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Chimpanzees, like Humans, Have Asymmetric Brains

By Russell Tenofsky

The two halves of the human brain are not symmetrical. This lopsidedness, which arises during brain development, may be a stamp of the adaptability of human brains, a new study suggests.


Chimpanzee brain (left) shows asymmetric shape; human brain (right) even more so. Illustration by Aida Gómez-Robles

Researchers compared geometric differences between brain scans of humans and chimpanzees. They observed structural asymmetries in both human and chimpanzee brains, but human brains were

If someone says you have a lopsided brain, don’t take it as an insult. It just means you’re evolved. As it turns out, chimpanzees have them too.

Unique Similarities Discovered in Brains

A new study points toward the structural asymmetries, or lopsidedness, in human and chimpanzee brains, an evolutionary trait that allows for a high degree of flexibility and adaptability.

“Humans and chimpanzees share a set of brain features involved in high-level cognitive and communicative functions.”As published in Proceedings of the Royal Society B, researchers at The George Washington University in Washington D.C. used magnetic resonance imaging (MRI) scans to study the differences between human and chimpanzee brains. They found human brains to have a greater variance of asymmetry, but both species’ brains are structurally asymmetrical.

According to the researchers, brain asymmetry is a sign of flexibility, or plasticity, and allows the brain to more easily adapt to different situations and conditions – an important aspect in human cognitive evolution.

“We know that plasticity is an important trait in the function of the brain,” lead study author Aida Gómez-Robles said.

Dr. Lori Marino, the NhRP’s Director of Science, argues that this research, and other similar studies, shows the unique similarities between chimpanzee and human brain functions.

“This study is one in a long line showing brain asymmetries are not unique to humans. Great apes, such as chimpanzees, have documented asymmetries in a number of similar areas of the brain,” said Dr. Marino. “In fact, chimpanzees possess a similarly enlarged region of the brain involved in language functions in humans.  This most recent study shows that, although human brains may be more asymmetric, humans and chimpanzees share a set of brain features involved in high-level cognitive and communicative functions.”

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