Biology Reference
In-Depth Information
So who were these transitional-looking hominins from Dmanisi?
Philip Rightmire, an expert on
Homo erectus
from Binghamton Uni-
noted that the populations of
Homo erectus
that lived in Africa, Java, and
China between 1.8 million and 1.6 million years ago had slightly different
combinations of features in their teeth and skulls, as did the Dmanisi
hominins who lived in the Caucasus. Rightmire believes all of these
populations derived from one widespread and highly varied species of
Homo.
Dmanisi hominins, he has suggested, may have been primitive
enough to warrant recognition as a separate subspecies,
Homo erectus geor-
gicus,
which could have been ancestral to the others: “One [possibility] is
that an early
Homo
population dispersed from Africa into the Caucasus,
where it then evolved the Dmanisi bauplan. Many of the characters dis-
played by the Dmanisi skulls . . . [are] consistent with viewing the Dma-
nisi population as ancestral to other
H. erectus
showing more advanced
morphology.”
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In an iconoclastic twist, Rightmire and his colleagues also raised the
possibility that the Dmanisi hominins might have originated in Eurasia
and that some of them could then have migrated to Africa, where they
evolved into the African subspecies
Homo erectus ergaster
(like WT 15K).
This sequence of events reverses the standard textbook assumption that
early
Homo
originated in Africa and then spread out to other parts of
the world. Although traditionalists would take exception to this model,
many agree that the Dmanisi hominins were probably close to the stem
of early
Homo.
Ian Tattersall, for example, has observed that the Dmanisi
population most plausibly represented an early departure “from Africa,
hard on the heels of the origin of
Homo
as (probably) best defined by
essentially modern postcranial form.”
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What is important in all of this can be gleaned from the ten partial
skeletons we just surveyed. In my opinion, seven of these hominins that
lived in Africa between 3.6 million and 1.8 million years ago were little
things who had not yet evolved the long legs and modern body propor-
tions that are indicative of habitual bipedalism (Kadanuumuu, Lucy,
