population

Assuming that there ahad not been any disease, and no plague, and foldk had ususally died aroudn age 80, how many people would be on the planet right now.
?

That’s hard to say. My WAG would be that without disease and plague to bring the population/life expectancy down, I’d say that a long, long time ago the planet would have been overcrowded enough that people would have been killing each other wholesale over food.

What if we tried to reduce our present population.
What would be the best way?
Offering money to sterilize?
What would be the highest population number that would keep us and the planet working a okay?

Well, since so much of the world’s population belongs to religions that condemn birth control, masturbation, non-coital sexual interaction, homosexuality, and/or abortion and encourage people to be fruitful and multiply, it seems that one really effective way of reducing the world population would be to get God behind your efforts. Good luck with that.
Beyond that, you also have to contend with cultures that value women in terms of their ferility, that esteem men according to their virility, that are based on extended family households or agrarian lifestyles and can use all the extra help they can get, that are woefully undereducated in just about everything including safe sex, and so on. And you’ll find cultures like this outside the US too…