The size of our brains cause us to be born “too soon”ren_Geo/Shutterstock
The theory of the “fourth trimester” suggests that babies are born when their bodies are still very fragile in order to allow for their relatively large brains to have room to be delivered. (Here are more bizarre facts about newborns that doctors don’t tell you.) “I always tell my patients that all babies are born too soon,” says Harvey Karp, MD, author of The Happiest Baby on the Block and creator of the “smart sleeper” SNOO. “Think about it—a horse can walk on the very first day of life, but by comparison, human babies are super immature. They can’t walk, run, or even burp without help from Mom or Dad.” A horse’s survival depends on his body, but human survival depends on our brain. “So, our species evolved to evict our little genius babies from the womb three months early—before their heads get so big that they risk getting stuck in the birth canal,” Dr. Karp says.
Brain folds have functionNaeblys/Shutterstock
Although Dr. Tarawneh says that the number of folds, or gyri, in the human brain doesn’t always equal intelligence, they do have a purpose. The folds allow for more surface area on the outer layer, or cortex, of the brain. “The cortex is the computational part on the outer surface of the brain, where the majority of the brain cells are,” Dr. Tarawneh says. Monkeys and dolphins also have wrinkly brains, whereas the surface of mice brains are smooth. But, scientists are still researching how these folds develop.
The nature of intelligence isn’t knownDean Drobot/Shutterstock
You can fake being smart (especially with these easy ways to look like a genius), but what really makes us intelligent, if not brain size and folds? “Although we still do not know all of the biological processes that explain intelligence, intelligent people probably have better connections between the neurons, referred to as synapses, and their neurons have stronger networks in certain brain regions that allow the brain cells to communicate with each other more efficiently,” Dr. Tarawneh says. She notes that anatomy may have something to do with it, as some studies suggest more intelligent people may have thicker cortices (the outer part of the two hemispheres), particularly in some parts such as the parietal lobe.