Origins of Us: S01E03: Brains

In this, the final episode, Alice looks at Brains. How we grew them so big and why we’re the only type of human left on the planet. How we think, feel, and behave is due to the actions of our ancestors. Was it our brains that helped us survive when other human species died out?

Millions of years of evolution have shaped our amazing bodies. But really, we are just another species of Ape. Well, apart from our brain – we have the ability to think, imagine and create in a way that has changed the world. And the ability to think about all of these things – about how and why we’re here.

In East Africa is where our story begin, in the Out of Africa theory, so for Alice there’s no better place to start looking. Unfortunately we’re the last type of humans, but there have been many types in the past. Looking at the skulls of humans, we start at around 300ml: 7 million years ago. Moving on to the first homo genus at 500ml: 3.5 million years ago. Finally, ending up with us 200,000 years ago with 1466ml skull cases. This is nearly 4 times the volume of that of our earliest ancestors.

We need to look at what was happening to Earth during the time that our ancestors brains were expanding. The Rift Valley, it seems, created a harsh environment and a struggle to survive. This area was changing every few hundred years , making it necessary for behaviour to adapt – to find new ways of acquiring food and water. It seems that the fluctuating environment and the size of the brain are linked, so this increase in size is the skill of adaptation.

Like us Chimpanzees life in social groups. The reaction of the group when mixed with a Dutch group is to assess who’s who. Making and keeping allies is necessary – as is finding out who to bully! Which shows mental flexibility, a trait used to figure out how to get varying types of food.

Although we have things in common, something that we can do that no other animal can’t, is read someone by their eye gaze. We can read a whole host of emotions from people’s eyes.

Making tools is an important feature of being human. Homo Habilis, only had a brain half the size of ours – but he’s the first human that we know used tools. Over time tools became more complex and enabled our ancestors to get to larger, wider variety of, food.

With tools to butcher meat and protect themselves, our ancestors were able to live in new areas. Stone hand axes tell us about the behaviour of our ancestors and their minds. In order to make a stone tool, we need to have an image in our mind. It is thought that this ability is related to language. While language is a massively important feature of being human – we have no certainty of when language first occurred. We can’t even check the fossil record, as vocal tracts are soft tissue, so don’t remain. But we do know our species use language, which enables us to teach and learn at a complexity that no other animal can match. We language we can take the things we think and the images in our mind and share them.

Having such large brains means that we have to be born before our heads get too big. This means that we have to be born before our brains are really ready – 8 years before it gets to the maximum size and mid-teens before we can really use it properly. Back to the Hadza tribe of the last episode we see that they breastfeed for 3 years, compared to the 6 months that seems normal in the West. Which certainly seemed odd to the Hadza women. We see that the grandmother is a very important person in the rearing of children. This seems to have effected how long we evolved to live for – an example being the Hadza women who live into their 70s. By living longer we are able to breed much higher numbers of offspring – more than any other ape. Grandparents helping in the caring for grandchildren, extra knowledge is passed on and more children can be born.

We know that when Homo Sapiens travelled the world, other species of human were already living there. Like in Europe with the Neanderthals. With a fairly similar sized brain case – why did we survive when Neanderthals didn’t? Looking at Neanderthal DNA we can see that we are closely related with the same origin. Also that our Sapien ancestors did mate with Neanderthals and that they had the genes for speech. But to really see why they died out, we need to look at where they lived.

Gorham’s cave can tell us a lot about how the Neanderthals lived around the same time as Homo Sapiens lived. We see that they were eating molluscs, showing a wider diet than previously thought. Also using fine flake tools, which while different to ours achieved the same end. Going right back into the cave, we see where the Neanderthals of the cave lived and slept – with a camp fire radiocarbon date of 28,000 years ago. This is the most recent date of any Neanderthal site – possibly one of the last places that they lived in. Climate change seems to have been the end of the Neanderthals. Their lack of ability to adapt to a warmer climate and wider open spaces.

Well, unfortunately, that’s the end of this TV series. I’ve found it to be a brilliant series. I know that there are other points of view regarding different theories of our populating the world and also that of different religious aspects. But I really enjoyed this series– the story of our evolution, with the discussions of culture and technology that were successfully included. I enjoyed the inclusion of the Hadza tribe and felt that it added a lot to the series. I hope that Alice will continue her journey into the evolutionary past of humans. This series was a really good follow up to the Human Journey of two years ago.