You need as many entrants in those fertile environments as possible because humans and societies are complex, leading to unpredictable outcomes as results of fa

You need as many entrants in those fertile environments as possible because humans and societies are complex, leading to unpredictable outcomes as results of factors that anyone raising kids may have discounted, not known about, or been unable to measure. You can't just make a perfect path and then get exactly the super-offspring you want. Thinking you can is literally the founding story of Buddhism (not discounting the significance of Buddhism, but his father was shooting for a perfect ruler, not an enlightened-but-impoverished visionary.) Edit to add: A side effect of all those people just barely going astray is that you get improvements in thought and technology across a span of many fields, which in turn brings future great achievements nearer to our reach.