“I’m sure we’ve got more surprises to come.”
At this point, there’s no evidence to indicate what wiped out the
Denisovans or the hobbits; however, the timing of their demise and the
general pattern of late-Pleistocene extinctions means there’s one obvious
suspect. Presumably, since they were closely related to us, both
Denisovans and hobbits had a long gestation period and therefore shared
the megafauna’s key vulnerability, a low reproductive rate. All that would
have been required to do them in would have been a sustained downward
pressure on the number of breeding adults.
And the same holds true for our next-closest kin, which is why, with
the exception of humans, all the great apes today are facing oblivion. The
number of chimpanzees in the wild has dropped to perhaps half of what it
was fifty years ago, and the number of mountain gorillas has followed a
similar trajectory. Lowland gorillas have declined even faster; it’s
estimated the population has shrunk by sixty percent just in the last two
decades. Causes of the crash include poaching, disease, and habitat loss;
the last of these has been exacerbated by several wars, which have pushed
waves of refugees into the gorillas’ limited range. Sumatran orangutans
are classified as “critically endangered,” meaning they’re at “extremely
high risk of extinction in the wild.” In this case, the threat is more peace
than violence; most of the remaining orangutans live in the province of
Aceh, where a recent end to decades of political unrest has led to a surge
in logging, both legal and not. One of the many unintended consequences
of the Anthropocene has been the pruning of our own family tree. Having
cut down our sister species—the Neanderthals and the Denisovans—many
generations ago, we’re now working on our first and second cousins. By
the time we’re done, it’s quite possible that there will be among the great
apes not a single representative left, except, that is, for us.
ONE of the largest assemblages of Neanderthal bones ever found—
remains from seven individuals—was discovered about a century ago at a
spot known as La Ferrassie, in southwestern France. La Ferrassie is in the