What properties of nature did our distant ancestors need to change so that their descendants through hundreds of thousands of generations read this article? We decided, taking into account the latest achievements of science, to compile our own list of factors that contributed to the development of the ancestors.
It should be noted that our list is not intended to compare the importance of the details listed in it. We do not assert that the monkey would become a man without something, or, on the contrary, that its development would be impossible without it. We are only stating facts known to us.
You also need to understand that the division into monkeys and people is conditional, since both people and modern monkeys, and their common ancestors belong to the order of primates, that is, monkeys. So man, as a species of the genus Homo, from the point of view of a biologist, is also a monkey, only more developed. And the term “man”, which is familiar to us, is a philosophical concept that defines a being that is integrated into a certain cultural environment and is inextricably linked with it.
The habit of moving on two hind limbs, keeping the body upright, is traditionally considered one of the characteristic features of Homo sapiens. In fact, she is pretty much older. Bipedalism was characteristic of all species of the genus Homo, and apparently arose even before its appearance.
All known Australopithecines, which were the predecessors of the genus Homo, and before them - the Ardipithecus, walked on two legs. Even the most ancient of our supposed ancestors known today - the Sahelanthropus who lived in the vicinity of Lake Chad about 6-7 million years ago - is also suspected of bipedality.
True, in his case (and in some others), the discussion is complicated by the fact that the scientists do not yet have leg bones at their disposal. The discussion is conducted on the basis of the location and structure of the occipital foramen, which in the found skull occupies a median position, like in bipedals. Opponents point to a flattening of the occipital bones, to which the neck muscles were attached. Therefore, our hero walked on four legs. Proponents of upright posture in response argue that the back of the head was posthumously deformed.
Obviously, the dispute will not be finally resolved until new, more complete, remains are found. It is noteworthy, however, that such a discussion is generally possible, because we are talking about a creature from the deepest antiquity.
It should be noted that great apes are generally characterized by modes of movement in which the front and hind limbs play different roles, which leads to a difference in their structure. Let us recall the gibbon, which clearly does not pretend to be our progenitor, but also a relative. He walks in trees, in fact, with his hands alone, and on the ground he can run on his hind legs. It is very likely that the rudiments of bipedality were formed even there - in our common ancestor with the gibbon.
This human ability is not lucky - it almost leaves no discernible traces. It is impossible to establish from the skeleton how talkative its owner was during his lifetime. Of course, experts are trying to use whatever crumbs they have: genetic material and skulls. It doesn't turn out very well. It is more or less known which parts of the brain are responsible for speech activity in humans. And by the structure of the skulls, one can judge how much they were developed in our relatives. Alas, this in itself does not prove anything. Both humans and chimpanzees have Broca's Center, for example. But in the former, he participates in speech activity, and in the latter, in mimic activity. How it was involved in ancestral forms is a big mystery.
Based on the totality of the available data, one can reasonably suspect the presence of Neanderthal speech. They had the right brain centers, the right genes (for example, the regulatory FOXP2), and just their daily life, according to the latest data, was too much like the life of our direct ancestors. As for all the other heroes, there is no reliable clarity here.
While hammering in a nail, a person is dealing with two objects - a hammer and a nail. Scrolling the minced meat on a manual meat grinder - with three: meat, a handle and minced meat, which must be laid out on a plate or board. When proving the theorem at the blackboard in the school, the number of objects increases to 5–6.
Anthropologists believe that the limit of the mind of Homo sapiens is the simultaneous operation of seven objects, information about which is stored in special areas of the brain.
In distant hot Africa, some chimpanzees are able to stab nuts with stones. For chimpanzees, the result of this activity is tasty and healthy. This skill is not inherited, primates learn it in childhood, and not everyone is given this cunning science.
The tricky process of cracking nuts
Depending on local traditions, when cracking a nut, the monkey either holds only it, or - the nut together with the anvil. In the first case, the intellect of our relative is addressed to two objects - a stone and a nut. In the second - to three. In the first case, almost all members of the population master the art of ingeniously obtaining food. In the second, about three quarters. Based on this (there are other observations that we will now omit), scientists believe that the limit of the intellectual capabilities of chimpanzees is 2-3 objects.
There is no reason to believe that our ancient ancestors were much more capable. Scientists conclude that the gradual increase in their ability to make stone tools is associated with the emerging ability to keep in mind more objects. The time frame for this process is not yet clear to us.
The activity of the nervous system of animals, like many other things, is regulated by hormones. In primate organisms, including humans, the regulation of some of the emotions and cognitive functions, such as remembering information, is assigned to endorphins. The precursor (that is, the raw material for the synthesis) of several of them is the prodynorphin protein.
The gene encoding this protein is different in chimpanzees and humans. A mutation inherent in humans has affected the regulatory part of the gene, which is responsible for its activation. In other words, the protein itself remains exactly the same, but the conditions for its synthesis have changed.
According to scientists, this led to the fact that the human body produces about 20% more prodynorphin than monkeys. This in itself is interesting, but even more interesting is that protein production occurs as a reaction to some kind of stimulus. Alas, we can only judge them in the most general terms, since the methods of modern science do not allow more: the colony of cells on which the study was carried out, of course, does not have an emotional status and does not change it in any way. For a full-fledged study, you need to raise a genetically modified person with a monkey gene and look at his behavior. It is clear that such an experiment is impossible today.
The gene changes that make it different from the monkey are inherent in all living Homo sapiens. This makes one think that the mutation had some kind of evolutionary significance. When it happened, now it is impossible to say.
The oldest human fire known at the moment is probably no more than 800 thousand years old. This honorary title is claimed by the remains of two fires: discovered in 2009 at the Gesher Benot Ya'akov site in Israel (690-790 thousand years) and found in the Spanish cave Cueva Negra in 2011 (600-800 thousand years).
By the fire of these bonfires, the then Homo erectus or Homo ergaster could warm themselves - it is still difficult to say more precisely. It is noteworthy that the age of both finds, despite the obvious geographic distance, is approximately the same.This suggests that about 700 thousand years ago (let's be careful with numerical estimates), the use of fire was already popular among people. Whether they knew how to light a fire or only store a flame obtained from somewhere, as described many times in fiction, is a big question.
In Africa, found about half a dozen places of possible starting of fires older than a million years or more. So far, it cannot be considered firmly proven that in these cases we are dealing with fire, set off by people, or at least under their control. Perhaps we are talking about natural fires or, in some cases, about manifestations of volcanism.
There is no doubt only about the Sapiens and Neanderthals. These, of course, knew how to handle fire - a hearth at their sites is almost obligatory.
Fire control leads us smoothly to the next steps.
Meat and its preparation
Most modern monkeys will not give up the role of situational predator. Busting a bird's nest is the cutest monkey business. And chimpanzees even arrange group hunting for lower monkeys. But the basis of nutrition is still plant food. Moreover, there are serious studies linking the intelligence level of primates with a love of fruit. This is logical. The sweeter the fruit and the more difficult it is to get to it, the smarter the one who manages to eat it must be.
Meanwhile, meat food is clearly more nutritious, and well-cooked meat is even more so. In 2007, American scientists conducted an experiment on feeding boiled meat to a Burmese python. It turned out that at the same time, energy consumption for digestion of food decreased by 12, 7% compared to food, for example, raw mice. And if the meat was also passed through a meat grinder, then the savings reached 23, 4% - almost a quarter!
The lab mice, who were also fed boiled meat, gained almost 30% more weight in five weeks than their mice who ate raw. Of course, the calorie content of food was nominally the same, but it was assimilated differently. Heat treated is lighter.
This suggests that if hunters had happened hundreds of thousands of years ago to eat game fried on a fire (they did not have a pot, let alone a meat grinder), the effect of eating it would be noticeably higher than that of raw food. It is likely that the size of the organism became larger, even without the participation of evolutionary mechanisms, simply because during the growth period a person ate well. And, of course, in the best conditions, his brain turned out to be a champion in energy intensity. In a modern person in infancy, the brain "eats" about a quarter of calories. With age, this share becomes smaller, but it still looks very impressive. Against the background of monkeys, in which the share of the brain in the total energy consumption is a few percent, this is a lot.
The brain of our ancient ancestors was once about the same size as that of today's great apes - 400-450 cm3… It gradually increased in size (the larger "thinker" clearly gave its carriers evolutionary advantages), but not to say that very quickly. Then something happened, and twice (!) With an interval of several hundred thousand years. Homo erectus brain averaged 1000 cm3, the midbrain of Neanderthals and Sapiens reached one and a half thousand "cubes". At the same time, the rest of the body also grew, but there the growth was less pronounced.
There is a well-argued opinion that changes in brain size are associated with diet. At the first stage, meat appeared in it, and the first increase in the brain is associated with this. And then they learned to fry the meat on fire, which made it, if not tastier, then certainly more nutritious, since it was absorbed much better. This dietary change is essentially a two-step process, so we'll see it as two steps from monkey to human.
By the way, modern chimpanzees spend about five hours a day chewing (not even getting!) Food. And the hunters living nearby of the most traditional way - only an hour.To be on the same level with the monkey, we need to sit in a restaurant for the whole evening.
The way of eating erectus and its immediate predecessors continues to be the subject of debate. It is very likely that they were more scavengers than hunters. Of course, such a relationship is not very aesthetically pleasing, but the animal bones found in the camps speak for themselves. Scratches from stone tools are usually located on top of (i.e. after) the marks left by the predators that gnawed at them.
Neanderthals were tough guys and killed their prey themselves. They ate almost exclusively on hunting meat. And he won them in an evolutionary competition (perhaps sometimes turning into real clashes) Homo sapiens - a versatile food, whose diet has long contained plants and fish.
Homo sapiens, having been born into the world, goes through several stages of maturation. One of them is adolescence. This is a difficult time, when a person, in fact, can already do anything, but at the same time knows too little, does not know enough and at every step risks finding himself some kind of adventure. The society treats his searches rather condescendingly, while not imposing full responsibility for them. As is commonly believed, this period ends somewhere around 17-19, when yesterday's teenager has already accepted the norms of behavior that have been established among adults and is ready for an independent life.
Modern monkeys do not have a full-fledged analogue of adolescence. The cub grows, and then, as soon as it can, acquires its own.
It is difficult to say how this was the case with the ancient people, because you cannot ask them. Judging by the remains of the Neanderthals, their children from an early age looked like adults. They probably reached sexual maturity by the age of 7–8. There is an assumption (for obvious reasons, it is difficult to argue) that this is where their childhood ended.
How things were with even more ancient primates is a mystery, but the circumstances of their life, of course, required an early start to reproduction.
But what about labor?
Stone tools are much better preserved than bones. Therefore, it is not surprising that anthropologists come across them much more often than the remains of their creators. Actually, they most often determine who made them. With some margin of error, of course. The stone chopper of the Olduvai culture was most likely made by someone from Homo habilis or ergaster, but the author of the products of the next - Acheulean - culture is probably Homo erectus.
And you can't say what and how this master thought, knocking stones against each other. I wanted to eat, most likely …