After reading a chapter in a Dawkins book on artificial selection in dogs, I got to wondering if there has ever been any artificial selction in humans. I realize this would take a few lifetimes and seems outlandish. Wouldnt it be quite possible to breed humans for certain jobs like prolonged spaceflight or even to expand brain capacity and mental function? Seems to me it would be possible to breed us for any use, though I have been wrong many times before
What would the process be for creating a human who can, let’s say, see in the dark like a nocturnal beast?
Ignoring ethical issues, there’s no difference between selective breeding humans and any other species. Find examples of people with the best traits in the area you want, and breed them together. Take the best of that and breed those together.
Of course, you can only optimize what’s there, not create new features altogether. I’m not sure if night vision in humans is any more achievable than a dog with green and blue fur.
The problem with selective breeding of humans is that the project would have to take multiple human lifetimes. We can imagine a nutty dictator instituting such a program, but is his nutty son going to continue the program, and his nutty grandson?
The reason animal breeding programs can continue for generations is that animal breeders typically agree on what makes a desirable animal. Chickens have been bred for thousands of years to produce more eggs, sheep to produce more wool, cows to produce more milk, meat animals to gain weight faster, and so on. So it isn’t just crazy Farmer George who wants chickens to produce more eggs, it’s every egg farmer in the world. So even when crazy Farmer George dies, the project continues.
So selective breeding of humans is possible, but it would likely require the supervision of an extremely long-lived species. And the other problem is that humans wouldn’t like it, so the humans would have to be slaves.
Artificial selection in humans typically operates under the moniker “eugenics”, which doesn’t have a very good track record in terms of implementation or effects. Sure, artificial breeding in humans could be done in theory, but in practice, it ends poorly for all concerned.
Aside from ethical questions, while it might be technically possible, it’s basically not feasible in the real world because of the long generation time of humans. To be effective, artificial selection demands rigorous control of reproduction (often including sibling or parent-offspring crosses) over a period of many generations. This is not going to be possible outside of a totalitarian regime that continues in power for several centuries at least.
It is sometimes alleged that selective breeding of slaves took place in some places, and that this can account for the dominance of African Americans in some fields of athletics. While there may have been some isolated, short-term attempts at this, it’s certain the selection could not have been strong enough, continued long enough, or involved enough of the population to have any effect on the general African American population.
I know this is a joke, but while selective breeding almost always involves inbreeding, it’s not synonymous with it. Selective breeding can also involve outcrosses to bring in beneficial traits from other lineages.
And those Hapsburgs could have used some of that …
But seriously, royalty is pretty well the only place I can think of where humans have paid serious attention, over many generations, to their own breeding - but they were not “selecting” for genetic traits, only for political advantages. The genetic effects tended to be, in some cases, unfortunate.
Wouldnt an abortion due to say, a congenital defect be considered artificial selection?
Or do I need to brush up on my understanding of the subject (obviously)
However it could be argued that our modern opinion on what is desirable might have an effect. People might argue that this is all natural, however in past ages, different things used to be seen as attractive compared to today. For instance pale skin used to be considered attractive in Tudor times (http://tudorswiki.sho.com/page/BEAUTY+in+Tudor+times), whereas being more tanned seemed to be desirable. In many parts of SE Asia today, pale skin is also considered attractive. I know this isn’t artificial selection but these factors are dictated by trends and must have some effect.
Not necessarily, since such a condition might well lead to miscarriage, or death anyway if carried to term.
If, however, any individual who lacked whatever traits you were attempting to select for was to be prevented from breeding, and any such individuals who have been found to have reproduced were then forced to abort (regardless of the viability of the fetus), then that sort of abortion could be considered artificial selection.
In the case of a defect that was heritable and which would not prevent breeding later on, then yes. However, this kind of selection is rarely going to be prevalent or intensive enough to have much impact on the general population. In many cases, congenital defects are due to recessive genes; to affect the gene frequencies much you would have to also eliminate the heterozygotes (who have only one copy of the defective gene) in which the defect is not expressed.
In any case, in your OP you were mostly talking about positive selection for desirable traits, rather than elimination of negative ones. That’s much harder, since you would have to eliminate breeding by all individuals that didn’t have the positive trait, rather than the few that had the negative one.
To the OP, what are you using as your definition of “artificial” in “artificial selection”? Just that it’s directed by humans? Because if that’s your standard, then all human breeding is artificial selection. It’s just that every human engaged in the experiment has different standards of what traits they’re breeding for.
It would only have an effect if it impacted your number of children. As an example, you’d have to show that attractive people average 4 kids and unattractive ones only average 3.
But you also have to factor in the length of time these trends are in place. Even a long-standing preference may only be two or three generations long. You’d want something consistent over dozens or hundreds of generations.
You’d also want to make sure people weren’t mucking the system up by considering non-genetic features of attractiveness, such as wealth and power. If ugly billionaires can obtain trophy wives, then you’ve eliminated the effectiveness of beauty in terms of selective breeding.
But again, you need a preference that lasted across many generations As you say, trends in whats attractive seem to vary pretty quickly across both time and space.
And aside from the long time periods involved, the fact is that its a lot harder to get people to breed with the partners you’d like them to then it is to regulate the partners of chickens or poodles. Even if their willing. If the prospective mother of your Kwisatz Haderach gets knocked up with some genetic low-life during a one night stand, your genetic breeding program is going to get set back.
So just the act of choosing a sexual partner by looking for certain traits like beauty and intelligence is “artificial selection”? Isnt that also natural selection? Animals in the wild do pretty much the same correct?
My ignorance on the topic troubles me and I intend to beat it to hell before the day is over
Would you guys say we are still evolving? Or have we become stagnant?
(Humans in general)
Artificial selection is selection for specific traits, regardless whether it’s done by humans or any other species (that is, “something humans do” isn’t part of the definition). Looking for certain traits in a mate is not the same as specifically breeding for those traits.
We are still evolving, though various selection pressures may be reduced in many populations because of social practices.
Yup. A lot of non-scientists have this distinction stuck in their minds between “natural” and “artificial”, but really, scientifically there’s no difference.
