FOSSILS ATTRIBUTED ‘ro GENUS HOMO: SOME GENERAL NOTES 589
As a coda to this descriptive second volume of our
series The Human Fossil Record, we feel compelled to
note that the primary signal emanating from the fos-
sils discussed in Volumes 1 and 2 is one of diversity: a
diversity that is not only abundantly evident at the
morphological level, but that is almost certainly also
significant at the systematic level. In this concluding
section, we thus look briefly at those fossils that have
been attributed to Homo at one time or another, and
note some questions that the morphological differ-
ences among them raise in their systematic interpreta-
tion. We do not intend this brief discussion to be ei-
ther comprehensive or definitive; rather, our intention
is to highlight issues that we feel deserve particular at-
tention from future hominid systematists. Most fun-
damentally, we want to emphasize that the genus
Homo, as currently used, has become something of a
wastebasket for a fairly motley assortment of fossils,
and that the existence of this convenient repository
has distracted attention away from needed examina-
tion of potential systematic structure within this by
now extensive group. Similarly, an excessive tradi-
tional reliance on time as a convenience for classifying
fossil hominids has diverted us from the concentration
on morphology that is particularly necessary for un-
derstanding evolutionary relationships within the
fairly close-knit group that this one-despite its inter-
nal diversity-clearly is. We hope that the focus on
morphology in these volumes will assist in alleviating
this imbalance.
The discussion that follows is not organized on the
basis of our particular understanding of what the genus
Homo contains, or on our own interpretation of rela-
tionships within this genus. Rather, each section takes a
group of hominid fossils that have, at one time or an-
other, been categorized together within the genus, and
briefly examines the issues that such received wisdom
raises. It is already quite evident that currently accepted
systematic frameworks for hominids are inadequate to
express the variety that is becoming more apparent with
each new discovery (see, e.g., Wood and Collard, 1999;
M. Leakey, 2001; Senut and Pickford, 2001). Clearly,
though, it would be premature for us to attempt any
formal revision of such frameworks in this volume. We
thus largely refrain in our discussion from making
systematic judgments, simply pointing out areas in
which we feel that future accomodations are likely to be
needed.
“EARLY HOMO
The notion of “early Homo” ultimately descends from
the creation by Louis Leakey and his colleagues of
Homo habilis, almost 40 years ago (L. Leakey et al.,
1964). This new species was erected to accommodate
the gracile materials from the lower levels of Tanza-
nia’s Olduvai Gorge, in a move that was brave at the
time and that, in hindsight, was necessary to break
away from the straitjacket of the then-prevailing min-
imalistic scenario of human evolution. Nonetheless, it
must be admitted that its creators’ systematic judg-
ment was heavily influenced by the cultural need that
they perceived to identify the maker of the Oldo-wan
tools found in these sediments as a member of our
own genus. This concern was directly generated by the
then-current notion of “Man the Toolmaker,” and it
was clearly expressed in the name that they chose for
their new species, which translates as “handy man.”
Morphologically, however, it has subsequently become
abundantly clear that the argument for including
these Olduvai specimens in a monophyletic genus
Homo is weak, as indeed is that for regarding all “early
Homo” as referable to habilis (e.g., Wood, 1992; Wood
and Collard, 1999; Tattersall and Schwartz, 2000).
The type specimen of Homo habilis, OH7, is un-
usual in both mandibular and parietal morphology.
Specifically, the lower jaw and especially the teeth of
OH7 are in many ways more reminiscent of various
Miocene hominoids than they are of Pleistocene
Homo; and, as may be inferred from one of the cranial
fragments (see Olduvai Gorge entry, this volume), it
appears that the foramen spinosum had been con-
tained within the temporal bone. This is a primitive
hominoid feature that, among the hominid clade as
currently accepted, is typically retained among the
australopiths (Braga et al., 1998). There is thus good
reason to revisit and re-evaluate the systematic posi-
tion of the Olduvai material. This necessity applies, of
course, not only to the Bed I material, including
OH24, but also to Bed I1 specimens such as OH13.
Similarly, Hill et al. (1992) described the isolated
hominid temporal bone discovered at Chemeron in
the Baringo Basin of northern Kenya as that of an
“early Homo,” primarily on the basis of characters of
the articular and tympanic regions. However, other