premolars. The molar size gradient of H. naledi follows
the M1 < M2 < M3 pattern, unlike the M3 < M2 < M1 pattern in
H. floresiensis, and the mandibular molars are relatively mesiodistally
long and buccolingually narrow compared to those of H. floresiensis.
H1
is distinguished from H. habilis in having a deep proximal palmar fossa
with a well-developed ridge distally for the insertion of the flexor
pollicis longus muscle on the first distal phalanx, and a more
proximodistally oriented trapezium-second metacarpal joint. It also
differs from both H. habilis and H. floresiensis by having a relatively
large trapezium-scaphoid joint that extends onto the scaphoid tubercle,
and from H. floresiensis in having a boot-shaped trapezoid with an
expanded palmar surface, and a relatively large and more
palmarly-positioned capitate-trapezoid joint (Tocheri et al., 2005,
2007; Orr et al., 2013).
The tibia of H. naledi differs from
those of all other known hominins in its possession of a distinct
tubercle for the pes anserinus tendon. The tibia differs from other
hominins except H. habilis, H. floresiensis, and (variably) H. sapiens
in its possession of a rounded anterior border.
Foot (F1)
The
H. naledi foot can be distinguished from the foot of H. habilis by the
presence of a flatter, non-sloping trochlea with equally elevated medial
and lateral margins, a narrower Mt1 base, greater proximolateral to
distomedial orientation of the lateral metatarsals, and a metatarsal
robusticity ratio of 1 > 5 > 4 > 3 > 2. Pedal morphology in
H. rudolfensis is currently unknown, and that of H. erectus is too
poorly known to allow for comparison. The H. naledi foot can be
distinguished from the foot of H. floresiensis by a longer hallux and
shorter second through fifth metacarpals relative to hindfoot length,
and higher torsion of the talar head and neck.
Maximum tibia
length for U.W. 101-484, compared to other nearly complete hominin tibia
specimens. Australopithecus afarensis represented by A.L. 288-1 and
KSD-VP-1/1 (Haile-Selassie et al., 2010); Homo erectus represented by
D3901 from Dmanisi and KNM-WT 15000; Homo habilis by OH 35; Homo
floresiensis by LB1 and LB8 (Brown et al., 2004; Morwood et al., 2005).
Chimpanzee and contemporary European ancestry humans from Cleveland
Museum of Natural History (Lee, 2001); Andaman Islanders from Stock
(2013). Vertical lines represent sample ranges; bars represent 1
standard deviation.
The endocranial volume of all H. naledi
specimens is clearly small compared to most known examples of Homo. We
combined information from the most complete cranial vault specimens to
arrive at an estimate of endocranial volume for both larger (presumably
male) and smaller (presumably female) individuals (larger composite
depicted in Figure 11). The resulting estimates of approximately 560cc
and 465cc, respectively, overlap entirely with the range of endocranial
volumes known for australopiths. Within the genus Homo, only the
smallest specimens of H. habilis, one single H. erectus specimen, and H.
floresiensis overlap with these values.
Maximum tibia length for
U.W. 101-484, compared to other nearly complete hominin tibia
specimens. Australopithecus afarensis represented by A.L. 288-1 and
KSD-VP-1/1 (Haile-Selassie et al., 2010); Homo erectus represented by
D3901 from Dmanisi and KNM-WT 15000; Homo habilis by OH 35; Homo
floresiensis by LB1 and LB8 (Brown et al., 2004; Morwood et al., 2005).
Chimpanzee and contemporary European ancestry humans from Cleveland
Museum of Natural History (Lee, 2001); Andaman Islanders from Stock
(2013). Vertical lines represent sample ranges; bars represent 1
standard deviation.
The endocranial volume of all H. naledi
specimens is clearly small compared to most known examples of Homo. We
combined information from the most complete cranial vault specimens to
arrive at an estimate of endocranial volume for both larger (presumably
male) and smaller (presumably female) individuals (larger composite
depicted in Figure 11). The resulting estimates of approximately 560cc
and 465cc, respectively, overlap entirely with the range of endocranial
volumes known for australopiths. Within the genus Homo, only the
smallest specimens of H. habilis, one single H. erectus specimen, and H.
floresiensis overlap with these values.
Like the skull, the
dentition of H. naledi compares most favorably to early Homo samples.
Yet compared to samples of H. habilis, H. rudolfensis, and H. erectus,
the teeth of H. naledi are comparatively quite small, similar in
dimensions to much later samples of Homo. With both small post-canine
teeth and a small endocranial volume, H. naledi joins Au. sediba and H.
floresiensis in an area distinct from the general hominin relation of
smaller post-canine teeth in species with larger brains (Figure 12).
Specimens
from the latest Lower Pleistocene and MP of Europe and Africa that
cannot be attributed to H. erectus were included in our comparisons.
These include fossils that have been attributed to H. heidelbergensis,
H. rhodesiensis, ‘archaic H. sapiens’, or ‘evolved H. erectus’ by a
variety of other authors. Specimens attributed to MP Homo include
materials from Eliye Springs, Arago, Atapuerca Sima de los Huesos, Bodo,
Broken Hill, Cave of Hearths, Ceprano, Dali, Elandsfontein, Jinniushan,
Kapthurin, Mauer, Narmada, Ndutu, Petralona, Reilingen-Schwetzingen,
Solo, Steinheim, Swanscombe. This grouping includes the following
specimens: KNM-ES 11693, Arago 2, Arago 13, Arago 21, Atapuerca 1,
Atapuerca 2, Atapuerca 4, Atapuerca 5, Atapuerca 6, Cave of Hearths,
SAM-PQ-EH1, Kabwe, Mauer, Ndutu, Salé, Petralona,
Reilingen-Schwetzingen, Steinheim.
Homo floresiensis
Order Primates LINNAEUS 1758
Suborder Anthropoidea MIVART 1864
Superfamily Hominoidea GRAY 1825
Family Hominidae GRAY 1825
Tribe Hominini GRAY 1825
Genus Homo LINNAEUS 1758
Homo naledi sp. nov. urn:lsid:zoobank.org:pub:00D1E81A-6E08-4A01-BD98-79A2CEAE2411
The
collection is morphologically homogeneous in all duplicated elements,
except for those anatomical features that normally reflect body size or
sex differences in other primate taxa. Therefore, although we refer to
the holotype and the paratypes for differential diagnoses; the section
describing the overall anatomy encompasses all morphologically
informative specimens.
Differential diagnosis
This
comprehensive differential diagnosis is based upon cranial, dental and
postcranial characters. The hypodigms used for other species are
detailed in the ‘Materials and methods’. We examined original specimens
for most species, except where indicated in the ‘Materials and methods’;
when we relied on other sources for anatomical observations we indicate
this. A summary of traits of H. naledi in comparison to other species
is presented in Supplementary file 2. Comparative cranial and mandibular
measures are presented in Table 1, and comparative dental measures are
provided in Table 2.
View this table:
View popupView inline
Table 1.
Cranial and mandibular measurements for H. naledi, early hominins, and modern humans
DOI: http://dx.doi.org/10.7554/eLife.09560.012
View this table:
View popupView inline
Table 2.
Dental measures for H. naledi and comparative hominin species
DOI: http://dx.doi.org/10.7554/eLife.09560.013
Cranium, mandible, and dentition (DH1, DH2, DH3, DH4, DH5, U.W. 101-377)
The
cranium of H. naledi does not have the well-developed crest patterns
that characterize Australopithecus garhi (Asfaw et al., 1999) and
species of the genus Paranthropus, nor the derived facial morphology
seen in the latter genus. The mandible of H. naledi is notably more
gracile than those of Paranthropus. Although maxillary and mandibular
incisors and canines of H. naledi overlap in size with those of
Paranthropus, the post-canine teeth are notably smaller than those of
Paranthropus and Au. garhi, with mandibular molars that are
buccolingually narrow.
H. naledi differs from Australopithecus
afarensis and Australopithecus africanus in having a pentagonal-shaped
cranial vault in posterior view, sagittal keeling, widely spaced
temporal lines, an angular torus, a deep and narrow digastric fossa, an
external occipital protuberance, an anteriorly positioned root of the
zygomatic process of the maxilla, a broad palate, and a small canine
jugum lacking anterior pillars. The anterior and lateral vault of H.
naledi differs from Au. afarensis and Au. africanus in exhibiting only
slight post-orbital constriction, frontal bossing, a well-developed
supraorbital torus with a well-defined supratoral sulcus, temporal lines
that are positioned on the posterior rather than the superior aspect of
the supraorbital torus, a root of the zygomatic process of the temporal
that is angled downwards approximately 30° relative to the Frankfort
Horizontal (FH) and which begins its lateral expansion above the
mandibular fossa rather than the EAM, a mandibular fossa that is
positioned medial to the wall of the temporal squame, a small
postglenoid process that contacts the tympanic, a coronally oriented
petrous, and a small and obliquely oriented EAM. The H. naledi mandible
exhibits a more gracile symphysis and corpus, a more vertically inclined
symphysis, a slight mandibular incurvation delineating a faint mental
trigon, and a steeply inclined posterior face of the mandibular
symphysis without a post incisive planum. The incisors of H. naledi
overlap in size with some specimens of Au. africanus, though the canines
and post-canine dentition are notably smaller, with relatively narrow
buccolingual dimensions of the mandibular molars. The maxillary I1 lacks
a median lingual ridge and exhibits a broad and uninflated lingual
cervical prominence, the lingual mesial and distal marginal ridges do
not merge onto the cervical prominence in the maxillary I2, the
mandibular canine exhibits only a weak lingual median ridge and a broad
and uninflated lingual cervical prominence, and the buccal grooves on
the maxillary premolars are only weakly developed. H. naledi exhibits a
small and isolated Carabelli's feature in the maxillary molars, unlike
the more prominent and extensive Carabelli's feature of
Australopithecus. Moreover, the H. naledi mandibular molars possess
small, mesiobuccally restricted protostylids that do not intersect the
buccal groove, differing from the typically enlarged, centrally
positioned protostylids that intersect the buccal groove in
Australopithecus.
The cranium of H. naledi differs from
Australopithecus sediba (Berger et al., 2010) in exhibiting sagittal
keeling, a more pronounced supraorbital torus and supratoral sulcus, a
weakly arched supraorbital contour with rounded lateral corners, an
angular torus, a well-defined supramastoid crest, a curved superior
margin of the temporal squama, a root of the zygomatic process of the
temporal that is angled downwards approximately 30° relative to FH, a
flattened nasoalveolar clivus, weak canine juga, an anteriorly
positioned root of the zygomatic process of the maxilla, and a
relatively broad palate that is anteriorly shallow. The H. naledi
mandible (DH1) has a mental foramen positioned superiorly on the corpus
that opens posteriorly, unlike the mid-corpus height, more laterally
opening mental foramen of Au. sediba. The maxillary and mandibular teeth
of H. naledi are smaller than those of Au. sediba, with mandibular
molars that are buccolingually narrow. The lingual mesial and distal
marginal ridges do not merge onto the cervical prominence in the
maxillary I2, the paracone of the maxillary P3 is equal in size to the
protocone, the protoconid and metaconid of the mandibular molars are
equally mesially positioned, and the lingual cusps of the molars are
positioned at the occlusobuccal margin while the buccal cusps are
positioned slightly lingual to the occlusobuccal margin. Also, Au.
sediba shares with other australopiths a protostylid that is centrally
located and which intersects the buccal groove of the lower molars,
unlike the small and mesiobuccally restricted protostylid that does not
intersect the buccal groove in H. naledi.
The cranium of H.
naledi differs from Homo habilis in exhibiting sagittal keeling, a
weakly arched supraorbital contour, temporal lines that are positioned
on the posterior rather than the superior aspect of the supraorbital
torus, an angular torus, an occipital torus, only slight post-orbital
constriction, a curved superior margin of the temporal squama, a
suprameatal spine, a weak crista petrosa, a prominent Eustachian
process, a small EAM, weak canine juga, and an anteriorly positioned
root of the zygomatic process of the maxilla. Mandibles attributed to H.
habilis show a weakly inclined, shelf-like post incisive planum with a
variably developed superior transverse torus, unlike the steeply
inclined posterior face of the mandibular symphysis of H. naledi, which
lacks both a post incisive planum or superior transverse torus. The H.
naledi mandible (DH1) has a mental foramen positioned superiorly on the
corpus that opens posteriorly, while the mental foramen of H. habilis is
at mid-corpus height and opens more laterally. The maxillary and
mandibular dentitions of DH1 are smaller than typical for H. habilis.
The mandibular P3 of H. naledi is more molarized and lacks the occlusal
simplification seen in H. habilis; it has a symmetrical occlusal
outline, and multiple roots (two roots: mesiobuccal and distal) not seen
in H. habilis. The molars of H. naledi lack crenulation, secondary
fissures, and supernumerary cusps that are common to H. habilis. The
protoconid and metaconid of the mandibular molars are equally mesially
positioned.
The cranium of H. naledi differs from Homo
rudolfensis by its smaller cranial capacity, and by exhibiting frontal
bossing, a post-bregmatic depression, sagittal keeling, a well-developed
supraorbital torus delineated by a distinct supratoral sulcus, temporal
lines that are positioned on the posterior rather than the superior
aspect of the supraorbital torus, an occipital torus, an external
occipital protuberance, only slight post-orbital constriction, a small
postglenoid process, a weak crista petrosa, a laterally inflated mastoid
process, a canine fossa, incisors that project anteriorly beyond the
bi-canine line, and a shallow anterior palate. As in H. habilis,
mandibles attributed to H. rudolfensis show a weakly inclined,
shelf-like post incisive planum with a variably developed superior
transverse torus, unlike the steeply inclined posterior face of the
mandibular symphysis of DH1, the latter of which lacks either a post
incisive planum or superior transverse torus. The mandibular symphysis
and corpus of H. naledi are more gracile than those attributed to H.
rudolfensis, and the H. naledi mandible (DH1) has a mental foramen
positioned superiorly on the corpus that opens posteriorly, unlike the
mid-corpus height, more laterally opening mental foramen of H.
rudolfensis. The maxillary and mandibular dentition of H. naledi is
smaller than that of most specimens of H. rudolfensis, with only KNM-ER
60000 and KNM-ER 62000 appearing similar in size for some teeth (Leakey
et al., 2012). The molars of H. naledi lack crenulation, secondary
fissures, or supernumerary cusps common in H. rudolfensis. The buccal
grooves of the maxillary premolars are weak in H. naledi, and the
protoconid and metaconid of the mandibular molars are equally mesially
positioned.
H. naledi lacks the typically distinctive long and
low cranial vault of Homo erectus, as well as the metopic keeling that
is typically present in the latter species. H. naledi also differs from
H. erectus in having a distinct external occipital protuberance in
addition to the tuberculum linearum, a laterally inflated mastoid
process, a flat and squared nasoalveolar clivus, and an anteriorly
shallow palate. The parasagittal keeling that is present between bregma
and lambda in H. naledi (DH1 and DH3) is less marked than often occurs
in H. erectus, including in small specimens such as KNM-ER 42700 and the
Dmanisi cranial sample. Also unlike most specimens of H. erectus, H.
naledi has a small vaginal process, a weak crista petrosa, a marked
Eustachian process, and a small EAM. The mandible of H. erectus shows a
moderately inclined, shelf-like post incisive planum terminating in a
variably developed superior transverse torus, differing from the steeply
inclined posterior face of the H. naledi mandibular symphysis, which
lacks both a post incisive planum or a superior transverse torus. The
mental foramen is positioned superiorly and opens posteriorly in DH1,
unlike the mid-corpus height, more laterally opening mental foramen of
H. erectus. The maxillary and mandibular incisors and canines of H.
naledi are smaller than typical of H. erectus. The mandibular P3 of H.
naledi is more molarized and lacks the occlusal simplification seen in
H. erectus, they reveal a symmetrical occlusal outline, and multiple
roots (2R: MB+D) not typically seen in H. erectus. Furthermore, the
molars of H. naledi lack crenulation, secondary fissures, or
supernumerary cusps common in H. erectus.
H. naledi lacks the
reduced cranial height of Homo floresiensis, and displays a marked
angular torus and parasagittal keeling between bregma and lambda that is
absent in the latter species. H. naledi further has a flat and squared
nasoalveolar clivus, unlike the pronounced maxillary canine juga and
prominent pillars of H. floresiensis. The mandible of H. floresiensis
shows a posteriorly inclined post incisive planum with superior and
inferior transverse tori, differing from the steeply inclined posterior
face of the H. naledi mandibular symphysis, which lacks both a post
incisive planum or a superior transverse torus. Dentally, H. naledi is
distinguishable from H. floresiensis by the mesiodistal elongation and
extensive talonid of the mandibular P4, and the lack of Tomes' root on
the mandibular premolars. The molar size gradient of H. naledi follows
the M1 < M2 < M3 pattern, unlike the M3 < M2 < M1 pattern in
H. floresiensis, and the mandibular molars are relatively mesiodistally
long and buccolingually narrow compared to those of H. floresiensis.
H.
naledi differs from Middle Pleistocene (MP) and Late Pleistocene (LP)
Homo (here we include specimens sometimes attributed to the putative
Early Pleistocene taxon Homo antecessor, and MP Homo heidelbergensis,
Homo rhodesiensis, as well as archaic Homo sapiens and Neandertals) in
exhibiting a smaller cranial capacity. H. naledi has its maximum cranial
width in the supramastoid region, rather than in the parietal region.
It has a clearly defined canine fossa (similar to H. antecessor), a
shallow anterior palate, and a flat and a squared nasoalveolar clivus.
H. naledi lacks the bilaterally arched and vertically thickened
supraorbital tori found in MP and LP Homo. H. naledi also differs in
exhibiting a root of the zygomatic process of the temporal that is
angled downwards approximately 30° relative to FH, a projecting
entoglenoid process, a weak vaginal process, a weak crista petrosa, a
prominent Eustachian process, a laterally inflated mastoid process, and a
small EAM. The H. naledi mandible tends to be more gracile than
specimens of MP Homo. The mandibular canine retains a distinct accessory
distal cuspulid not seen in MP and LP Homo. Molar cuspal proportions
for H. naledi do not show the derived reduction of the entoconid and
hypoconid that characterizes MP and LP Homo. The mandibular M3 is not
reduced in DH1, thus revealing an increasing molar size gradient that
contrasts with reduction of the M3 in MP and LP Homo.
H. naledi
differs from H. sapiens in exhibiting small cranial capacity, a
well-defined supraorbital torus and supratoral sulcus, a root of the
zygomatic process of the temporal that is angled downwards approximately
30° relative to FH, a large and laterally inflated mastoid with
well-developed supramastoid crest, an angular torus, a small vaginal
process, a weak crista petrosa, a prominent Eustachian process, a small
EAM, a flat and squared nasoalveolar clivus, and a more posteriorly
positioned incisive foramen. The H. naledi mandible shows a weaker, less
well-defined mentum osseum than H. sapiens, as well as a slight
inferior transverse torus that is absent in humans. The mental foramen
is positioned superiorly in H. naledi, unlike the mid-corpus height
mental foramen of H. sapiens. The mandibular canine possesses a distinct
accessory distal cuspulid not seen in H. sapiens. Molar cuspal
proportions for H. naledi do not show the derived reduction of the
entoconid and hypoconid that characterizes H. sapiens. The mandibular M3
is not reduced in H. naledi, thus revealing an increasing molar size
gradient that contrasts with reduction of the M3 in H. sapiens.
Hand (H1)
H.
naledi possesses a combination of primitive and derived features not
seen in the hand of any other hominin. H1 is differentiated from the
estimated intrinsic hand proportions of Au. afarensis in having a
relatively long thumb ((Mc1 + PP1)/(Mc3 + PP3 + IP3)) (Rolian and
Gordon, 2013; Almécija and Alba, 2014). It is further distinguished from
Au. afarensis, Au. africanus, and Au. sediba in having a well-developed
crest for both the opponens pollicis and first dorsal interosseous
muscles, a trapezium-scaphoid joint that extends onto the scaphoid
tubercle, a relatively large and more palmarly-positioned
capitate-trapezoid joint, and/or a saddle-shaped Mc5-hamate joint. H.
naledi also differs from Au. sediba in that it lacks mediolaterally
narrow Mc2-5 shafts (Kivell et al., 2011). Manual morphology of Au.
garhi is currently unknown.
H1 is distinguished from H. habilis
in having a deep proximal palmar fossa with a well-developed ridge
distally for the insertion of the flexor pollicis longus muscle on the
first distal phalanx, and a more proximodistally oriented
trapezium-second metacarpal joint. It also differs from both H. habilis
and H. floresiensis by having a relatively large trapezium-scaphoid
joint that extends onto the scaphoid tubercle, and from H. floresiensis
in having a boot-shaped trapezoid with an expanded palmar surface, and a
relatively large and more palmarly-positioned capitate-trapezoid joint
(Tocheri et al., 2005, 2007; Orr et al., 2013).
H1 is dissimilar
to hand remains attributed to Paranthropus robustus/early Homo from
Swartkrans (Susman, 1988; Susman et al., 2001) in having a relatively
small Mc1 base and proximal articular facet, a saddle-shaped Mc5-hamate
joint, and more curved proximal and intermediate phalanges of ray 2–5.
Manual
morphology of H. rudolfensis is currently unknown, and that of H.
erectus is largely unknown. Still, H1 differs from a third metacarpal
attributed to H. erectus s. l., as well as from Homo neanderthalensis
and H. sapiens by lacking a styloid process (Ward et al., 2013).
H1
is further distinguished from H. neanderthalensis and H. sapiens by its
relatively small facets for the Mc1 and scaphoid on the trapezium, its
low angle between the Mc2 and Mc3 facets on the capitate, and by its
long and curved proximal and intermediate phalanges on rays 2–5.
H1
is differentiated from all known hominins in having a Mc1 that combines
a mediolaterally narrow proximal end and articular facet with a
mediolaterally wide distal shaft and head, a dorsopalmarly flat and
strongly asymmetric (with an enlarged palmar-lateral protuberance) Mc1
head, and the combination of an overall later Homo-like carpal
morphology combined with proximal and intermediate phalanges that are
more curved than most australopiths. H1 also differs from all other
known hominins except H. neanderthalensis in having non-pollical distal
phalanges with mediolaterally broad apical tufts (relative to length).
Femur (U.W. 101-1391)
The
femur of H. naledi differs from those of all other known hominins in
its possession of two well-defined, mediolaterally-running pillars in
the femoral neck. The pillars run along the superoanterior and
inferoposterior margins of the neck and define a distinct sulcus along
its superior aspect.
Tibia (U.W. 101-484)
The tibia of H.
naledi differs from those of all other known hominins in its possession
of a distinct tubercle for the pes anserinus tendon. The tibia differs
from other hominins except H. habilis, H. floresiensis, and (variably)
H. sapiens in its possession of a rounded anterior border.
Foot (F1)
The
foot of H. naledi differs from the pedal remains of Au. afarensis, Au.
africanus, and Au. sediba in having a calcaneus with a weakly developed
peroneal trochlea. F1 also differs from Au. afarensis in having a higher
orientation of the calcaneal sustentaculum tali. F1 can be further
distinguished from pedal remains attributed to Au. africanus in having a
higher talar head and neck torsion, a narrower Mt1 base, a dorsally
expanded Mt1 head, and greater proximolateral to distomedial orientation
of the lateral metatarsals. The H. naledi foot can be further
differentiated from the foot of Au. sediba in having a proximodistally
flatter talar trochlea, a flat subtalar joint, a diagonally oriented
retrotrochlear eminence and a plantar position of the lateral plantar
process of the calcaneous, and dorsoplantarly flat articular surface for
the cuboid on the Mt4 (Zipfel et al., 2011). Pedal remains of Au. garhi
are currently unknown, and those of P. robustus are too poorly known to
allow for comparison.
The H. naledi foot can be distinguished
from the foot of H. habilis by the presence of a flatter, non-sloping
trochlea with equally elevated medial and lateral margins, a narrower
Mt1 base, greater proximolateral to distomedial orientation of the
lateral metatarsals, and a metatarsal robusticity ratio of 1 > 5 >
4 > 3 > 2. Pedal morphology in H. rudolfensis is currently
unknown, and that of H. erectus is too poorly known to allow for
comparison. The H. naledi foot can be distinguished from the foot of H.
floresiensis by a longer hallux and shorter second through fifth
metacarpals relative to hindfoot length, and higher torsion of the talar
head and neck.
The foot of H. naledi can be distinguished from
the foot of H. sapiens only by its flatter lateral and medial malleolar
facets on the talus, its low angle of plantar declination of the talar
head, its lower orientation of the calcaneal sustentaculum tali, and its
gracile calcaneal tuber.
Description
H. naledi exhibits
anatomical features shared with Australopithecus, other features shared
with Homo, with several features not otherwise known in any hominin
species. This anatomical mosaic is reflected in different regions of the
skeleton. The morphology of the cranium, mandible, and dentition is
mostly consistent with the genus Homo, but the brain size of H. naledi
is within the range of Australopithecus. The lower limb is largely
Homo-like, and the foot and ankle are particularly human in their
configuration, but the pelvis appears to be flared markedly like that of
Au. afarensis. The wrists, fingertips, and proportions of the fingers
are shared mainly with Homo, but the proximal and intermediate manual
phalanges are markedly curved, even to a greater degree than in any
Australopithecus. The shoulders are configured largely like those of
australopiths. The vertebrae are most similar to Pleistocene members of
the genus Homo, whereas the ribcage is wide distally like Au. afarensis.
H.
naledi has a range of body mass similar to small-bodied modern human
populations, and is similar in estimated stature to both small-bodied
humans and the largest known australopiths. We estimated body mass from
eight femoral specimens for which subtrochanteric diameters can be
measured (‘Materials and methods’), with results ranging between 39.7 kg
and 55.8 kg (Table 3). No femur specimen is sufficiently complete to
measure femur length accurately, but the U.W. 101-484 tibia preserves
nearly its complete length, allowing a tibia length estimate of 325 mm
(Figure 10). Estimates for the stature of this individual based on
African human population samples range between 144.5 and 147.8 mm.
Again, this stature estimate is similar to small-bodied modern human
populations. It is within the range estimated for Dmanisi postcranial
elements (Lordkipanidze et al., 2007), and slightly smaller than
estimated for early Homo femoral specimens KNM-ER 1472 and KNM-ER 1481.
Some large australopiths also had long tibiae and presumably comparably
tall statures, as evidenced by the KSD-VP 1/1 skeleton from
Woranso-Mille (Haile-Selassie et al., 2010).
View this table:
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Table 3.
Dinaledi body mass estimates from femur specimens preserving subtrochanteric diameters
DOI: http://dx.doi.org/10.7554/eLife.09560.014
Figure 10.
Download figureOpen in new tabDownload powerpointFigure 10. Maximum tibia length in H. naledi and other hominins.
Maximum
tibia length for U.W. 101-484, compared to other nearly complete
hominin tibia specimens. Australopithecus afarensis represented by A.L.
288-1 and KSD-VP-1/1 (Haile-Selassie et al., 2010); Homo erectus
represented by D3901 from Dmanisi and KNM-WT 15000; Homo habilis by OH
35; Homo floresiensis by LB1 and LB8 (Brown et al., 2004; Morwood et
al., 2005). Chimpanzee and contemporary European ancestry humans from
Cleveland Museum of Natural History (Lee, 2001); Andaman Islanders from
Stock (2013). Vertical lines represent sample ranges; bars represent 1
standard deviation.
DOI: http://dx.doi.org/10.7554/eLife.09560.015
The
endocranial volume of all H. naledi specimens is clearly small compared
to most known examples of Homo. We combined information from the most
complete cranial vault specimens to arrive at an estimate of endocranial
volume for both larger (presumably male) and smaller (presumably
female) individuals (larger composite depicted in Figure 11). The
resulting estimates of approximately 560cc and 465cc, respectively,
overlap entirely with the range of endocranial volumes known for
australopiths. Within the genus Homo, only the smallest specimens of H.
habilis, one single H. erectus specimen, and H. floresiensis overlap
with these values.
Figure 11.
Download figureOpen in new
tabDownload powerpointFigure 11. Virtual reconstruction of the
endocranium of the larger composite cranium from DH1 and DH2 overlaid
with the ectocranial surfaces.
(A) Lateral view. (B) Superior view. The resulting estimate of endocranial volume is 560cc. Scale bar = 10 cm.
DOI: http://dx.doi.org/10.7554/eLife.09560.016
Despite
its small vault size, the cranium of H. naledi is structurally similar
to those of early Homo. Frontal bossing is evident, as is a marked
degree of parietal bossing. There is no indication of metopic keeling,
though there is slight parasagittal keeling between bregma and lambda,
and some prelambdoidal flattening. The cranial vault bones are generally
thin, becoming somewhat thicker in the occipital region. The
supraorbital torus is well developed, though weakly arched, and is
bounded posteriorly by a well-developed supratoral sulcus. The lateral
corners of the supraorbital torus are rounded and relatively thin. The
temporal lines are widely spaced, and there is no indication of a
sagittal crest or temporal/nuchal cresting. The temporal crest is
positioned on the posterior aspect of the lateral supraorbital torus,
rather than on the superior aspect as in australopiths. At the
posteroinferior extent of the temporal lines, they curve
anteroinferiorly presenting a well-developed angular torus. The crania
have a pentagonal outline in posterior view, with the greatest vault
breadth located in the supramastoid region. The nuchal region exhibits
sexually dimorphic development of nuchal muscle markings and the
external occipital protuberance, and there is a clear indication of a
tuberculum linearum in addition to the external occipital protuberance.
In superior view the vault tapers from posterior to anterior, though
post-orbital constriction is slight. The squamosal suture is low and
gently curved, and parietal striae are well defined. The lateral margins
of the orbits face laterally. A small zygomaticofacial foramen is
typically present near the center of the zygomatic bone. The root of the
zygomatic process of the maxilla is anteriorly positioned, at the level
of the P3 or the P4. There is no indication of a zygomatic prominence,
and the zygomatic arches do not flare laterally to any extent. The root
of the zygomatic process of the temporal is angled downwards
approximately 30° relative to FH. The root of the zygomatic process of
the temporal begins to laterally expand above the level of the
mandibular fossa, rather than above the level of the EAM as in
australopiths. The mandibular fossa is somewhat large, and moderately
deep. The articular eminence of the mandibular fossa is saddle-shaped,
and oriented posteroinferiorly. Almost the entire mandibular fossa is
positioned medial to the temporal squama. The entoglenoid process is
elongated and faces primarily laterally. The postglenoid process is
small and closely appressed to the tympanic, forming part of the
posterior wall of the fossa. The petrotympanic is distinctly coronally
oriented. The vaginal process is small but distinct. The crista petrosa
is weakly developed and not notably sharpened. There is a strong
Eustachian process. The external auditory meatus is small, oval-shaped,
and obliquely oriented, and a distinct suprameatal spine is present. The
mastoid region is slightly laterally inflated. The mastoid process is
triangular in cross-section, with a rounded apex and a mastoid crest.
The digastric groove is deep and narrow, alongside a marked juxtamastoid
eminence. The canine juga are weakly developed and there is no
indication that anterior pillars would have been present. A shallow,
ill-defined canine fossa is indicated. The nasoalveolar clivus is flat
and square-shaped. The parabolic-shaped palate is broad and anteriorly
shallow, becoming deeper posteriorly.
The mandibular dentition of
H. naledi is arranged in a parabolic arch. The alveolar and basal
margins of the corpus diverge slightly. A single, posteriorly opening
mental foramen is positioned slightly above the mid-corpus level,
between the position of the P3 and the P4. The mandibular corpus is
relatively gracile, with a well-developed lateral prominence whose
maximum extent is typically at the M2. A slight supreme lateral torus
(of Dart) weakly delineates the extramolar sulcus from the lateral
corpus. The superior lateral torus is moderately developed, running
anteriorly to the mental foramen where it turns up to reach the P3
jugum. The marginal torus is moderately developed, and defines a
moderate intertoral sulcus. The posterior and anterior marginal
tubercles are indicated only as slight roughenings of bone. The gracile
mandibular symphysis is vertically oriented. A well-developed mental
protuberance and weak lateral tubercles are delineated by a slight
mandibular incisure, thereby presenting a weak mentum osseum. The
post-incisive planum is steeply inclined and not-shelf-like. There is no
superior transverse torus, while a weak, basally oriented inferior
transverse torus is present. The anterior and posterior subalveolar
fossae are continuous and deep, overhung by a well-developed alveolar
prominence. The extramolar sulcus is moderately wide. The root of the
ramus of the mandible originates high on the corpus at the level of the
M2. Strong ectoangular tuberosities are indicated. A large mandibular
foramen is present, with a diffusely defined mylohyoid groove.
Like
the skull, the dentition of H. naledi compares most favorably to early
Homo samples. Yet compared to samples of H. habilis, H. rudolfensis, and
H. erectus, the teeth of H. naledi are comparatively quite small,
similar in dimensions to much later samples of Homo. With both small
post-canine teeth and a small endocranial volume, H. naledi joins Au.
sediba and H. floresiensis in an area distinct from the general hominin
relation of smaller post-canine teeth in species with larger brains
(Figure 12).
Figure 12.
Download figureOpen in new tabDownload powerpointFigure 12. Brain size and tooth size in hominins.
The
buccolingual breadth of the first maxillary molar is shown here in
comparison to endocranial volume for many hominin species. H. naledi
occupies a position with relatively small molar size (comparable to
later Homo) and relatively small endocranial volume (comparable to
australopiths). The range of variation within the Dinaledi sample is
also fairly small, in particular in comparison to the extensive range of
variation within the H. erectus sensu lato. Vertical lines represent
the range of endocranial volume estimates known for each taxon; each
vertical line meets the horizontal line representing M1 BL diameter at
the mean for each taxon. Ranges are illustrated here instead of data
points because the ranges of endocranial volume in several species are
established by specimens that do not preserve first maxillary molars.
DOI: http://dx.doi.org/10.7554/eLife.09560.017
In
comparison to H. habilis, H. rudolfensis, and H. erectus, the teeth of
H. naledi are not only small, but also markedly simple in crown
morphology. Maxillary and mandibular molars lack extensive crenulation,
secondary fissures and supernumerary cusps. The M1 has an equal-sized
metacone and paracone, and has a slight expression of Carabelli's trait
represented by a small cusp or shallow pit. I1 exhibits slight occlusal
curvature with trace marginal ridges and variably small tuberculum
dentale. I2 exhibits greater occlusal curvature and tuberculum dentale
expression but neither upper incisor has double shovelling or
interruption groove. The mandibular canines of H. naledi have a small
occlusal area, and have a distal marginal cuspule as a topographically
distinct expression of the cingular margin. The P3 is double-rooted,
fully bicuspid with metaconid and protoconid of approximately equal
height and occlusal area separated by a distinct longitudinal groove,
has a distally extensive talonid, and an occlusal outline approximately
symmetrical with respect to the mesiodistal axis. P4 likewise has a
distally extensive talonid and approximately symmetrical occlusal
outline (Figure 5). M1 and M2 lack cusp 6 and cusp 7, except for very
slight expression in a small fraction of specimens, and have a very
faint subvertical depression rather than a distinct or extensive
protostylid. Like australopiths and some early Homo specimens, H. naledi
has an increasing molar size gradient in the mandibular dentition (M1
< M2 < M3).
The lower limb of H. naledi is defined not only
by a unique combination of primitive and derived traits, but also by
the presence of unique features in the femur and tibia. Like all other
bipedal hominins, H. naledi possesses a valgus knee and varus ankle. The
femoral neck is long, anteverted, and anteroposteriorly compressed.
Muscle insertions for the M. gluteus maximus are strong and the femur
has a well-marked linea aspera with pilaster variably present. The
patella is relatively anteroposteriorly thick. The tibia is
mediolaterally compressed with a rounded anterior border, a large
proximal attachment for the M. tibialis posterior, and a thin medial
malleolus. The fibula is gracile with laterally oriented lateral
malleolus, a relatively circular neck and a convex surface for the
proximal attachment of the M. peroneus longus. Unique features in the
lower limb of H. naledi include a depression in the superior aspect of
the femoral neck that results in two mediolaterally oriented pillars
inferoposteriorly and superoanteriorly, and a strong distal attachment
of the pes anserinus on the tibia.
The foot and ankle of H.
naledi are largely humanlike (Figure 9). The tibia stands orthogonally
upon the talus, which is moderately wedged, with a mediolaterally flat
trochlea having medial and lateral margins at even height, a form
distinct from the strong keeling seen in OH 8 (H. habilis) and several
tali from Koobi Fora. The talar head and neck exhibit strong, humanlike
torsion; the horizontal angle is higher than in most humans, similar to
that found in australopiths. The calcaneus is only moderately robust,
but possesses the plantar declination of the retrotrochlear eminence and
plantarly positioned lateral plantar process found in both modern
humans and Au. afarensis. The peroneal trochlea is small, unlike that
found in australopiths and similar only to that in H. sapiens and
Neanderthals. The talonavicular, subtalar joints and calcaneocuboid
joints are humanlike in possessing minimal ranges of motion and evidence
for a locking, rigid midfoot. The intermediate and lateral cuneiforms
are proximodistally elongated. The hallucal tarsometatarsal joint is
flat and proximodistally aligned indicating that H. naledi possessed an
adducted, non-grasping hallux. The head of the first metatarsal is
mediolaterally expanded dorsally, indicative of a humanlike windlass
mechanism. The foot possesses humanlike metatarsal lengths, head
proportions, and torsion.
The phalanges are moderately curved,
slightly more so than in H. sapiens. The only primitive anatomies found
in the foot of H. naledi are the talar head and neck declination and
sustentaculum tali angles, suggestive of a lower arched foot with a more
plantarly positioned and horizontally inclined medial column than
typically found in modern humans (Harcourt-Smith et al., 2015).
The
axial skeleton presents a combination of derived (mainly aspects of the
vertebrae) and seemingly primitive (mainly the ribs) traits. The
preserved adult T10 and T11 vertebrae are proportioned similarly to
Pleistocene Homo, with transverse process morphology most similar to
Neandertals. The neural canals of these vertebrae are large in
comparison to the diminutive overall size of the vertebrae,
proportionally recalling Dmanisi H. erectus, Neandertals, and modern
humans. The 11th rib is straight (uncurved), similar to Au. afarensis,
and the shape of the upper rib cage appears narrow, as assessed from
first and second rib fragments, suggesting that the thorax was pyramidal
in shape. The 12th rib presents a robust shaft cross-section most
similar to Neandertals. This combination is not found in other hominins
and might reflect allometric scaling at a small trunk size.
The
Dinaledi iliac blade is flared and shortened anteroposteriorly,
resembling Au. afarensis or Au. africanus. The ischium is short with a
narrow tuberoacetabular sulcus, and the ischiopubic and iliopubic rami
are thick, resembling Au. sediba and H. erectus. This combination of
iliac and ischiopubic features has not been found in other fossil
hominins (Figure 13).
Figure 13.
Download figureOpen in new tabDownload powerpointFigure 13. Selected pelvic specimens of H. naledi.
U.W.
101-1100 ilium in (A) lateral view showing a weak iliac pillar
relatively near the anterior edge of the ilium, with no cristal tubercle
development; (B) anterior view, angled to demonstrate the degree of
flare, which is clear in comparison to the subarcuate surface. U.W.
101-723 immature sacrum in (C) anterior view; and (D) superior view.
U.W. 101-1112 ischium in (E) lateral view; and (F) anterior view,
demonstrating relatively short tuberacetabular diameter. Scale bar = 2
cm.
DOI: http://dx.doi.org/10.7554/eLife.09560.018
The
shoulder of H. naledi is configured with the scapula situated high and
lateral on the thorax, short clavicles, and little or no torsion of the
humerus. The humerus is notably slender for its length, with prominent
greater and lesser tubercles bounding a deep bicipital groove, with a
small, non-projecting humeral deltoid tuberosity and brachioradialis
crest. Distally, the humerus has a wide lateral distodorsal pillar and
narrow medial distodorsal pillar, and a medially-displaced olecranon
fossa with septal aperture. The Dinaledi radius and ulna diaphyses
exhibit little curvature. The radius has a globular radial tuberosity,
prominent pronator quadratus crest, and reduced styloid process.
The
hand shares many derived features of modern humans and Neandertals in
the thumb, wrist, and palm, but has relatively long and markedly curved
fingers (Kivell et al., 2015). The thumb is long relative to the length
of the other digits, and includes a robust metacarpal with
well-developed intrinsic (M. opponens pollicis and M. first dorsal
interosseous) muscle attachments (Figure 6). The pollical distal phalanx
is large and robust with a well-developed ridge along the distal border
of a deep proximal palmar fossa for the attachment of flexor pollicis
longus tendon. Ungual spines also project proximopalmarly from a
radioulnarly expanded apical tuft with a distinct area for the ungual
fossa. The wrist includes a boot-shaped trapezoid with an expanded
non-articular palmar surface, an enlarged and palmarly-expanded
trapezoid-capitate joint, and a trapezium-scaphoid joint that extends
further onto the scaphoid tubercle. Overall, carpal shapes and articular
configurations are very similar to those of modern humans and
Neandertals, and unlike those of great apes and other extinct hominins.
However, the H. naledi wrist lacks a third metacarpal styloid process,
has a more radioulnarly oriented capitate-Mc2 joint, and has a
relatively small trapezium-Mc1 joint compared to humans and Neandertals.
Moreover, the phalanges are long (relative to the palm) and more curved
than most australopiths.
Discussion
The overall morphology of
H. naledi places it within the genus Homo rather than Australopithecus
or other early hominin genera. The shared derived features that connect
H. naledi with other members of Homo occupy most regions of the H.
naledi skeleton and represent distinct functional systems, including
locomotion, manipulation, and mastication. Locomotor traits shared with
Homo include the absolutely long lower limb, with well-marked linea
aspera, strong M. gluteus maximus insertions, gracile fibula and
generally humanlike ankle and foot. These aspects of the lower limb
suggest enhanced locomotor performance for a striding gait. The H.
naledi hand shares aspects of Homo morphology in the wrist, thumb and
palm, pointing to enhanced object manipulation ability relative to
australopiths, including Au. sediba (Kivell et al., 2011; Kivell et al.,
2015). H. naledi lacks the powerful mastication that typifies
Australopithecus and Paranthropus, with generally small teeth across the
dentition, gracile mandibular corpus and symphysis,
laterally-positioned temporal lines, slight postorbital constriction and
non-flaring zygomatic arches. The upper limb, shoulder and ribcage have
a more primitive morphological pattern, but do not preclude affiliating
H. naledi with Homo, particularly considering that postcranial remains
of H. habilis appear to reflect an australopith-like body plan (Johanson
et al., 1986). Locomotor, manipulatory, and masticatory systems have
both historical and current importance in defining Homo (Wood and
Collard, 1999; Holliday, 2012; Antón et al., 2014), and H. naledi fits
within our genus in these respects.
The structural configuration
of the H. naledi cranium, beyond the functional aspects of mastication,
is likewise shared with Homo. As in many specimens of H. erectus and H.
habilis, the H. naledi vault includes a well-developed and moderately
arched supraorbital torus, marked from the frontal squama by a
continuous supratoral sulcus, frontal bossing. Further, as in many H.
erectus crania, H. naledi exhibits a marked angular torus and occipital
torus. The H. naledi face includes a flat and squared nasoalveolar
clivus, comparable to H. rudolfensis (Leakey et al., 2012), and weak
canine fossae. While its anatomy places it unambiguously within Homo,
the H. naledi cranium and dentition lack many derived features shared by
MP and LP Homo and H. sapiens. The australopith-like features of the
postcranium, including the ribcage, shoulder, proximal femur, and
relatively long, curved fingers, also depart sharply from the morphology
present in MP humans and H. sapiens. The similarities of H. naledi to
earlier members of Homo, including H. habilis, H. rudolfensis, and H.
erectus, suggest that this species may be rooted within the initial
origin and diversification of our genus.
The fossil record of
early Homo and Homo-like australopiths has rapidly increased during the
last 15 years, and this accumulating evidence has changed our
perspective on the rise of our genus. Many skeletal and behavioral
features observed to separate later Homo from earlier hominins were
formerly argued to have arisen as a single adaptive package, including
increased brain size, tool manipulation, increased body size, smaller
dentition, and greater commitment to terrestrial long-distance walking
or running (Wood and Collard, 1999; Hawks et al., 2000). But we now
recognize that such features appeared in different combinations in
different fossil samples (Antón et al., 2014). The Dmanisi postcranial
sample (Lordkipanidze et al., 2007) and additional cranial remains of H.
erectus from Dmanisi (Gabunia et al., 2000; Vekua et al., 2002;
Lordkipanidze et al., 2013) and East Africa (Spoor et al., 2007; Leakey
et al., 2012), demonstrate that larger brain size and body size did not
arise synchronously with improved locomotor efficiency and adaptations
to long-distance walking or running in H. erectus (Holliday, 2012; Antón
et al., 2014). Further, the discovery of Au. sediba showed that a
mosaic of Homo-like hand, pelvis and aspects of craniodental morphology
can occur within a species with primitive body size, limb proportions,
lower limb and foot morphology, thorax shape, vertebral morphology, and
brain size (Berger et al., 2010; Carlson et al., 2011; Kivell et al.,
2011; Churchill et al., 2013; DeSilva et al., 2013; Schmid et al.,
2013). H. naledi presents yet a different combination of traits. This
species combines a humanlike body size and stature with an
australopith-sized brain; features of the shoulder and hand apparently
well-suited for climbing with humanlike hand and wrist adaptations for
manipulation; australopith-like hip mechanics with humanlike terrestrial
adaptations of the foot and lower limb; small dentition with primitive
dental proportions. In light of this evidence from complete skeletal
samples, we must abandon the expectation that any small fragment of the
anatomy can provide singular insight about the evolutionary
relationships of fossil hominins.
A recent phylogenetic analysis
of fossil hominins based on craniodental morphology placed Au. sediba at
the base of the genus Homo (Dembo et al., 2015), in agreement with
earlier analyses of this species (Berger et al., 2010). The cranial and
dental affinities identified between Au. sediba and Homo include many
features shared by H. naledi. But H. naledi and Au. sediba share
different postcranial features with other species of Homo. Resolving the
phylogenetic placement of H. naledi will require both postcranial and
craniodental evidence to be integrated together. Such integration poses a
challenge because of the poor representation of several key species
both within and outside of Homo, most notably H. habilis, for which
postcranial evidence is slight, and H. rudolfensis for which no
associated postcranial remains are known. We propose the testable
hypothesis that the common ancestor of H. naledi, H. erectus, and H.
sapiens shared humanlike manipulatory capabilities and terrestrial
bipedality, with hands and feet like H. naledi, an australopith-like
pelvis and the H. erectus-like aspects of cranial morphology that are
found in H. naledi. Enlarged brain size was evidently not a necessary
prerequisite for the generally human-like aspects of manipulatory,
locomotor, and masticatory morphology of H. naledi.
Although it
contains an unprecedented wealth of anatomical information, the Dinaledi
deposit remains undated (Dirks et al., 2015). Considering that H.
naledi is a morphologically primitive species within our genus, an age
may help elucidate the ecological circumstances within which Homo arose
and diversified. If the fossils prove to be substantially older than 2
million years, H. naledi would be the earliest example of our genus that
is more than a single isolated fragment. The sample would illustrate a
model for the relation of adaptive features of the cranium, dentition
and postcranium during a critical time interval that is underrepresented
by fossil evidence of comparable completeness. A date younger than 1
million years ago would demonstrate the coexistence of multiple Homo
morphs in Africa, including this small-brained form, into the later
periods of human evolution. The persistence of such a species with clear
adaptations for manipulation and grip, alongside MP humans or perhaps
even alongside modern humans, would challenge many assumptions about the
development of the archaeological record in Africa.
The depth of
evidence of H. naledi may provide a perspective on the variation to be
expected within fossil hominin taxa (Lordkipanidze et al., 2013;
Bermúdez de Castro et al., 2014). The entire Dinaledi collection is
remarkably homogeneous. There is very little size variation among adult
elements within the collection. Eight body mass estimates from the femur
(Table 2) have a standard deviation of only 4.3 kilograms, for a body
mass coefficient of variation (CV) of only 9%. The CV of body mass
within most human populations is substantially higher than this, with an
average near 15% (McKellar and Hendry, 2009). Likewise, the size
variation of cranial and dental elements is minimal. With 11 mandibular
first molars, the CV of buccolingual breadth is only 3.2% and for 13
maxillary first molars the CV of buccolingual breadth is only 2.0%
(buccolingual breadth is used because it is not subject to variance from
interproximal wear). Not only size, but also anatomical shape and form
are homogeneous within the sample. Almost every aspect of the morphology
of the dentition, including the distinctive form of the lower
premolars, the distal accessory cuspule of the mandibular canines, and
the expression of nonmetric features that normally vary in human
populations, is uniform in every specimen from the collection. The
distinctive aspects of cranial morphology are repeated in every
specimen, and even the aspects that normally vary among individuals of
different body size or between sexes exhibit only slight variation among
the Dinaledi remains. One of the most unique aspects of H. naledi is
the morphology of the first metacarpal; the derived aspects of this
anatomy are present in every one of seven first metacarpal specimens in
the collection (Figure 14). Unlike any other fossil hominin site in
Africa, the Dinaledi Chamber seems to preserve a large number of
individuals from a single population, one with variation equal to or
less than that found within local populations of modern humans.
Figure 14.
Download figureOpen in new tabDownload powerpointFigure 14. First metacarpals of H. naledi.
Seven
first metacarpals have been recovered from the Dinaledi Chamber. U.W.
101-1321 is the right first metacarpal of the associated Hand 1 found in
articulation. U.W. 101-1282 and U.W. 101-1641 are anatomically similar
left and right first metacarpals, which we hypothesize as antimeres,
both were recovered from excavation. U.W. 101-007 was collected from the
surface of the chamber, and exhibits the same distinctive morphological
characteristics as all the first metacarpals in the assemblage. All of
these show a marked robusticity of the distal half of the bone, a very
narrow, ‘waisted’ appearance to the proximal shaft and proximal
articular surface, prominent crests for attachment of M. opponens
pollicis and M. first dorsal interosseous, and a prominent ridge running
down the palmar aspect of the bone. The heads of these metacarpals are
dorsopalmarly flat and strongly asymmetric, with an enlarged
palmar-radial protuberance. These distinctive features are present among
all the first metacarpals in the Dinaledi collection, and are absent
from any other hominin sample. Their derived nature is evident in
comparison to apes and other early hominins, here illustrated with a
chimpanzee first metacarpal and the MH2 first metacarpal of
Australopithecus sediba.
DOI: http://dx.doi.org/10.7554/eLife.09560.004
The
Dinaledi collection is the richest assemblage of associated fossil
hominins ever discovered in Africa, and aside from the Sima de los
Huesos collection and later Neanderthal and modern human samples, it has
the most comprehensive representation of skeletal elements across the
lifespan, and from multiple individuals, in the hominin fossil record.
The abundance of evidence from this assemblage supports our emerging
understanding that the genus Homo encompassed a variety of evolutionary
experiments (Antón et al., 2014), with diversity now evident for fossil
Homo in each of the few intensively explored parts of Africa (Leakey et
al., 2012). But as much as it advances our knowledge, H. naledi also
highlights our ignorance about ancient Homo across the vast geographic
span of the African continent. The tree of Homo-like hominins is far
from complete: we have missed key transitional forms and lineages that
persisted for hundreds of thousands of years. With an increasing pace of
discovery from the field and the laboratory, more light will be thrown
on the origin of humans.
Materials and methods
Comparative hominin specimens examined in this study
In
the differential diagnosis of H. naledi, we have compared the holotype
DH1, paratypes, and other referred material to fossil evidence from
previously-identified hominin taxa. Our goal is to provide a diagnosis
for H. naledi that is clear in reference to widely recognized hominin
hypodigms. Different specialists continue to disagree about the
composition and anatomical breadth represented by these hominin taxa and
attribution of particular specimens to them (see e.g., Wood and
Collard, 1999; Lordkipanidze et al., 2013; Antón et al., 2014 on early
Homo taxa). We do not intend to take any position on such disagreements
by our selection of comparative samples for H. naledi.
We have
been cautious in our attribution of postcranial specimens to hominin
taxa, particularly in the African Plio-Pleistocene, where it has been
demonstrated multiple hominin taxa coexisted in time, if not in
geographical space. Because the purpose of this study is differential
diagnosis in reference to known taxa, unattributed specimens are not
germane, although in certain cases there are well-accepted attributions
to genus for specimens (e.g., Homo sp. or Australopithecus sp.) as cited
below. We have included some specimens in comparisons because they are
relatively complete, even if they cannot be attributed to a species,
because few hominin taxa are represented by evidence across the entire
skeleton. For some anatomical characters, parts are preserved only for
MP or later hominin samples, so we have included such comparisons to
make clear how H. naledi compares in these elements to the (few) known
fossil examples.
This study relies upon observations and
measurements taken from original fossils by the authors, observations
taken from casts, and observations taken from the literature. These
observations are in large part standard anatomical practice; where
features are specially described in previous studies we have referenced
those here. For this study, a cast collection was assembled including
the Phillip V. Tobias research collection at the University of the
Witwatersrand and loans of cast materials from the University of
Wisconsin–Madison, University of Michigan, American Museum of Natural
History, New York University, University of Colorado–Denver, University
of Delaware, Texas A&M University, and the personal collections of
Peter Schmid, Milford Wolpoff and Rob Blumenschine. We extend our
gratitude to the curators of fossil collections and the generosity of
these institutions in facilitating this research, both in South Africa
and throughout the world.
This list of skeletal materials extends
the list of craniodental comparative material used in diagnosing Au.
sediba, with many of the hypodigms identical to that study (Berger et
al., 2010). Where we have had first-hand access to original specimens,
we rely upon our own observations; we therefore do not refer readers to
other sources for these data.
Australopithecus afarensis
The
samples attributed to Au. afarensis from Hadar, Laetoli, the Middle
Awash, Woranso-Mille and Dikika were utilized. For this taxon we relied
upon published reports (Johanson et al., 1982; Kimbel et al., 2004;
Drapeau et al., 2005; Alemseged et al., 2006; Haile-Selassie et al.,
2010; Ward et al., 2012), in addition to our own observations on
original fossils and casts.
Australopithecus africanus
The
samples attributed to Au. africanus from Taung, Sterkfontein and
Makapansgat were employed. Original specimens were examined first-hand
by the authors.
Australopithecus garhi
The cranium BOU-VP-12/130 from Bouri was included, with data taken from a published report (Asfaw et al., 1999).
Australopithecus sediba
The
partial skeletons MH1 and MH2 from Malapa, South Africa were included
in this study, based on examination of the original specimens by the
authors.
Paranthropus aethiopicus
The cranium KNM-WT 17000 was examined first-hand for this study.
Paranthropus boisei
Samples
from the Omo Shungura sequence, East Lake Turkana, Olduvai Gorge and
Konso were included in this study. Original specimens from Olduvai Gorge
and East Lake Turkana were examined first-hand, while casts and
published reports (Tobias, 1967; Suwa et al., 1996, 1997;
Domínguez-Rodrigo et al., 2013) were used to study the Omo and Konso
materials. Our postcranial considerations of P. boisei are very limited
and we did not rely upon the association of KNM-ER 1500 (Grausz et al.,
1988) to derive information about the postcranial skeleton of P. boisei.
Paranthropus robustus
The
samples from Kromdraai, Swartkrans, Sterkfontein, Drimolen, Gondolin,
and Coopers were included in this study. First-hand observations of
original specimens from all localities were used with the exception of
Drimolen fossils, which were compared using published reports (Keyser,
2000; Keyser et al., 2000).
Homohabilis
Samples from Olduvai
Gorge, East Lake Turkana, the Omo Shungura sequence, Hadar, and
Sterkfontein were included in this study. Original Olduvai Gorge and
East Lake Turkana fossils were examined first-hand, while for the Omo
and Hadar materials we relied on our original observations on casts and
originals and published reports (Boaz and Howell, 1977; Tobias, 1991;
Kimbel et al., 1997). We include the following fossils in the hypodigm
of H. habilis: A.L. 666-1, KNM-ER 1478, KNM-ER 1501, KNM-ER 1502, KNM-ER
1805, KNM-ER 1813, KNM-ER 3735, OH 4, OH 6, OH 7, OH 8, OH 13, OH 15,
OH 16, OH 21, OH 24, OH 27, OH 31, OH 35, OH 37, OH 39, OH 42, OH 44, OH
45, OH 62, OMO-L894-1, and Stw 53. We recognize that some authors
(including some of the authors of this paper) prefer to classify OH 62,
Stw 53 and A.L. 666-1 outside of H. habilis, (e.g., as Homo gautengensis
which we do not recognize as valid), or even outside the genus Homo;
these specimens expand the morphological and temporal variability
encompassed within H. habilis.
Homorudolfensis
Samples from
Olduvai Gorge, East Lake Turkana, and Lake Malawi were included in this
study. The East Lake Turkana fossils available prior to 2010 were
examined first-hand, while for the Olduvai and Lake Malawi fossils and
KNM-ER 60000, 62000, and 62003 we relied on original observations on
fossils and casts as well as published reports (Schrenk et al., 1993;
Blumenschine et al., 2003; Leakey et al., 2012). We include the
following fossils in the hypodigm of H. rudolfensis: KNM-ER 819, KNM-ER
1470, KNM-ER 1482, KNM-ER 1483, KNM-ER 1590, KNM-ER 1801, KNM-ER 1802,
KNM-ER 3732, KNM-ER 3891, KNM-ER 60000, KNM-ER 62000, KNM-ER 62003, OH
65, and UR 501. We do recognize that KNM-ER 60000 and KNM-ER 1802
present some conflicting anatomy that some authors have argued precludes
them as conspecific specimens (Leakey et al., 2012); by considering
both, we aim to be conservative as they encompass more variation within
H. rudolfensis.
Homo erectus
Samples from Buia, Chemeron,
Daka, Dmanisi, East and West Lake Turkana, Gona, Hexian, Konso,
Mojokerto, Olduvai Gorge, Sangiran, Swartkrans, Trinil, and Zhoukoudian
were included in this study. South African material is of special
interest in this comparison because of the geographic proximity, and
because of the difficulty of clearly identifying Homo specimens within
the large fossil sample from Swartkrans. In particular, the following
specimens from Swartkrans are considered to represent H. erectus: SK 15,
SK 18a, SK 27, SK 43, SK 45, SK 68, SK 847, SK 878, SK 2635, SKW 3114,
SKX 257/258, SKX 267/2671, SKX 268, SKX 269, SKX 334, SKX 339, SKX 610,
SKX 1756, SKX 2354, SKX 2355, SKX 2356, and SKX 21204. It has been
suggested (Grine et al., 1993, 1996) that SK 847 and Stw 53 might
represent the same taxon, and that this taxon is a currently undiagnosed
species of Homo in South Africa. However, we agree with Clarke (1977;
2008) that SK 847 can be attributed to H. erectus, and that Stw 53
cannot. Because there is no clear indication that more than one species
of Homo is represented in the Swartkrans sample, we consider all this
material to belong to H. erectus. We considered ‘Homo ergaster’ (and
also ‘Homo aff. erectus’ from Wood, 1991) to be synonyms of H. erectus
for this study; Turkana Basin specimens that are attributed to H.
erectus thus include KNM-ER 730, KNM-ER 820, KNM-ER 992, KNM-ER 1808,
KNM-ER 3733, KNM-ER 3883, KNM-ER 42700, KNM-WT 15000. Olduvai specimens
include OH 9, OH 12 and OH 28. Original fossil materials from Chemeron,
Lake Turkana, Swartkrans, Trinil, and Dmanisi were examined first-hand
by the authors, while the remainder were based on casts and published
reports (Weidenreich, 1943; Wood, 1991; Antón, 2003; Rightmire et al.,
2006; Suwa et al., 2007).
A large number of postcranial specimens
have been collected from the Turkana Basin and appear consistent with
the anatomical range otherwise found in Homo, and inconsistent with
known samples of Australopithecus and Paranthropus from elsewhere. These
include KNM-ER 1472, KNM-ER 1481, KNM-ER 3228, KNM-ER 737, and others.
We may add other fossils from other sites lacking association with
craniodental material, such as the partial BOU-VP 12/1 skeleton and even
the Gona pelvis. These specimens attributable to Homo but not
necessarily to a particular species did inform our understanding of
variability within the genus, but for the most part these specimens do
not inform our differential diagnosis of H. naledi relative to
particular species. For example, the key element of femoral morphology
of H. naledi in contrast to other species is the presence of two
well-defined mediolaterally running pillars in the femoral neck; the
isolated specimens of early Homo do not contradict this apparent
autapomorphy. Likewise, no isolated specimens inform us about the
humanlike aspects of foot morphology in H. naledi. In these cases, the
lack of associations for this evidence actually is less important than
the lack of specimens that replicate the distinctive features of the H.
naledi morphology.
Middle Pleistocene Homo
Specimens from the
latest Lower Pleistocene and MP of Europe and Africa that cannot be
attributed to H. erectus were included in our comparisons. These include
fossils that have been attributed to H. heidelbergensis, H.
rhodesiensis, ‘archaic H. sapiens’, or ‘evolved H. erectus’ by a variety
of other authors. Specimens attributed to MP Homo include materials
from Eliye Springs, Arago, Atapuerca Sima de los Huesos, Bodo, Broken
Hill, Cave of Hearths, Ceprano, Dali, Elandsfontein, Jinniushan,
Kapthurin, Mauer, Narmada, Ndutu, Petralona, Reilingen-Schwetzingen,
Solo, Steinheim, Swanscombe. This grouping includes the following
specimens: KNM-ES 11693, Arago 2, Arago 13, Arago 21, Atapuerca 1,
Atapuerca 2, Atapuerca 4, Atapuerca 5, Atapuerca 6, Cave of Hearths,
SAM-PQ-EH1, Kabwe, Mauer, Ndutu, Salé, Petralona,
Reilingen-Schwetzingen, Steinheim.
Homo floresiensis
Specimens
from Liang Bua, Flores as described by Brown et al., 2004; Morwood et
al., 2005, Jungers et al., 2009a, Jungers et al., 2009b, and Falk et
al., 2005 were included in this study.
Scanning and virtual reconstruction methods
The
calvariae (DH1-4) were scanned using a NextEngine laser surface scanner
(NextEngine, Malibu, CA) at the following settings: Macro, 12 divisions
with auto-rotation, HD 17k ppi. Depending on the complexity of the
surface relief, either two or three complete scanning cycles were
completed per specimen, resulting in multiple 360° scans. Each
individual scan was trimmed, aligned, and fused (volume merged) in the
accompanying ScanStudio HD Pro software. For each specimen, the
individual 360° scans were then aligned and merged in GeoMagic Studio
14.0 (Raindrop Geomagic, Research Triangle Park, NC), creating a final
three-dimensional model of the specimen. Given the fragmented nature of
the calvariae specimens, both the ectocranial and endocranial surfaces
were captured in the scans.
DH3 consisted primarily of portions
of the right calvaria. However, a small section of the frontal and the
parietal crossed the mid–sagittal plane. For this reason, it was
possible to mirror image the surface scan to approximate the left
calvaria and obtain a more complete visualization of the complete
calvaria (Figure 15). The virtual specimen of DH3 was mirrored in
GeoMagic Studio, and manually registered (aligned) using common points
along the frontal crest and sagittal suture. The registration procedure
in GeoMagic Studio is an iterative process that refines the alignment of
specimens to minimize spatial differences between corresponding
surfaces. In this manner, the program is able to match the position
overlapping surfaces, in addition to their angulation and curvature.
Figure 15.
Download figureOpen in new tabDownload powerpointFigure 15. Posterior view of the virtual reconstruction of DH3.
The
resultant mirror image is displayed in blue. The antimeres were aligned
by the frontal crest and sagittal suture using the Manual Registration
function in GeoMagic Studio 14.0.
DOI: http://dx.doi.org/10.7554/eLife.09560.020
The
same procedures were used to mirror image and create a virtual
reconstruction of DH2 and the occipital portion of DH1 (Figure 16). The
occipital and vault portions of DH1 were reconstructed based on the
anatomical alignment of the sagittal suture, sagittal sulcus, parietal
striae, and the continuation of the temporal lines across both the
specimens.
Figure 16.
Download figureOpen in new tabDownload powerpointFigure 16. Virtual reconstruction of (A) DH2 and (B) occipital portion of DH1.
The actual specimen displays its original coloration and the mirror imaged portion is illustrated in blue.
DOI: http://dx.doi.org/10.7554/eLife.09560.021
Virtual reconstruction of composite crania and estimation of cranial capacity
In
order to virtually estimate the cranial capacity, composite crania were
constructed from the surface scans and mirror imaged scans of the
calvariae. Two separate composite crania were created; the relatively
smaller-sized calvariae (DH3 and DH4) were combined into one composite,
and the larger-sized calvariae (DH1 and DH2) composed the larger
composite cranium.
The smaller composite cranium, DH3 was
mirrored in GeoMagic Studio 14.0, and merged with the original scan as
outlined above. The surface scan of DH4 was uploaded and registered
(aligned) to the DH3 model using overlapping temporal features (e.g.,
the external auditory meatus). No scaling was performed. DH4 was then
mirror imaged to complete the occipital contour. The resultant model
suggests a general concordance between the specimens in both size and
shape with a close alignment of vault surfaces and anatomical features
between specimens (Figure 17).
Figure 17.
Download figureOpen in
new tabDownload powerpointFigure 17. Postero-lateral view of the virtual
reconstruction of a composite cranium from DH3 and DH4.
(A) The
surface scan of DH3 was mirror imaged and merged as described in
Supplementary Note 8. (B) The scan of DH4 was aligned to the DH3 model.
(C) DH4 was then mirror imaged to complete the occipital contour (D).
DOI: http://dx.doi.org/10.7554/eLife.09560.022
For
the larger composite cranium, the surface model of DH2 and its mirror
image was then uploaded, registered (aligned), and merged with the
mirror-imaged model of DH1. No scaling was performed. The congruency
between the specimens in the resultant model suggests that DH1 and DH2
are similar in both size and vault shape (Figure 18).
Figure 18.
Download figureOpen in new tabDownload powerpointFigure 18. Virtual reconstruction of a composite cranium from DH1 and DH2.
The
surface model of DH2 (blue), consisting of the original scan merged
with the mirror image, was then uploaded and aligned with the
mirror-imaged DH1 model (pink). Note the similarity in size and shape
between DH1 and DH2 observed in the posterior (A) anterior (B) lateral
(C) and superior (D) views.
DOI: http://dx.doi.org/10.7554/eLife.09560.023
Virtual reconstruction of cranial capacity
The
composite model of DH3 and DH4 was used to estimate the cranial
capacity for the smaller morphotype. In GeoMagic Studio 14.0, the
endocranial surface of the composite was carefully selected from the
ectocranial surface and copied as a new object. In order to obtain a
volume calculation the model has to be a closed surface, meaning that
all of the holes in the surface model had to be filled. Small holes in
the model were filled using the ‘Fill by Curvature’ function. Larger
holes were filled in by sections. For example, the cranial base was
filled in using a number of transverse sections, so that in the absence
of the cranial base the contour of the various cranial fossae and the
petrous portions of the temporal could be preserved as best as possible.
When appropriate (e.g., around angular portions of the petrous bone),
small sections were filled using a flat hole filling function. The new
surfaces created by the hole-filling mechanism were carefully monitored
and repeated until an acceptable model that appeared to best approximate
the missing portions was obtained. The result is a closed model
approximation of the endocranium, of which a volume can be calculated by
GeoMagic Studio (Figure 19, Figure 20). The volume of the smaller
composite cranium (DH3 and DH4) indicates a cranial capacity of
approximately 465 cm3.
Figure 19.
Download figureOpen in new
tabDownload powerpointFigure 19. Virtual reconstruction of the
endocranium of the composite cranium from DH3 and DH4.
(A) Lateral view. (B) Superior view. (C) Inferior view. In all views, anterior is to towards the left.
DOI: http://dx.doi.org/10.7554/eLife.09560.024
Figure 20.
Download
figureOpen in new tabDownload powerpointFigure 20. Virtual
reconstruction of the endocranium of the composite cranium from DH3 and
DH4 overlaid with the ectocranial surfaces.
(A) Lateral view. (B) Superior view.
DOI: http://dx.doi.org/10.7554/eLife.09560.025
In
order to determine whether significant errors were being introduced in
the manner that the cranial base was filled in the above procedures, the
endocranial volume of DH3/DH4 was also virtually calculated using the
cranial base of Sts 19 as a model. A 3D model of Sts 19 was mirrored and
aligned to the DH3/DH4 model using the external auditory meatus and
common points on the internal surface of the petrous portion as a guide
(Figure 21). The Sts 19 model was then scaled by 0.97 to obtain an
optimal fit between the two models.
Figure 21.
Download figureOpen
in new tabDownload powerpointFigure 21. Virtual reconstruction the
DH3/DH4 cranial base using a model of Sts 19.
(A) Right lateral view. (B) Left lateral view. (C) Posterior view. (D) Inferior view.
DOI: http://dx.doi.org/10.7554/eLife.09560.026
After
the Sts 19 model was merged with the DH3/DH4 model, the endocranial
surface was extracted and reconstructed as described above (Figure 22).
The resultant endocranial volume using the Sts 19 cranial base was 465.9
cm3. This value is in agreement with the first estimate and suggests
that using a model cranial base did not significantly alter the results.
Figure 22.
Download
figureOpen in new tabDownload powerpointFigure 22. Virtual
reconstruction the DH3/DH4 endocranial volume using a cranial base model
of Sts 19.
Right lateral view.
DOI: http://dx.doi.org/10.7554/eLife.09560.027
The
larger composite cranium, consisting of DH1 and DH2, lacks most of the
frontal region. In order to create a closed endocranial surface for a
volume estimate, the frontal region from the smaller composite cranium
was scaled by 5%, and then registered (aligned) and merged to the model
of the larger composite cranium. As with the smaller composite cranium,
the endocranial surface was then selected and converted to a new object,
and the remaining holes filled based on the curvature of the surface.
The volume of the closed endocranial model was calculated using GeoMagic
Studio. The cranial capacity (endocranial volume) of the larger
composite model is approximately 560cc.
Body mass estimation methods
Eight
femoral fragments from the Dinaledi collection allow a direct
measurement of the subtrochanteric anteroposterior and mediolateral
diameters (Table 3). We developed two regression equations to estimate
body mass from these diameters based on the masses of modern human
samples. MCE measured body masses of a sample of 253 modern European
individuals, 128 males and 125 females, collected from the Institute for
Forensic Medicine in Zurich, Switzerland. Body masses were taken at
time of forensic evaluation. This sample yields the following regression
equation relating body mass to subtrochanteric diameter, where FSTpr
refers to the product of the femoral subtrochanteric mediolateral and
anteroposterior
breadths:Body Mass=0.060×FSTpr+13.856,SEE=6.78,r=0.50,p=<0 .001.="" br="">
We further examined a broader sample of 276 modern humans
taken from a number of populations around the world, with data measured
by TWH. The body masses of individuals were estimated from femur head
diameter, using the average of results obtained from Grine et al. (1995)
and Ruff et al. (1997). The sample includes 115 females, 155 males, and
6 individuals of indeterminate
sex.Body Mass=0.046×FSTpr+24.614,SEE=5.82,r=0.82,p<0 .001.="" br="">Stature estimation methods
We collected data from
skeletal material representing two African population samples. We use
only African populations in this comparison because the ratio of tibia
length to femur length, and thereby the proportion of stature
constituted by tibia length, varies between human populations both today
and prehistorically. Although we do not know this proportion for H.
naledi, we adopt the null hypothesis that they likely had tibia/femur
proportions similar to other African population samples.
95 male
and female Kulubnarti individuals from medieval Nubia are curated at the
University of Colorado, Boulder. Data were collected by HMG, including
estimates of living stature based on the Fully method (Fully, 1956;
Raxter et al., 2006), and these were used to develop a regression
equation relating tibia length to stature. The resulting equation
is:Stature=0.295×TML+48.589,SEE=3.13,r=0.90,p<0 .001.="" br="">
We
(HMG and TWH) collected measurements from 38 African males and 38
females curated within the Dart Collection of the University of the
Witwatersrand. Specimens were randomly chosen with no preference for
specific African ethnic groups. Cadaveric statures are documented for
this collection, the regression equation relating tibia length to
stature in this sample
is:Stature=0.223×TML+75.350,SEE=6.50,r=0.63,p<0 .001.="" br="">
