Our Superior Brain
Origins of Us - Brains
Our bodies are amazing machines, honed over millions of years of evolution. But our basic flesh and bones aren't that different from our closest ape relatives, chimpanzees. Fundamentally, we are just another species of ape, but we do feel ourselves to be different, to be special, and that comes down to the very striking difference between us and any other species on Earth. - Our Brain.
We are creatures of the mind. We have an ability to think, imagine and create, that has changed the world. We have the ability to ponder the very nature of our own existence. The emergence of the human mind is one of the great mysteries, and it's a question which has been tackled by religion, philosophy and science. And, as a scientist, I believe the answer is physical, the mind is a product of the brain.
And, if we want to understand the way we think and act today, we need to look at where we came from.
So, why did our ancestors brains get bigger? Its a difficult question, and we're not going to be able to answer it just by looking at their skulls. But what we can do is look at the wider context, the environment they lived in.
The Rift Valley has been called the crucible of human evolution. It's long been thought that it was the struggle to survive here, in this harsh habitat, that drove our evolution.
But there is a price to pay for having such a big brain. Giving birth is one of the most painful and dangerous experiences women have to endure. It does seem rather odd, given that reproduction is essential to the survival of any species, that, for humans, childbirth can be so difficult and painful. And that's all down to the large heads of our big-brained babies.
Humans are the only species that need help to give birth. Our babies' heads are so big that it's astounding they can get out at all.
You can see, from the image below, the space through which the baby has to pass. from the inside to the outside, and it is quite a narrow space. If we look at the size of the baby's head, you can see that it is going to be a pretty tight fit.
The gap is so small that the baby's head must be oriented just right for it to pass through the opening, hence the need for outside assistance and, often, the need to resort to caesarean section for the baby's birth.
We're born with the biggest brain our mother's anatomy can cope with. But to ensure that a baby can be born, he has to come out before his brain is really ready, which means he's completely helpless. Compared with most newborn mammals, a human newborn's brain is relatively immature. They don't have much control over their bodies and even less ability to make sense of the world around them.
It will be about eight years before the brain reaches it's full size and it'll be mid-teens before it's properly mature. Growing our big brains takes time, and while it's happening, our children need looking after. And that has shaped our lives in ways you might not expect.