Dinosaurs’ reign on earth ended sixty-six-million years ago. That’s when an asteroid crashed into our planet at twelve miles per second—typical meteor speed—burying itself nineteen miles deep. The impact created a crater fifty miles wide. Scientists estimate the asteroid’s diameter at seven-and-a-half miles.
The crater is not visible today. It now is buried two-thirds of a mile under the Yucatan Peninsula. When the asteroid hit, the area was seawater. The impact generated a tsunami and sent gases and debris into the upper atmosphere blocking the sun. Lack of sunlight and the resultant cooling exterminated much of life on earth. Goodbye dinosaurs.
After sixty-five-million-and-some years with no dinosaurs, humans appeared on the world’s stage. All humans trace their origins to Africa. The main Homo sapiens diaspora was about fifty-to-seventy-thousand years ago.
Anthropologists have lately been studying a human skull found in Eurasia dating back 210,000 years, the oldest human bone found outside Africa. It appeared that Homo sapiens first left Africa much earlier than previously thought.
But also found in the very same cave, in southern Greece, was another skull, probably Neanderthal. This one was 40,000 years younger. This discovery becomes more interesting, as researchers have been unable to find any living descendants of the older human. Scientists concluded that the first dispersal from Africa failed and this branch of humankind died out and was eventually replaced by Neanderthals. Neanderthal success was temporary, though. Over a few tens-of-thousand years, they lost the contest for world domination to Homo sapiens, who are considered to be modern humans.
Scientific research goes on. So far, fossils unearthed in Africa still predate any discovered in Eurasia by 100,000 years. None of the recent evidence contradicts the general conclusion that Homo sapiens left Africa generally on a 100,000-year cycle, as the Saharan and Arabian deserts expanded and ebbed.