You know the phrase: Men are from Mars, women are from Venus ... but what if we're all from Alpha Centauri?
An American ecologist by the name of Dr Ellis Silver thinks that he might have spotted a few telltale signs that humans did not originate from Earth, and that we're actually beings from another world.
There is a pretty well-accepted theory out there that organic matter may have been delivered to planet Earth by meteors, perhaps as single-celled organisms or just as the building blocks of life such as amino acids.
But Dr. Silver goes one step further: That we arrived as fully formed, complex organisms, between 60,000 and 200,000 years ago. Perhaps we interbred with Neanderthals, perhaps we're just straight up aliens, all Silver knows is that there are some things about our physiology that just doesn't add up.
Citing everything from sunburn to childbirth in his book Humans are not from Earth: a scientific evaluation of the evidence, Dr. Ellis Silver points out all of the things that seem to contradict the idea that we evolved over millions of years in our earthly environment. Who knows, perhaps Earth is even some kind of prison colony, and we've been sent to this little galactic backwater to learn our lesson whilst the rest of the universe zooms about in lightships?
Granted, these theories should probably be taken with a healthy pinch of salt, but what does the venerable Dr. Silver have to say about the possibility that we're all just spacemen?
11. Bad Backs
If we evolved on this planet, why does just standing up on it hurt us?
Silver argues that the gravity on our home planet must've been stronger, and so we're progressively growing taller and taller with each generation, causing us to have bad backs.
It is thought, in the wider scientific community, that on planets with stronger gravity, human-like life forms would evolve to be much shorter and stockier to deal with the extra gravity bringing them down.
When that gravity isn't there, we apparently start to grow like forced rhubarb, ending up so tall and willowy that our own skeletons can't support us very well.
There could also be a counter argument that the gravitational pull on our home planet is, in fact, weaker, and the fact that our bodies will slowly bow to the pressure of Earth's gravity over our lifetimes is proof that we evolved to deal with weaker gravity.
As we grow older, we hunch over and even shrink, gravity slowly wears us down, starting with a crick in the neck and ending with a hunchback.
Silver also wonders about the possibility that the food on this planet is more nutritious than on our home planet, causing a growth spurt.
If we spent all our time back home chewing on tough, woody vegetation (yum), then were sudden plunged into a world of strawberries and fillet steak, it's possible that all of those abundant nutrients made us shoot up like a 14-year-old boy who lives on McDonalds and Red Bull.