Part 3
The evolution of to evolve the behavioral
defenses against our family hominid inventiveness in Africa
was a two-edged sword: it caused the extinction of many of
Africa’s largest animals in the earlier parts of the
Pleistocene, but it also forced the surviving members of that
continent’s megafauna which have enabled a relatively
large number of its members to survive into the present.
When Raymond Dart announced in 1925 that he’d
identified an ancient, ape-like ancestor of our species in
South Africa, his claim was denied, derided and ignored for
nearly twenty years. It was only in the late 1940s that the
scientific establishment finally acknowledged that the being
which Dart had named “Australopithecus africanus”
had been a human-like one, situated on or near the line of
our species’ ancestry.
Dart didn’t only think that Australopithecus
resembled humans on a physical level – he also
thought that they had begun resemble us mentally.
He argued, as we’ll see in this Part, that Australopithecus
had gone a long way toward the “acquisition of articulate
speech,” and became convinced that it could use weapons
to hunt animals larger than itself. In fleshing out this “they
had begun resemble us mentally” scenario, Dart got lots
of details wrong: his “australopithecans” almost
certainly could not – as he thought they could – make
fire. In this and other respects, his intuition had run ahead
of the archeological facts available in his lifetime. But
that intuition was prescient in other respects, and its guiding
assumption – that the relatively close physical
resemblance between our species and Australopithecus must,
to some degree, have been reflected in the behavior
of the latter – has begun to seem more credible since
stone tools and butchered bones have been found in association
with Australopithecus garhi who we’ll meet
in Chapters 9 and 10.
Dart’s two insights – that the human family evolved
in Africa, and that hominid ingenuity began to make its appearance
relatively early in the evolutionary history of our family – offer
an explanation for why the megafauna of Africa (and of south
Asia to which African hominids emigrated around 2 million
years ago) experienced numerous extinctions early in the Pleistocene.
Paradoxically, those insights can also explain, as I argued
in Chapter 1, why land-animals as big as elephants and rhinos
have survived in Africa and south Asia and nowhere
else.
How believable is it that early hominids could have had such
a dramatic impact on the megafauna they lived with? With the
publication of a 1966 article in Nature, Paul Martin
became the first person to put together a reasoned argument
that hominids exterminated several kinds of megafauna in Africa
in the early part of the Pleistocene. Relatively little was
known about the timing of early-Pleistocene events at that
time, but Paul was able to marshal enough reliable facts to
construct an argument which remains, to this day, persuasive
and solid.
Paul returned to this topic in a chapter (“Prehistoric
Extinctions: The Global Overview”) in the 1984 Quaternary
Extinctions which he edited with Richard Klein, but didn’t
publish anything on the subject of the early-Pleistocene extinctions
after that date. Until very recently, the late Wilhelm Schüle,
whose work we’ll touch on throughout this Part, has
been the only other writer to make a case for the proposition
that those extinctions had been caused by hominids.
I was satisfied, after reading the writings of Paul Martin
(and those of Wilhelm Schüle) on the subject, that hominids
had wiped out the megafauna which Africa lost in the
early Pleistocene, but the question of how they had done so
still niggled. I was fully persuaded that early-Pleistocene
hominds had been efficient hunters, but so are cheetahs, and
cheetahs have never, as far as anyone knows, exterminated
a large number of their prey species. What was the x-factor
which made the behavior of early Homo deadly enough
to wipe out some of the big animals it preyed on and competed
with?
I suspected, as many people do, that it must
be connected, in some way, to the intellectual capabilities
of our family, but it was only when I discovered the work
of the psychologist Leda Cosmides and her co-author, the anthropologist
John Tooby that I felt that I might be starting to understand
the real power of those capabilities. As we’ll see in
this Part, Cosmides and Tooby reasoned that, as soon as hominids
became able to construct advantageous new behaviors “ontogenetically,”
(i.e. by inventing them), they must have gained an
enormous and indeed destructive advantage over prey
animals and competitors whose ecological options remained
restricted to putting such behaviors together “phylogenetically,”
(i.e. evolving them).
* * *
In Chapter 7, which starts this Part off, I describe some
of the European and Asian hominid finds which preceded Dart’s
discovery of Australopithecus in Africa, and I discuss
the Piltdown fraud. “Why the discussion of Piltdown?,”
a valued advisor asked me, “Doesn’t that take
us too far away from the rise of hominid inventiveness, and
its impact on the African megafauna?” My advisor may
well be right on that score, but writing a book involves compromises,
and I decided, in the end, to retain Chapter 7, because I
found that I couldn’t explain the twenty-year failure
of the anthropological establishment to accept and acknowledge
Dart’s discovery that the human family originated in
Africa, without saying something about the fraud that had
so much to do with that delay.
As the preceding paragraph might show, I’ve tried,
in this Part, not only to tell the story of how our bodies
and minds evolved on the African continent, but to describe,
in addition, how present-day humans became aware of that
this took place. I’ve focused on the growth of
that awareness, because I don’t believe it has reached
the “mature” or “relatively complete”
level that many people assume it has. Anyone who accepts the
argument I’ll be making in this Part – viz. that
hominids had a profound effect on the megafauna of early-
and mid-Pleistocene Africa – will, for example, have to
venture well beyond the orthodox belief that the human family’s
technological, linguistic and cognitive powers remained, until
the last forty thousand years or so, at a rudimentary level.
