A new study released this week details how humans and Neanderthals were approximately 99.84 percent alike.
Research was published in the online journal Science.
Two researchers from Hebrew University in Jerusalem, Eran Meshorer, stem cell biologist, and Liran Carmel, computational biologist, led the team that discovered the 0.12 percent difference.
The researchers said that this meant that prehistoric humans and Neanderthals were similar enough to mate and were "essentially the same species."
Human genomes usually differ from each other by just 0.1 percent, according to the study.
This discovery also means we are "just" 98.8 percent similar to chimpanzees and 98.4 percent similar to gorillas, as far as shared DNA goes.
The team of researchers used different computer models to compare eipenomes of Neanderthals, homosapiens, and Denisovans, a third human relative, according to the study.
The researchers believe that that Neanderthals evolved from a common ancestor named Homo Heidelbergensis.
Human genes include a "cellular on-off switch" which establishes which specific gens will or won't be active, according to the study.
Somewhere between 700,000 and 300,000 years ago, Neanderthals went off from Heidelbergensis and populated a portion of Eurasia before becoming extinct.
The last Neanderthals likely perished some 40,000 years ago, according to the study.
The team said that by taking the numerous modifications into account, the difference between human DNA and that of a chimpanzee increases to about 5 percent.