What PODs, post-1400, could have led to a much higher number of people being alive today? The POD must be a human event, not a geological event. How many deaths could have been avoided? How many new births might have occurred?
I think one of the most important factors would be stopping or reducing the trans-Atlantic slave trade, which killed millions not only in the process of enslavement but in the warfare that resulted from it (American Civil War for instance). However, I don't know if there's any POD that could do this. Preventing the smallpox epidemics among American Indians would help a lot, but this might not be possible after 1400. Any war that can be prevented should be, but I'm really more interested in demographic and technological changes. A more scientifically advanced world will probably be a more populous one. So maybe this question is partly asking, how can you speed up the scientific revolution. Medicine and agriculture are probably the most important fields.
Thank you for taking part in this discussion. I look forward to hearing your responses.