Even if it is; the availability of pretty much perfect contraceptives negates that to a large degree. The use of contraceptives is cultural, not biological.
So we'll hit a replacement problem long before natural selection has time to catch up. The replacement issue has already real implications, this will become much more obvious in the course of the next 30 years.
Any relevant change on the population size the propensity for fertility can have; it will take (three, four, five , ...) generations to manifest.
So we'll hit a replacement problem long before natural selection has time to catch up. The replacement issue has already real implications, this will become much more obvious in the course of the next 30 years.
Any relevant change on the population size the propensity for fertility can have; it will take (three, four, five , ...) generations to manifest.