Researchers contend that children’s brain growth outpaces body growth, as their developing brains require so much energy to prepare for the challenges of adult life.
In a new study, data was analyzed from PET and MRI brain scans. The findings indicate that enormous amounts of energy are used by the human brain in the first few years of life. Physical growth is less of a priority for development during those years, and brain development is of critical importance.
In one example, a 5 year old’s brain uses twice as much of the energy fuel glucose as the brain of an adult. The peak of this use of energy occurs around age 4, and body growth slows. The rate that the brain burns energy in a four year old is equal to two thirds of what the entire body uses at rest, according to the study’s authors.
The findings support a longstanding theory about why children grow so slowly, said the authors of the study, published this week in the journal Proceedings of the National Academy of Sciences.
“Our findings suggest that our bodies can’t afford to grow faster during the toddler and childhood years because a huge quantity of resources is required to fuel the developing human brain,” first author Christopher Kuzawa, a professor of anthropology at Northwestern University, said in a university news release.
“As humans we have so much to learn, and that learning requires a complex and energy-hungry brain,” he added.
The findings also explain some common observations made about young children, the researchers said.
“After a certain age it becomes difficult to guess a toddler or young child’s age by their size,” Kuzawa said. “Instead you have to listen to their speech and watch their behavior. Our study suggests that this is no accident.”