Lowly Origin: Where, When, and Why Our Ancestors First Stood
xx + 396 pp. Princeton
University Press, 2003. $35.
With the exception of our large brain and attendant linguistic
skills, no physical manifestation of humanity's divergence from an
apelike ancestor has evoked greater ink flow than upright,
two-legged walking. Because the fossil record of our lineage
documents the primacy of bipedalism over brains (by at least 2
million years), modern explications of human origins have focused on
the environmental challenges that early hominids overcame by
standing upright on the ground and moving about on two legs. In most
such tellings, the probability of making a successful shift to the
ground from the trees varies inversely with the abruptness of the
ecological transition across which it supposedly occurred. If the
shift was precipitous—from tree-dwelling in a closed forest to
ground-dwelling on an open savanna, for instance—then the
plunge to terra firma must have been downright heroic and its
In Lowly Origin, Jonathan Kingdon aims to dispel the
timeworn idea that prehominids must have confronted such a drastic
challenge. He was inspired by recently recovered African fossils
indicating that from 6 to 4 million years ago bipedal hominids
inhabited varied environments that included ample tree cover.
Kingdon spins out a scenario in which the earliest hominids became
terrestrial and bipedal in increments, long before moving into open
country. In his view, the rise of hominid bipedalism was almost
inevitable, and although it constituted a "symbolic
moment" in human evolution, it was not a "sudden leap."
Kingdon, a senior research associate in the Institute of Biological
Anthropology and Department of Zoology at the University of Oxford,
is a largely self-trained expert on the biogeography of African
mammals (he is the author and illustrator of the superb multivolume
East African Mammals: An Atlas of Evolution in Africa).
In Lowly Origin he has written an original and engaging
account of human evolution as the evolution of "just one more
African mammal." Readers accustomed to stories about human
origins that invoke unusual, exceptional or unprecedented conditions
and causes will find this book a refreshing change of pace.
According to Kingdon, the common ancestor of chimpanzees and humans
was a Eurasian "Tree Ape" that immigrated into eastern and
central Africa in the Late Miocene (about 10 million years ago).
Some populations of these apes became part of an endemic mammalian
fauna (surviving today only in part of southeastern Tanzania)
adapted to life in coastal, open woodlands. In these littoral zones,
in contrast to the closed inland forests inhabited by chimps and
gorillas today, deciduous trees predominate in a seasonally and
topographically varied range of relatively open habitats, and food
resources are concentrated near the forest floor. During the latest
Miocene, these "East Coast Ground Apes" (the ancestors of
you and me), after being isolated from their inland-forest-loving
cousins to the west (the ancestors of the chimpanzee) by expanding
zones of aridity, evolved unique adaptations to committed
terrestrial feeding. Kingdon imagines a kind of
"squat-foraging": He believes that our vertically short
pelvis, curved lumbar spine and forwardly placed articulation
between the head and neck, which we usually associate with the
acquisition of bipedalism, were initially mechanisms that helped to
stabilize the upright trunk of these pre-bipeds while they fed on
Flowing from his intimate knowledge of African natural history,
biogeography and evolution, Kingdon's scenario is vivid and
compellingly detailed—all the more so because earliest human
evolution in this telling is so unexceptional, the product
of universal ecological factors and evolutionary forces operating on
"just one more African mammal." Currently, though, his
theory is not testable. Kingdon knows that the fossil evidence for
these Miocene inhabitants of the East African coastal zone is
nonexistent—although this is no defect in his argument in
particular, as fossils documenting human and ape evolution between
12 and 6 million years ago are currently next-to-nonexistent
anywhere in Africa. However, when confronted with the actual fossil
record, Kingdon's storyline is less convincing. He downplays the
importance of the 6- to 7-million-year-old Sahelanthropus
tchadensis fossil from Chad, whose canine-tooth and skull-base
characteristics appear to place it on our side of the chimp-human
split (it is thus something of a geographic anomaly in his scheme),
while promoting the contemporaneous Orrorin tugenensis from
Kenya as the earliest known hominid species, for which a less
convincing case has so far been made by its discoverers (in
published descriptions, the Orrorin canines are distinctly apelike
and the evidence for bipedalism is ambiguous).
By the time we reach a period for which there is a fairly dense
fossil record (beginning about 4 million years ago), bipedal
hominids were already spread out over much of Africa. Kingdon posits
that long-distance inland migrations along wooded river courses
during humid climatic phases spurred the transition from an upright
squatting ground forager to striding bipeds—bipeds
plural, because Kingdon believes, not unreasonably, that these river
basins, isolated from one another by zones of aridity that hominids
were not yet ready to master, were the main centers of hominid
adaptive and taxonomic diversity in the Pliocene.
In the northeast, Australopithecus eventually spread widely
to become the "first truly mobile, open country form." But
Kingdon misinterprets these hominids, including A.
afarensis (the species to which "Lucy" belongs),
as clumsy bipeds with gorillalike life histories who retained too
many apelike characteristics too late in time to figure in the
ancestry of humans. (He thinks that all the known australopiths
roaming eastern Africa in the Pliocene became overly specialized and
went extinct in the early Pleistocene.) That role, in his view, is
reserved for the southern species A. africanus, which
Kingdon contends is fundamentally more humanlike than Lucy and other
eastern hominids in its brain size (larger), degree of sexual
dimorphism (smaller), and hand structure (more adept at
manipulation, enhancing the efficiency of terrestrial foraging and
predisposing it to tool manufacture)—none of which will sound
very familiar to most paleoanthropologists or knowledgeable lay
readers. As far as can be told, A. africanus and A.
afarensis are basically similar in these attributes, and
otherwise the evidence supporting a unique link between A.
africanus and Homo is ambiguous at best. In fact the
phylogenetic relationship of A. africanus to late Pliocene
hominids remains one of the outstanding uncertainties in paleoanthropology.
Kingdon is not on intimate terms with these fossils; his ideas about
them rely heavily on other sources, among which he seems unable to
sort the credible from the implausible. For example, he asserts that
some early Homo species were semi-aquatic (a latter-day nod
toward Elaine Morgan's "Aquatic Ape") and that early
Homo erectus (also known as H. ergaster)
originated in the Atlas Mountains of northwestern Africa and then
migrated into eastern Africa—ideas that are well outside the
mainstream of paleoanthropological thinking.
Kingdon is at his best in drawing together the strands of ecology,
geology and evolutionary biology in a sweeping view of changing
ancient African landscapes. This is the best popular account of that
subject I have read. Unfortunately, Kingdon populates the terrain
with stand-ins for the real hominids, whose histories await a more
discerning and persuasive rendering than that on offer here. Despite
this central weakness, Lowly Origin deserves to be read and
admired for its brilliant evocation of the African backdrop to our evolution.
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