Last Ape Standing: The Seven-Million-Year Story of How and Why We Survived Read Free Page B

earth about seven million years ago, and so that is where we shall begin. 1
    When compared with the billions of years it has taken to make a universe or its suns and planets, seven million years may appear minute, but to those of us who aren’t stars, comets, oceans or mountain ranges it remains a very, very long time. We are used to measuring time in hours and days, months and years, perhaps generations when forced to push the envelope. Epochs and eons bend the mind and are as incomprehensible as light–year–measured galactic distances or quantum calculations computed in qubits.
    To help wrap our minds around these numbers, imagine that we could squeeze the seven million years that have passed between the arrival of
Sahelanthropus tchadensis
and the present into a single year’s calendar, and then plot the arrival—and in some cases the departure—of every known human species from January to December. Let’s call this the Human Evolutionary Calendar or HEC. If we look at it this way,
tchadensis
arrives January 1. Lucy, the famous upright walking member of a line of savanna apes known as
Australopithecus afarensis
, who lived about 3.3 million years ago, appears July 15. Neanderthals don’t show up until near Thanksgiving, November 19, and we
Homo sapiens sapiens
finally reveal ourselves near the winter solstice, December 21, a little more than a week before the end of the year.

    Looking at this timeline, you can’t help but conclude the human species seems to have gotten off to a slow start, at least based on the current sketchy evidence. b Following
tchadensis
nothing at all happens for more than a million years, then a creature researchers call
Orrorin tugenensis
(Millennium Man) finally appears just before the spring equinox—on March 8. Like
tchadensis, tugenensis
didn’t leave much for us to inspect—two jaw fragments and three molars. Later finds turned up a right arm bone and a small piece of thigh—altogether enough information for paleontologists to conclude that
Orrorin
was almost certainly human, and lived about 5.65 to 6.2 million years ago, mostly in wet grasslands and fairly thick forests that eventually became the Tungen Hills of modern Kenya. Thus the name
tugenensis
. Whether he walked upright all the time or even part of the time is debated, but if he spent his days between grasslands and jungle, he may have done a bit of both, walking on all fours in the forest and upright now and again in and among the trees and grasslands he called home.
    As we move into spring not one, but three new and indisputably human species arrive. On March 18 two emerge from the mists of time:
Ardipithecus ramidus
and
Ardipithecus kadabba
; then on May 20,
Australopithecus anamensis
. These were all distinct species, yet all three bear a stronger resemblance to today’s chimpanzees than to us, and all three probably walked upright sometimes, and at other times on all fours.
    By summer in the HEC, signs emerge that the human experiment was gathering momentum. Multiple species begin to appear and overlap. Recalling their names is a little like trying to follow the characters in a Russian novel, but bear with me. (We can thank the brilliant zoologist Carl Linnaeus for the long and respected tradition of assigning elongated, Latin names to all living things.) In mid–October,
Paranthropus robustus
(sometimes known as
Paranthropus crassidens
) arrives. Then on July 4,
Kenyanthropus platyops
; ten days later,
Australopithecus afarensis
(Lucy); and then in August,
Paranthropus aethiopicus
and
Australopithecus garhi
join the ranks of humans that have walked the planet.
    These creatures, each of whom found their way in and out of time and the plains and forests of Africa, arose and departed subject to the cantankerous whims of evolution. When we compress time this way, it’s easy to forget that some of these species lived for hundreds of thousands of years. All of them were intelligent, with brains that ranged from the