If you accept the heritability for age at first birth has not been measured wrong, then the hypothesis put forth by this paper will come about.
Perhaps I over stated the case by saying inevitable. It's quite feasible that the consequences of highly fertile people overbreeding will be a reduction in civilizational complexity, which will lowerthe total population.
> If anyone thinks the paper is wrong, they are stating that the measures of those values are wrong. The rest is inevitable.
> If you accept the heritability for age at first birth has not been measured wrong, then the hypothesis put forth by this paper will come about.
First you argue that if the paper is right, the measurements must be right. Then you argue that if the measurements are right, the paper must be right. Both arguments seem illogical, especially when used in that combination.