The Arabs either abandoned their old and helpless or buried them alive; the ancient Persians and Armenians left them in the deserts to be devoured by wild beasts; the early Romans threw everyone over 60 into the Tiber; many North American Indians left the old, the sick, and the weak behind when they moved camp, as did American pioneers crossing the plains in the 19th century.
The growth of foundling homes in China, France, Cuba and other parts of the civilized world show that today most infants are abandoned in the hopes they will be picked up; leaving children in railway stations or railway station lockers still occurs. Some South African tribes take their old people into the wilderness and leave them in a small enclosure with a little food and water; Melanesians either burn or bury alive their elderly.
When the going gets touch, everyone leaves.