602 FOSSILS ATTRIHUTEL) TO GENUS HOMO: SOME GENERAL NOTES
characteristic or complex of characteristics should be
given primacy in systematic considerations. We ac-
knowledge, in sum, not only that species are variable (in
their degree of variability as well as in anatomical de-
tails), but that morphological innovatioddifferentiation
and speciation are independent processes. Inevitably,
then, there can be no one-to-one correspondence
between any specifiable degree of morphological diver-
gence and the establishment of the historically inde-
pendent entities that species most fundamentally are
(Tattersall, 1986). Nonetheless, morphology is all that
the fossil record gives us upon which to make system-
atic judgments (neither time nor geography being an
adequate arbiter for that purpose: see Eldredge and
Tattersall, 1975); and the unmistakable signal that we
find in the living world today, as presumably in the
past, is one of astonishing taxic diversity-although,
among hominids, the extent of that diversity will pre-
sumably always be debated, for the reasons that we
have just given. We obviously do not wish to claim that
all of the morphologies that we have enumerated in
this brief discussion are of high taxonomic significance,
and we fully realize that many of the alternative charac-
ter states that we have noted will prove ultimately to re-
flect within-species variation. Nonetheless, there is no
reason to believe that hominids (certainly before the
advent of the extraordinary creature that behaviorally
modern Homo sapiens undeniably is) evolved by rules
different from those observed by all of the other myriad
living components of nature.
If we are correct in this, there is every reason to
suppose that the history of our kind proceeded
through a complex process of evolutionary experimen-
tation and of ecological competition, speciation, and
extinction, rather than through one of gradual within-
lineage burnishing. And if so, it is taxic diversity,
rather than linearity and unwavering continuity, that
we should expect to find among extinct hominids.
Not surprisingly, the record bears out the accuracy of
this expectation. Moreover, even our cursory survey
indicates that the fossils that we have described in
these volumes present us with a greater morphological
and, almost certainly, systematic variety than tradition
has recognized. Some morphs and taxa, such as Homo
sapiens and Homo neanderthalensis, have already come
into focus as distinctive (and distinctively variable)
systematic as well as morphological entities. Some
taxa, such as Homo erectus and Homo heidelbergensis, are
just beginning to take on some discernible outline.
Others, Homo antecessor among them, are clearly
distinctive entities but are exceedingly poorly known.
And some are, as yet, no more than hinted at within
morphologically heterogeneous groupings of ho-
minid fossils that perforce remain extremely poorly
defined (variants of “early Homo” are a good case in
point here).
In these two volumes of The Human Fossil Record,
we have focused on morphological fundamentals and
have deliberately refrained from making systematic
judgments. For, at this stage in the evolution of pale-
oanthropology, it seems more useful to point out the
existence of the numerous systematic problems posed
by the hominid fossil record as currently known than
to try to solve them. Nevertheless, we hope that
the brief comments above, in conjunction with the
descriptions that they follow, will prompt others to
examine, in a systematic light, the morphological
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