It wouldn’t necessarily die out even in that case, because there are lots of other factors than that predator involved in who survives and reproduces. There are going to be brown haired people who die for other reasons, and blonde haired people who aren’t killed by the predator.

Even if the recessive gene is always fatal if you get two copies of it, and the gene is the only factor in survival, it’s still going to take a long time for it to disappear, because humans take so long to get to reproductive age.

For the same reason that Covid and HIV/AIDS were successful- it can be passed on by asymptomatic carriers. You can have one copy of a recessive gene and be unaffected by it.

Tay Sachs is a disease that is caused by having two copies of a recessive gene. It’s pretty much always fatal if you have it, and it kills people before they are old enough to have kids. But you can have one copy of the Tay Sachs gene and not even know it. If the other parent of your children doesn’t have the gene, it doesn’t affect you or your children at all. The problem only happens when two carriers have children together. Even then, only 1 in 4 of their children will have Tay Sachs.

It gets more interesting if having one copy of a recessive gene is beneficial. There are several recessive genes where, if you get one copy of the gene, you have more resistance to malaria. Sickle cell anemia is the most famous example. If malaria is a significant problem where you live, someone with one copy of the recessive gene might be more likely to survive and reproduce than someone with no copies would.

It’s even more complicated with humans, because having as many children as you possibly can isn’t necessarily the best reproductive strategy for humans. We’re K strategists, which means we tend to have fewer children and put more parental resources into the ones we do have, rather than just having as many children as possible. If two carriers of a recessive gene have children together, but only have a few children, there’s a decent chance that none of their children will inherit two copies of the gene.

The environment doesn’t stay the same, and who’s fittest can change. New diseases happen, as we’ve all seen in the past few years. There are also a lot of non-genetic factors that determine which humans survive and reproduce.

One of the things that made human cities unhealthy until modern times was that they didn't have a good system for getting poop away from where people lived. Bats don't have sewers either, so their poop (and any pathogens it contains) stays where other bats can easily come in contact with it.

That would make sense if they were talking about animals that could be domesticated. It would be pretty hard to domesticate whales. If you did, you couldn't use them for farm work or transportation, the way you can with horses, cows, or llamas. You couldn't get wool or milk from them, like you can from sheep.

I got my kids each a new pair of snow pants.

Ah! This is why my daughter insisted that I check my email for anything about a school delay this morning. They must have said at her school yesterday that that was likely. I had been wondering why she thought there might be a delay.

Mr Putin, tear down this wall! We made you do it once, we'll make you do it again. And the longer you put it off, the less pleasant it is going to be for you, personally.

The hot water pipe to our shower unfroze yesterday, and it seems there’s no harm done. Wishing the same for everyone else who has been dealing with frozen pipes.

/u/ovodrizzle13, I hope your friends and family in Buffalo are all okay.

What evidence would there be that people had (or didn’t have) acne in prehistoric times? They wouldn’t have left any written evidence or popping videos, or anything like that. Not every culture has a tradition of realistic portraits (and some of those that do would deliberately leave out something like acne). I suppose there could be tools for popping pimples, but could we be sure that was how it was used? People can pop pimples without specialized tools, so a lack of those tools wouldn’t necessarily mean that there was no acne.

Awwww, are the poor widdle babies being triggered by HIMARS?