When we think about the differences between human beings and other animals, intelligence quickly comes to mind. We are the species that dominates the world thanks to the cognitive development that we humans have had, so superior to the rest of the species. The difference between living in a tree or in an apartment has only one culprit organ: the brain. What has happened in our evolution so that we have become so intelligent? How do we go from monkey to showing off these bobbleheads with thinking machines?
The selfish organ
Well, of course, not with few hardships. Maintaining this brain is exhausting . In proportion to what it occupies in our body and the energy it requires of us, the brain is the most selfish organ we have.
The adult brain weighs about one and a half kilos, it is barely two percent of the total, but it demands twenty percent of our oxygen, twenty-five percent of all our glucose and twenty percent of all our energy. in resting state . The brain never stops and we already know that a machine running 24 hours a day all year has a high energy cost.
All in all, it seems that for now it is working out profitable for us. However, the journey over millions of years that has brought us to this brain does not have a simple or linear explanation.
Problems and factors in the evolution of the brain
“This organ has undergone important changes during our evolution that are intimately linked to our way of moving, to the morphology of the skeleton, but also to growth and development, diet and culture […] The fundamental keys to our evolution can be understood as a whole. Each important event has been able to awaken the next, as necessary links in an evolutionary chain that has brought us to the present moment.
We have a big initial problem: the brain is a viscous mass that we don’t know how it works . We have a few ideas, but we have a lot to learn about the genetic mechanism that initiates the formation of our thinking machine and the development it has under the protection of our skull.
One of the most striking aspects is that the brain was getting bigger in the human species spread throughout the old world. That is, it is not that a more intelligent lord arose in Africa and his offspring became our ancestors, but that human beings in Africa and Eurasia had parallel developments of their brains.
In fact, a recent study argues that the modern brain is more current than previously thought. Between 1.7 and 1.5 million years ago, the frontal lobe areas of the hominin brain underwent a reorganization. This part of the brain is what allows us to use tools and articulate a language.
This change occurred in Africa and from this continent two important migrations departed, each with a different brain. The first ones came out with a brain more similar to that of the apes, the following ones already had one similar to ours.
“The fact that the brain of early Homo was not as developed as previously thought makes us understand that the evolution of our brain was quite complex and went through several stages.”
Another problem in studying the evolutionary development of the brain continues to have to do with its viscous nature: unlike bones, the soft tissue of the brain disappears easily and, if it is not kept frozen, it would be difficult for us to have the fossil of the brain of one of our ancestors. What remains for us is to study it based on the structure of our skulls, which paleoneurology is responsible for.
How has the evolution of the human brain been?
Knowing the difficulties in investigating this process and the various connected elements that influence brain development, what summary can we draw about the evolution of the brain?
The brain began to grow from the first hominid species, but a qualitative leap was produced, to a large extent, by social competition .
“When humans have to compete for needs and social status, which provides greater access to existing resources, a larger brain is an advantage.”
Our brain developed in areas with more population. Therefore, we are witnessing a feedback in which the growth of the brain allows us to be more social and society pushes us to develop the brain more . A cycle that has not stopped generating increasingly complex social systems and that continues to develop today. The constant need to adapt to societies and environments with different climates has made the human brain the most developed among the species on our planet.
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Martínez, Y. 2009. The human brain developed thanks to social competitiveness. tendencies21.levante-emv.com.
Ponce de León, M. 2021. The primitive brain of early Homo. Science 372, 6538, 165-171. DOI: 10.1126/science.aaz0032.