The evolution of the human brain: this is how it developed in our ancestors.

This is how the brain of our bipedal ancestors is estimated to have changed.

Our brain is one of our most complex and important organs, as well as one of those that took the longest to finish developing (and that's without taking into account that throughout our lives we do not stop creating synaptic connections).

It is a structure that is present in the vast majority of animals and that has developed in different ways and evolved in different ways depending on the species over millions of years.

Focusing again on the human being, little by little different structures and capacities have emerged in our ancestors as evolution continued its course, being at present the brain of our species the last of the genus Homo that remains alive. In this article we will try to approach how the human brain has evolved to the present day.

The evolution of the human brain

Analyzing what the brain of our now extinct ancestors was like is an arduous and complex task. In fact, a direct observation of an encephalon of species previous to ours (and even of ancestors within our same species) is not possible.

The main problem in determining how the human brain has evolved is quite simple and at the same time extremely complex: the brain is soft tissue, which means that the brain is a very complex organism. is soft tissue, so it does not fossilize and ends up rotting and disappearing.. This implies that, with the possible exception of subjects who died frozen and were preserved in ice, the observation of a hominid brain is not possible in a direct way.

This does not imply that assessing brain evolution is impossible, and there is even a science dedicated to it. We are talking about paleoneurology, which studies how the brain structure of our ancestors must have been, based on the analysis of the endocranial structure of the brain. based on the analysis of the endocranial structure of the brain..

Thus, in the same way that paleontology is a scientific discipline despite the fact that it studies aspects of reality of which only a few remains are left, in this case it is also possible to obtain scientific knowledge about organs that we can only know from what surrounded them.

Paleoneurology

The main element that allows us to try to observe how the human brain has evolved is the cranial capacity, i.e., the amount of brain volume that would fit inside the skull of a given species.. Not only the size, but also the morphology can give us clues about more or less developed regions.

Another aspect to be taken into account, and which in fact is also linked to the emergence and progressive increase of intellectual capacity, is the level of Blood irrigation that these brains possess.

A functional brain requires a constant energy supply, and the more efficient the supply of oxygen and nutrients, the better it functions. And this means that the higher the level of cranial capacity and the greater the functionality of the brain, the more energy and therefore the more blood was needed to carry the basic nutrients to the brain. When we talk about fossils or bones, the simplest way to try to calculate the level of blood flow in the brain is to to calculate the blood flow level of our ancestors is through the observation of the intracranial orifices that allow the passage of blood vessels. that allow the passage of blood vessels through it.

The development of the encephalon in the different species of hominins

Mainly based on the cranial capacity and its morphology, we will try to approach how the human brain has evolved throughout evolution and in some of the most representative and well-known species of the hominin group, formed by bonobos, chimpanzees, our biped ancestors and us, the sapiens.

It should be noted that many of the following conclusions are purely hypothetical, debatable and subject to multiple inferences..

On the other hand, we must keep in mind that we still do not have a good knowledge of the evolutionary tree of our ancestors, since we only know it approximately from estimates (debatable and debated) about the position that each species occupies in the taxa of evolution.

Ardipithecus ramidus

Ardipithecus is probably one of the earliest ancestors of humans ever found, although the Aahelanthropus tchadensis (about which there is disagreement as to whether it was the first species of human or chimpanzee, and may even be the ancestor that distinguished the two species) or the orrorin tugenensis are even older. This being, with ape-like characteristics, had a small skull of approximately 350 cubic centimeters (that of chimpanzees). (that of today's chimpanzees ranges between 275 and 500).

This species was already bipedal, but its small encephalon made the vast majority of higher cognitive abilities improbable at best. The fact that they lived in collectivity indicates a certain level of a certain level of socialization, similar to that of the family groups of other present-day great apes. other present-day great apes. Knowledge of this species and its capabilities is limited.

Australopithecus afarensis

Australopithecus is a genus of hominid related to us, being one of the first types of hominin that existed after Ardipithecus.

Among the different existing species, one of the best known is the afarensis. This species was characterized by a skull with a relatively small cranial capacity, of about 400-480 cubic centimetersof around 400-480 cubic centimeters (not being larger in size than that of a large number of chimpanzees, although in size in proportion to the body it would be somewhat larger). The interior of the skull had different air cavities that protected the encephalon. There is a strong prognathism.

The morphology could reflect the existence of a relatively small frontal lobe, having few superior cognitive capacities and its capacity for reasoning and planning being quite limited in comparison to a current human being. Nor did it possess an excessively large parietal lobe, not being probable the existence of developed cerebral areas that allowed complex oral language and not possessing a high and not possessing a high level of creativity or memory. Apparently the dorsal part of the skull was larger, something that is linked to the processing capacity of visual perception.

Homo habilis

The Homo habilis was one of the earliest representatives of the genus homo. Homo habilis possesses a larger and somewhat more rounded skull, with a cranial capacity of about 600-640 cubic cm.

It has been discovered that this species was capable of creating crude toolsIt has been found that this species was able to create crude tools, which requires a certain planning ability and a frontal area development somewhat superior to the previous species. It also requires greater hand-eye coordination, with the motor area probably being somewhat larger. The fact that remains have been detected that indicate that they hunted also suggests the ability to generate strategies and an improved level of communication.

The bulging of the parts of the cranial vault corresponding to Broca's and Wenicke's areas is observed, being not improbable the emergence of a very rudimentary form of language, strongly supported by gestures and visual communication in general. There is probably a higher level of blood supply to the brain.

Homo erectus

The cranial volume of this species ranges between 800 and 1000 cubic centimeters, being this species the one that began to dominate and use fire as a tool. They created tools and hunted cooperatively. Although to a lesser extent than later species, they probably possessed a somewhat more developed frontal lobe.. The elongation of the back of the skull could indicate a greater development of the occipital, parietal and temporal lobes.

Homo neanderthalensis

Neanderthal man is our closest extinct relative and in fact lived with our species for thousands of years. coexisted with our species for thousands of years..

The cranial capacity of homo neanderthalensis could be even greater than ours, reaching between 1400 and 1900 cubic centimeters. This means that it is not known what level of abstraction they could reach. However, the morphology of their skull suggests that they had a somewhat smaller frontal a frontal somewhat smaller than that of the sapiensbut at the same time a greater size of the regions of the occipital lobe, dedicated to body self-control and perception.

It is known that they took care of their sick, probably had a language similar to ours and sometimes carried out burials, in addition to mastering a relatively developed type of lithic industry called Mousterian lithic industry. All of this implies that they possessed a language area and that had the capacity for abstraction, empathy and a high degree of self-awareness..

Homo sapiens

Our species, which has traditionally been considered the most evolved and intelligent, is characterized at the cerebral level by a wide development of the neocortex and especially by the enormous size of our frontal lobe. This is one of the elements that stand out the most in us and that allows us to perform and possess higher cognitive functions such as reasoning or abstraction.

Artistic creation was also long considered exclusive to our species, although it is now considered that Neanderthals were also able to make various cave paintings and ornamental elements. In terms of energy and nutrient consumption, it is estimated that our brains use up to 20% of what we consume. It is also considered that the level of blood flow in our brains has increased sixfold compared to the first hominids..

However, our cranial capacity is smaller compared to that of the Neanderthals, being ours between 1300 and 1800 cubic centimeters. Although their greater cranial capacity does not mean that they had more or less intelligence (depending to a great extent on the organization of the brain and not only on its size), we cannot help but reflect that perhaps earlier or different species were much more capable than originally thought, being something to be valued in the future.

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