On the Evolution of Lactase Persistence in Humans

Area of Science:

• Human evolution
• Genetics
• Anthropology

Background:

• Lactase persistence, the ability to digest lactose in adulthood, varies significantly across human populations.
• This trait is considered an adaptation to dairy animal domestication and milk consumption.
• While five variants are known, the genetic basis is monogenic in Eurasia and polygenic in Africa.

Purpose of the Study:

• To explore the complex evolutionary history and selective pressures of lactase persistence.
• To address discrepancies in lactase persistence frequencies, such as low rates in Central Asian herders versus high rates in some African hunter-gatherers.
• To investigate factors beyond caloric advantage that may have driven selection for lactase persistence.

Main Methods:

• Review of existing genetic and anthropological data on lactase persistence.
• Analysis of evolutionary convergent and gene-culture coevolutionary models.
• Comparative population genetics studies.

Main Results:

• Lactase persistence frequencies and underlying genetic architectures differ significantly between Eurasian and African populations.
• Observed patterns challenge simple explanations, suggesting complex selective pressures and coevolutionary dynamics.
• The role of milk processing in reducing lactose content complicates the understanding of selection.

Conclusions:

• The evolutionary story of lactase persistence is not fully understood and requires further investigation.
• Discrepancies in frequencies and selection pressures necessitate a re-evaluation of current hypotheses.
• Understanding lactase persistence offers insights into human adaptation, gene-culture coevolution, and dietary flexibility.