Some animals can reach incredible speeds, but we humans excel in endurance.
Our two-legged evolution, foot structure and cooling system make us unique in long-distance running.
I saw a crab walking on the beach. It cut me off while I was walking on the shoreline. I followed it a little bit with my eyes to get a better look at it: it stopped for a while and started again. I had never noticed how fast a crab runs (really fast). I also tried to chase it but it was much faster than me. I’m not fast and I’ve come to terms with it but getting beaten by a crab was not on the agenda.
So I tried to figure out how fast it goes. The speeds they can reach fluctuate depending on the species but range from 5 to 6 mph to much more. Some speak of 22 miles per hour, which means 35 km/h! That seems like a lot to me, and let’s say that even if they were doing 7 to 8 mph they would already be very fast, even considering that in relation to their bodies, they go even faster. To say: if we humans could run at speeds comparable to their body size/distance ratio we should reach 500 km/h.
Of course, we have an advantage that allows us to sit at the table and eat them in soup: fishing nets.
Joking aside (animal rights activists, sorry), our advantage is that they maintain those speeds for a very short time and over modest distances, while we are the animal with the most endurance of all. In fact, there are so many of them faster than we are: not only crabs but also cats and dogs, without bothering cheetahs or peregrine falcons.
Yet we are the only species that has evolved to the point of covering more distance before giving way. At the expense of speed, which we left to other species for a practical reason: at the dawn of hunting-and we are really talking about hundreds of thousands of years ago-our ancestors understood that they could not compete in terms of speed but only in terms of endurance. In other words, hunting meant going after a prey for a long time, until it could take no more, tore out, and, weakened, was much easier to hunt.
How did we achieve this?
How many animals do you know run on 2 legs? If you answered “Only human beings,” I’m sorry to correct you. We are in good company: some birds, gorillas (even if they rest their front legs occasionally), kangaroos, ostriches and meerkats also run on two legs/feet. Nor are they all.
Ostriches are also much faster than we are: they reach 70 km/h and run because they do not have a sufficiently developed wing structure to make them fly.
We, however, continue to remain unique in our resistance: in short, we eventually catch the ostrich, partly because if it runs too long it is likely to have a heart attack.
What has allowed us to be so resilient? There are different theories, and to begin with, we need to understand why we stood up in the first place. It was by no means a foregone conclusion, except that–according to one such theory–one fine day a very long time ago the fact that we stood upright made us realize that we could have a very interesting point of view of our surroundings, making us, for example, visually probe the terrain better, thus identifying danger but also prey.
From that point on, the evolution was continuous and unstoppable, until it led us to the form we have today. In which each part responds to a function and purpose and in which everything has evolved to make the act of running as efficient as possible. In short, when we say that we are made to run, we are saying something very true.
Standing and moving on only two legs allows less energy to be expended, conserving more to increase endurance. Using only two of the four available limbs also leaves the other two free for grasping things or weapons and for balancing the running motion.
Feet, no longer paws
Our feet are percentually a small part of our body, yet they are also mechanically among the most interesting areas. According to Daniel Lieberman, a human evolutionary biologist at Harvard University, for example, we have short fingers to prevent them from breaking during running. We have very strong tendons to withstand loads, the arch of the foot itself works like a spring, and our glutes are so big to keep the torso from bending forward, helping it stay upright.
Our spine has eventually evolved to the point of being flexible because being bipedal means keeping half the body balanced while the lower half does all the work. That’s right: arms and spine and head form a very complicated static system that must always be balanced on a moving body part (the legs) so as not to get in the way while running. Military jets flying at supersonic speeds need on-board computers to control every minute attitude and course adjustment, but it’s not like our trunk does much less.
The cooling system
Our greatest advantage lies not in our muscles or trim but in how we cool down. How in short we can dissipate heat. Indeed, some, like McDougall, argue that it is the fact that we know how to thermoregulate ourselves by sweating that gives us the ultimate advantage. In fact, being able to keep our body temperature within guarded values allows us not to go into crisis, thus avoiding the collapse of the cardiovascular system.
This is made possible by the fact that by standing upright, we also have a larger exchange surface area than a quadruped, increased further by the fact that we are little or no furry animals. The heat-exchanging surface of the skin is thus in direct contact with the air and can cool faster.
If during your next training session you are overtaken by a jaguar, you can safely shout after it, “Run, run: I’m going to catch you anyway.” And then run.
(Inspired by Livescience)