It’s simple: place your arm on a flat surface and extend the palm of your hand; joins the thumb with the little finger and, if a tendon protrudes as seen in the , the palmaris longus, which other species of primates such as the oraguntan use effectively. Humans don’t use it. In fact, 14% of the population no longer have it.
evolution in action. When we talk about human evolution, we usually talk about milk. 11,000 years ago, when livestock farming was born, human beings began to consume milk out of hunger, even if it sat us (literally) like a kick in the stomach. Human beings, like the vast majority of mammals, could consume milk during a very specific period of their lives. As they grow older, the ability to produce lactase (and break down lactose) disappears.
Some 7,000 years ago, evolution and chance began to propagate one of the greatest genetic revolutions in history: the ability to produce lactase throughout life. It was such a frankly good mutation that it has been spreading very quickly and now, in the West, it seems normal to us. Even so, today, only 35% of humanity can safely consume lactose. It is pure evolution in action and, of course, it is not the only case.
A curious muscle called palmaris longus. In most humans, there is a muscle that arises from the medial epicondyle of the humerus and the fascia that covers it and inserts on the palmar aponeurosis. However, its absence (whether congenital or postoperative) does not affect the function of the hand.
In fact, surgeons have used the palmaris longus tendon for many years to replace other tendons when they rupture: it’s easy to remove and doing so is harmless. It helps to flex the hand and tightens the palmar aponeurosis, but since it plays a very weak role, the fact that it disappears is of no consequence.
An evolution that goes faster and faster. As we said a few years ago, human evolution has not stopped. Moreover, there are reasons to think that it is more accelerated than ever. The most obvious is that many more people are born than before, and chance can produce what was previously extremely unlikely: once it occurs, natural selection does the rest. And yes, the long palm grove is a striking example, but it is by no means the most important. The best (as always) is yet to come.
