Echoing qwern’s comment for a citation for their belief. This seems like such a near human universal that I’d really want to see a better source than a Wikipedia article without further sourcing. If a diet reduced conception levels that much I’d expect to a) have heard about what the food in question is in that context and b) see a selection pressure against those who ate that diet.
It also doesn’t require a very high conception rate to make the sex-pregnancy connection. I’d be surprised if one couldn’t make that connection at any pregnancy rate that was able to keep population levels at least constant. And any such society is going to have shorter life-spans and high infant mortality, which would mean that the minimum pregnancy level would be pretty high.
It seems more plausible to me that the connection goes in the other direction: the highly polyamorous culture has made it more difficult to see the sex-pregnancy connection. But even that seems a bit of a stretch.
ETA: So this looks like a source but some of the other mentions of the “Baloma” belief on the internet (none in reliable sources as far as I can tell) claim that the belief is that sex is a method of opening the womb to the baloma, which would mean that the sex-pregnancy connection is understood, but possibly not that the child inherits any traits from the father. More sources are seriously needed to pin down what is happening here.
I’m trying to remember where I first read about the Trobrianders, and failing. The Ethical Slut, maybe? Malinowski seems to be responsible for most of the scholarship on them, which I agree is a little suspicious.
IIRC, the yams in question have an unusually high level of progesterone, which does (or at least should) have observable effects on fertility rates. But I think there was more to it than that—if I remember my original source, I’ll definitely pass it along.
Echoing qwern’s comment for a citation for their belief. This seems like such a near human universal that I’d really want to see a better source than a Wikipedia article without further sourcing. If a diet reduced conception levels that much I’d expect to a) have heard about what the food in question is in that context and b) see a selection pressure against those who ate that diet.
It also doesn’t require a very high conception rate to make the sex-pregnancy connection. I’d be surprised if one couldn’t make that connection at any pregnancy rate that was able to keep population levels at least constant. And any such society is going to have shorter life-spans and high infant mortality, which would mean that the minimum pregnancy level would be pretty high.
It seems more plausible to me that the connection goes in the other direction: the highly polyamorous culture has made it more difficult to see the sex-pregnancy connection. But even that seems a bit of a stretch.
ETA: So this looks like a source but some of the other mentions of the “Baloma” belief on the internet (none in reliable sources as far as I can tell) claim that the belief is that sex is a method of opening the womb to the baloma, which would mean that the sex-pregnancy connection is understood, but possibly not that the child inherits any traits from the father. More sources are seriously needed to pin down what is happening here.
I’m trying to remember where I first read about the Trobrianders, and failing. The Ethical Slut, maybe? Malinowski seems to be responsible for most of the scholarship on them, which I agree is a little suspicious.
IIRC, the yams in question have an unusually high level of progesterone, which does (or at least should) have observable effects on fertility rates. But I think there was more to it than that—if I remember my original source, I’ll definitely pass it along.