Answer:
It can be explained by hybridization among human and neanderthal ancestral populations.
Step-by-step explanation:
Next-generation sequencing (NGS) technologies coupled with bioinformatics tools have enabled to confirm admixture between Neanderthals and humans. The technique to identify admixture events consists in discovering nucleotide regions from neanderthal genomes that could be inserted in human genomes, thereby the observed sequence homology must be statistically significant (e-value). This emergent research field is known as paleogenomics.