Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: syhprum on 19/12/2017 18:49:40
-
There are various inheritable human characteristics that, in a captive animal population, would be bred for; the one that most comes to mind is resistance to HIV.
In a captive slave environment, slaves were bred to be muscular and docile and the effects are still apparent in the USA.
-
https://en.wikipedia.org/wiki/Repository_for_Germinal_Choice
-
"Have there been any voluntary selective breeding programs of humans2
Yes.
Essentially every single choice of partner is a choice that "they look like they would be a good mother/ father for my kids.
-
Not every choise of partner is determined by the possibility of off spring in many cases the pleasure to be obtained from sexual activity is the deciding factor.
I had in mind more scientifically controlled breeding which to the best of my knowledge which has only ever been done with a captive population.
-
Most countries screen sperm donors (and presumably egg donors too).
This is mainly to exclude diseases, rather than to include beneficial characteristics.
But isn't the absence of disease a beneficial characteristic?
See: https://en.wikipedia.org/wiki/Screening_of_potential_sperm_bank_donors
-
http://www.spiegel.de/international/nazi-program-to-breed-master-race-lebensborn-children-break-silence-a-446978.html refers to a semi-voluntary program of "encouraged" selective breeding.
-
Yes, there have been plenty of examples of selective breeding experiments in humans, usually conducted subconsciously but on a huge scale and with religious conviction (excuse the pun).
Specifically, some groups choose to marry exclusively within a population; this is usually for cultural reasons, and the results are a selective breeding experiment over many generations.
At the trivial end of the scale, this can lead to various stereotypical features becoming more pronounced in a population - like a predisposition for low IQ displayed among members of the British aristocracy.
More seriously, genetic inbreeding can manifest as inborn errors of metabolism and neurological problems. Muslims and Jews marrying their cousins or exclusively within a small community - and thereby enriching the frequencies of deleterious genes - is one oft-seen example.
-
Having grown up during the war continually stuffed with anti German propaganda as time passes it is good to read more balanced accounts of historic events.
Sadly it seems that no good has ever come out of Human selective breeding.
When I visit the Midwest in the spring where they are all fanatically anti abortion I will point this Das Spiegel article out !
-
Given that there are so many genes, and the reproductive system doesn't distinguish between "good" and "bad" genes, it seems statistically odd that inbreeding amplifies the bad ones but not the good ones. This tends to suggest that bad genes somehow outnumber or dominate good genes, so the species is eventually doomed anyway.
-
Given that there are so many genes, and the reproductive system doesn't distinguish between "good" and "bad" genes, it seems statistically odd that inbreeding amplifies the bad ones but not the good ones. This tends to suggest that bad genes somehow outnumber or dominate good genes, so the species is eventually doomed anyway.
It doesn't need to select for "bad" genes.
If you have a single copy of a faulty gene- like the classic one for haemophilia in the European royal family- it's not so much of a problem.
If you have two copies of the faulty gene (or no "good" version) then you do have an acute problem.
Inbreeding increases that chances of getting two similar genes.
Essentially, it's the flip side of "biodiversity is good".
-
But equally if two parents had complementary "better" genes, you'd expect the offspring to be gifted in some way, but this seems not to happen in tight communities.
-
From a scientific point of view the German experiment in selective breeding was very ill conceived they sought to breed for the vague concept of some pure Aryan appearance not for disease resistance or anything useful.
With the collapse of the NAZI regime in 1945 cultural factors took over and the offspring were not considered desirable but SS bastards.
-
But equally if two parents had complementary "better" genes, you'd expect the offspring to be gifted in some way, but this seems not to happen in tight communities.
That's not what I'd expect, because I know about this
https://en.wikipedia.org/wiki/Regression_toward_the_mean
-
Jews marrying their cousins or exclusively within a small community - and thereby enriching the frequencies of deleterious genes - is one oft-seen example.
Ashkenasi Jews in the USA can now access a genetic testing service which checks for a variety of recessive genes. This allows 2 people who are interested in each other as potential partners to query the database to detect any possibility of having children suffering these genetic diseases - before the relationship gets too serious.
Participation is voluntary, and it is set up to maintain a high level of anonymity (participants don’t even know their own results); genetic counseling is available for those who are unsure of the severity of the impact.
This service was started by a doctor who had 4 boys with Tay-Sachs disease. It’s first major achievement was shutting down the Tay-Sachs ward in a New York hospital.
This is not aimed at changing the frequency of genes in the population, but in reducing the number of individuals with a dangerous combination of genes.
Have there been any voluntary selective breeding programs of humans?
This podcast talks about some quaint US examples (and some ruthless ones too).
https://www.cshl.edu/good-genes-bad-science/#single-collapse-0