Yeah I saw that. I don't think we can tell much from it. Do you think it's revealing?
It doesn't seem like they show evidence for anything more than significant correlation. Other theories (like birth trauma reduction) could explain it just as well.
This thread is a good example of why I don't usually comment on YC. People don't take the discussions seriously enough. They ask a question and don't followup. It's not worth explaining things carefully here.
Web forums need better notification when someone responds to you. And each site has to reinvent the wheel. I remember people asked for this for months on reddit before it got the little envelope icon.
It's just too bad.
Upper-body fat has negative effects and lower-body fat has positive effects on the supply of long-chain polyunsaturated fatty acids that are essential for neurodevelopment. Thus, waist-hip ratio (WHR), a useful proxy for the ratio of upper-body fat to lower-body fat, should predict cognitive ability in women and their offspring. Moreover, because teenage mothers and their children compete for these resources, their cognitive development should be compromised, but less so for mothers with lower WHRs. These predictions are supported by data from the Third National Health and Nutrition Examination Survey. Controlling for other correlates of cognitive ability, women with lower WHRs and their children have significantly higher cognitive test scores, and teenage mothers with lower WHRs and their children are protected from cognitive decrements associated with teen births. These findings support the idea that WHR reflects the availability of neurodevelopmental resources and thus offer a new explanation for men's preference for low WHR.