Neanderthal Origins of Human Disease

Approximately 2% of human DNA contains mutations of Neanderthal origin, providing compelling proof for interbreeding. This finding has recently led scientists to think further about the “Neanderthal” gene variants which persist in the human genome, and their legacies for health and disease. A study published in this week’s edition of Nature Magazine suggests that many of our genes originated in Neanderthals; some have helped us to adapt to inclement Eurasian weather, while others predispose us to type 2 diabetes, Crohn’s disease and other immunological disorders.

These fascinating results were obtained by Professor David Reich and colleagues at Harvard Medical School. They sequenced, analysed and compared gene sequences taken from the complete Neanderthal genome and the genomes of African and non-African human subjects. This allowed them to assess the influence of human migration (from Africa to Eurasia) and inter-breeding on human traits and disease vulnerability.

Non-Africans and Neanderthals shared keratin protein production gene variants, which influence both hair colour and skin and nail thickness. Moreover, it seems that genes relating to diseases of immune function, such as biliary cirrhosis and systemic lupus erythematosus, originated in Neanderthals. Even our ability to give up smoking could relate to gene variants which arose in our long-extinct cousins.

One of the most interesting findings reported by Prof. Reich’s group relates to the lack of similarity in gene sequences at the X and Y chromosomes of human subjects and Neanderthals. Considerable differences in these regions may account for the relative infertility of hybrid human-Neanderthal offspring and their failure to survive as a sub-species.

This research not only answers outstanding questions about what Neanderthals were really like, but also hints at their involvement in the evolution of humans migrating to Eurasia. Prof. Reich and colleagues now aim to draw upon the 500,000 strong reserves of the UK biobank to delve deeper into a host of gene variants thought to have arisen in Neanderthals.