I’ve been blogging since August 2007. Which seems quite a long time, looking back on it :-) Anyway, because I’m kind of rushed at the moment – & on the theory that new(ish) readers might not have delved all that far into the back issues, I thought I’d repost a couple of pieces from way back then, just to keep you going.
I was looking through the SciTech Daily website (a good place to go for new reading in a whole range of science areas) when I saw the link to an article on the evolution of running in Homo. Followed it, read the article – & thought, this is really interesting.
The article describes research on the efficiency of walking and running in humans. It notes that the Achilles tendon linking calf muscles to the heel is essential for energy-efficient running. Chimps and gorillas don’t have this long tendon, and the research team comment that it would be very interesting to know at what point in our evolutionary history the Achilles tendon evolved:
But if, as seems likely, early humans lacked an Achilles tendon then whilst their ability to walk would be largely unaffected our work suggests running effectiveness would be greatly reduced, with top speeds halved and energy costs more than doubled.
In humans, the Achilles tendon acts as a shock absorber and also stores energy. It stretches as your foot comes down (the braking phase), gaining elastic potential energy. Then, it releases that energy through recoil as you push off from the ground again. That is, the tendon is acting like a spring – one that can save up to 50% of the metabolic cost of running through reducing the work done by the muscles themselves. This makes Homo quite good at endurance running, something that would be essential for active hunting out on the savannah.