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Pere Renom

“We have given you, O Adam, no visage proper to yourself, nor endowment properly your own, in order that whatever place, whatever form, whatever gifts you may, with premeditation, select, these same you may have and possess through your own judgement and decision […] We have made you a creature neither of heaven nor of earth, neither mortal nor immortal as the free and proud shaper of your own being, fashion yourself in the form you may prefer.”

Giovanni Pico della Mirandola

Evolve standing

published on 17.07.2020

Humans are exceptional mammals, not only for our intelligence, but also for our biped locomotion. In fact, apart from kangaroos, we are the only strict biped mammals. Bipedalism appears to have provided several adaptive advantages: it increases the field of view, it decreases the body surface exposed to sunlight, and it frees the hands. We have a series of anatomical modifications for walking straight, at the level of the skull, spine, pelvis, lower extremities and feet. But bipedalism is much earlier than humans. The vast majority of dinosaurs were bipeds, such as carnivores Spinosaurus, Allosaurus, and Giganotosaurus, or herbivores such as Parasaurolophus. From the fossil remains we know that it was a very different bipedism from ours, since it implied an almost horizontal or parallel spine to the ground, with the head and tail counterbalancing, and tilting on the strong hind limbs. Evolutionarily this position seems to give more speed in the race to both predators and prey. Today, there are still some quadruped lizards, which run away on two legs when they feel threatened.
The most direct living descendants of dinosaurs are birds. Certain groups, such as struciforms, have lost flight ability and instead developed great running speed. They are true downy dinosaurs. In this group we find the ostrich in Africa, the emu and the cassowary in Oceania, and the rhea in South America.
Both birds and humans rest all body mass on their feet. Jordi García, a sports podiatrist, uses a pressure platform to explain how humans walk and run. At a walking pace, we always keep at least one foot on the ground, and the bridge of the foot absorbs pressure and helps to move forward. Instead, the race is a succession of jumps, and in some instants there is no foot on the ground. Therefore, much more energy is required, and it is obtained from the muscle and tendon systems of the leg and foot, acting as a spring. At more speed, it is necessary to accumulate more energy in the spring, which is obtained by strengthening the muscle and tendon system, and reducing the support surface on the ground. This has been the strategy of the running birds, and as a result they reach a speed of about 50 km/h in a sustained manner, and 70 km/h in a sprint.
One of the oldest evidences of bipedalism in hominids corresponds to traces found in volcanic ash in Laetoli (Tanzania), dated at 3.7 million years old, and attributed to Australopithecus afarensis. In those days, brain volume was much lower than it is today, indicating that bipedalism preceded encephalization. On two legs evolution walked towards human intelligence and towards animal speed. Who has no head, has legs.

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