Chimpanzees
Origins of Us - Bones
Our story began around six million years ago, with apes who lived in an ancient African forest. In many ways they would have been similar to the apes that still live in the forests here today. I'm here in the ancient forest of Kibale in Uganda, which covers about 700 square kilometre and I'm hoping to do something really special, and that's to track down some of our c;psest living relatives - chimpanzees.
I want to get close enough to see how their bodies work, but getting near to the wild chimps who live in this dense, wet forest isn't easy. Franci Mugurusi is my guide. He's been studying the chimps here for nearly 20 years. We are so closely related to chimpanzees , we share nearly 99% of our DNA with them. But, although we're genetically close, we are not descended from them.
A young cimpanzee
Looking at chimpanzees helps us understand where we've come from and that's not because we've evolved from them, of course we haven't, but if we trace back each of our family trees far enough we reach a point where they come together, we have a common ancestor with chimpanzees, going back about six or seven million years ago.
Now, their ancestors stayed in the forests, whereas ours moved out. If we can find out how and why we did that, well, that's the story of how we became human.
Our evolutionary journey is written into our bodies and into the way we use them. A chimpanzee's body is built for a particular wat of getting around. Dr Roberts is watching a chimp sleeping on the forest floor. He's got these wonderfully long arms and very short legs. He's a climber. His feet are wonderful. He's still got this grasping ability in his feet tha we've lost. He's able to grip onto things and climb. His great toe, his big toe, is set out to the side so it makes his feet like hands. Millions of years ago, our ancestors would have had feet which grasped like this. In six million years, our body plan has become very different, with our long legs and feet for walking on.
So what was it that set our ancestors off on a different path, a path that would lead us to colonise the globe, whilst other apes stayed in the African forest? And, when did we start to change?
Fossilised Skull
Its always been a puzzle. Until this extraordinary fossil was discovered just a few years ago. This is Toumai, also known as sahelanthropus tchdensis, and its not putting it too strongly to say his discovery caused something of a stir. He certainly looks like and ape and she compares it to a modern chimpanzee skull. But there's something very special about Toumai.
I want to show you the foramen magnum underneath the chimpanzee skull. This is where the spinal cord exits the skull. The foramen magnum of Toumai is directly below the skull showing the skull balancing on an erect spine. This is an ape who stood upright on two legs. And not only that, this is a bipedal ape, who dates to six or seven million years ago.
This is a hugely significant moment in our story. It means that Toumai was moving around on two legs very close to the time our ancestors split from the chimpanzees. Ther's no question, he's more chimpanzee-like than human ,but Toumai puts standing up right at the start of our journey.
In the six million years since Toumai stood upright our skeleton has undergone many changes.
