Nov 16, 2018 03:49 AM
https://theconversation.com/human-evolut...ver-105683
EXCERPT: . . . Though modern healthcare frees us from many causes of death, in countries without access to good healthcare, populations are continuing to evolve. Survivors of infectious disease outbreaks drive natural selection by giving their genetic resistance to offspring. Our DNA shows evidence for recent selection for resistance of killer diseases like Lassa fever and malaria. Selection in response to malaria is still ongoing in regions where the disease remains common.
Humans are also adapting to their environment. Mutations allowing humans to live at high altitudes have become more common in populations in Tibet, Ethiopia, and the Andes. [...] Diet is another source for adaptations. Evidence from Inuit DNA shows a recent adaptation that allows them to thrive on their fat-rich diet of Arctic mammals. [...]
We may well be adapting to unhealthy diets too. One study of family genetic changes in the US during the 20th century found selection for reduced blood pressure and cholesterol levels, both of which can be lethally raised by modern diets.
Yet, despite these changes, natural selection only affects about 8% of our genome. According to the neutral evolution theory, mutations in the rest of the genome may freely change frequency in populations by chance. If natural selection is weakened, mutations it would normally purge aren’t removed as efficiently, which could increase their frequency and so increase the rate of evolution.
But neutral evolution can’t explain why some genes are evolving much faster than others. [...] Though scientists can see these changes are happening – and how quickly – we still don’t fully understand why fast evolution happens to some genes but not others....
MORE: https://theconversation.com/human-evolut...ver-105683
EXCERPT: . . . Though modern healthcare frees us from many causes of death, in countries without access to good healthcare, populations are continuing to evolve. Survivors of infectious disease outbreaks drive natural selection by giving their genetic resistance to offspring. Our DNA shows evidence for recent selection for resistance of killer diseases like Lassa fever and malaria. Selection in response to malaria is still ongoing in regions where the disease remains common.
Humans are also adapting to their environment. Mutations allowing humans to live at high altitudes have become more common in populations in Tibet, Ethiopia, and the Andes. [...] Diet is another source for adaptations. Evidence from Inuit DNA shows a recent adaptation that allows them to thrive on their fat-rich diet of Arctic mammals. [...]
We may well be adapting to unhealthy diets too. One study of family genetic changes in the US during the 20th century found selection for reduced blood pressure and cholesterol levels, both of which can be lethally raised by modern diets.
Yet, despite these changes, natural selection only affects about 8% of our genome. According to the neutral evolution theory, mutations in the rest of the genome may freely change frequency in populations by chance. If natural selection is weakened, mutations it would normally purge aren’t removed as efficiently, which could increase their frequency and so increase the rate of evolution.
But neutral evolution can’t explain why some genes are evolving much faster than others. [...] Though scientists can see these changes are happening – and how quickly – we still don’t fully understand why fast evolution happens to some genes but not others....
MORE: https://theconversation.com/human-evolut...ver-105683