Imagine you were a caveman living in 70.000 BC and a visionary caveman friend would predict that in the far future: "People will be able to fly, and there will one day be more people flying above the surface of the Earth than there are people on it now". It would be an mind boggling caveman prediction. Still the numbers add up. Today there are on average 8.000 planes in the sky carrying over half a million people. Although at the end of the Stone Age there were already a few million of people roaming the planet, this period lasted 3.4 million years and there were less people. Researchers believe that around 70.000 BC the World population went down to roughly a thousand reproductive adults. One study says we hit as low as 40 "breeding pairs". If these numbers are correct there are today even more pilots in the sky than people alive at that time. More likely, there was a drastic dip and then 5.000 to 10.000 bedraggled Homo Sapiens struggled together in hunting and gathering for thousands of years until, in the late Stone Age, we humans began to recover, to eventually dominate not only the surface but also the skies of the Earth. Who knows, in the long run there will be more people living in the Galaxy than there are on Earth today. Indeed, it is a bold statement, although our friend the caveman would have thought the same 70.000 BC. Image via Flightradar24.com.