Even though it has only been known that Neanderthals and humans interbred as of 2010, there is already a large scientific conversation about what genetic traits the two species have in common, how these genes came to spread, and what effect they have had on the human species. The article titled “Neanderthals Leave Their Mark on Us” discusses the timeline of scientific discovery considering Neanderthal and human special relations, as well as a vague picture of the two species within evolutionary history.

Although humans and Neanderthals originally one and the same, branching off 600,000 years ago according to the article, physical separation across continents allowed the two independent species to develop. As the article notes, Neanderthals lived in the colder climates of Europe and Asia, while humans lived in Africa. At last between 37,000 to 85,000 years ago, the two species met again when some humans migrated to Neanderthal-filled land. The ability to determine when human and Neanderthal DNA mixed is an excellent indication of when this migration occurred. As it is impossible for the two species to have met without sharing space, this further data enhances the argument of human migration out of Africa.

What troubled scientist for a long time after making the discovery was a lack of an accurate sample of Neanderthal DNA. With an accurate sample, scientists were able to trace specific genes, identifying where they would be in the human genome. However, this problem has mostly subsided due to an intact genetic sample from a Neanderthal toe bone. The genes of this particular Neanderthal have been compared to those of humans, and numerous similarities have been found between this Neanderthal and hundreds of European and Asian humans. Regrettably, however, all of the Neanderthal-specific genes that this particular Neanderthal didn’t have are therefore still unknown, and there is no way to trace and identify these other genes.

The article lists several genes that humans have received from the Neanderthal population, and it is difficult to say exactly why these particular genes flourished and others did not. Some appear to deal with the makeup of skin and hair. The article does not venture into specifics as to what the resulting differences are, but a scientist explains that these changes may have allowed for adaptation to a colder climate, or possibly helped to prevent catching diseases particular to the area. There are many problems in the way of determining why a particular gene flourished. For one, there can be a variety of possible evolutionary benefits to any particular genetic difference, but just because something may have been beneficial for a particular reason does not mean that is the actual reason the gene flourished. A trait such as lighter hair could have succeeded due to Vitamin D intake, sexual selection, camouflage, or the use of light hair creating baskets, and all that scientists are able to do is muse about the possibilities.

Finally, the article stresses the fact that not all of the discovered Neanderthal traits are beneficial, and in fact, some appear to be entirely detrimental. For example, there are Neanderthal genes found in human DNA that increase the risk of diabetes and lupus. The carriers of these genes likely survived in spite of these genes, and now the traits have spread across the European and Asian populations. Luckily, now that these genes have been identified, it is possible to inform parents of the risk of their child contracting or developing a particular disease. In most cases, this would mean extra precautions, but in others, it could mean advising couples who are in the process of decided whether to, and how to have children.