Is There a Gene for Motherhood?

[mike_c]

48. there are lots of theories....

A single gene controlling maternal instincts is a new finding in mammals and hasn't been generalized beyond mice yet, although if it survives challenge there's no reason to suspect it doesn't have similar functions in other vertebrates. But that's not likely related in any way to the other matter I was responding to, your assertion about a "gay gene."

I presumed you meant that there cannot be a gay gene-- or genes-- because it would be selected against through lowered reproductive output. My point was that there ARE lots of known instances in which phenotypes (with usually unknown underlying genetic foundations) are selected FOR in populations even though they undermine reproduction. There is a whole body of theory that attributes altruism in general and reproductive altruism in particular to such things as shared genetic identity beyond individuals, for example. But I certainly didn't mean to imply that those mechanisms or their genetic basis are well understood or known, or even generally agreed upon. But that doesn't change the circumstance that there are plenty of documented instances of behaviors that LOWER individual reproductive output being maintained in populations for long periods of time, suggesting that they are at least not maladaptive and selected against. There are also lots of instances in which phenotypes that would appear deleterious are maintained because they confer side benefits that outweigh lowered reproductive fitness. So the chain of logic that leads to your statement about a gay gene being selected against is not necessarily well supported by the actual evidence among numerous species of animals, including vertebrates, even mammals.