Source: TW
It is interesting that it was almost as if the brain and testis of sapiens were protected against the genetic influence of Neanderthals. Not surprisingly, the Neanderthal variants contribute to depression & addiction in sapiens.
We had argued that the explosive parallel increases in brain size in the late lineages Homo was driven by interspecies conflict. They likely created lineage-specific genetic backgrounds wherein brain expressed alleles from other others would malfunction.