A person has five fingers on his hands and feet. Not all of them, of course, HERE READ FOR AN EXAMPLE HERE. But usually we have five fingers, because that is how many fingers were in the monkeys from which we descended, and the monkeys inherited five-toed limbs from their ancestors, and so on, up to the ancient amphibians that lived more than 300 million years ago. This is for those who believe in the theory of Evolution, although for some it is a MYTH.
Apparently, the common ancestor of all modern terrestrial vertebrates had five-toed limbs. In other words, the five-toed limb is a primitive, original limb structure for all terrestrial vertebrates. In most species, including humans, this structure has been preserved to this day.
Why did it happen ?
SOME VERTEBRATES HAVE A DECREASE IN THE NUMBER OF FINGERS or even a complete loss of them, sometimes together with the limbs themselves. This usually happened in those animals, which, for some reason, some fingers began to interfere, became "extra". For example, the ancestors of horses developed a large hoof on the middle toe, the toe itself grew greatly, and the rest of the fingers became unnecessary, they only interfered with the growth of the middle toe, and gradually disappeared. The ancestors of man, apparently, did not have such situations that some fingers became "extra". Therefore, they all survived.
The question, therefore, boils down to why the common ancestor of all modern terrestrial vertebrates had a five-fingered limb. Scientists today believe that there was no special reason for this. The five-toed limb does not have any fundamental design advantages over the four- or six-fingered. Apparently, five-fingeredness was fixed in the evolution of vertebrates purely by chance.
Among the oldest fossil tetrapods, as paleontologists have found out, there were forms with a different number of toes: for example, ichthyosteg had seven toes on its hind legs (the front ones were not preserved), acanthosteg had eight toes on its front paws and at least the same number on its hind legs … The legs evolved from the fins of fish, the fingers from the rays of these fins, and the number of fin rays in those fish from which terrestrial vertebrates originated was variable.
Apparently, the number of toes also varied in the most ancient terrestrial tetrapods. It happened by chance that it was the five-fingered forms that gave rise to the whole variety of modern tetrapods, and animals with a different number of fingers died out. But they died out, most likely, not because they had an unsuccessful number of fingers, but for some completely different reasons, in connection with some other, more significant "shortcomings" of their structure. In principle, it could well have been "lucky" not with five-fingered, but, say, seven-fingered ancient amphibians. And then, perhaps, people would now have seven fingers on their hands.
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We need to be properly balanced for our bodies to function easily and correctly. For those born with extra fingers, things are not so easy. Nature has also tried to work on animals and insects: insects usually have 6 legs, and a spider has 8, and this is the right amount for them to exist normally. This is why the dog has exactly 4 legs, not 5, and so on. Many people believe that our system of calculus is decimal precisely because we have 10 fingers. If we had 6 or 8 fingers, the system would probably change.
There is another interesting question. Do we really need all the fingers? The answer is no, or rather, not quite. Surprisingly, the most essential toes on the feet are the big ones, they help keep balance. Some are convinced that all fingers are needed. On the hands, the thumb and forefinger are the most important. The rest just help, but the main manipulations are carried out by these two.
Would life become worse if six fingers developed on a person's hands?
An extra finger near the little finger would make some tasks easier. We could play more complex musical instruments, type faster and grip objects more tightly. "A wider arm would make it easier to play basketball," says Cliff Tabin, a geneticist at Harvard Medical School who studies limb evolution in vertebrates. “But the fine motor skills of our hand are mainly the thumb and forefinger. An extra little finger wouldn't have played a big role."
However, the greatest impact would be in the field of mathematics, and a different counting system would have surprisingly profound implications.
Counting man
All over the world people count in dozens. Anthropologists believe that we owe this ten-digit counting system to the number of fingers on our hands. It seems natural to us, but this is only because we are used to it. If we had six fingers on each hand, we would definitely get used to the 12-digit system, Tebin is sure, while the numbers would be like this: 1, 2, 3, 4, 5, 6, 7, 8, 9, x, y, 10. "We would think that the 12-digit system is the simplest and most natural, and the 10-digit system would be as incomprehensible as the 14-digit system," says the scientist.
Perhaps there is not much difference how to count - tens or dozens, but Mark Shangizi thinks differently. The head of the laboratory for the study of properties of human perception at the research institute in Idaho, USA, believes that many human achievements, be it mathematics, speech or music, progress rapidly when human culture takes the most natural form of expression of this achievement.
“In my book The Revolution of Visual Perception, I argued that our ability to read so well is related to the shape of the letters, which in the process of cultural development began to look natural. Their shapes and curves can be seen in nature, and therefore they activate our visual object recognition mechanism, which allows us to read, explains Shangizi. - In my next work, I explained that we have the ability to understand speech due to the fact that, culturally, speech developed as something natural. That is, in its sound, the noise from solid objects can be traced, which could be heard in the habitats where we evolved."
When culture takes advantage of evolutionary conditions and creates natural ways of doing things, we do great. When culture fails to engage human evolution, we undertake a new task uncertainly, unnaturally and pitifully, the scientist notes. For example, performing logical tasks is a classic case when we seem to be insufficiently adapted, since even the simplest concepts in logic are frankly complex and for really smart people.
Coming back to counting fingers, it should be noted that 12 fingers would significantly affect the mathematical ability of people. After all, the number 12 has many more factors than the number 10.
“The choice of counting system can affect reading as well. As a result, instead of reading letters that we are used to, we would have to read bar codes (and we would never be able to do it well, despite long training),”explains Shangizi.
According to the scientist, it is difficult to say for sure whether the transition from a 10-digit system of counting to a 12-digit system would turn us into a person who counts. But it would certainly be a major blow to our "digital technology", which makes the most of cultural evolution for our achievement.
The rule of thumb?
Extra toes sometimes appear as a birth defect. This is called "polydactyly" and is a common genetic error. But natural selection hasn't made these extra fingers permanent. Why not? According to Cliff Tabin, one more finger does not provide anything new, and therefore does not provide any evolutionary advantages on a global level. If we were to develop a truly necessary sixth finger, it would probably grow out of the wrist as an extra thumb.
This is the standard model for the few tetrapods (tetrapods) inhabiting the Earth, such as the panda, which have an extra thumb. It is actually an extension of the wrist bone used by pandas to support when grasping bamboo.
But Shangizi argues that humans could not have had an extra thumb. He developed a theory to explain the five-digit number of fingers on a limb in the animal kingdom, which he called the "law of finiteness." It is a simple mathematical formula derived from the rules for the number of nodes in computer networks, which provides the optimal number of limbs needed by the body to communicate with the outside world based on its size. The law states that when the limbs are very long relative to the body, there should ideally be six (for example, insects). With the shortening of the limbs, their number increases to large values (for example, millipedes). The law also suggests the number of toes required for a limb based on their size. Considering that they must be of the correct length to cover the palm,the optimal number of fingers for a person's hand is the number five.
"If we needed one more finger to perform newfangled tasks (typing, surgery, fanning, etc.), this would be a significant deviation from the optimal morphology for which our hands have evolved, namely, grabbing various objects." - explains Shangizi.
Some neurologists agree that six fingers are too many. In modern prosthetics, robotic arms are being developed that work perfectly with two, three and four fingers. Therefore, the normal number would be four rather than six.