The Neanderthals' brains grew differently from the Sapiens. Neanderthal (Homo neanderthalensis) Neanderthal brain mass

Neanderthal (lat. Homo neanderthalensis ) - an extinct species from the genus People (lat. Homo). The first people with the features of Neanderthals (Protoneanderthals) appeared in Europe about 600 thousand years ago. Classical Neanderthals were formed about 100-130 thousand years ago. The latest remains date from 28-33 thousand years ago.

Opening

The remains of H. neanderthalensis were first discovered in 1829 by Philippe-Charles Schmerling in the Angie caves (modern Belgium), it was a child's skull. In 1848, the skull of an adult Neanderthal was found at Gibraltar (Gibraltar 1). Naturally, neither the one nor the other finds at that time was considered as evidence of the existence of an extinct species of people, and they were classified as the remains of Neanderthals much later.

The type specimen (holotype) of the species (Neanderthal 1) was found only in August 1856 in a limestone quarry in the Neandertal valley near Dusseldorf (North Rhine-Westphalia, Germany). It consists of the cranial vault, two femurs, three bones from the right arm and two from the left, part of the pelvis, fragments of the scapula and ribs. A local gymnasium teacher, Johann Karl Fulroth, was interested in geology and paleontology. Having received the remains from the workers who found them, he drew attention to their complete fossilization and geological position and came to the conclusion about their considerable age and important scientific significance. Then Fulroth gave them to Hermann Schaafhausen, professor of anatomy at the University of Bonn. In June 1857 the discovery was announced, it happened 2 years before the publication of Charles Darwin's work "The Origin of Species". In 1864, at the suggestion of the Anglo-Irish geologist William King, the new species was named after the place of its discovery. In 1867, Ernst Haeckel proposed the name Homo stupidus (ie Stupid Man), but in accordance with the rules of the nomenclature, the name Kinga remained the priority.

In 1880, the jaw of a child H. neanderthalensis was found in the Czech Republic, along with tools from the Mousterian period and bones of extinct animals. In 1886, perfectly preserved skeletons of a man and a woman were found in Belgium at a depth of about 5 m, also together with numerous Mousterian instruments. Subsequently, the remains of Neanderthals were found in other places on the territory of modern Russia, Croatia, Italy, Spain, Portugal, Iran, Uzbekistan, Israel and other countries. To date, the remains of more than 400 Neanderthals have been found.

The status of the Neanderthal as a previously unknown species of ancient man was not established immediately. Many prominent scientists of that time did not recognize him in this capacity. Thus, the outstanding German scientist Rudolf Virchow rejected the thesis of a "primitive man" and considered the Neanderthal skull to be just a pathologically altered skull of a modern man. And the doctor and anatomist Franz Mayer, having studied the structure of the pelvis and lower extremities, hypothesized that the remains belonged to a man who spent a significant part of his life on horseback. He suggested that it could be a Russian Cossack from the era of the Napoleonic wars.

Classification

Almost from the moment of discovery, scientists have been debating the status of the Neanderthals. Some of them are of the opinion that the Neanderthal is not an independent species, but only a subspecies of modern man (Latin Homo sapiens neanderthalensis). This is largely due to the lack of a clear definition of the species. One of the signs of the species can be called reproductive isolation, and genetic research suggests that Neanderthals and modern humans interbred. On the one hand, this supports the point of view about the status of Neanderthals as a subspecies of modern man. But on the other hand, there are documented examples of interspecies crossing, as a result of which fertile offspring appeared, therefore this trait cannot be considered decisive. At the same time, DNA and morphological studies show that Neanderthals are still an independent species.

Origin

Comparison of the DNA of modern humans and H. neanderthalensis shows that they descended from a common ancestor, having separated, according to various estimates, from 350-400 to 500 and even 800 thousand years ago. The likely ancestor of both of these species is the Heidelberg man. Moreover, the Neanderthals descended from the European population of H. heidelbergensis, and modern humans - from the African and much later.

Anatomy and morphology

Men of this type had an average height of 164-168 cm, weight about 78 kg, women - 152-156 cm and 66 kg, respectively. The brain volume is 1500-1900 cm 3, which exceeds the average brain volume of a modern person.

The vault of the skull is low, but long, the face is flat with massive superciliary arches, the forehead is low and strongly inclined back. The jaws are long and wide with large teeth, protruding forward, but without chin protrusion. Judging by the wear of their teeth, Neanderthals were right-handed.

Their physique was more massive than that of a modern person. The ribcage is barrel-shaped, the torso is long, and the legs are relatively short. Presumably, the dense physique of the Neanderthals is an adaptation to cold climates, because due to a decrease in the ratio of body surface to its volume, the body's loss of heat through the skin decreases. The bones are very strong, this is due to the highly developed muscles. The average Neanderthal was significantly stronger than modern humans.

Genome

Early studies of the H. neanderthalensis genome focused on mitochondrial DNA (mDNA) studies. Because Under normal conditions, mDNA is inherited strictly through the maternal line and contains much less information (16569 nucleotides versus ~ 3 billion in nuclear DNA), the importance of such studies was not too great.

In 2006, the Max Planck Institute for Evolutionary Anthropology and 454 Life Sciences announced that they would be sequencing the genome of Neanderthals over the next few years. In May 2010, preliminary results of this work were published. Studies have shown that Neanderthals and modern humans could interbreed, and every living person (except Africans) carries between 1 and 4 percent of the genes of H. neanderthalensis. Sequencing of the entire Neanderthal genome was completed in 2013, and the results were published in Nature on December 18, 2013.

Habitat

Fossil remains of Neanderthals were found in a large territory of Eurasia, which includes such modern countries as Great Britain, Portugal, Spain, Italy, Germany, Croatia, Czech Republic, Israel, Iran, Ukraine, Russia, Uzbekistan. The easternmost find is the remains found in the Altai Mountains (Southern Siberia).

However, it should be borne in mind that a significant part of the period of existence of this species fell on the last glaciation, which could destroy evidence of the habitation of Neanderthals in more northern latitudes.

No traces of H. neanderthalensis have yet been found in Africa. This is probably due to the adaptation to the cold climate of both themselves and the animals that formed the basis of their diet.

Behavior

Archaeological evidence suggests that Neanderthals spent most of their lives in small groups of 5-50. There were almost no old people among them, because most of them did not live to be 35 years old, but some individuals survived to 50. There is a lot of evidence of Neanderthals caring for each other. Among those studied, there are skeletons with traces of cured injuries and diseases, therefore, during the healing, the tribesmen fed and protected the wounded and sick. There is evidence that the dead were buried, and funeral offerings are sometimes found in the graves.

It is believed that Neanderthals rarely met outsiders in their small territory or left it themselves. Although occasionally there are finds of high-quality stone products, the sources of which are located more than 100 km away, they are not enough to conclude that there is trade or at least regular contacts with other groups.

H. neanderthalensis made extensive use of various stone tools. However, over hundreds of thousands of years, their manufacturing technology has changed very little. In addition to the obvious assumption that the Neanderthals, despite their large brains, were not very smart, there is an alternative hypothesis. It lies in the fact that due to the small number of Neanderthals (and their number never exceeded 100 thousand individuals), the likelihood of innovation was small. Most of the stone tools of the Neanderthals belong to the Mousterian culture. Some of them are very sharp. There is evidence of the use of wooden tools, but they themselves have hardly survived to this day.

The Neanderthals used a variety of weapons, including spears. But most likely they were used only in close combat, and not for throwing. This is indirectly confirmed by the large number of skeletons with traces of trauma inflicted by large animals that the Neanderthals hunted and which constituted the bulk of their diet.

Previously, it was believed that H. neanderthalensis ate exclusively on the meat of large land mammals such as mammoths, bison, deer, etc. However, later finds showed that small animals and some plants also served as food. And in the south of Spain, traces of the Neanderthals feeding on marine mammals, fish and shellfish were also found. However, despite the variety of food sources, getting enough food was often a challenge. Skeletons with signs of malnutrition-related diseases are evidence of this.

It is assumed that the Neanderthals were already proficient in speech. This is indirectly evidenced by the production of sophisticated tools and the hunting of large animals, requiring communication for learning and interaction. In addition, there is anatomical and genetic evidence: the structure of the hyoid and occipital bones, the hypoglossal nerve, the presence of a gene responsible for speech in modern humans.

Extinction hypotheses

There are several hypotheses explaining the disappearance of this species, which can be divided into 2 groups: associated with the appearance and spread of modern humans and with other reasons.

According to modern concepts, modern man, having appeared in Africa, gradually began to spread to the north, where by this time the Neanderthal was widespread. Both of these species coexisted for millennia, but ultimately the Neanderthal was completely supplanted by modern humans.

There is also a hypothesis linking the disappearance of the Neanderthals with climate change caused by the eruption of a large volcano about 40 thousand years ago. This change led to a decrease in the amount of vegetation and the number of large herbivorous animals that fed on vegetation and, in turn, were the food of the Neanderthals. Accordingly, the lack of food led to the extinction of H. neanderthalensis themselves.

The brains of newborn Neanderthals were almost the same in size and shape as those of Sapiens babies, but in adults of the two human species, the brain shape is significantly different. Anthropologists from France and Germany found that key differences formed in the first year of life. In sapiens, during this period, the brain becomes more rounded due to the accelerated growth of the parietal and temporal regions, as well as the cerebellum. The presence of a pronounced "phase of globularization" in the development of the brain of infants is a unique feature of our species; it is not found in apes or Neanderthals. Most likely, other hominid fossils did not have it either. These results support the view that very large brains evolved in Sapiens and Neanderthals in parallel, rather than inheriting from a common ancestor.

There is no consensus among anthropologists as to whether there were significant intellectual differences between Neanderthals and modern humans. One of the important arguments in favor of the high cognitive potential of Neanderthals is the findings associated with the so-called Chatelperon culture (see: Châtelperronian). At several points in Western Europe, bone remains of Neanderthals were found in the same layers with complex stone and bone products, similar to the Upper Paleolithic industry of the Cro-Magnons-Sapiens. Anthropologists argue whether the Neanderthals independently invented these "high technologies" or borrowed them from the Sapiens, who at that time (about 35-30 thousand years ago) had already spread widely across Europe. However, new radiocarbon dating data indicate that these objects may not have been made by Neanderthals: it is possible that everything is explained by the mixing of archaeological layers (T. Higham et al. Chronology of the Grotte du Renne (France) and implications for the context of ornaments and human remains within the Châtelperronian // PNAS... Published online before print October 18, 2010).

New article by French and German anthropologists published in the journal Current biology, gives another reason to doubt that the Neanderthals had exactly the same minds as modern people.

In terms of volume, the brain of the Neanderthals was practically the same as ours, but noticeably different in shape. Sapiens have a more rounded brain, Neanderthals have an elongated brain. The authors decided to find out at what stage of individual development this difference was formed.

The brain itself is almost never preserved in a fossil state, but its size, shape, and partly structure (the relative development of different areas) can be judged by the endocrane - a cast of the inner part of the cranium. The authors used a complex method of mathematical description of the shape of the brain, based on the analysis of the relative position of several dozen “reference points” that can be found on the endocrane of anthropoids. This technique allows one to compare the shape of the endocrane of different species at different stages of development, abstracting from the absolute size of the brain.

First, the authors applied this technique to tomograms of the skulls of 58 modern humans and 60 chimpanzees of different ages, including 7 newborns of each species. It turned out that key differences in the nature of changes in brain shape with age are observed in the first year of life. In modern humans, during this period, "globularization" occurs (that is, the brain becomes more rounded) due to the accelerated growth of the parietal and temporal regions, as well as the cerebellum. As a result, the vault of the human skull acquires a characteristic convex, domed shape. In chimpanzees, the “globularization phase” is absent (S. Neubauer et al., 2010.).

The authors then compared age-related changes in brain shape in modern humans and Neanderthals. They used reconstructions of the endocranes of 9 Neanderthals: one newborn (Le Moustier 2 cave; see: B. Maureille, 2002. Anthropology: A lost Neanderthal neonate found), one year-old child (Pech-de-l'Azé cave; see: M Soressi et al., 2007. The Pech-de-l "Azé I Neandertal child: ESR, uranium-series, and AMS 14 C dating of its MTA type B context), two older children (Roc de Marsal cave and Engis village ), a teenager (Le Moustier 1 cave) and four adults.

The analysis showed that newborn Neanderthals and Sapiens are very similar to each other in both brain size and shape. However, in the period from birth to the appearance of the first milk teeth, the brain of our closest fossil relatives grew in a completely different way from ours (see figure). Nothing similar to the "globularization phase" characteristic of small sapiens was observed in Neanderthal infants. As a result, in adult Neanderthals, the brain remained elongated, and the roof of the skull did not acquire the dome-shaped outlines characteristic of Sapiens.

Of course, as long as only one skull of a newborn Neanderthal and one of a one-year-old is known, the conclusions obtained cannot be considered absolutely reliable and definitive. However, the authors attempted to reduce the dependence of the findings on a tiny sample of Neanderthal babies. Based on the known trajectory of the brain shape change in Sapiens, as well as from the known brain shape of adult Neanderthals, they calculated what the brain of newborn Neanderthals would look like if their development followed the same trajectory as ours. The result is a completely unreal creature with an extremely elongated head, which has little in common with newborn sapiens and with the skulls of Le Moustier 2 and Pech-de-l'Azé. The authors also calculated what would happen from newborn sapiens if their brains developed along a "Neanderthal" trajectory. The result of this simulation was very similar to that of a typical adult Neanderthal.

Apparently, the absence of a globularization phase is a plesiomorphic (that is, ancient, original, primitive) sign of anthropoids. It was probably common to the common ancestor of humans and chimpanzees, as well as to all hominid fossils, including Neanderthals. The rounded shape of the brain and the rapid growth of the parietal and temporal regions immediately after birth is an apomorphic (that is, evolutionarily new, advanced) trait of the Sapiens.

It is possible that the acquisition of this apomorphia was associated with significant functional changes in the brain, for example, with the complication of the mechanisms of integration of sensory information and the formation of mental models of the surrounding world. To put it simply, the new evidence indirectly suggests that the mind of the Neanderthals could be significantly different from ours. If we take into account that in direct competition with sapiens on the territory of Europe, Neanderthals, as you know, were the losers, then the assumption arises that the models of the world created by the sapiens' brains were more practical, that is, they made it possible to make more accurate predictions. In addition, the results obtained support the view that the very large brain was acquired by the Sapiens and Neanderthals as a result of parallel evolution, and not inherited from a common ancestor (which apparently belonged to the late archantropians or H. heidelbergensis in a broad sense).

Sources:
1) Philipp Gunz, Simon Neubauer, Bruno Maureille, Jean-Jacques Hublin. Brain development after birth differs between Neanderthals and modern humans // Current biology... 2010. V. 20. P. R921 – R922.
2) Simon Neubauer, Philipp Gunz, Jean-Jacques Hublin. Endocranial shape changes during growth in chimpanzees and humans: A morphometric analysis of unique and shared aspects // Journal of human evolution... 2010. V. 59. P. 555-566.
3) Ann Gibbons. Neandertal Brain Growth Shows A Head Start for Moderns // Science... 2010. V. 330. P. 900-901.

Note. The middle column shows the measurement results, which often appear in the modern literature as the most realistic, and the right column shows the results of all measurements (in brackets) and their average values.

In a recent summary by the American researcher R. Holloway, who spent many years studying the endocranes of fossil hominids, the figure 1487 cm 3, calculated for 28 skulls of different sex and age, appears as the average volume of the brain cavity of Neanderthals. As for modern people, different sources give different numbers as typical values \u200b\u200bfor them, but in general, if we exclude pathologies (microcephalism), the extreme range of variations will be from about 900 to 1800 cm 3, and the average indicator will be about 1350-1400 cm 3. According to the Canadian anthropologist J. Rushton, who measured the heads of 6325 American military personnel, the average size of the cerebral cavity varies in representatives of different races from 1359 cm 3 to 1416 cm 3.

Therefore, it turns out that the volume of the endocrane in modern humans is, on average, at least 100 cm 3 less than that of Neanderthals. On the contrary, in terms of relative size, that is, the ratio of brain size to body size, Homo sapiens, perhaps, albeit insignificantly, is still ahead of its closest relatives. However, even if this is really so (which still needs confirmation), then it is still not worth deluding ourselves with this circumstance. The fact is that in primates, as the comparison of data obtained for more than two dozen different genera shows, the absolute brain size correlates better with the results of assessing the level of intellectual abilities than the relative size. Of course, there are exceptions to this rule (chimpanzees, for example, are considered smarter than gorillas, although the latter have larger brains), but this is generally the trend.

Does the pattern found in monkeys apply to humans? Do humans also have a connection between absolute brain size and intellectual ability? This very delicate issue remains controversial. Some experts believe that there is no such connection. "The cerebral cavity," say proponents of this point of view, "is like a wallet, the contents of which matter much more than its size." Others, on the other hand, are confident that there is a connection, and that, in general, there is a strong positive correlation between brain size, on the one hand, and IQ, on the other. Whether it is so or not, but as for the progressive increase in the brain in members of the genus Homo, then it seems beyond doubt that the growing role of intellect and culture was the main factor behind this process. This confidence is based not only on the fact that the first noticeable leap in endocrane size in hominids chronologically coincides with the appearance of the earliest stone tools and other archaeological evidence of the complication of cultural behavior. The point is that the brain, along with the heart, liver, kidneys and intestines, is one of the most energy-costly anatomical organs. While the total weight of these organs averages only 7% of the body weight in humans, their metabolic energy consumption exceeds 75%. The brain weighs 2% of body weight, while it consumes about 20% of the energy received by the body. The larger the brain, the more time and effort its owner has to spend on getting food in order to replenish energy costs. Instead of quietly resting in a secluded place, he is forced to wander the jungle or savannah for extra hours in search of edible plants and animals, every minute at the risk of turning from a hunter into a victim of more powerful predators. Therefore, for most species, a large brain, such as that of primates and, especially, humans, is an unaffordable luxury. An increase in its size could become possible only if the accompanying increase in the energy load on the body was compensated for by some important advantages that provided a favorable effect of natural selection for the "highbrow". Taking into account the functions of the brain, it is difficult to doubt that these advantages were associated primarily with the development of intelligence (memory, thinking abilities) and beneficial changes in behavior, an increase in its plasticity and efficiency.

In this respect, one more chronological coincidence is apparently not accidental. Archaeological evidence suggests that the emergence of the genus Homo accompanied by changes in the nature of the diet of human ancestors, namely an increase in meat consumption. Although the character of tooth wear in hominids of the Olduvai era (approximately 2.6-1.6 million years ago) suggests that the basis of their diet was still plant products, meat food, as can be seen from the abundance of animal bones in some of the most ancient sites, and also from the presence of tools there that served for butchering carcasses, it has also acquired an important value. This can be considered an important condition for brain growth, since a decrease in the proportion of plant foods in the diet of our ancestors and an increase in the proportion of animal food - much more nutritious and fairly easily digestible - created an opportunity to reduce the size of the intestine, which, as already mentioned, is also among the most energetically "Expensive" organs. This decrease should have helped to maintain the overall metabolic balance at the same level, despite the significant growth of the brain. It is no coincidence that modern humans have much smaller intestines than other animals of a similar size, and the energy gain resulting from this is inversely proportional to the losses associated with an enlarged brain.

Figure: 7.1. Virtual cast of the brain cavity of the Neanderthal skull of Saccopastore 1 (source: Bruner et al. 2006)

In a word, judging by the size of the brain, we have to conclude that the Neanderthals, at least, were not inferior to us. But maybe they were losing in terms of the complexity of its structure? Maybe the contents of their cranium, despite its large size, were simple, monotonous and primitive? To answer this question, anthropologists have at their disposal endocranial ebbs, that is, casts, dummies of the cerebral cavity. They make it possible to get an idea not only about the volume of the brain of fossil forms, but also about some important features of its structure, which are reflected in the relief of the inner surface of the cranium (Fig. 7.1). So, a comparison of the endocranial casts of Neanderthals and Homo sapiens does not allow us to identify any significant differences that would definitely indicate the intellectual superiority of one species over another. Yes, the brain of the Neanderthals had a slightly different shape and was located in the skull a little differently than the brain of modern people (Fig. 7.2). In particular, in Homo sapiens its parietal part is clearly more developed, while the temporal and frontal margins, on the contrary, seem to be relatively reduced. However, the functional significance of these features remains unclear. On the whole, as R. Holloway, one of the most authoritative specialists in this field, put it, the brain of the Neanderthals "was already completely human, without any significant differences in its organization from our own brain." A number of other researchers studying the evolution of the brain have a similar opinion. Some of them believe that Neanderthals could have the same intellectual abilities as modern humans, and the different shape of the skulls of the former and the latter reflects different evolutionary strategies that served to solve the same problem: “to pack a large brain into a small container” (K. Tsolikofer).

Figure: 7.2. With approximately the same volume, the brain of a Neanderthal ( left) was somewhat different from the brain of modern people ( on right) in shape, as well as in position in the skull. The functional significance of these differences remains unclear (

Did Charles Darwin renounce his theory of human evolution at the end of his life? Did ancient people find dinosaurs? Is it true that Russia is the cradle of mankind, and who is the Yeti - isn't it one of our ancestors, lost for centuries? Although paleoanthropology, the science of human evolution, is flourishing, the origins of man are still surrounded by many myths. These are anti-evolutionist theories, legends generated by mass culture, and pseudo-scientific ideas that exist among educated and well-read people. Do you want to know how everything was "in reality"? Alexander Sokolov, editor-in-chief of the portal ANTROPOGENEZ.RU, has collected a whole collection of such myths and checked how consistent they are.

Alternatively, the endocrane (an impression of the inner cavity of the skull) is measured with a sliding compass. Find the distances between certain points and substitute them in the formulas. Of course, this method gives a greater error, since the result strongly depends both on where the compass was placed (the desired point cannot always be found accurately), and on the formulas.

It is even less reliable when measurements are taken not from the endocrane, but from the skull itself. For obvious reasons, it is difficult to measure the inside of the skull, therefore, the external dimensions of the skull are determined and special formulas are used. The error here can be very large. To reduce it, you need to take into account the thickness of the walls of the skull and its other features.

(It's great when we have a perfectly preserved whole skull in our hands. In practice, we have to extract as much information as possible from the incomplete set that is available. There are formulas for estimating the brain volume even by the size of the femur ...)

There is undeniable positive correlation between brain size and intelligence. It is not absolutely strict (the correlation coefficient is less than one), but it does not at all follow from this that “size does not matter”. Correlations of this kind are never absolutely strict. The correlation coefficient is always less than one, no matter what dependence we take: between muscle mass and strength, between leg length and walking speed, etc.

Indeed, there are very smart people with small brains and stupid people with large ones. Often in this context Anatole France is remembered, whose brain volume was only 1017 cm? - normal volume for Homo erectus and much lower than average for Homo sapiens. This, however, does not at all contradict the fact that intensive selection for intelligence promotes brain enlargement. For such an effect, it is quite enough that the enlargement of the brain increases the likelihood that the individual will be smarter even slightly. And the probability is certainly increasing. Having carefully examined the tables of the brain volume of great people, often cited as refutation of the dependence of the mind on brain size, it is easy to see that the vast majority of geniuses still have larger brains.

Apparently, there is a relationship between size and intelligence, but in addition to this, many other factors affect the development of the mind. The brain is an extremely complex organ. We cannot know the details of the structure of the brain of Neanderthals, but from casts of the cranial cavity (endocranes) we can estimate, at least, the general shape.

In Neanderthals, the width of the brain is extremely large, - writes S.V. Drobyshevsky, - the maximum for all groups of hominids. The relatively small sizes of the frontal and parietal lobes are very characteristic, while the occipital lobes are very large. In the orbital region (at the site of the Broca zone), relief hillocks were developed. The parietal lobe was strongly flattened. The temporal lobe was almost modern in size and proportion, but a tendency to increase the expansion of the lobe in the posterior part and lengthening along the lower edge can be noted, in contrast to what is more common in representatives of the modern human species. The fossa of the cerebellar vermis in European Neanderthals was flat and wide, which can be considered as a primitive trait.

The brain of H. neanderthalensis differed from the brain of modern humans, probably by a greater development of subcortical centers of subconscious control over emotions and memory, but at the same time less conscious control over these functions.

Were the ancient people smarter than us?

The average brain volume of a modern person is about 1400 cubic centimeters, which is quite a large value for our body size. Man has grown a large brain for himself in the course of evolution - anthropogenesis. Our ape-like ancestors, who did not have large claws and teeth, descended from trees and moved on to life in open spaces, began to develop the brain. Although this development did not immediately go quickly - in Australopithecus the brain volume (about 500 cubic centimeters) practically did not change for six million years. The jump in its increase took place two and a half million years ago. In early Homo sapiens, the brain has already grown significantly - in Homo erectus (Homo erectus), its volume is from 900 to 1200 cubic centimeters (this is covered by the range of the modern human brain). The Neanderthals had a very large brain - 1400-1740 cubic centimeters. which is on average more than ours. Early Homo sapiens on the territory of Europe - Cro-Magnons - simply plug us in the belt with their brain: 1600-1800 cubic centimeters (although Cro-Magnons were tall - 180-190 centimeters, and anthropologists find a direct connection between brain size and height).

The brain in human evolution not only increased, but also changed in the ratio of different parts. Paleoanthropologists examine the brains of fossil hominids from a skull cast - an endocrane that shows the relative size of the lobes. The frontal lobe developed most rapidly, which is associated with thinking, consciousness, the appearance of speech (Broca's zone). The development of the parietal lobe was accompanied by an improvement in sensitivity, synthesis of information from various senses, and fine motor skills of the fingers. The temporal lobe supported the development of hearing, providing sound speech (Wernicke's zone). For example, in erectus, the brain grew in width, the occipital lobe and cerebellum increased, but the frontal lobe remained low and narrow.

And in Neanderthals, in their very large brain, the frontal and parietal lobes were relatively poorly developed (compared to the occipital). In Cro-Magnons, the brain became much higher (due to an increase in the frontal and parietal lobes) and acquired a spherical shape.

So, the brain of our ancestors grew and grew, but, paradoxically, about 20 thousand years ago, the opposite trend began: the brain began to gradually decrease. So modern humans have a smaller average brain size than Neanderthals and Cro-Magnons. What is the reason?

WHO IS SMARTER? ANTHROPOLOGIST'S OPINION

Anthropologist Stanislav Drobyshevsky (Associate Professor of the Department of Anthropology, Faculty of Biology, Moscow State University) answers: “There are two answers to this question: one is liked by everyone, the other is correct. The first is that the size of the brain is not directly related to intelligence, and the structure of the Neanderthals and Cro-Magnons was simpler than ours, but the technical incompleteness was compensated for by the large size, and that supposedly not completely. In reality, we know absolutely nothing about the neural structure of the brain of ancient people, so such an answer is complete speculation, consoling the conceit of modern people. The second answer is more real: ancient people were smarter. They had to solve a bunch of survival problems, and think very quickly, unlike us, who are presented with everything on a silver platter, and even chewed, and there is no need to rush anywhere. Ancient people were generalists - each kept in his head a complete set of information necessary to survive in all situations, plus there had to be the ability to reactively think in unforeseen situations. We also have a specialization: everyone knows a tiny piece of their information, and if something happens - “contact a specialist”.

The brain of a Neanderthal differs from ours in only one phase of development

The findings of Neanderthal children provide an opportunity to trace how their large brains developed. Scientists from the Max Planck Institute for Evolutionary Anthropology in Leipzig, together with their French colleagues, have reconstructed the comparative brain development of Neanderthal and Homo sapiens. First, scientists performed computed tomography of the skull of 58 modern people. And then they did the same, placing the skulls of nine Neanderthals of different ages in the tomograph.

Although the size of the skull of a Neanderthal is no less than ours, in shape they differ significantly. But in newborns of both species, the brain box is almost the same in shape - in a Neanderthal infant, it is quite slightly more elongated. And then the development paths diverge. In a modern person, during the period from the absence of teeth to an incomplete set of incisors, not only the size but also the shape of the cerebral box changes - it becomes more spherical. And then it increases only in size, but almost does not change in shape. Biologists have decided that this is a key process of brain shaping that Neanderthals lack. The shape of the skull of their newborns, adolescents and adults is almost the same. The total difference is in one critical stage immediately after birth. Probably, scientists believe that such a noticeable change in shape is accompanied by a transformation of the internal structure of the brain and the development of a neural network, which creates conditions for the development of intelligence. Scientists have published an article on the development of the brain of different human species in the journal Current Biology.

Who is smarter? Neuroscientist opinion

Sergey Savelyev, head of the laboratory for the development of the nervous system at the Institute of Human Morphology, Russian Academy of Medical Sciences, shared his opinion: “This is due to the fact that there is an artificial selection in the human population aimed at reducing individual variability and targeted selection of highly socialized mediocrity. And to destroy too smart and asocial individuals. Such a community is more manageable, it consists of more predictable people, which is always beneficial. At all times, society sacrificed the pathogens of tranquility in favor of non-conflict and stability. Previously, they were simply eaten, and later they were expelled from the community. It is because of this, from my point of view, because of the migration of the smartest outcasts, and the resettlement of mankind began. And in sedentary, conservative and more socialized groups, there was a hidden selection to consolidate some of the most convenient and favorable behavior properties for maintaining the community. Behavioral selection led to brain shrinkage. "

Myth 1

THE BIGGER THE BRAIN, THE SMARTER IT IS

Brain sizes vary quite a bit among modern humans as well. So, it is known that Ivan Turgenev's brain weighed 2012 grams, and Anatole France's was almost a whole kilogram less - 1017 grams. But this does not mean at all that Turgenev was twice as smart as Anatole France. Moreover, it was recorded that the owner of the heaviest brain - 2900 grams - was mentally retarded.

Since the most important part of the brain is nerve cells, or neurons (they form the gray matter), it can be assumed that the larger the brain, the more neurons it contains. And the more neurons, the better they work. But the brain has more than just
neurons, but also glial cells (they perform a supporting function, direct the migration of neurons, supply them with nutrients, and according to recent data
- and participate in information processes). In addition, part of the brain mass is formed by white matter, which is composed of conductive fibers. That is, there is a connection between the size of the brain and the number of neurons, but not a direct one. And there is obviously no link between brain size and intelligence.

The brain can be "pumped up" on a treadmill

A study by an international team of scientists and published in the journal PNAS has shown that aerobic exercise (treadmill exercise) in old age builds up the hippocampus, an area of \u200b\u200bthe brain that is very important for memory and spatial learning. Its volume was determined in a magnetic resonance imager. It is believed that with age, the hippocampus shrinks at a rate of 1-2% per year. Experts believe that this atrophy of the hippocampus is directly related to age-related weakening of memory. So, in elderly subjects who were engaged on a treadmill for a year, the volume of the hippocampus not only did not decrease, but even increased, and also improved spatial memory compared to the control group. The reason is again in stimulating the formation of new neurons.

Myth 2

NERVE CELLS DO NOT RESTORE

Since neurons do not divide, it has long been believed that the formation of new nerve cells occurs only during embryonic development. Scientists discovered that this is not so a few years ago. It turned out that in the brains of adult laboratory rats and mice there are zones in which new neurons are born - neurogenesis. Their source is nerve tissue stem cells (neural stem cells). It was later found that humans also have such zones. Research has shown that new neurons actively grow contacts with other cells and are involved in learning and memory. Let's repeat: in adult animals and humans.

Further, scientists began to study what external factors can influence the birth of neurons. And it turned out that neurogenesis is enhanced with intensive learning, with enrichment of environmental conditions and with physical activity. And the most powerful factor inhibiting neurogenesis was stress. Well, this process slows down with age. What is true for laboratory animals, in this case, can be completely transferred to humans. Moreover, observations and studies on humans confirm this. That is, in order to enhance the formation of new nerve cells, you need to train the brain, learn new skills, memorize more information, diversify your life with new experiences and lead a physically active lifestyle.

In old age, this leads to the same effect as in younger years. But stress for the birth of new neurons is destructive.

GYM FOR MOUSE

Neurophysiologists from Taiwan (National Cheng Kung University Medical College) worked with mice of different ages - young (3 months), adults (7 months), early middle age (9 months), middle age (13 months) and old (24 months). The animals received daily physical activity through training in the wheel, every day for an hour. After five weeks of training, the scientists studied what changes had occurred in their brains compared to the "unsportsmanlike" rodents, which were just sitting in cages all this time. Using special staining, the number of dividing cells, maturing neuronal cells and mature neurons in the hippocampus was counted. At first. the researchers found that neurogenesis declined with age. The number of newly formed nerve cells in middle-aged mice was only about 5% of the number of new neurons in young mice. But five weeks of vigorous exercise played a role: the rate at which new neurons emerge in middle-aged athletic mice doubled compared to non-athletic mice. Understanding the mechanisms, scientists found that exercise increased the content of protein - a neurotrophic factor that stimulates the division and differentiation of neural cells. What is true for mice is in this case true for humans, the authors of the article in Nature argue. So physical activity in middle and old age gives a good chance to keep the brain healthy for a long time.

STRESS DAMAGES BRAIN, INTERESTING LIFE - RESTORES

Childhood stress is especially bad for the brain. Its consequences affect the psyche, behavior and intellectual abilities of an adult. But there is a way to offset the damaging effects of early stress. As Israeli scientists have shown on laboratory rats, you can help if you enrich the victim's habitat. Stress destroys the brain through hormones, which include corticosteroids produced in the adrenal glands, as well as pituitary and thyroid hormones. Their increased level causes changes in dendrites - short processes of neurons, reduces synaptic plasticity, especially in the hippocampus, slows down the formation of new nerve cells in the dentate gyrus of the hippocampus, and so on. Such disorders during the development of the brain do not go unnoticed.

Experts from the Institute for the Study of Affective Neuroscience, University of Haifa, divided laboratory rats into three groups. One was subjected to three days of stress at a young age, the second was placed in an enriched environment after stress, the third was left as a control. Rats, which had to live in an enriched environment, were moved to a large cage, where there were many interesting objects: plastic boxes, cylinders, tunnels, platforms and running wheels.

On testing, rats from the stress group showed increased fear and decreased curiosity and learned worse. They had a reduced motivation to explore a new environment, which can be compared to the loss of interest in life, which often happens in a person in a state of depression. But being in an enriched environment compensated for all of the stress-induced behavioral disturbances.

Scientists suggest that enriching the environment protects the brain from stress for several reasons: it stimulates the production of proteins - nerve growth factors, activates neurotransmitter systems and favors the formation of new nerve cells. They published the results in PLoS ONE magazine. These results are most directly related to orphans, whose early childhood was spent in an orphanage. Only an interesting and eventful life, which the adoptive parents will try to create for them. will help smooth out difficult life experiences.

THE HUMAN BRAIN WORKS AT 10/6/5/2%

This idea was very widespread until recently. Usually it was cited as the rationale that the brain has a latent potential that we do not use. But modern research methods do not support this thesis. “It arose from the fact that when we learned to register the electrical activity of individual neurons, it turned out that very few of all neurons at the measurement point are active at any given time,” says Olga Svarnik, head of the laboratory of systemic neurophysiology and neural interfaces of the NBIK Center of the Russian Research Center Kurchatovsky institute ". There are about 1012 neurons in the brain (the number is constantly being refined), and they are very specialized: some are electrically active while walking, others - while solving a mathematical problem, others - during a love date, etc. It's hard to imagine what would happen if they suddenly decide to make money at the same time! “In the same way as we are not able to realize all our experience at the same time, that is, we cannot simultaneously drive a car, jump rope, read, etc., - explains Olga Svarnik, - so do all our nerve cells cannot and should not be active at the same time. But this does not mean that we do not use the brain one hundred percent. "

“This was invented by those psychologists who themselves use the brain by two percent,” Sergei Saveliev categorically asserts. - The brain can only be used completely, nothing can be turned off in it. According to physiological laws, the brain cannot work less than half, because even when we do not think, a constant metabolism is maintained in neurons. And when a person begins to work intensively with his head, to solve some problems, the brain begins to consume almost twice as much energy. Everything else is fiction. And no brains can be trained so as to intensify their work tenfold. "

THE BRAIN IS A VERY ENERGY EXPENDING ORGAN

Scientists have long calculated that an intensively working human brain consumes a quarter of the resources of the entire body. And at rest - 10% of the body's energy. At the same time, brain mass is only 2% of body weight.

Myth 4

A PART OF THE BRAIN RESPONSES FOR EACH ACTION

Indeed, in the cortex of the human cerebral hemispheres, neuroscientists distinguish zones associated with all the senses: vision, hearing, smell, touch, taste, as well as associative zones where information is processed and synthesized.

And magnetic resonance imaging (MRI) records the activity of certain areas during various activities. But the brain map is not absolute, and there is growing evidence that things are much more complicated. For example, not only the well-known Broca's area and Wernicke's area are involved in the speech process, but also other parts of the brain. And the cerebellum, which has always been associated with the coordination of movements, is involved in a wide variety of brain activities. With the question whether there is specialization in the brain, we turned to Olga Svarnik: “There is a specialization in the brain at the level of neurons, and it is quite constant,” the specialist answered. - But it is more difficult to distinguish specialization at the level of structures, because completely different neurons can lie side by side. We can talk about an accumulation of neurons, such as columns, we can talk about segments of neurons that are activated at the same moment, but it is impossible to really highlight any large areas that are customary to highlight. MRI reflects the activity of blood flow, but not the work of individual neurons. Probably, according to the images obtained by MRI, we can tell where, with a greater or lesser probability, one or another specialization of neurons can be found. But it seems wrong to me to say that some zone is responsible for something. "

NEURON JENNIFER ANISTON

“The specialization of neurons,” says Olga Svarnik, “can be illustrated by a curious example known as the Jennifer Aniston neuron phenomenon. Since a person, naturally, cannot stick electrodes into the brain for experimental purposes, this information was obtained on patients with epilepsy, in whom electrodes were implanted in the brain to localize the focus. So, in such a patient in the brain, among other neurons, a neuron was found that responded with an electric discharge at the moment when a photograph of actress Jennifer Aniston appeared on the monitor. These could be completely different photos of the actress - the neuron always "recognized" her. In another experiment, a neuron was found that only responded to the Simpsons demonstration. And so on. "

Myth 5

THE BRAIN IS A COMPUTER

According to Olga Svarnik, comparing the brain with a computer is nothing more than a metaphor: “We can fantasize that there are certain algorithms in the brain, that a person has heard information and is doing something. But to say that our brains work this way would be wrong. Unlike a computer, there are no functional blocks in the brain. For example, the hippocampus is thought to be a structure responsible for memory and spatial orientation. But the neurons of the hippocampus behave differently, they have different specialization, they do not function as a whole. "

And here is what the biologist and popularizer of science Alexander Markov (Institute of Paleontology RAS) thinks on the same issue: “In a computer, all signals exchanged between elements of logic circuits have the same nature - electrical, and these signals can only be received by one of two values \u200b\u200b- 0 or 1. The transmission of information in the brain is not based on a binary code, but rather on a ternary. If the exciting signal is correlated with one, and its absence with zero, then the inhibitory signal can be likened to minus one.

But in fact, the brain uses several dozen types of chemical signals - it's just as if a computer uses dozens of different electrical currents ... And zeros and ones could have dozens of different, say, colors. The most important difference is that the conductance of each particular synapse ... can change depending on the circumstances. This property is called synaptic plasticity. There is one more radical difference between the brain and an electronic computer. In a computer, the main amount of memory is stored not in the logical electronic circuits of the processor, but separately, in special storage devices. There are no areas in the brain that are specifically designated for long-term storage of memories. All memory is recorded in the same structure of interneuronal synaptic connections, which is at the same time a grandiose computing device - an analogue of a processor "

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