Joseph, this is the study (it's old)
Okay, and now that I've read it ...
You left out a lot of details:
"He described the onset of several pathologies: violence and aggression, with rats in the crowded pen “going berserk, attacking females, juveniles and less-active males.” There was also “sexual deviance.” Rats became hypersexual, pursuing females relentlessly even when not in heat.
The mortality rate among females was extremely high. A large proportion of the population became bisexual, then increasingly homosexual, and finally asexual. There was a breakdown in maternal behavior. Mothers stopped caring for their young, stopped building a nest for them and even began to attack them, resulting in a 96 percent mortality rate in the two crowded pens. Calhoun coined a term—“behavioral sink”—to describe the decay."
It could be a result of the hypersexuality and a breakdown of discrimination in sexual partners. I don't really see how this directly maps to humans. Among other things, we're naturally a much more sexual race, like bonobos. Hypersexuality in a rat means having sex with a female that isn't in heat.
Anyway, the study isn't talking about gene expression. This discussion has to do with genes. The study has to do with the effects of societal factors upon behavior.
Interesting article, for other reasons, though. Thanks.
More studies needed, in other words.
Personally, I think we're breeding for religion in the US, though. A first-world country gives even the the hyper-religious the benefit of good medicine. Most religious sects don't refuse medical care, just a handful like the Christian Scientists and the Jehovah's Witnesses. The Mormons, Southern Baptists, Pentecostals, and Catholics are out-breeding us rather badly, I believe.
Then we have this recent quiverful movement. If you have 19 kids, I don't think enough will get killed off by stupid things to bring the family back to parity.