Matthew Healey Posted almost 3 years ago Why is everybody concerned about "how to solve the problems of 10 billion humans" instead of "how NOT TO REACH that amount of people"? An interesting idea, given that the 10 billion figure is largely based on projections of current growth it almost appears to have become fact, rather than a potential future (some of the climate change projects make assumptions that the earths population will plateau and then decrease in the late 2080s). The key i think would be to think about what it is that causes population growth. For example: A woman and a man have a single child, the child grows up, the parents pass away, we are now net -1 person on the planet. Add a second child and we break even, add a 3rd and we are net +1 person, and so on (I'm excluding the people who do not have children for whatever reason). I recall reading somewhere that based on statistics those from lower income backgrounds are more likely to have more children. An example given was a farming family, whereby having more children meant there was more free labour (also linked to low education levels). You would also have to look at maternal and infant health issues, religious beliefs etc.