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 the one that develops later (without taking into account that throughout our lives we keep making synaptic connections) .

It is a structure present in a large majority of animals and which has developed in different ways and evolved in different ways in different species over millions of years.

By focusing again on the human being, little by little different structures and capacities appeared in our ancestors according to the evolution which followed its course, being currently the brain of our species the last of the surviving genus Homo. In this article, we will try to approach a as has been the evolution of the human brain until today.

    The evolution of the human brain

    Analyzing what the brains of our now-extinct ancestors looked like is a difficult and complex task. In fact, direct observation of a brain of species prior to ours (and even ancestors within our own species) is not possible.

    And is the main problem in determining how the human brain evolved quite simple and at the same time extremely complex: the brain it is soft tissue, so it does not fossilize and eventually rot and disappear. This implies that, with the possible exception of dead subjects frozen and kept on ice, the observation of a hominid brain is not directly possible.

    This does not mean that it is impossible to assess the evolution of the brain in a way, there is even a science dedicated to it. We are talking about paleoneurology, which studies the brain structure of our ancestors. based on the analysis of the endocranial structure.

    Thus, in the same way that paleontology is a scientific discipline despite the study of aspects of reality of which only a few remain, in this case it is also possible to obtain scientific knowledge about the organs that we can only know what they surround.

    paleoneurology

    The main element that allows us to try to observe the evolution of the human brain is the cranial capacity, that is to say the amount of brain volume that could be inside a skull of a given species. Not only the size, but also the morphology can give us clues on more or less developed regions.

    Another aspect to consider, and which in fact is also linked to the onset and progressive increase of intellectual capacities, is the level of blood supply that these brains had.

    A functioning brain needs a constant supply of energy, functioning better, the more the supply of oxygen and nutrients is efficient. And that means that at a higher level of cranial capacity and greater functionality of the brain, it takes a lot more energy and therefore more blood to carry basic nutrients to the brain. When it comes to fossils or bones, the easiest way to try the calculation of the blood flow of our ancestors is done by observing the intracranial orifices that allow the passage of blood vessels through it.

    Brain Development in Different Hominid Species

    Mainly on the basis of cranial capacity and its morphology, we will try to approach how the human brain evolved during evolution and in some of the most representative and well-known species of the hominid group., Formed by the bonobos, the chimpanzees, our bipedal ancestors and us, the sapiens.

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

    On the other hand, we must keep in mind that we do not yet know well the evolutionary tree of our ancestors, since we only know it approximately from estimates (debatable and debated) on the position occupied by each species in taxa. evolution.

    Ardipithecus ramidus

    Ardipithecus is probably one of the oldest human ancestors ever found, although Aahelanthropus tchadensis (on which there is disagreement with each other would be the first species of human or chimpanzee, and may even be l ancestor who distinguished the two species) or Orrorin tugenensis are even older. This being, of monkey characteristics, had a small skull of about 350 cubic cm (Chimpanzees today range from 275 to 500).

    This species was already bipedal, but its small brain makes the vast majority of superior cognitive abilities at best unlikely. The fact that they lived in a community 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 related genus of hominid, being one of the earliest types of hominids to exist after Ardipithecus.

    Among the various existing species, one of the best known is Afarensis. this species it was characterized by a skull with relatively low cranial capacity, About 400-480 cm3 (not being larger in size than that of a large number of chimpanzees although in size proportional to the body yes it would be a little larger). The inside of the skull had different air cavities that protected the brain. There is a strong prognathism.

    The morphology might reflect the existence of a relatively small frontal lobe, having little superior cognitive ability and its reasoning and planning ability being quite limited compared to a modern human being. He also did not have an excessively large parietal lobe, not being probable the existence of developed cerebral areas which would allow a complex oral language and not possessing a high level of creativity or memory. Apparently, the dorsal part of the skull was larger, which is related to the processing ability of visual perception.

      Man

      Homo habilis was one of the first representatives of the genus Homo. Homo habilis has a larger and slightly more rounded skull, with a cranial capacity of approximately 600 to 640 cubic cm.

      It was discovered that this species he was able to create raw tools, Which requires a certain skill of planning and a development of the frontal zone slightly higher than the preceding species. It also requires better hand-eye coordination, with the motor area likely being slightly larger. The fact that remains were detected indicating that they were hunting also suggests the ability to generate strategies and an improvement in the level of communication.

      We observe the pumping of the parts of the cranial vault corresponding to the Broca and Wenicke zones, and the emergence of a very rudimentary form of language, strongly supported by gestures and visual communication in general, is not improbable. The blood supply to the brain is probably higher.

        Straight man

        The cranial volume of this species oscillates between 800 and 1000 cubic cm, being this species the one that began to dominate and to use fire as a tool. They created tools and hunted cooperatively. Although to a lesser extent than more recent species, probably they had a slightly more developed frontal lobe. Lengthening of the back of the skull could indicate further development of the occipital, parietal, and temporal lobes.

        Homo neanderthalensis

        Neanderthals are our closest and de facto extinct relatives coexisted with our species for thousands of years.

        The cranial capacity of Homo neanderthalensis could be even higher than ours, and can reach between 1400 and 1900 cubic cm. This makes it impossible to know what level of abstraction they might reach. However, the morphology of his skull suggests a forehead slightly smaller than that of sapiensBut in turn, a larger size of the regions of the occipital lobe, devoted to self-control and the perception of the body.

        If you know they took care of their patients, they probably had a similar language to ours and sometimes did burials, in addition to mastering a relatively developed type of lithic industry called the Mosterian lithic industry. All this implies that they owned a domain of the language and that they had a capacity for abstraction, empathy and a high degree of self-awareness.

        homo sapiens

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

        Artistic creation was also considered for a long time exclusive of our species, although at present it is considered that Neanderthals could also make various cave paintings and ornamental elements. In terms of 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 to our brain has increased six-fold compared to the first hominids.

        However, our cranial capacity is lower than that of Neanderthals, ours being around 1,300 to 1,800 cubic cm. While their larger cranial capacity doesn’t mean that they had more or less intelligence (depending largely on the organization of the brain and not just their size), we can’t help but think that maybe- being previous or different species were much more capable than originally thought being something to be valued in the future.

        Bibliographical references:

        • Bradford, HF (1988). Fundamentals of Neurochemistry. Barcelona: Work.
        • Bruner, E .; Mantini, S .; Musso, F .; De La Cuétara, JM; Ripani, My Sherkat, S. (2011). The evolution of the meningeal vascular system in humans: from cerebral form to thermoregulation. American Journal of Human Biology, 23 (1): pages 35-43.
        • Carotenuto, F .; Tsikaridze, N .; Rook, L .; Lordkipanidze, D .; Longo, L .; Condemi, S. and Raia, P. (2016). Safe Adventure: The Biogeography of the Spread of Homo erectus Outside of Africa. Journal of Human Evolution. 95. pages 1 to 12.
        • Morgado, I. (2005). Psychobiology: from genes to cognition and behavior. Ariel Neuroscience.
        • Seymour, RS; Bosioc, V. and Snelling, EP (2017). Fossil skulls reveal that blood flow to the brain increased faster than brain volume during human evolution. Open Science of the Royal Society.

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