Dopamine may just be the factor that separates humans from other species on Earth.
According to a research team, a brain system that's in charge of everything from addiction to autism may have evolved differently in humans than in great apes.
Humans Are Unique Because Of Dopamine?
This said system handles the generation of dopamine, a key brain chemical that makes people feel pleasure.
"Humans have evolved a dopamine system that is different than the one in chimpanzees," according to Nenad Sestan, one of the authors of the study and also a neuroscience professor at Yale University.
Published on Thursday, Nov. 23, in the Science journal, the study could help explain why humans act so differently than their nearest relatives despite both of their brains being significantly similar. Furthermore, it might give an inkling as to why humans are more prone to suffering from mental disorders, one of which is autism.
The team's conclusions are the result of a massive, multicenter effort to compare brains of various species. The researchers observed 247 brain tissues from five macaque monkeys, five chimpanzees, and six humans.
The Human Brain's Reward System
A gene called TH, involved in dopamine production, was found in the neocortex of human brains — but not chimpanzees, the team discovered.
Dopamine plays a key role in the human brain's reward system, which is responsible for things such as sex, food, and drug addiction. Not only that, dopamine also aids the brain in regulating emotions, memory, and even movement. Abnormal levels of this chemical often lead to a variety of disorders, some of them being schizophrenia, autism, or Parkinson's disease.
It remains unclear how different dopamine systems affect the human brain, according to Sestan, but researchers now know where to begin looking. The biggest question is why TH is present in humans and not chimpanzees.
"Our brains are three times larger, have many more cells and therefore more processing power than chimpanzee or monkey," according to Andre M.M. Sousa, one of the study's authors and also a postdoctoral researcher in Sestan's lab. "Yet there are also distinct small differences between the species in how individual cells function and form connections."
Dopamine is more than just about seeking pleasure. It is also pivotal in cognitive abilities, which humans excel at, including learning, concentrating, and planning ahead.
It could take a long while before scientist are able to truly explain why the human brain is far ahead of other species and what exactly makes it unique. This study is a small step in that direction. Eventually, they might also be able to explain why humans suffer from complex mental illnesses.