NumberCounters

The number of people with autism-spectrum disorders is increasing faster than the number of those with any other single neuropsychiatric condition.  Without doubt, this is partly discovery through better diagnosis techniques.  But there is significant real growth too.

People with autism are more than twice as likely than people without to have fathers and grandfathers who are engineers.   Further, it is known that autism is strongly heritable.

The Industrial Revolution made engineering one of the most secure of human professions.  Engineers only occasionally get rich and famous, of course, but they almost always live comfortable lives.  They are often among the last to find themselves unemployed when times are hard, and economic pick-up sees them in the vanguard of those back to work.

And a comfortable life is an optimal basis for the raising of children.  Perhaps, since the Industrial Revolution, simple Darwinian selection has acted to increase the proportion of descendants of engineers in the population.

Perhaps further, a side-effect of this increase is the increase in autism-spectrum disorders that we are now seeing.