Hate to say it but was the natural balance for humans, famine,war, and disease, disaster.
We kind of bucked that trend survived really well and procreated sporadically.
As young adults, and kids we find our groups or lone it, then create alliances and basicly want to procreate and fight or argue passionately who we dont get on with,
milenia ago we procreated, and had fights the fights often resulting in killing who we didnt agree with, that fight or flight is still in us to this day but we are able to control this syndrome.
So probably in the past the earth and nature did ok thanks to us all either dying at some stage in our lives, and being replaced by our sons or daughters.
I think thats prob why in a lot of families alegiences are drawn and you either hate your siblings or get on depending on status and wealth todays alpha male/female status in times gone as tribes we prob fought to the death or took flight and set up another life miles away from your family setting up your own or going it alone.
Its a natural thing to look after your family or yourself and fight earn work for a bit of the pie.
I think that is why neighbours fall out, families argue at christmas, and wars start, its hard wired into evry human and maybe if every inch of soil is lived on by humans in the future it may happen again.