There is another possible explanation for the increase in autism. It is possible that social and health services allow people who carry the gene to reproduce and live better than they were able to before.

This happens in other areas where the kind of traits that would have been selected out can now be accommodated by modern health and science (diabetes?).

The future of mankind (if there is one) will probably include many genetic diseases and non conformities that would otherwise have been selected against by a species with poorer health and procedures for survival and reproduction (IVF?).