Sapiens: a brief History of Humankind

Homo sapiens
, the brain accounts for about 2–3 per cent of total body
weight, but it consumes 25 per cent of the body’s energy when the body is at rest.
By comparison, the brains of other apes require only 8 per cent of rest-time
energy. Archaic humans paid for their large brains in two ways. Firstly, they spent
more time in search of food. Secondly, their muscles atrophied. Like a government
diverting money from defence to education, humans diverted energy from biceps
to neurons. It’s hardly a foregone conclusion that this is a good strategy for
survival on the savannah. A chimpanzee can’t win an argument with a 
Homo
sapiens
, but the ape can rip the man apart like a rag doll.
Today our big brains pay o nicely, because we can produce cars and guns that
enable us to move much faster than chimps, and shoot them from a safe distance
instead of wrestling. But cars and guns are a recent phenomenon. For more than 2
million years, human neural networks kept growing and growing, but apart from
some int knives and pointed sticks, humans had precious little to show for it.

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What then drove forward the evolution of the massive human brain during those 2
million years? Frankly, we don’t know.
Another singular human trait is that we walk upright on two legs. Standing up,
it’s easier to scan the savannah for game or enemies, and arms that are
unnecessary for locomotion are freed for other purposes, like throwing stones or
signalling. The more things these hands could do, the more successful their owners
were, so evolutionary pressure brought about an increasing concentration of
nerves and nely tuned muscles in the palms and ngers. As a result, humans can
perform very intricate tasks with their hands. In particular, they can produce and
use sophisticated tools. The rst evidence for tool production dates from about 2.5
million years ago, and the manufacture and use of tools are the criteria by which
archaeologists recognise ancient humans.
Yet walking upright has its downside. The skeleton of our primate ancestors
developed for millions of years to support a creature that walked on all fours and
had a relatively small head. Adjusting to an upright position was quite a
challenge, especially when the sca olding had to support an extra-large cranium.
Humankind paid for its lofty vision and industrious hands with backaches and sti
necks.
Women paid extra. An upright gait required narrower hips, constricting the
birth canal – and this just when babies’ heads were getting bigger and bigger.
Death in childbirth became a major hazard for human females. Women who gave
birth earlier, when the infants brain and head were still relatively small and
supple, fared better and lived to have more children. Natural selection
consequently favoured earlier births. And, indeed, compared to other animals,
humans are born prematurely, when many of their vital systems are still under-
developed. A colt can trot shortly after birth; a kitten leaves its mother to forage
on its own when it is just a few weeks old. Human babies are helpless, dependent
for many years on their elders for sustenance, protection and education.
This fact has contributed greatly both to humankind’s extraordinary social
abilities and to its unique social problems. Lone mothers could hardly forage
enough food for their o spring and themselves with needy children in tow.
Raising children required constant help from other family members and
neighbours. It takes a tribe to raise a human. Evolution thus favoured those
capable of forming strong social ties. In addition, since humans are born
underdeveloped, they can be educated and socialised to a far greater extent than
any other animal. Most mammals emerge from the womb like glazed earthenware
emerging from a kiln – any attempt at remoulding will scratch or break them.
Humans emerge from the womb like molten glass from a furnace. They can be
spun, stretched and shaped with a surprising degree of freedom. This is why today
we can educate our children to become Christian or Buddhist, capitalist or

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socialist, warlike or peace-loving.
*
We assume that a large brain, the use of tools, superior learning abilities and
complex social structures are huge advantages. It seems self-evident that these
have made humankind the most powerful animal on earth. But humans enjoyed
all of these advantages for a full 2 million years during which they remained weak
and marginal creatures. Thus humans who lived a million years ago, despite their
big brains and sharp stone tools, dwelt in constant fear of predators, rarely
hunted large game, and subsisted mainly by gathering plants, scooping up insects,
stalking small animals, and eating the carrion left behind by other more powerful
carnivores.
One of the most common uses of early stone tools was to crack open bones in
order to get to the marrow. Some researchers believe this was our original niche.
Just as woodpeckers specialise in extracting insects from the trunks of trees, the
rst humans specialised in extracting marrow from bones. Why marrow? Well,
suppose you observe a pride of lions take down and devour a gira e. You wait
patiently until they’re done. But it’s still not your turn because first the hyenas and
jackals – and you don’t dare interfere with them scavenge the leftovers. Only then
would you and your band dare approach the carcass, look cautiously left and right
– and dig into the edible tissue that remained.
This is a key to understanding our history and psychology. Genus 
Homo
’s
position in the food chain was, until quite recently, solidly in the middle. For
millions of years, humans hunted smaller creatures and gathered what they could,
all the while being hunted by larger predators. It was only 400,000 years ago that
several species of man began to hunt large game on a regular basis, and only in
the last 100,000 years – with the rise of