The odds of archaeologists finding a nearly complete skeleton went up dramatically when humans began to bury their dead in formal graves. But
this began only about 50 000 years ago, a relatively recent date in terms of human origins and only a small portion of the four-million-year
history of our ancestral line. Before formal burial, the physical remains of our ancestors were processed by the environment in the same way
as any other dead animal: chewed up by scavengers, dispersed in a river bed, on the open veld or in a cave, and finally preserved by
fossilisation as isolated bones. Nearly complete skeletons in the fossil record of our earliest ancestors are as rare as the proverbial
‘hen’s teeth’. The discovery of the hominins from Malapa announced by Lee Berger1 has been just such a rare
Berger and his colleagues1 provide the initial description and context for two fossil specimens recovered from the Malapa site
in the Cradle of Humankind, just outside of Krugersdorp, South Africa. The skeletons are securely dated to between 1.95 and 1.78 million
years ago,2 placing them at a critical juncture of human evolution; around the time of the first appearance of the genus Homo.
The bones are well preserved and were in a state of semi-articulation at discovery, demonstrating no sign of scavenger activity. They were
deposited, along with other debris including non-hominin animal bones, in a water-washed environment deep within what would then have been
a typical limestone cavern. The two individuals must have fallen to their deaths down a vertical solution shaft and then been washed into a
sediment trap deep within an underground river. What had been unlucky for them was very fortunate for Berger and, ultimately, fortunate for
us. They had lain buried for nearly 2 million years until erosion exposed the site on the surface and the bones were noticed by Berger’s
The two skeletons are not quite complete. The first, designated MH1, a juvenile approximately 12–13 human years at death, is
represented by about 40% of the skeleton, which includes much of the cranium and mandible. The second, MH2, is an adult, but has fewer
bones preserved and is missing its cranium. The percentage preservation of MH1 is about the same as the partial skeleton ‘Lucy’
from Hadar in Ethiopia (AL 288-1), but less than the Nariokotome boy (KMN-WT 15000) from Kenya and, the almost complete but still to be
excavated, ‘Little Foot’ skeleton from Sterkfontein (Stw 573). Although rare, these partial or nearly complete skeletons provide
the researchers with information about body proportions and functional anatomy that is much more difficult to glean from isolated bones, so
their value cannot be understated.
Berger and his colleagues1 have considered the anatomy of their find and have come to the conclusion that it represents a new
species that they have named Australopithecus sediba. In this they had a choice: either they could have lumped the specimens
into the pre-existing category of Au. africanus, or placed it into the more advanced group known as Homo habilis, but they
felt that its anatomical features were a ‘unique combination of primitive and derived traits’. The cranium, in particular,
gives clues that these individuals had not yet crossed the line of humanity that we code with the name Homo and thus best fit within
the Australopithecine anatomy that was common in the period before 2 million years ago. The cranial volume is relatively small and there is
a suite of anatomical features on the cranial vault, face and jaws that are clearly ‘primitive’ (i.e. Australopithecine). But
the post-cranium gives another suite of clues, especially in the pelvis, that are highly reminiscent of the anatomy of Homo. Berger
and his colleagues1 conclude by emphasising that the transition from Australopithecus to Homo was not a smooth
process and that there was a mosaic of features appearing at different times. For them, Australopithecus sediba is on the transition
line of, but still within, the Australopithecines.
The unfolding lineage of human evolution in the Plio-Pleistocene of Africa has been a centre of debate for decades. There are two clear
lines of Australopithecine evolution: firstly, a gracile variety that appeared around 4 million years ago, including Ardipithecus,
followed by Australopithecus afarensis around 3.5 million years ago and Au. africanus about a million years later and,
secondly, a robust line identified as the separate genus Paranthropus, appearing around 2.5 million years ago and existing alongside
early Homo until about 1.5 million years ago. But where did Homo come from? Tobias has designated Au. africanus as the
ancestor,3,4,5 but Johanson and White
6,7 pushed for Au. afarensis, after its discovery was announced in 1978. The
Johanson and White6,7 model suggested an early separation for Homo
and a long dead-end path for Au. africanus. The
profusion of new fossils discovered in east Africa in the 1980s and 1990s seemed to support branching human lines between 2 and 3 million
years ago, implying that early Homo was one of a nest of natural experiments in hominin speciation. The new discovery at Malapa
places the late-divergence model back on the table and, again, brings Au. africanus into the range of possible ancestors for early
So, how will these specimens from Malapa be received by the scientific community? Anatomical detail is always open to interpretation and,
as other scholars get a chance to study the bones, there will be new opinions, but the real issues will be about the taxonomy of the specimen
and the philosophical meaning of the categories. Much of the debate will revolve around the validity of the taxon Homo habilis, a name
that was originally coined by Leakey, Tobias and Napier8 and based on the fossils from Olduvai Gorge in Tanzania. Homo habilis
was not an ‘easy sell’ to the palaeoanthropological community. Some scientists rejected the taxon because they felt it was
unnecessary; there was simply not enough difference between the specimens of H. habilis and those of Au. africanus to
warrant a new species. However, Berger and his colleagues1 have suggested that some of the specimens placed into H. habilis,
such as the Sterkfontein skull Stw 53 and the Olduvai post-cranial set OH 62, are more like their discovery and less like Homo. This
will certainly open up the whole H. habilis argument once again. The relatively late date for Malapa might also trigger some debate.
Australopithecus garhi, a relatively newly identified species of Australopithecus, discovered in east Africa and dating from
around 2.5 million years ago,9 was associated with animal bone that had been chopped with stone tools and thus may represent the
same anatomical grade described from Malapa. Phillip Tobias5 has said that the hallmark of humanity was the manufacture of stone
tools and, as such, Au. garhi could make a better ancestor, both in terms of behaviour and anatomy, than the Malapa remains that are
more recent by half a million years.
Early in January 2010, a group of international scholars met in Johannesburg, under the auspices of the Institute for Human Evolution at the
University of the Witwatersrand, to gather information about the post-cranial bones of the Australopithecines. The workshop, in honour of the
late Charles Lockwood, provided a real opportunity to discuss the anatomy of the accumulating set of fossil bones stored in Johannesburg and
the plan was to discuss the production of a definitive volume on the post-cranial anatomy of the genus Australopithecus. Berger was
invited but chose not to attend. The workshop project is on-going and it is anticipated that the skeleton of ‘Little Foot’
(Stw 573) will be made available during 2010, as it is removed from the adhering matrix that has held it for the past 3 million years.
The specimen, Stw 573, is at least 2.7 million years old and comes from the lower members of the Sterkfontein cave deposit.10
This age is important because it is either an early form of Au. africanus, or it is the first evidence we have found of Au.
afarensis outside of east Africa. Either way, the fact that it is so complete means that it represents our best opportunity by far
to study the ‘whole body’ anatomy of these creatures. Hopefully Berger will make his new specimens available as well, now
that his find has been officially announced. One of the outcomes of the January workshop was the recognition that naming new species on
the basis of single specimens (or double in the case of Malapa) may not be the wisest idea when the species under observation is extremely
variable. It is precisely this kind of discussion involving anatomical experts and the full range of available specimens that will lead to
the consensus that will ultimately make clear the importance of the new finds from Malapa.
Simplified chart of Plio-Pleistocene Australopithecine evolution with late and early divergence points
for the genus Homo
1. Berger LR, de Ruiter DJ, Churchill SE, et al. Australopithecus sediba: A new species of Homo-like Australopith from South Africa. Science. 2010;328:195–204.
2. Dirks PHGM, Kibii JM, Kuhn BF, et al. Geological setting and age of Australopithecus sediba from southern Africa. Science. 2010;328:205–208.
3. Tobias PV. Australopithecus, Homo habilis, tool-using and tool-making. S Afr Archaeol Bull. 1965;20:167−192.
4. Tobias PV. Australopithecus afarensis and A. africanus: Critique and an alternative hypothesis. Palaeontol Afr. 1980;23:1−17.
5. Tobias PV. Olduvai Gorge: The skulls, endocasts and teeth of Homo habilis. Cambridge: Cambridge University Press; 1991.
6. Johanson DC, White TD, Coppens Y. A new species of the genus Australopithecus (Primates: Hominidae) from the Pliocene of eastern Africa. Kirtlandia. 1978;28:1–14.
7. Johanson DC, White TD. A systematic assessment of early African hominids. Science.1979;202:321–330.
8. Leakey LSB, Tobias PV, Napier JR. A new species of the genus Homo from Olduvai Gorge. Nature. 1964;202:7−9.
9. Asfaw B, White T, Lovejoy O, Latimer B, Simpson S, Suwa G. Australopithecus garhi: A new species of early hominid from Ethiopia. Science. 1999;284(5414):629–635.
10. Clarke RJ. First ever discovery of a well-preserved skull and associated skeleton of an Australopithecus. S Afr J Sci. 1998;94:460–463.