Origins of Us - Bones
Standing up on two legs had an important knock-on effect. It freed up our arms. The anatomy of our legs was completely transformed as our ancestors became consummate runners and walkers. But, what about our aems and our hands? We have really mobile shoulders. We have forearms which can rotate 180 degrees, and a grasping hand.
Now, these are all relics of our tree living ancestry, but we took those old adaptations and used them for something completely new, something that in turn, would shape our future.
And that, was making tools. As far as we know, the first stone tool maker was Homo habilis, appearing around two and a half million years ago. And every human species since has refined and developed that tool-making ability.
But, we aren't the only animals who use tools. So what is it about being human that makes our tools so special? To find out, I've come to the Uganda Wildlife Education Centre. Here we see chimps using stick to fish for termites and Dr Roberts notes the clumsy way they grasp the sticks.
So, could the secret to human tool use be the way we use our hands? Our hands move with incredible precision. They contain a quarter of the bones in the body. Surprisingly, our fingers themselves have few muscles in them, yhey're mainly moved by tendons from the forearm. Yet anatomically, our fingers and thumbs are very similar to those of our chimpanzee cousins.
There must be something going on which makes our hands unique, and uniquely able to make and use tools. To unlock the mystery of the human hand, I've come to the capital of the United States, Washington DC. Here, new research is shedding light on the evolution of our hands.
Professor Brian Richmond. And, for his test, I need to have one of my hands wrapped up in some very technical electronic equipment.
This very strange glove-like contraption looks like I'm about to play a bizarre virtual reality computer game. But, in fact, these blue strips are pressure transducers, which are going to allow me to capture information about how my hand works in real time.
The special strips in the glove measure the pressure I'm generating through each of my fingers. The bones and joints of our hands, the muscles and the nerves that supply them, are set up in such a way that we have incredibly fine control over the movement of our hands.
But, its not really about moving our hands freely in space, it's about the pressure that we can apply to objects.
Prof. Richmond "In chimpanzees, all of the fingers are very firmly attached within the hand. But in our hand, the third is firmly attached and the others are more mobile, particularly the fifth finger. So, er can move that little finger within the hand much more than an ape can, and we can rotate that little finger around to meet the thumb. Its almost like having a thumb on the other side."
But there's something else we have and chimpanzees don't. It's very obvious when you compare the bones. The thumb in a human hand is just so much longer and thicker.
Prof. Richmond "If you think how powerful a chimpanzee's hand is, ironically, the thumb is quite weak compared to the big powerful thumb that we have."
But, that big thumb is a relatively new bit of anatomy. It's only been around for the last tqo and a half million years. And it first appears in Homo habilis, our ancestors who made those early stone tools. It seems more than a coincidence that big thumbs appear at the same time as stone tools, and its always been thought that the two are linked. It's becoming clear that it's how our ancestors used the tools they made that shaped our anatomy
Dexterous and powerful hands were fundamentally important to the success of our ancestors. Our species Homo sapiens only appeared on the planet around 200,00 years ago, but we are the most successful human species aver.
With our hands we could make the tools and technology which allowed us to colonise every corner of the globe. But, they also enabled us to do much more than taht. They gave us the means to transform the world around us.