That doesn't necessarily imply polygamy, and it doesn't necessarily imply "incels". Imagine a society in which women get married at age 16 and typically die during childbirth before they reach the age of 32, and men get married at age 32, if they live that long, which most of them don't, and then get married again when the first wife dies during childbirth. I'm not saying that's how it was, but some societies were a bit like that and I think you could probably get the 80% and 40% numbers with a set-up something like that.