Do you know why a person has five fingers

Look at your hand. Most likely, the number of fingers that you find there will be five. There are, of course, exceptions - if you won the sixth in the genetic lottery. Or, on the contrary, they showed negligence when cutting New Year's salad or a blank on the machine. But the standard number is always five.

Other animals usually have no more of these body parts either. Downward deviations occur: for example, in horses there is only one finger, but what kind of nail is on it. But six-fingered and seven-fingered creatures are also rare among our smaller brothers, a genetic exception to the rule. Ever wondered why?

Scientists also thought about this and came to the conclusion that just like that happened.

The earliest amphibians, stegocephalians,

had quite a varied number of fingers. So, acanthostegi on each paw of them was eight, while Ichthyostega has seven. The fact is that the limbs of amphibians happened from the fins of the fish, the fingers from the rays in these fins, and there are many of them.

But over time, six-, seven- and eight-fingered stegocephalians died out - this It happened 360 million years ago at the end of the Devonian. And the five-fingered ones survived and gave rise to amphibians, and then to reptiles, birds, mammals and humans as well. The structure of the brush came to us from them.

In the process of evolution, many animals have lost extra fingers. For example, in carnivorous therapod dinosaurs, on the front paw of their was three, and the most famous, tyrannosaurus rex, has two. These creatures used jaws, not paws, to capture prey, so they didn’t need fingers. And what is not used, sooner or later becomes a vestige or disappears altogether.

True, it cannot be said that six or seven fingers are worse from the point of view of evolution than five. For example, pandas developed a kind of replacement for an additional finger, transforming metacarpal bone - they need this in order to grab the bamboo.

And amphibians with eight fingers died out in antiquity, not because their polydactyly interfered with them, but according to others reasons. For example, in the same Acanthostega, the ribs turned out to be too short to ensure the normal functioning of the lungs out of water. The structure of the limbs has nothing to do with it.

In general, people have five fingers only because our distant ancestors had just as many of them - that's all. It happened 360 million years ago, and then nature did not need to change anything.