There is strong evidence fertility decreases if there is a lack of vitamin D, which would correlate with the thesis that fertility decreases for human kind in g

There is strong evidence fertility decreases if there is a lack of vitamin D, which would correlate with the thesis that fertility decreases for human kind in general (as we expose ourselves less and less to the sun): https://www.ncbi.nlm.nih.gov/pubmed/28667465 https://www.ncbi.nlm.nih.gov/pubmed/28667465