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.)
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.)