For example, during pregnancy African Americans are said to have a higher chance of getting preeclampsia or gestational diabetes. Genetically, what’s happening here?
In: 72
The last 2-3 thousand years are a bit of an exception in terms of how easily humans of different races could mix whether it be due to movement, military, or cultural reasons.
For the tens to hundreds of thousands of years before that, humans typically reproduced with people of similar race. Because of that, there are selective pressures to favor certain traits.
Low nutrition diet but your culture values large, physically strong warriors? Then the people who can convert food into physical bulk would have reproductive advantage and spread their genes more than those who don’t have the trait. The American Samoans are 40 times more likely to play in the NFL compared to their percentage of US population. However, American Samoans have one of the highest obesity rates in the world and their airlines charge tickets based on weight! One trait can provide positive and negative benefits.
For your African American pregnancy risk example, it’s possible some traits in the past were favorable and common for the race in the past for that sort of lifestyle. But now with a modern diet and/or lack of the same types of physical movement/labor, the trait provides disadvantages.
Usually, these increased chances relate to a genetic bottleneck event. This is where a relatively small population of an animal (including humans) expand and colonize an entire area with their relatively small basket of genes. This most often happens with migration where a small group moves to a new area but occasionally happens when a population is almost completely wiped out and then regrows.
Black Americans are a perfect example. The millions of modern black Americans often trace their heritage to a fairly small number of captured and trafficked slaves. The Africans who were trafficked to America weren’t picked randomly from the genetically diverse population of western Africa. They were usually specific towns, tribes, clans, or other distinct populations. Often people who were already related to each other through generations of living in the same region.
So if a particular clan of people, by random chance, carry a gene that predisposes them to a health problem like diabetes or pre-eclampsia, and they get trafficked to America, suddenly you have an oddity where a very large proportion of the black slaves in America have that gene. That population wasn’t allowed much travel. Wasn’t allowed to marry anyone outside or their group. But did expand into millions of people. And so you end up with millions of people who have a weirdly high rate of a particular gene because that gene happened to get kidnapped onto a slave ship a couple centuries ago.
The last 2-3 thousand years are a bit of an exception in terms of how easily humans of different races could mix whether it be due to movement, military, or cultural reasons.
For the tens to hundreds of thousands of years before that, humans typically reproduced with people of similar race. Because of that, there are selective pressures to favor certain traits.
Low nutrition diet but your culture values large, physically strong warriors? Then the people who can convert food into physical bulk would have reproductive advantage and spread their genes more than those who don’t have the trait. The American Samoans are 40 times more likely to play in the NFL compared to their percentage of US population. However, American Samoans have one of the highest obesity rates in the world and their airlines charge tickets based on weight! One trait can provide positive and negative benefits.
For your African American pregnancy risk example, it’s possible some traits in the past were favorable and common for the race in the past for that sort of lifestyle. But now with a modern diet and/or lack of the same types of physical movement/labor, the trait provides disadvantages.
The last 2-3 thousand years are a bit of an exception in terms of how easily humans of different races could mix whether it be due to movement, military, or cultural reasons.
For the tens to hundreds of thousands of years before that, humans typically reproduced with people of similar race. Because of that, there are selective pressures to favor certain traits.
Low nutrition diet but your culture values large, physically strong warriors? Then the people who can convert food into physical bulk would have reproductive advantage and spread their genes more than those who don’t have the trait. The American Samoans are 40 times more likely to play in the NFL compared to their percentage of US population. However, American Samoans have one of the highest obesity rates in the world and their airlines charge tickets based on weight! One trait can provide positive and negative benefits.
For your African American pregnancy risk example, it’s possible some traits in the past were favorable and common for the race in the past for that sort of lifestyle. But now with a modern diet and/or lack of the same types of physical movement/labor, the trait provides disadvantages.
Usually, these increased chances relate to a genetic bottleneck event. This is where a relatively small population of an animal (including humans) expand and colonize an entire area with their relatively small basket of genes. This most often happens with migration where a small group moves to a new area but occasionally happens when a population is almost completely wiped out and then regrows.
Black Americans are a perfect example. The millions of modern black Americans often trace their heritage to a fairly small number of captured and trafficked slaves. The Africans who were trafficked to America weren’t picked randomly from the genetically diverse population of western Africa. They were usually specific towns, tribes, clans, or other distinct populations. Often people who were already related to each other through generations of living in the same region.
So if a particular clan of people, by random chance, carry a gene that predisposes them to a health problem like diabetes or pre-eclampsia, and they get trafficked to America, suddenly you have an oddity where a very large proportion of the black slaves in America have that gene. That population wasn’t allowed much travel. Wasn’t allowed to marry anyone outside or their group. But did expand into millions of people. And so you end up with millions of people who have a weirdly high rate of a particular gene because that gene happened to get kidnapped onto a slave ship a couple centuries ago.
Usually, these increased chances relate to a genetic bottleneck event. This is where a relatively small population of an animal (including humans) expand and colonize an entire area with their relatively small basket of genes. This most often happens with migration where a small group moves to a new area but occasionally happens when a population is almost completely wiped out and then regrows.
Black Americans are a perfect example. The millions of modern black Americans often trace their heritage to a fairly small number of captured and trafficked slaves. The Africans who were trafficked to America weren’t picked randomly from the genetically diverse population of western Africa. They were usually specific towns, tribes, clans, or other distinct populations. Often people who were already related to each other through generations of living in the same region.
So if a particular clan of people, by random chance, carry a gene that predisposes them to a health problem like diabetes or pre-eclampsia, and they get trafficked to America, suddenly you have an oddity where a very large proportion of the black slaves in America have that gene. That population wasn’t allowed much travel. Wasn’t allowed to marry anyone outside or their group. But did expand into millions of people. And so you end up with millions of people who have a weirdly high rate of a particular gene because that gene happened to get kidnapped onto a slave ship a couple centuries ago.
Diseases will tend to wipe out certain populations aside from those in the population which have some resistance to it. In some cases, one disease can help protect you from another.
Malaria is persistent in Africa but having sickle-cell protects you from infections because the trypanasomes can attack sickle cells. Cystic fibrosis persisted in Northern European populations because it provided protection from cholera, which was big in the region. Pale skin is advantageous to people living further from the equator because it helps those people synthesize Vitamin D better but exposure to more sun makes you more susceptible to skin cancer.
Genetics is not about what is stronger, just what can survive longest to replicate.
[removed]
Diseases will tend to wipe out certain populations aside from those in the population which have some resistance to it. In some cases, one disease can help protect you from another.
Malaria is persistent in Africa but having sickle-cell protects you from infections because the trypanasomes can attack sickle cells. Cystic fibrosis persisted in Northern European populations because it provided protection from cholera, which was big in the region. Pale skin is advantageous to people living further from the equator because it helps those people synthesize Vitamin D better but exposure to more sun makes you more susceptible to skin cancer.
Genetics is not about what is stronger, just what can survive longest to replicate.
Diseases will tend to wipe out certain populations aside from those in the population which have some resistance to it. In some cases, one disease can help protect you from another.
Malaria is persistent in Africa but having sickle-cell protects you from infections because the trypanasomes can attack sickle cells. Cystic fibrosis persisted in Northern European populations because it provided protection from cholera, which was big in the region. Pale skin is advantageous to people living further from the equator because it helps those people synthesize Vitamin D better but exposure to more sun makes you more susceptible to skin cancer.
Genetics is not about what is stronger, just what can survive longest to replicate.
Latest Answers