Denisovan, or 'Polar Neandertal'

Known from a few scrappy pieces, the Siberian Denisovans (Homo sp. or Homo sapiens ssp., depending on how large you like your species) are a true challenge to reconstruct. We have their entire genome, but know almost nothing about their anatomy. The few fossil elements we have are not morphologically distinct from Neandertals (Homo neanderthalensis or Homo sapiens neanderthalensis) or humans (Homo sapiens sapiens).

But the genomic facts are highly intriguing:

1) Some Oceanian humans have inherited up to 6% of their nuclear DNA from Denisovans (with the highest ratios in Meganesia [Australia and New Guinea]).

2) The nuclear DNA indicates a common ancestor with Neandertals, shortly after the split from proto-humans.

3) But the mitochondrial DNA indicates a motherline that branched off much earlier. (Possibly Homo erectus?)

4) Genes for pigments are consistent with dark skin.

Here I've imagined a Siberian Denisovan as a sort of "polar Neandertal". As with polar bears, his skin is dark, trapping heat, but his pelage is light, allowing for camouflage against the taiga and tundra. He is the last of his kind -- his southern kin mixed with the strange, baby-faced people who keep invading from the west. But he does not welcome them. He will fight to his death.