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Microcephalin, a gene regulating brain size, continues to evolve adaptively in humans
Patrick D Evans1, Sandra L Gilbert, Nitzan Mekel-Bobrov
1Howard Hughes Medical Institute, Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA.
Science (New York, N.Y.)
|September 10, 2005
Summary
A human brain gene, Microcephalin (MCPH1), evolved rapidly due to positive selection. A specific variant spread quickly, suggesting ongoing human brain evolution and plasticity.
Area of Science:
- Evolutionary biology
- Human genetics
- Neuroscience
Background:
- The Microcephalin (MCPH1) gene is crucial for regulating human brain size.
- MCPH1 has undergone significant positive selection throughout human evolution.
Purpose of the Study:
- To investigate the evolutionary history of a specific Microcephalin (MCPH1) genetic variant in modern humans.
- To determine if this variant's frequency increase is consistent with neutral drift or positive selection.
Main Methods:
- Analysis of genetic data to track the frequency of the Microcephalin (MCPH1) variant over time.
- Statistical modeling to assess the likelihood of the observed frequency changes under neutral and selective pressures.
Main Results:
- A specific Microcephalin (MCPH1) variant, originating ~37,000 years ago, exhibited a frequency increase too rapid for neutral drift.
- The rapid spread strongly suggests this variant was driven by positive natural selection.
Conclusions:
- The Microcephalin (MCPH1) gene has continued to evolve adaptively in anatomically modern humans.
- This indicates ongoing evolutionary plasticity in the human brain.
- MCPH1 is a key candidate for studying the genetic basis of human brain-related variations.
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