There is plenty of scientific discussion on the genetic origins of various human populations and the genetic differences between them. It also makes the news quite often, as people are interested in knowing where they come from.
Human populations tend to migrate and mix too frequently to form distinct subspecies (or “races”). We end up with a continuum of populations, and even distant populations are often genetically close. We can still observe something resembling breeds: populations that have been selected for various traits but that are otherwise genetically similar to each other.
Anonsays:
“We end up with a continuum of populations”
Like the continuum of colors?
“distant populations are often genetically close”
Like England and Australia?
“Human populations tend to migrate and mix too frequently to form distinct subspecies”
If there is a continuum of populations with frequent gene flow between them, there are no subspecies. That’s the way biologists have defined their terminology.
Europeans and Aboriginal Australians are at opposite ends of the continuum. Both groups are believed to descend from the same relatively small populations that migrated out of Africa around 70000 years ago. Aboriginal Australians were separated from the rest of humanity long enough that they might have formed a subspecies at one point. Because of the recent population bottleneck, they were still genetically close to Eurasians and Native Americans. Of course, that separation no longer exists due to the high intermarriage rates between Aboriginal Australians and recent immigrants.
The pygmy phenotype is believed to be a genetic adaptation to hunter-gatherer life in tropical rainforests. It has developed independently in Africa, Southeast Asia, and South America. There is also evidence that suggests that multiple populations have developed the phenotype independently on each continent. Because pygmy populations frequently mix with neighboring non-pygmy populations, they cannot be considered subspecies.
Anonsays:
“Because pygmy populations frequently mix with neighboring non-pygmy populations, they cannot be considered subspecies.”
How do they stay short if they mix?
“If there is a continuum of populations with frequent gene flow between them, there are no subspecies”
As long as the selective pressure exists, the population can sustain a certain degree of incoming gene flow without changes in phenotype distribution. Pygmies remain short for the same reason as native Europeans still have light skin, despite millennia of migrations from the Eurasian Steppe, Middle East, and North Africa.
The Indian caste system is a nice natural experiment in genetic differentiation. However, it has only lasted for around 70 generations, which is a short time in evolution. For a comparison, many dog breeds have been separated for hundreds of even thousands of generations, but they still belong to the same subspecies of the gray wolf.
There is plenty of scientific discussion on the genetic origins of various human populations and the genetic differences between them. It also makes the news quite often, as people are interested in knowing where they come from.
Human populations tend to migrate and mix too frequently to form distinct subspecies (or “races”). We end up with a continuum of populations, and even distant populations are often genetically close. We can still observe something resembling breeds: populations that have been selected for various traits but that are otherwise genetically similar to each other.
“We end up with a continuum of populations”
Like the continuum of colors?
“distant populations are often genetically close”
Like England and Australia?
“Human populations tend to migrate and mix too frequently to form distinct subspecies”
Pygmies are not a subspecies?
If there is a continuum of populations with frequent gene flow between them, there are no subspecies. That’s the way biologists have defined their terminology.
Europeans and Aboriginal Australians are at opposite ends of the continuum. Both groups are believed to descend from the same relatively small populations that migrated out of Africa around 70000 years ago. Aboriginal Australians were separated from the rest of humanity long enough that they might have formed a subspecies at one point. Because of the recent population bottleneck, they were still genetically close to Eurasians and Native Americans. Of course, that separation no longer exists due to the high intermarriage rates between Aboriginal Australians and recent immigrants.
The pygmy phenotype is believed to be a genetic adaptation to hunter-gatherer life in tropical rainforests. It has developed independently in Africa, Southeast Asia, and South America. There is also evidence that suggests that multiple populations have developed the phenotype independently on each continent. Because pygmy populations frequently mix with neighboring non-pygmy populations, they cannot be considered subspecies.
“Because pygmy populations frequently mix with neighboring non-pygmy populations, they cannot be considered subspecies.”
How do they stay short if they mix?
“If there is a continuum of populations with frequent gene flow between them, there are no subspecies”
Indian castes?
As long as the selective pressure exists, the population can sustain a certain degree of incoming gene flow without changes in phenotype distribution. Pygmies remain short for the same reason as native Europeans still have light skin, despite millennia of migrations from the Eurasian Steppe, Middle East, and North Africa.
The Indian caste system is a nice natural experiment in genetic differentiation. However, it has only lasted for around 70 generations, which is a short time in evolution. For a comparison, many dog breeds have been separated for hundreds of even thousands of generations, but they still belong to the same subspecies of the gray wolf.
Any good textbooks on all this stuff?
Thanks for this article
Fst ( a measure of genetic differentiation) between Europeans and West Africans is 0.153.
Fst between timber wolves and coyotes: 0.153