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Molecular evolution of microcephalin, a gene determining human brain size

Yin-Qiu Wang1, Bing Su

  • 1Key Laboratory of Cellulr and Molecular Evolutioin, Kunming Institute of Zoology, The Chinese Academy of Sciences (CAS), Kunming, China.

Human Molecular Genetics
|April 2, 2004
PubMed

Insights

The microcephalin gene is crucial for human brain development. Our study reveals this gene experienced positive selection, contributing to brain size evolution in primates and humans.

Area of Science:

  • Genetics
  • Evolutionary Biology
  • Neuroscience

Background:

  • Microcephalin gene mutations cause primary microcephaly, a condition linked to reduced brain size.
  • The microcephalin gene plays a significant role in human brain development.

Purpose of the Study:

  • To investigate the molecular evolution of the microcephalin gene across primate species.
  • To understand the evolutionary pressures shaping the microcephalin gene, particularly in relation to brain evolution.

Main Methods:

  • Sequencing the coding region of the microcephalin gene in humans and 12 non-human primate species.
  • Conducting neutrality tests and phylogenetic analysis.
  • Performing synonymous/non-synonymous and codon-based analyses.

Main Results:

  • Microcephalin is highly polymorphic in human populations, with numerous substitutions and amino acid changes.
  • Evidence suggests recent human population expansion and Darwinian positive selection contribute to microcephalin's variation.
  • Positive selection on microcephalin was detected during the evolution of humans and great apes, coinciding with brain enlargement.

Conclusions:

  • The microcephalin gene's evolution is influenced by population dynamics and positive selection.
  • Specific amino acid sites under positive selection may have driven brain enlargement during primate evolution and human origins.

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