What if we applied the same logic to deer licenses we did to murdering humans...

Basically whenever the population of humans grows to high, and they lack a natural predator, then hunting humans is legal (you need to get a license of course) until the population is brought under control.

If that seems a bit too immoral we can just introduce some natural predator in larger numbers to balance it out, like we should start releasing 100 cheetahs into NEw York's central park every day and just let them run wild from there out into the city.