I should preface this by saying that I spend a lot of time reviewing scientific papers for private sector firms searching for red flags. So certain issues in sc

I should preface this by saying that I spend a lot of time reviewing scientific papers for private sector firms searching for red flags. So certain issues in scientific papers become common enough that they, sort of, jump out at you right away. That's why, in fairness to HN user wufufufu, we should point out that they do NOT control for the age of the female. They only say that the male in the reproductive couple was aged X. (No indication as to the health of the female either.) In general, when a wholly biological effect is observed in human study populations, without reference to a preceding controlled study on, say, mice, your antennae go up. Now in the private sector, that means that the people I worked for would adjust or shuffle resources to account for the likelihood of partners or customers bringing successful legal actions. (Or, perhaps, cancel projects altogether.) But here all it means is that you probably can go ahead and have kids if you are thinking about it and are already over 35. Humans, (and several other animals), have been doing this for millennia. It's very likely not older people having kids that will eradicate us. (Or even lead to our decline, to be perfectly frank.)