40 minutes ago, Ken Fabian said:

I think it would make a significant difference to overall reproductive success - not necessarily to the birth rate but the group ability to support itself and provide well for the ones that are born. A prevalence of even low grade allergies will impact the group's success.

So then, why was it not bred out in the first 100,000 years? How is it able to persist and increase in a hugely expanded human population?

10 minutes ago, Peterkin said:

So then, why was it not bred out in the first 100,000 years? How is it able to persist and increase in a hugely expanded human population?

Why do you think susceptibility to allergies of the distant past has not been bred out? We may well tolerate allergens now that our ancient ancestors were plagued with. I expect novel allergens keep emerging - other lifeforms keep evolving them - as well as expect the migrations and expansions into new territories exposed people to different ones. Some of those migrations were very recent.

Is absolute immunity to allergies even possible? I am not sure it is something we can expect to evolve.

47 minutes ago, Ken Fabian said:

I expect novel allergens keep emerging - other lifeforms keep evolving them - as well as expect the migrations and expansions into new territories exposed people to different ones. Some of those migrations were very recent.

Funny, that's what I said. 

 

48 minutes ago, Ken Fabian said:

Why do you think susceptibility to allergies of the distant past has not been bred out?

Allergy as a class of ailment has not been bred out. Nobody said the profile of allergic reactions in any given region has not changed. 

On 8/8/2022 at 2:04 AM, mistermack said:

The OP question is interesting though. Why doesn't evolution weed out all disorders? Especially inherited ones.

 

 

Evolution does not weed out all disorders because the causes of some disorders are evolving as well.

On 8/11/2022 at 3:55 AM, OldChemE said:

Evolution does not weed out all disorders because the causes of some disorders are evolving as well.

In a way, that's what people are suggesting for allergies. If a lifestyle with too much hygiene applied to young babies is responsible for the increase. 

In that case, allergies may have been lurking all along in our dna, as a tendency, but only became an actual disorder when the lifestyle evolved. Evolution is not going to weed out a tendency so long as it doesn't evolve into a disorder in a significant number of cases.