Some genes were beneficial to Homo sapiens while others researchers believe were harmful. Geneticists were led to believe this because they found "holes" in the human genomes that do not connect back to their closest extinct relatives. According to the study, the gene that is involved in human speech does not have any connections to Neanderthals. The study also indicated that the two groups were too distantly related to successfully breed. David Reich found that hybrids had issues with fertility. This information was a surprise to researchers because most animals need to be separated by a larger number of generations before they become their own species.
Researchers are constantly discovering new information about human genomes and how they relate back to our ancestors. Continuing to do research on this topic can help to make discoveries in other areas such as the medical field. It is very important and necessary that we find out as much as possible about our genes.