What if -

In say ten thousand years time, during our evolvement we had disrupted our atmosphere sufficiently to make it denser. Would there be that much less light, that our eyes would evolve to be larger and darker, as the pupil takes over as much of the eyes surface as possible, so as to allow in more light. As our technology advances and keeps inventing things to make our lives even easier, the strength requirements of the human body would significantly decrease. I take it that our bodies would then be smaller, with the exception of the head, we would be that much more intelligent that our cranial cavity would have to increase. In addition any drastic change to the amount of light would definitely change the colour of our skin. Too much sun burns our skin, so what would too little do - freeze it ?

Taking all of this into account and the fact that we are often visited by UFO's. Take the Roswell crash for example, there was a small craft and three bodies recovered. A small craft could not travel across interstellar space, is there really any way that it could be equipped for such a long journey, and nobody has ever reported a mothership anywhere in space. An engineer that apparently worked on the propulsion system of the recovered craft, reported that there were only three seats in the craft. I would've thought that if you were going to travel light years across the universe, you would send more than three of your civilization. What if it were time travel, instead of the assumed space travel.

The aliens are commonly described as "greys" , they are small, around four feet tall. Their heads are larger in ratio to their bodies, do they sound like our evolvement. Also, whenever abductions are reported, time has stopped on various clocks and watches, if it were time travel, they would be able to control time.

Could we be their past, and they, our future ??