Natural selection that favors individuals with intermediate traits while selecting against extreme variations. It maintains the status quo and reduces genetic variation around the population mean.
From Latin 'stabilis' meaning 'firm or steady' and 'selectio' meaning 'choice'. The concept was developed in the 1930s by population geneticists studying how selection can maintain rather than change population characteristics.
Human birth weight is a perfect example - babies that are too small or too large have lower survival rates, so selection favors the 'just right' middle range! It's like evolution's quality control system, keeping things within optimal specifications.
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