Human microevolution, ooh. That sounds like a good guess. Google is showing me some results… it will take a while to parse them.
I would be very interested to hear evidence to the contrary, though.
Well the first thing that comes to mind is the incredibly horrible failure rate of common contraceptives, and the unplanned pregnancy rate and birth rate that goes with them.
If there’s any trait at all that’s connected with this—inability to afford more expensive methods, not caring about reliability enough to get an IUD or something more effective, dexterity level too low to correctly apply the product, impulse control issues / inability to think under pressure or when excited, forgetfulness, inability to resist temptation, etc. those traits are likely to reproduce faster than their counterparts. Considering that half our population growth is unintended, I’m pretty concerned about it.
The situation could be that (if a genetic irresponsibility trait exists and is responsible for a large portion of unintended pregnancies that go full term) even if the responsible portion of the population is larger, that the irresponsible portion begins it’s generations sooner, and it’s growth outstrips that of the responsible portion of the population, overpowering it in a short time.
We’re also doing things like removing sociopaths out of the population and putting them into jails. This probably reduces the rate at which they reproduce, though I’d expect far slower evolution there, if any, than I would with something that influences contraceptive failure.
We select certain types of people (or they select themselves) for the military. When they go off to war, they’re more likely to die before reproducing. Since Americans tend to send their soldiers away, they’re also a lot less likely to reproduce before dying in a war than soldiers defending a home territory where they have access to lovers.
If welfare creates a perverse incentive to have more children, any trait that might make welfare appealing to a person could end up being reproduced.
People who get a 2 or 4 year degree have more free evenings in which to find a lover and take care of a child. Contrast that with people who get a higher level degree. They have to wait longer before they’ll be ready.
People in certain industries work very long hours. They might not get a chance to meet someone or might decide they can’t have kids working as many hours as they do.
For these last two groups, if they’re determined to have kids, they’ll probably find a way to do it—but they may be significantly delayed compared with someone who gets a 4-year degree, works a 40 hour week and can start having kids when they’re still in their early 20′s. The delay of a few years probably wouldn’t make much of a difference one or two generations away, but if there are any traits that result in one getting a higher level degree or working longer hours, those people probably won’t reproduce as fast as others.
Well the first thing that comes to mind is the incredibly horrible failure rate of common contraceptives, and the unplanned pregnancy rate and birth rate that goes with them.
By “evidence” I mean evidence that allele frequencies have noticeably changed. These are all hypotheses about things that might be affecting allele frequencies but, again, my standing assumption is that the timescales are too short.
Not only is the timescale too short (human societies change drastically over single-digit generation times, far too short for strong evolution) but all these traits are horrifically polygenic and dependant upon the exact combination of thousands of loci all around your genome that interact. There is also the extremly strong case against genetic determinism in most human behavior.
The traits that I am aware of that show strong evolution all have had thousands of years to be selected for, like lactose tolerance in people descended from herders, resistance to high altitude with a hemoglobin change in Tibet, apparent sexual selection for blue eyes in Europeans and thick hair in East Asians, smaller stature in basically all long-term agriculturalist populations… I think I read about a particular immune system polymorphism in Europe that was selected for a few hundred years ago though because it conveyed partial resistance to the black death.
Not only is the timescale too short (human societies change drastically over single-digit generation times, far too short for strong evolution)
I can see a couple interpretations of this. One is that given observed changes in behavior, it is hard to distinguish cultural change from genetic change. The other is that the cultural environment changes rapidly, so one might not expect the direction of its selective pressure to be maintained for long enough to produce “strong evolution.” Depending on the definition of “strong evolution,” that is tautologous. But why did you introduce the vague qualifier “strong”?
but all these traits are horrifically polygenic and dependant upon the exact combination of thousands of loci all around your genome that interact.
“almost anyone who knows much about evolutionary biology” would know that this does not interfere with the potential for selection, but that excludes virtually all cell biologists. Learn some quantitative genetics in the kingdom of the blind. It’s true that no single allele will shift much, but an aggregate shift in thousands of genes can be measured.
There is also the extremly strong case against genetic determinism in most human behavior.
I have never seen a useful use of the phrase “genetic determinism,” but only ever seen it used as a straw man or a sleight of hand. How much of your comments apply to height?
The traits that I am aware of that show strong evolution all have had thousands of years to be selected for
Things that are easier to observe are observed before things that are harder to observe. A selective sweep at a single locus is the easiest thing to observe, though the faster and more recent the sweep, the easier to observe.
This really depends on your concept of “strong evolution”. If that is jargon meant to refer to a conglomeration of changes that makes the organism different all over, I would agree. If we’re just talking about this in terms of “Is it possible that something of critical importance could significantly change in a few generations?” then I say “Yes, it is possible.”
I assume you consider responsibility to be an important trait. Even if a change to the trait of responsibility alone may not qualify as “strong evolution” to you, would you say that it would be of critical importance to prevent humanity from losing the genes required for responsibility in even half it’s population?
In a world where 40% of the people get here by accident, and we can tell that a lot of their parents failed to use their contraceptives consistently, are you unconcerned that there could be a relationship between irresponsible use of birth control and irresponsible genes being reproduced more rapidly than responsible genes?
The traits that I am aware of that show strong evolution all have had thousands of years
But today’s situation is not the same. We have technologies now that could result in much more powerful unintended consequences just as it results in powerful intended ones. Birth control pills, for instance, didn’t exist thousands of years ago. Our lives and environments are so different now (and are continuing to change rapidly) that we should not assume that our present and future selection pressures will match the potency of the selection pressures in the past. To do so would be to make an appeal to history.
I haven’t found any evidence that allele frequencies have changed—I just started to look into this, and didn’t even have a search term when I started. Due to that, I thought it was obvious that I didn’t have anything on micro-evolution, so I gave you the evidence I do have which, even though does not do anything to support the idea that allele frequencies are being influenced, does support the idea that there’s potential for a lot of influence.
Hmm. A contraceptive and unplanned pregnancy survey by 23andme would be so interesting… I wonder if they do things like that… If I get a useful response to my request for a credible source on their accuracy, I will investigate this. (I want to get their service anyway but am demanding a credible source first.)
Human microevolution, ooh. That sounds like a good guess. Google is showing me some results… it will take a while to parse them.
Well the first thing that comes to mind is the incredibly horrible failure rate of common contraceptives, and the unplanned pregnancy rate and birth rate that goes with them.
Evidence:
In not even four years, about 25% of people using condoms became pregnant. Birth control pills were similar. http://www.jfponline.com/Pages.asp?AID=2603
“49% of pregnancies in the United States were unintended” http://www.cdc.gov/reproductivehealth/UnintendedPregnancy/index.htm
“These pregnancies result in 42 million induced abortions and 34 million unintended births” (world population growth was 78 million for contrast) http://www.arhp.org/publications-and-resources/contraception-journal/september-2008
If there’s any trait at all that’s connected with this—inability to afford more expensive methods, not caring about reliability enough to get an IUD or something more effective, dexterity level too low to correctly apply the product, impulse control issues / inability to think under pressure or when excited, forgetfulness, inability to resist temptation, etc. those traits are likely to reproduce faster than their counterparts. Considering that half our population growth is unintended, I’m pretty concerned about it.
The situation could be that (if a genetic irresponsibility trait exists and is responsible for a large portion of unintended pregnancies that go full term) even if the responsible portion of the population is larger, that the irresponsible portion begins it’s generations sooner, and it’s growth outstrips that of the responsible portion of the population, overpowering it in a short time.
We’re also doing things like removing sociopaths out of the population and putting them into jails. This probably reduces the rate at which they reproduce, though I’d expect far slower evolution there, if any, than I would with something that influences contraceptive failure.
We select certain types of people (or they select themselves) for the military. When they go off to war, they’re more likely to die before reproducing. Since Americans tend to send their soldiers away, they’re also a lot less likely to reproduce before dying in a war than soldiers defending a home territory where they have access to lovers.
If welfare creates a perverse incentive to have more children, any trait that might make welfare appealing to a person could end up being reproduced.
People who get a 2 or 4 year degree have more free evenings in which to find a lover and take care of a child. Contrast that with people who get a higher level degree. They have to wait longer before they’ll be ready.
People in certain industries work very long hours. They might not get a chance to meet someone or might decide they can’t have kids working as many hours as they do.
For these last two groups, if they’re determined to have kids, they’ll probably find a way to do it—but they may be significantly delayed compared with someone who gets a 4-year degree, works a 40 hour week and can start having kids when they’re still in their early 20′s. The delay of a few years probably wouldn’t make much of a difference one or two generations away, but if there are any traits that result in one getting a higher level degree or working longer hours, those people probably won’t reproduce as fast as others.
By “evidence” I mean evidence that allele frequencies have noticeably changed. These are all hypotheses about things that might be affecting allele frequencies but, again, my standing assumption is that the timescales are too short.
Not only is the timescale too short (human societies change drastically over single-digit generation times, far too short for strong evolution) but all these traits are horrifically polygenic and dependant upon the exact combination of thousands of loci all around your genome that interact. There is also the extremly strong case against genetic determinism in most human behavior.
The traits that I am aware of that show strong evolution all have had thousands of years to be selected for, like lactose tolerance in people descended from herders, resistance to high altitude with a hemoglobin change in Tibet, apparent sexual selection for blue eyes in Europeans and thick hair in East Asians, smaller stature in basically all long-term agriculturalist populations… I think I read about a particular immune system polymorphism in Europe that was selected for a few hundred years ago though because it conveyed partial resistance to the black death.
I can see a couple interpretations of this. One is that given observed changes in behavior, it is hard to distinguish cultural change from genetic change. The other is that the cultural environment changes rapidly, so one might not expect the direction of its selective pressure to be maintained for long enough to produce “strong evolution.” Depending on the definition of “strong evolution,” that is tautologous. But why did you introduce the vague qualifier “strong”?
“almost anyone who knows much about evolutionary biology” would know that this does not interfere with the potential for selection, but that excludes virtually all cell biologists. Learn some quantitative genetics in the kingdom of the blind. It’s true that no single allele will shift much, but an aggregate shift in thousands of genes can be measured.
I have never seen a useful use of the phrase “genetic determinism,” but only ever seen it used as a straw man or a sleight of hand. How much of your comments apply to height?
Things that are easier to observe are observed before things that are harder to observe. A selective sweep at a single locus is the easiest thing to observe, though the faster and more recent the sweep, the easier to observe.
This really depends on your concept of “strong evolution”. If that is jargon meant to refer to a conglomeration of changes that makes the organism different all over, I would agree. If we’re just talking about this in terms of “Is it possible that something of critical importance could significantly change in a few generations?” then I say “Yes, it is possible.”
I assume you consider responsibility to be an important trait. Even if a change to the trait of responsibility alone may not qualify as “strong evolution” to you, would you say that it would be of critical importance to prevent humanity from losing the genes required for responsibility in even half it’s population?
In a world where 40% of the people get here by accident, and we can tell that a lot of their parents failed to use their contraceptives consistently, are you unconcerned that there could be a relationship between irresponsible use of birth control and irresponsible genes being reproduced more rapidly than responsible genes?
But today’s situation is not the same. We have technologies now that could result in much more powerful unintended consequences just as it results in powerful intended ones. Birth control pills, for instance, didn’t exist thousands of years ago. Our lives and environments are so different now (and are continuing to change rapidly) that we should not assume that our present and future selection pressures will match the potency of the selection pressures in the past. To do so would be to make an appeal to history.
I haven’t found any evidence that allele frequencies have changed—I just started to look into this, and didn’t even have a search term when I started. Due to that, I thought it was obvious that I didn’t have anything on micro-evolution, so I gave you the evidence I do have which, even though does not do anything to support the idea that allele frequencies are being influenced, does support the idea that there’s potential for a lot of influence.
Hmm. A contraceptive and unplanned pregnancy survey by 23andme would be so interesting… I wonder if they do things like that… If I get a useful response to my request for a credible source on their accuracy, I will investigate this. (I want to get their service anyway but am demanding a credible source first.)