>>202983631. Important food source for certain animals higher in the food chain.
2. Spread disease to kill the weak and infirm aka Evolutionary Pressure.
3. A natural deterrent to higher primates invading dense northern forest areas.
Basically, the whole universe operated like a finely build Swiss watch except for human beings, whose opposable thumbs and large brains have ruined everything. If there was a God, he would wipe the Planet of humanity or force it back to its Hunter-gatherer/Hunter-herder roots for they are they only way to live on this Planet in perpetuity. Any other questions?
