Exploring the unique physiological traits of the Sama-Bajau free-divers, known as 'Sea Nomads', who have developed larger spleens for extended underwater dives. The text delves into recent human evolutionary genetics, revealing rapid changes in traits like lactase persistence and pigmentation. It also discusses the pace of human genetic diversification, ongoing natural selection in societies, modern medicine's influence on evolution, and the impact of education and lifestyle on human evolution.
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The Sama-Bajau people have evolved larger spleens to extend their time spent submerged during free-diving
The continued reliance on free-diving suggests potential for further evolutionary developments in the Sama-Bajau's physiology
The larger spleen adaptation is not found in agricultural or less aquatic societies, where it offers no particular advantage
Recent advancements in genomic science have enabled geneticists to detect subtle changes in human evolution over recent history
By examining single nucleotide polymorphisms (SNPs), researchers have identified rapid changes in allele frequencies that affect traits such as lactase persistence and pigmentation
Studies have shown that natural selection has favored polygenic traits like increased stature, larger cranial volume, and broader pelvic width
The vast majority of single nucleotide variants in the human genome have arisen in the last 5,000 to 10,000 years, a period marked by rapid population growth and increased genetic variation
European Americans show a higher mutation load than African Americans, likely due to a bottleneck effect during the Out-of-Africa migration
Despite the rise in potentially harmful mutations, the prevalence of disease is not necessarily higher, as many conditions require multiple genetic changes to manifest
The inhabitants of Cape Verde have developed resistance to malaria in just 20 generations
Traits such as the timing of first childbirth, body size, and length of reproductive life continue to evolve in human populations
Factors such as cultural preferences and health conditions can also influence reproductive success and the evolution of traits in human populations
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Role of spleen in mammalian dive reflex
Spleen contracts to release oxygen-rich red blood cells during dives, extending submersion time.
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Natural selection in Sama-Bajau
Favors individuals with larger spleens for prolonged diving capability.
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Potential for further evolutionary developments in Sama-Bajau
Continuous free-diving lifestyle may lead to more physiological adaptations over time.
