Says a new paper at BIO-Complexity by Ola Hossjer and Ann Gauger.
It is definitely possible for us to have come from a starting point of two. Whether by a bottleneck or by a unique event the numbers say it is possible. 2 million years corresponds to the time of the first hominid to be called Homo, Homo erectus. His exact time and place of origin are unknown but are thought to be in Africa. The 500,000-year mark is near the time of the Neanderthals and Denisovans.
But these numbers are not fixed in stone. They are subject to change: a change in population structure, mortality, mutation rate, birth rate, migration, selection, all can influence the results. The amount of initial diversity, or its distribution, can as well. Changing the population size or time by half can be reversed by multiplying the mutation rate by two. In other words, we have a relationship than can be tweaked and studied, and its parameters can be worked out, but as one of its creators said, the model is “underdetermined.” That’s putting it mildly.
Once again, the precise age of the first couple is not the main point of this study. That there could be a first couple at all is the point.Ann Gauger, “New BIO-Complexity Paper: We Could Have Come from Two” at Evolution News and Science Today