Much of this analysis got here from the thoughts and laboratory of Daniel Lieberman, a professor of human evolutionary anatomy at Harvard University and writer of the brand new e-book “Exercised,” which delves into train and evolution. At first, most of his and different scientists’ work associated to evolution and operating centered on decrease our bodies, since legs play such an apparent half in how we get from one place to a different.

But Dr. Lieberman additionally was all in favour of runners’ higher our bodies and, particularly, their heads. As a longtime marathon runner himself, he knew {that a} secure head is crucial for profitable operating, however not essentially a easy factor to realize. Running is propulsive. You push off, rise after which brake forcefully towards the bottom with each stride, inserting forces in your head that might make it flop uncontrollably, like that bobbing ponytail.

How we handle to maintain our heads secure, nevertheless, has not been altogether clear. Like most cursorial species, or animals that run, together with canines and horses, we have now a well-developed nuchal ligament, a tissue that connects the cranium and neck. That is just not the case in species that aren’t pure runners, like apes or swine.

When he was a younger scientist, Dr. Lieberman recalled, he enticed pigs — who’re inelegant runners — onto treadmills to check their biomechanics. Their heads jiggled like bobbleheads after they had been compelled to run, prompting Dr. Lieberman and his colleagues to conclude they lacked a nuchal ligament, a discovering borne out by anatomical research.

But we people even have the problem of being upright, on two legs. Presumably to steadiness ourselves whereas operating, we started, sooner or later, to swing our arms. Dr. Lieberman guessed that the arm swing helped to stabilize our heads. But, in that case, there must be coordination between the muscular tissues in our forearms and shoulders, he thought, despite the fact that these muscular tissues don’t bodily join. They would wish to fireside collectively and with comparable drive throughout operating, in the event that they had been to achieve success in stabilizing our heads.