> I was lost on your assumption that depressed people wouldn't have a chance to reproduce as much.

It isn't my assumption (I would bet that it is empirically false - though that would of course be speculation since one would need to do a study to know).

It is an assumption behind the view that depression constitutes an evolutionary dysfunction. This is a view that is popular. Especially with Jerome Wakefield - and it is cited in the majority of textbooks on abnormal psychology and psychiatry. To say that x constitutes an evolutionary dysfunction is just to say that if you take the people with x they will survive and reproduce (on average) less than those without x. Not in every particular case (evolutionary fit individuals sometimes get struck by lightening - which is to say that there are other forces in play such as genetic drift). But to say that x is an evolutionary dysfunctioning trait kind of is to say that one would expect its frequency to lessen in the population over time. Whereas rates of mental illness are on the increase...

And that needs explaining.