New genetic findings suggest that early humans living about one million years ago became at one point very close to extinction.
Well, this genetic evidence suggests that the population of early human species back then, including Homo erectus, Homo ergaster and archaic Homo sapiens, was made up of about 18,500 individuals. It is widely held that modern humans evolved from Homo erectus.
One might assume that hominin numbers were expanding at that time, if for no other reason, than because evidence shows that members of our Homo genus were spreading across Africa, Asia and Europe.
To make these estimates we can analyze Alu sequences. These are short snippets of DNA that move between regions of the genome. They move with such low frequency, however, that their presence in a region suggests it is quite ancient. Because older Alu-containing regions have had time to accumulate more mutations, we are able to estimate the age of a region based on its nucleotide diversity. The comparison was made between the nucleotides in the old regions with the overall diversity in the two genomes to estimate differences in overall population size, and thus genetic diversity between modern and early humans.
“This is an original approach because they show that you can use mobile elements…to flag a region of the genome,”said Cédric Feschotte, an evolutionary geneticist from the University of Texas at Arlington.
The effective population researchers estimate at about 18,500 reveals that the extent of genetic diversity among hominins living one million years ago was between 1.7 and 2.9 times greater than among humans today.
It would make sense that the diminished genetic diversity, one million years ago, suggests that our human ancestors experienced a catastrophic event at that time, one as devastating as a purported massive volcano, thought to have nearly annihilated humans 70,000 years ago.
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