Why Human Brains Are Smarter Than Chimp Brains

By on February 3, 2012

FRIDAY, Feb. 3 (HealthDay News) –
Extended synaptic development may explain why humans are intellectually superior to primates, a new study suggests.

During the first few years of life, human babies’ mental abilities continue to develop and absorb information and experiences from the environment in a way that far surpasses even the closest primate relatives of humans.

This is due to extended synaptic development, according to the study published online Feb. 1 in the journal Genome Research. The finding sheds new light on the biology and evolution of human brain development, according to the researchers.

“Why can we absorb environmental information during infancy and childhood and develop intellectual skills that chimpanzees cannot?” senior author Philipp Khaitovich, of the Chinese Academy of Sciences and the Max Planck Institute for Evolutionary Anthropology, asked in a journal news release. “What makes the human brain so special?”

He and his colleagues investigated how genes are read, or expressed, during brain development in young humans, chimps (which are closely related to humans), and macaques, a more distantly related species of primate.

The researchers focused on the prefrontal cortex, a more recently evolved brain region associated with abstract thought, planning, impulse control and problem solving, and the cerebellum, an ancient brain region involved in motor control.

“Among all developmental changes specific to the human brain, one process — synaptogenesis — clearly stood out,” Khaitovich said.

Synaptogenesis, the foundation of learning and memory in the brain, involves the formation of synaptic connections, strengthening useful connections and eliminating useless connections, he explained.

In humans, peak expression of synaptic genes in the prefrontal cortex doesn’t occur until about age five. In chimps and macaques, this occurs in the first year of life. This human-specific change occurs only in the prefrontal cortex, not in the cerebellum.

“Our findings suggest that the human brain remains extremely plastic and susceptible to environmental input during the first five years of life,” Khaitovich said. “Our study uncovers one of the important mechanisms potentially involved in evolution of human cognition.”

More information

The U.S. National Institute of Mental Health has more about brain development during childhood and adolescence.

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