Was ability to run early man's Achi...(eletons; we use what we know about skele...)

This model is a virtual robot where we can activate muscles and get it to move its legs in a physically realistic fashion; the tricky bit is getting it to actually walk or run without falling over.

However, if we use big enough computers and let the model fall over enough times it is possible for the simulation to learn which muscles to fire and when in order to get the model to walk properly. Even better we can ask the computer to find ways of minimising fuel cost and maximising top speed since that is what we think animals have to do.

Dr Sellers initially looked at walking and his models suggested that even as early as 3.5 million years ago our human ancestors were able to walk as efficiently as modern humans. His research also showed that they preferred to walk a little slower than we do but only because they were much smaller and had quite short legs.

The team also used the computer model to look at particular parts of the human locomotion system, including the Achilles tendon, which they showed acts like a big spring to store energy during running; when the tendon was removed from the model the top running speed was greatly reduced.

We have only just started to look at running and so there are still plenty of questions to answer, said Dr Sellers. But whilst these very early fossils could walk well, our initial findings suggest that efficient running came about quite a bit later in the fossil record.

How we evolved from our common ancestor with chimpanzees six million years ago is a fundamental question. Walking upright seems to be the very first thing that distinguishes our ancestors from other apes, so finding out about this should help us map the evolutionary pathway to modern humans.

The next really interesting question is to look in more detail at running. It has bee
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