The most difficult genes riddles

The last universal common ancestor (LUCA) is the most recent population of organisms from which all organisms now living on Earth have a common descent. LUCA is not thought to be the first living organism on Earth, but only one of many early organisms, whereas the others became extinct. In 2016 study identified a set of 355 genes inferred to have been present in LUCA. LUCA is estimated to have lived some 3.5 to 3.8 billion years ago in the Paleoarchean era.

Interbreeding between Neanderthals with modern humans took place several times. Neanderthal-derived DNA was found in the genome of contemporary populations in Europe and Asia, it accounts for 1–4% of modern genomes. Neanderthal genes are absent from most modern populations in sub-Saharan Africa.

It is much less likely for a woman to be red-green colorblind than a man, since this common type of color blindness is caused by a recessive gene in the X chromosome. For a woman, both of her X chromosomes would have to be affected. A man only has one X chromosome, so he is more likely to be color-blind.