Right, this is my take on this theory, stop me if I get a little far fetched and way off base please...
Some time in the not too distant future the earth and mankind suffer a terrible disaster that leaves the earths surface almost uninhabitable.(the
disaster could be asteroid impact, all out nuclear war or some other "end of time"scenario)
The humans that are left have to retreat under the earths surface due to the disaster. Years may be spent under the surface waiting and hoping that
soon they can resurface and start again. By this time decades and possibly centuries start to go by with no end in sight.(maybey the earths atmosphere
has been severely damaged and is not recovering very well?)
Now all these years hidden underground start to take a toll on the human body, it is dark most of the time so evolution true to its word starts to
adapt our bodies, our eyes start to grow larger to take in more of the ambient light, after a long time they may develop into REALLY large eyes
similar to the greys.
The tunnels the humans now live in are very small and have low roofs causing the humans to stoop a lot, evolution again kicks in over the centuries
and humans now are born a lot smaller to be accomodated in their new environment.
Due to lack of stimulus for the human senses our hidden senses start to surface, telepathy, e.s.p etc
With the humans never being able to go out in the sun safely anymore(due to solar radiation being too strong for the weakened atmosphere) their skin
tone gets paler and paler until it almost becomes GREY.
Now living in tunnels and underground caverns etc there is no areas for any recreation such as sports and entertainment so the only thing to keep
these humans ammused is to read, and write and basically educate themselves as a means of passing the time. Over the years evolution again starts
adjusting the human body to fit its environment, the brain starts to evolve and grows bigger and bigger to acomodate all the information that it is
being given constantly, now a bigger brain possibly means a more intelligent and advanced race.
A more intelligent and advanced race might have the solution so that they can now come out from the subterrain world they have been living in now for
possibly a thousand or so years with the solution to once again being able to live on the surface.
These humans that step out have large brains, large eyes, small bodies, pale skin and mental powers previously unknown to the humans that first
decended into the underworld. If they met the earlier humans, this "new" version would look positively "ALIEN"
Now this much advanced version of the humans have the ability and knowledge to create time travel, now a lot of the history has been distorted and
lost by the passage of time, like all sensible beings these new humans know that to know where their future is going the must know where their past
came from. So like all curious beings they send "archaeologists" back to study and fill in the gaps from their past.
Thus our modern day "grey" and UFO phenomenon explained as humans from the future.
Another little spin on this theory is that due to small communites in the sub world leads to a lot of inbreeding resulting in fertility problems in
the future, this could explain the supposed experiments etc that have been carried out on abductees.
Well thats my suggestion for this topic, I hope some of you find it interesting. Any comments and thoughts about it are greatly appreciated.