-- Robert Preidt
THURSDAY, May 3 (HealthDay News) -- New research suggests that a
partial duplication of a gene played a significant role in a major
advance in human brain evolution that occurred a few million years
The SRGAP2 gene has been duplicated at least twice during human
evolution, first about 3.5 million years ago and again about 2.5
million years ago. The second duplication produced only a partial
copy of the gene, the study authors said.
This partial copy acts at exactly the same time and place as the
original gene, allowing the partial copy to interact with and block
the original gene's function, according to the findings published
online May 3 in the journal
The partial copy of the SRGAP2 gene seems to have appeared at
the same time that the fossil records show a transition from our
extinct Australopithecus ancestors to the genus Homo, which led to
and includes modern humans.
This point in human evolution is also when our ancestors' brains
began to expand and major advances in intelligence likely occurred,
according to Franck Polleux, an expert in brain development at
Scripps Research Institute in La Jolla, Calif., and Evan Eichler, a
genome scientist at the University of Washington in Seattle.
The researchers said that SRGAP2 and other human-specific gene
duplicates may explain why humans are much more intelligent than
other primates, despite few apparent differences in their genome
"We may have been looking at the wrong types of mutations to explain human and great ape differences," Eichler said in a journal news release. "These episodic and large duplication events could have allowed for radical -- potentially earth-shattering -- changes in brain development and brain function."
The findings also may provide clues to neurodevelopmental
disorders, including autism, epilepsy and schizophrenia, the
The U.S. Institute of Neurological Disorders and Stroke has more
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