do all beings have past lives? Is it a truth in Buddhism that all beings have past lives? How does Buddhism explain new life? For example, would the increasing amount of population be explained by some us having shared past lives?
yes I'm pretty sure that all beings have past lives . there was an old saying from Buddhist litriture where if you cut short the life of any living creature (intetially killing) then you are forcing that being to be born again to go through the process of life again .also the Buddha said that some have had a birth of another species and through good karma became human etc the same is true for humans going back to another lower realm ie animal if bad karma prevails...as to the rest of your questions I hope someone else will jump in ..edit : in reference to your last question about population ...yes there is a possibility as I've mentioned. Humans are born again again this is samasra ...