Tired of those snooty scientists telling you that you were not designed by a devine being? You can take comfort that their precious theory of evolution predicts that one day they will all be extinct.
The top of the science ladder is a research job at a university or government lab. Imagine you are wanting to get this job. All you have to do is go through four years of undergraduate school, and get into a good graduate school. In graduate school, you will be worked like a dog, first with classwork, and then to produce papers for your mentor, not to mention your own research.
Upon getting a Ph. D., you are now qualified to work for 4-6 years in a postdoctoral position, where you will work like a dog to get research funding and write papers for your mentor. Only then will you be qualified for a tenure track position at a university, where you will spend the next 6 years working like a dog chasing research funding and writing papers in the hope of getting tenure.
All that time spent in the lab and office does not leave a lot of time to find a mate and raise children. It would be easiest to wait until after tenure. A smart, driven scientist, focused on career, might get tenure by age 36, but that path guarantees far more hours in the lab and writing papers and grant proposals. In 2003, the average age at which science faculty got tenure was 39. Fertility for both sexes peaks in the 20’s and beings to decline quickly for women over 35. The decline is slower for men, though studies have found higher incidence of birth defects and more difficulty in getting a woman pregnant for men over 40.
At best, we can expect that scientists will be less likely to conceive children than the general population. When they do have children, they will likely be able to have fewer children, and those children will have higher incidence of birth defects. At least one parent will have less time to care to spend on child-rearing, and possibly both — after all, scientists are most likely to spend time around, and ultimately mate with, other scientists.
Evolution is all about survival of the fittest, and the evolutionary definition of fitness is ability to pass genes on to the next generation. To the extent that genetics contributes to ability to do science, and science happens in academia, the current system is removing the genes that lead to high academic performance from the gene pool. You might argue that a fair amount of science gets done in start companies and research divisions of larger companies. That is true, but it is also true that many of those people work hours competing with those in academia.