Spawning only a few babies as "we" do it is important to only spawn healthy babies. The first test is the "great swim" of the sperm. The second is the health of

Spawning only a few babies as "we" do it is important to only spawn healthy babies. The first test is the "great swim" of the sperm. The second is the health of the mother in the next 9 month and the "last" one is surviving birth. This making only the fittest/suitable survive. And that is why "routing" it something hard makes sense.