Impact of Neanderthal Interbreeding: genes vs gene expression

[Jordan (Jordan Mantha)]

Infographic: History of Ancient Hominin Interbreeding

This article seems like a good overview of hominin interbreeding, but what I found more interesting was the discussion of this figure:

sequences that originated in Neanderthals tend to have “less impact through protein and more impact through gene expression,”

Is there an obvious mechanism for why this would be the case?

For more in-depth discussion see the main article :

Neanderthal DNA in Modern Human Genomes Is Not Silent

And the primary literature with the newest results:

https://www.cell.com/ajhg/fulltext/S0002-9297(19)30164-8

[swamidass (S. Joshua Swamidass)]

Negative selection against Neanderthal coding genes and regulatory elements when in a Sapiens genome background could explain this.

[Jordan (Jordan Mantha)]

That’s what I was thinking.

I wonder, would we find the same thing within modern humans? In other words, are the differences between human populations (i.e. “races”) similarly preferentially in the regulatory regions rather than coding regions.