Humans have extraordinarily developed brains compared to other animals. Mammals weighing 60 Kg. they have an average brain of 200 cubic centimeters .
The Sapiens modern has a brain that averages 1200-1400 cubic centimeters .
The brain of the Neanderthal it was even bigger.
In Homo Sapiens the brain is worth about 2-3% of total body weight, but consumes 25% of the body's energy when it is in a state of rest .
In comparison, the brains of the other monkeys they require only 8% of the energy in a resting state .
Archaic humans paid for having large brains in two ways.
First, they spent more time searching for food. Secondly, their muscles atrophied.
The skeleton of our ancestors had developed over millions of years to support a creature that walked on all fours and had a relatively small head.
Adjusting to stand upright was a huge challenge, especially when the scaffolding had to support a large skull.
Being able to see more from above and using industrious hands, humanity he paid for it with back pain and stiff necks .
It cost the women even more.
The upright gait required tighter hips, thus narrowing the vaginal canal - and this as the heads of the babies got bigger and bigger.
For female humans, death in childbirth became a huge danger. Women who gave birth earlier, when the baby's brain and skull were still relatively small and soft, fared better, could survive more easily and give birth to more children. Consequently, natural selection favored early births.
And indeed, if you compare it with other animals, humans are born prematurely, when many of their vital systems are not yet developed .
Shortly after being born, a foal can pull up and start trotting; a kitten detaches from its mother to look for food for itself only a few weeks after it is born. Human babies are helpless, and for years they remain dependent on their ancestors for sustenance, protection and education .