Table of contents:
- Neurotransmitters are “signaling molecules” - biologically active chemicals through which an electrochemical impulse is transmitted from a nerve cell through the synaptic space (point of contact) to neurons and between neurons, as well as, for example, from neurons to muscle tissue or glandular cells
- Scientists are confident that the neurochemical profile of the human brain was formed as a result of natural selection due to various reproductive characteristics
Video: Brain Chemistry - The Key To Humanity - Research
Research that compares us to primates and examines areas of the brain associated with social behavior could provide a biological explanation for Shakespeare, Gandhi, and Einstein in humans, rather than, say, chimpanzees.
Excavation of ancient artifacts, bones, records can tell a lot about our evolutionary past: what our ancestors looked like, how they walked, what they ate. But there is something that the fragments of skeletons cannot reveal to us: why did people evolve, or rather, why did people evolve? Why, of all the primates, only a few were capable of development? And why were only humans capable of such complex thoughts, emotions and behavior?
The team of scientists taking on new research in this area decided to approach the question from the side of chemistry: to create a profiling of chemical compounds in our brain known as neurotransmitters.
Neurotransmitters are “signaling molecules” - biologically active chemicals through which an electrochemical impulse is transmitted from a nerve cell through the synaptic space (point of contact) to neurons and between neurons, as well as, for example, from neurons to muscle tissue or glandular cells
According to the researchers' hypothesis, the profiles of human neurotransmitters differ from those of the great apes, which should explain our more developed cognitive abilities. And scientists tried to prove it with their work.
The experiment was conducted by several institutes and centers, but anthropologists Owen Lovejoy and Mary Ann Rahati, who led the study at Kent State University, decided to start with an estimate of the total number of neurotransmitters in humans, chimpanzees, gorillas, baboons and monkeys.
Scientists have carefully studied substances in the striatum of the brain, which is responsible for social behavior and communication. It turned out that in this part of the brain, a person has significantly more dopamine activity, one of the functions of which is the mental reward of social activity and behavior in society. In the striatum, in particular, dopamine contributes to the development of such behavioral characteristics and abilities inherent only to humans as functioning within a complex social formation (group) and mastery of speech.
Also, the brains of humans, gorillas, and chimpanzees have higher levels of serotonin than other primates. In the striatum, this hormone is responsible for cognitive function and control. For example, the higher the serotonin level, the lower the aggression (and, conversely, the lower its level, the less pronounced social skills).
However, such a neurotransmitter as acetylcholine is also responsible for the level of aggression: the less it is, the less aggression. The researchers noted that primates have much higher levels of this neurotransmitter than humans.
“So, we see something in common in humans and great apes: a high level of serotonin allows them to carry out complex social interactions,” Rahati emphasizes, “but with a high level of acetylcholine, animals show more aggressiveness, while in humans it is suppressed due to a reduced level of this neurotransmitter. … That is, we can say that the behavior of humans and primates is influenced by a whole cocktail of various chemical compounds, collected in different proportions."
Scientists are confident that the neurochemical profile of the human brain was formed as a result of natural selection due to various reproductive characteristics
And it was this evolution of the "chemical signature" of humanity (the very neurochemical profile that the authors of the work tried to build) that helped us in the race for survival to beat monkeys and prehistoric people after our separation from chimpanzees six million years ago. Scientists are even inclined to believe that high levels of dopamine in the striatum could lead to monogamy as a more beneficial type of social communication for the development of the genus.
Clifford Jolly, an anthropologist at New York University who was not involved in the study, believes the hypothesis is plausible. “The suggestion that differences in neurochemical brain profiles between monkeys and humans correlate with differences in temperament and social communication is still a hypothesis, although the rationale is powerful,” he says. "And it is very likely that the described difference in the levels of hormones and neurotransmitters in the striatum did play an important role in the evolution of human behavior and may explain the high level of empathy between people, which is an innate characteristic of the species."
Previously, the ability to empathize was explained by the fact that our ancestors had a larger brain in relation to the body than primates, and natural selection in favor of a non-aggressive population (the so-called "self-domestication hypothesis") helped to survive and thrive. When planning a new study, Rahati wanted to understand exactly how much the size of the brain actually led to self-domestication. In this context, it seemed logical to her to explore just the striatum, which is responsible for socialization. As a result, she now believes that the root cause of everything was precisely our "chemical signature", which contributed to the fact that the human brain "swelled".
"Our research can recreate the mechanism of the emergence of a large brain in humans," which has anatomical confirmation. So, for example, ancient people, hominids, according to excavations, existed even before the human brain increased. Rakhati also notes that this species has significantly shorter "fangs", which for a long time played an important role in attracting the attention of females by males. This suggests that the signals for mating have lost their formidable message, people have become more "civilized", as we would say now. “And the decrease in the level of aggression, which we see here in prehistoric people,” emphasizes the researcher, “just indicates that the neurochemical profile has changed. After all, in modern people we see the relationship between the level of neurotransmitters and aggression. It is especially important thatthat the alleged chemical changes occurred before the human brain increased in size."
Scientists plan to continue their research to find even more convincing evidence for their hypotheses. In particular, they are going to study monogamous primates to show that they have higher levels of dopamine, lower acetylcholine, and they behave differently from their more aggressive brethren
By Bret Stetka, Medscape Editor, Scientific American Author, et al.