The story of the hand

The story of the hand goes back to the origin of terrestrial vertebrates, between 390 and 340 million years ago. In those times, some fish ventured to colonize the terrestrial environment and the first amphibians emerged. Those animals had 6, 7 and up to 8 fingers on each leg, but they ended up becoming extinct and only 5-finger amphibians survived. Consequently, all his descendants present 5 fingers. Throughout evolution, that 5-finger hand has specialized to give wings to birds or bats, hooves to horses, claws to felines or fins to cetaceans. Our hand basically serves to take, but we also use it to count. The decimal system is based on powers of 10, such as the number of fingers. To measure we also use the inch and the span. The fingers do not contain muscles and move through 5 tendons that connect them to the muscles of the palm and forearm. The hand is a puppet of some muscles, which, in turn, are a puppet of the brain.