Evidently Retha is tilted on its axis, perhaps more so than Earth. The nights at the landing site are 2 hours long.When they return through the mist, they are cleaned, shaven, and returned to their uniforms. Alphan uniforms disappear, but dental work remains. The time warp also changes clothes and hair (beards suddenly appear), and instantly gives them a social structure and hunting skills (note the pit trap and mammoth tusk).It has four forward-facing long toes and a deep heel imprint, suggesting a large plantigrade bipedal animal like a therapod dinosaur or ostrich. Other animals in the forest include creatures with long mammoth-like tusks, and the animal that made the footprint found by Koenig and Helena.These tribes largely wiped out the original Cro Magnon hunter gatherers, although a small proportion of their DNA survives, along with a little from the Neanderthal early humans that lived in Europe before the Cro Magnon.
Lighter skin evolved much later, in the middle East and central Asia light skinned tribes entered Europe bringing the new invention of agriculture, around 7000 years ago. It is generally believed that some forms of spoken language begin with either Homo ergaster (1.8-1.3 million years ago) or Homo heidelbergensis (0.6-0.2 million years ago). The depiction of the grunting cave dwellers in this episode thus does them a disservice. From the evidence of their art and tool making, and regional trade, they must have had language.
They were nomadic hunter gathers caves would have been temporary homes, not permanent. Their culture, termed Upper Palaeolithic, included sophisticated stone, bone and horn tools, the first spears and whistles, and the first cave paintings. In Europe Cro Magnon arrived about 40,000 years ago. The first modern humans appear in Africa 200,000 years ago, and spread from Africa around the world between 120,000 and 60,000 years ago.
The name comes from the rock shelter of Cro Magnon in the Dordogne Valley in France, in which skeletons were discovered in 1868. Cro Magnon were the first modern human species in Europe, contemporaneous with and displacing the Neanderthal.