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

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

It is a structure present in a great majority of animals and that has been developing from time to time. different ways and evolving 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 according to evolution it continued its course, being at present the brain of our species the last of the genus Homo that remains with life. In this article we will try to approach How has the human brain evolved up to the present?.

• Related article: "Parts of the human brain (and functions)"

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 a brain from species before ours (and even from ancestors within our own species) is not possible.

And it is that the main problem to determine how the brain of the human being has evolved is quite simple and at the same time extremely complex: the brain it is soft tissue, so it does not fossilize and ends up rotting and disappearing. This implies that, with the possible exception of subjects who freeze to death and have been preserved in ice, the observation of a hominid brain is not directly possible.

This does not imply that assessing brain evolution is impossible, as 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 analysis of the endocranial structure.

Thus, in the same way that paleontology is a scientific discipline despite studying aspects of reality that barely remain some remains, in this case it is also possible to obtain scientific knowledge about organs that we can only know from what the surrounded.

paleoneurology

The main element that allows us to try to observe how the human brain has evolved is the cranial capacity, that is, the amount of brain volume that would fit inside a 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 take into account, and which in fact is also linked to the emergence and progressive increase in intellectual capacity, is the level of blood supply that these brains possessed.

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

The development of the brain in the different species of hominins

Mainly based on the cranial capacity and its morphology, we are going to try to approximate how the brain of the human being has evolved throughout evolution and in some of the most representative and well-known species of the hominin group, made up of bonobos, chimpanzees, our bipedal ancestors, and us, the sapiens.

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

On the other hand, we must bear in mind that we still do not know the evolutionary tree of our ancestors well, since we only know it from approximate way from estimates (debatable and debated) about the position that each species occupies in the taxa of the evolution.

Ardipithecus ramidus

Ardipithecus is probably one of the oldest ancestors of humans ever found, although the Aahelanthropus tchadensis (about which there is disagreement between whether it would be the first species of human being or chimpanzee, may even be the ancestor that distinguished both species) or the orrorin tugenensis are even more ancient. This being, with simian characteristics, had a small skull of approximately 350 cubic cm. (That of current chimpanzees ranges from 275 to 500).

This species was already bipedal, but its small brain makes the vast majority of higher cognitive abilities unlikely at best. The fact that they lived collectively indicates a certain level of socialization, similar to that of family groups of other great apes current. 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 to exist after Ardipithecus.

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

The morphology could reflect the existence of a frontal lobe relatively small, having few higher cognitive abilities and being quite limited in reasoning and planning capacity compared to a current human being. Nor did it have an excessively large parietal lobe, not probable the existence of developed brain areas that would allow complex oral language 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.

• Related article: "Areas of the brain specialized in language: their location and functions"

Homo habilis

He Homo habilis He was one of the first representatives of the genus Homo. Homo habilis has a larger and somewhat more rounded skull, with a cranial capacity of around 600-640 cubic cm.

This species has been found was able to create crude tools, which requires a certain planning ability and a development of the frontal area somewhat higher than the previous species. It also requires more hand-eye coordination, with the motor area probably being somewhat larger. The fact that remains have been detected that indicate that they were hunting also suggests the ability to generate strategies and an improvement in the level of communication.

The bulging of the parts of the cranial vault that correspond to the areas Broca's and Wenicke's, not being unlikely 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.

• Related article: "The 7 types of lithic industry: the origins of technology"

erectus

The cranial volume of this species oscillates between 800 and 1000 cubic cm, 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, probably they had a somewhat more developed frontal lobe. Elongation of the posterior part of the skull could indicate further development of the occipital, parietal, and temporal lobes.

homo neanderthalensis

Neanderthal man is our closest extinct relative and indeed he lived with our species for thousands of years.

The cranial capacity of Homo neanderthalensis could be even greater than ours, being able to reach between 1,400 and 1,900 cubic cm. This means that it is not known what level of abstraction they could reach. However, the morphology of its skull suggests a somewhat smaller frontal than that of sapiens, but in turn a larger size of the occipital lobe regions, dedicated to body self-control and perception.

It is known that they took care of their patients, they probably had a language similar to ours and sometimes they carried out burials, in addition to dominating a relatively developed type of lithic industry called lithic industry Mousterian. All this implies that they had an area of ​​language and that they 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 by cerebral level due to a wide development of the neocortex and especially due to the enormous size of our lobe frontal. This is one of the elements that stands out the most in us and that allows us to carry out and possess higher cognitive functions such as reasoning or abstraction.

Artistic creation was also considered for a long time exclusive to our species, although currently It is considered that the Neanderthals could also make different cave paintings and elements ornamental. When it comes to energy and nutrient consumption, it is estimated that our brain uses up to 20% of what we consume. It is also considered that the level of blood supply that our brain has has increased six times compared to the first hominids.

However, our cranial capacity is smaller compared to that of Neanderthals, ours being around 1,300 to 1,800 cubic cm. Although their greater cranial capacity does not mean that they had more or less intelligence (depending to a large extent on the organization of the brain and not only on their size), we cannot help thinking that perhaps previous or different species were much more capable than originally thought, being something to value in a future.

Bibliographic references:

• Bradford, H.F. (1988). Fundamentals of Neurochemistry. Barcelona: Labor.
• Bruner, E.; Mantini, S.; Musso, F.; De La Cuétara, J.M.; Ripani, M. and Sherkat, S. (2011). The evolution of the meningeal vascular system in the human genus: From brain shape to thermoregulation. American Journal of Human Biology, 23 (1): pp. 35 - 43.
• Carotenuto, F.; Tsikaridze, N.; Rook, L.; Lordkipanidze, D.; Longo, L.; Condemi, S. & Raya, P. (2016). Venturing out safely: The biogeography of Homo erectus dispersal out of Africa. Journal of Human Evolution. 95. pp. 1 - 12.
• Morgado, I. (2005). Psychobiology: From genes to cognition and behavior. Ariel Neuroscience.
• Seymour, R.S.; Bosioc, V. and Snelling, E.P. (2017). Fossil skulls reveal that blood flow rate to the brain increased faster than brain volume during human evolution. Royal Society Open Science.