Just as coyotes and wolves would be ‘cousin’ species, although more distantly related.
And it is not five times more difference just in genetic markers, it would be, overall, about five times more differences over all the DNA of the genome.
If the absolute difference in DNA of the genome among humans was 3 million out of 3 billion total base pairs, you would expect, when comparing humans and neanderthals, around 9-15 million base pair differences out of that 3 billion, not the same 3 million.
It is the total amount of differences in the genome, or via comparison of neutral genetic regions, that one derives that the time line of divergence, one that (in this case) agrees nicely with the fossil record.
If there were the same number of base pair differences, it would imply an equal time of divergence. But the amount of difference between a human genome and a neanderthal genome should be three to five times more than the amount of difference between any two human’s genome, which would indicate their divergence around five times longer ago (less than 100,000 years ago, compared to some 500,000 years ago).
Can only go by what I read, and the following report is over 3 years old, but note the numbers:
"The results from the new studies confirm the Neanderthal's humanity, and show that their genomes and ours are more than 99.5 percent identical, differing by only about 3 million bases."This is a drop in the bucket if you consider that the human genome is 3 billion bases," said Edward Rubin of the Lawrence Berkeley National Laboratory, who led one of the research teams.
For comparison, the genomes of chimpanzees, our closest living relatives, differ from humans by about 30 million to 50 million base pairs."
Note the figure of "differing by only about 3 million bases." They then miscalculate this as one-half of one percent, when it should be one-tenth of one percent.
Here is a newer report saying:
"A newly released study published in Science magazine raises new questions about ancient life by concluding much of the DNA from Neanderthal specimens is "within the variation of present-day humans for many regions of the genome." "
Point is, I've seen nothing yet suggesting that Neanderthal nuclear DNA differences were more than 3 million base pairs, or more than the variances amongst modern humans. Of course, these would not be the same 3 million differences.
So again I ask: if it's "human" for humans to vary by 3 million amongst ourselves, why is it not quite "human" for Neanderthals to also vary from us by 3 million base pairs?