Our prehistoric ancestors didn't make it past 30 very often, and don't tell me humans
have changed that much that our preoccupations - especially among the younger set -
weren't focused around sex and gratuitous violence then as now. And they didn't
have video games that we know of, so they resorted to drawing on the walls.

People like to assign deep meanings to the actions of our ancestors, when often
their big focal points were pretty much the same as ours. This is why aliens (ancient
astronauts) got assigned to drawings and artifacts starting back in the 1970s. Think
our descendants will be any more aware of their history (us)?