A new study sheds light on how human brains become so large compared to their animal counterparts. Scientists show that contrary to popular belief humans didn't grow larger brains due to social interactions but instead due to environmental challenges that made them rise to the occasion of survival.
This changes the way how the development of the brain is viewed in the scientific community.
The Large Size Of Human Brains
Previous theories had the human brain growing due to increasing complexities of interactions between humans. In a new study published in the journal Nature, Mauricio Gonzalez-Forero and Andy Gardner of St. Andrews University in Scotland say that they have figured out the reason why human brains grew about six times larger than expected. Human brains use 20 percent of the body's energy needs.
Researchers used a mathematical model to measure how much ecological and social problems have an effect on the growth of brain size. This model was used in a hypothetical population of females, it followed how their brains adapted to the challenges they were presented with challenges.
In the model, scientists entered data such as a newborn's brain size and the energy costs of the brain and reproductive organs. Researchers also included information that was presented in previous theories such as environmental and social challenges.
This information was able to determine how each challenge impacts the ability of the brain to grow. It calculated how much energy would be needed to grow the brain. Scientists found out that more difficult mental demands make brains grow larger.
Researchers expected to find that social challenges would play a much larger role in the development of the brain. Computer data showed that 60 percent of brain growth came from a person having to deal with the environment on their own. Along with 30 percent that came from cooperating with other people to deal with the environment, and 10 percent came from dealing with the competition with other people.
Data also concluded that cooperation was associated with decreasing brain size because it allows people to rely on each other's resources and save energy by growing smaller brains. Social demands didn't lead to an increase in human brain sizes.
Mathematical Model
Gonzales-Forero previously came up with the mathematical model to determine the development of larger brain sizes while working with colleagues at the University of Lausanne in Switzerland. The model predicts how much energy is used to drive brain growth at different ages with different biological challenges.
