You'll wake up in your cave, rub some sticks together until enough friction is caused to start a small fire. However it doesn't light because there's not enough oxygen left to get it lit today, so you'll go outside, sit down with your carcass of dead rat, and, using your flint stone knife, try and carve out a hunk of delicious hind quarter that just so "happens" to be good enough to consume raw (as if you had a choice).
You'll "tweet" about the whole experience by sticking your hands to the cave wall, and use your mouth to spray a slurry of crushed stone, mud and spit in order to leave some amazing hand prints as a testament to your delicious meal. Two or three others (the sum total remnants of human civilization) stop by to have a look at your beautiful handiwork. Everyone smiles through their remaining couple of teeth in amazement until they get tired from lack of adequate oxygen, and go to sleep...
In several million years, a sentient being, descended from roaches, looks at the wall and wonders why such an apparent lower life form would feel the need to hold obvious religious ceremonies in honor of an assumed "appendage-and-mud god". Another sentient being dismisses the whole thing as a happen stance of natural caustic atmospheric erosion of a bygone era which just somehow resembles something a non-insect could put on a wall. But, of course, everyone knows better than this, as no being other than insects have ever had enough brain power to perform such a wilful act of self-determination.
Years later, a group of the species are watching a holographic presentation on the wall, as they renew their discussion of possible natural evolution of the species. A few of the class members secretly blaarghch their thoughts about the concept that they may be descendants of the beings that made the marks on the wall. Through mental telepathy onto the popular new UNEEDATHORAX(R) bacterial data transference storage system(c) (quark based), for all of their friends to contemplate later on that night while their communal hive mother isn't paying attention(lots of babies coming). The collective thought snickers from the group to let all involved how ridiculous the concern of their elders about the ugly stone, mud and spit on a wall really is, as they absent mindedly smash minuscule humanoid looking "ants" on the space-walks with the hard, sharpened, pointed brains on their ends of their appendages. Snarrghk!!!
We are the people our parents warned us about --Jimmy Buffett
