10 Fascinating Ways Neanderthal DNA Unlocks Hidden Strengths and Challenges in Your Health

Imagine a time, over 250,000 years ago, when early humans roamed Europe and Asia, encountering and mingling with a now-extinct group of human relatives: the Neanderthals. These interactions weren’t just friendly exchanges or competitive stand-offs; they also involved interbreeding, leaving a genetic legacy that still impacts many of us today. Even though Neanderthals vanished around 40,000 years ago, their DNA lives on, woven into the genetic fabric of nearly everyone outside of Africa. On average, about 2% of the genome of non-African people is of Neanderthal origin, and new research is revealing how these ancient genes still affect our health in surprising ways.

The Genetic Imprint of Neanderthals

Thanks to advancements in genome-sequencing technology, scientists have been able to explore the DNA inherited from our Neanderthal ancestors. The first Neanderthal genome was sequenced in 2013, opening a window into the past and providing insights into how this DNA influences modern human biology.

While many Neanderthal traits may have been beneficial in the past, helping early humans survive new environments, some of these inherited genes come with unexpected side effects in the modern world. Let’s dive into some intriguing ways that Neanderthal DNA still influences our bodies today.

1. Allergy Risk: An Overzealous Immune System

Ever wonder why some people have severe allergic reactions while others barely sniffle? Part of the answer may lie in our ancient past. In 2016, scientists discovered that certain Neanderthal genes influence proteins called Toll-like receptors (TLRs), which help kickstart our immune system when pathogens attack. These hypervigilant receptors might have provided an advantage against ancient infections, but today, they seem to overreact to harmless substances like pollen, animal dander, or food allergens, increasing the risk of allergies.

2. COVID-19 Susceptibility: A Mixed Bag of Risks

Interestingly, some Neanderthal genes have both positive and negative impacts on how our bodies respond to infections. During the COVID-19 pandemic, researchers discovered that Neanderthal DNA on chromosome 3 increased the risk of severe illness from SARS-CoV-2 for certain individuals. However, another Neanderthal gene variant on chromosome 12 was found to reduce the risk of severe COVID-19 complications, demonstrating the complex influence of our ancient DNA.

3. Diabetes Risk: A Metabolic Misstep

Neanderthal DNA may also contribute to the modern epidemic of type 2 diabetes, particularly in people of Latin American descent. A mutation in the gene SLC16A11, involved in fatty acid metabolism, has been linked to a higher risk of developing type 2 diabetes. This genetic trait, passed down from Neanderthals, may have once helped our ancestors store fat more effectively during times of scarcity. Today, however, it seems to play a role in the body’s struggle to regulate blood sugar levels.

4. Pain Sensitivity: A Legacy of Sharp Survival Instincts

In Latin America, some people carry a variant of the SCN9A gene, inherited from Neanderthals, which makes them more sensitive to pain from sharp objects. A 2023 study found that individuals with this gene variant tend to feel sharper, more intense pain when their skin is pierced. This sensitivity might have been a survival advantage for our ancestors, alerting them quickly to injuries in dangerous environments.

5. Nicotine Addiction: An Unintended Side Effect

A 2016 study found that a Neanderthal mutation in the gene SLC6A11 might increase the likelihood of nicotine addiction among people of European descent. This gene plays a role in brain signalling, and while Neanderthals obviously didn’t smoke, this trait may have helped with other survival-related behaviours in their time. Today, however, it might make some people more susceptible to nicotine addiction.

6. Fertility: Enhanced Reproductive Success

A remarkable finding in 2020 revealed that nearly one-third of European women carry a Neanderthal gene variant that enhances fertility. This variant, affecting the hormone receptor for progesterone, helps prepare the uterus for pregnancy, reduces bleeding risks, and lowers miscarriage rates. It seems that this genetic gift from our Neanderthal ancestors still benefits modern human reproduction.

7. Sensitivity to Sunlight and Hair Loss: A Nordic Advantage

As early humans migrated to Eurasia, they faced less intense sunlight compared to Africa. Neanderthal genes related to sensitivity to sunlight, tanning ability, and hair growth might have helped our ancestors adapt to these conditions. For instance, a 2017 study found that about 66% of Europeans carry a Neanderthal gene variant that increases the risk of childhood sunburn and poor tanning. These traits, while potentially disadvantageous today, could have helped ancient humans maximize limited sunlight exposure for vitamin D synthesis.

8. Depression and Light Sensitivity

Some researchers have found links between Neanderthal DNA and mood disorders like depression, especially in people of European descent. The theory is that this may be related to adaptations for light exposure, as Neanderthal gene variants appear to influence ultraviolet light protection. These genes might have helped our ancestors cope with less sunlight in Northern climates, but today, they may also play a role in seasonal mood disorders.

9. “Viking Disease”: An Ancient Grip

Dupuytren’s disease, also known as “Viking disease,” is a condition where the fingers become permanently bent. Scientists have found that Neanderthal DNA may increase the risk of developing this condition, especially in people of European descent. Gene variants inherited from Neanderthals seem to influence the flexibility of the hand tissues, linking our ancient DNA to a modern health issue.

10. Autoimmune Disorders: A Double-Edged Sword

Neanderthal gene variants are also implicated in autoimmune diseases such as lupus and Crohn’s disease. While these genes may have helped our ancestors fight infections by making the immune system more aggressive, in today’s cleaner environments, this can backfire, leading to autoimmune disorders where the body mistakenly attacks its own tissues.

Surprising Discoveries

It’s long been believed that Neanderthal genes were only carried by non-African populations, the result of early human ancestors interbreeding with Neanderthals after they migrated out of Africa. However, recent studies reveal an unexpected twist in the tale of our shared ancestry: modern African populations also carry Neanderthal DNA, with about 0.3% of their genomes originating from these ancient relatives. This Neanderthal ancestry likely arrived in Africa through a backflow of European migrants over the last 20,000 years, meaning our genetic exchange with Neanderthals is even more complex and global than once thought.

The genetic legacy of Neanderthals is actually strongest in East Asians, who have a Neanderthal DNA proportion of around 8% to 24%, compared to 2% in Europeans. This is likely because early Homo sapiens in Europe experienced a dilution in their Neanderthal DNA when a wave of early farmers with minimal Neanderthal genes migrated into the region from the Middle East around 10,000 years ago. East Asian populations, however, did not experience this same influx and retained a larger portion of Neanderthal ancestry.

Interestingly, this intermingling of genes didn’t lead to a distinct survival advantage or disadvantage, as far as we know. So, the variation in Neanderthal ancestry across populations isn’t due to evolutionary pressure but instead reflects our species’ incredible history of movement, mixing, and adaptation across the globe.

A Complex Legacy

It’s fascinating to think that our Neanderthal ancestors, who lived tens of thousands of years ago, still influence our daily lives in such profound ways. From how we react to sunlight to our risks for certain diseases, the legacy of these ancient encounters is written in our genes. Though these Neanderthal traits might have been advantageous in the past, in today’s world, they offer a unique glimpse into our evolutionary journey and the surprising ways our bodies carry the history of our species.

Understanding these genetic influences not only helps us appreciate our deep ancestral roots but also opens new avenues for medical research, as we learn to navigate the complexities of inherited traits from our long-lost relatives. Who knew that the ghosts of our ancient past still walk with us, encoded in the DNA of millions today?

Reference list Ågren, R., Patil, S., Zhou, X., Palotie, A., Daly, M., Riley-Gills, B., Jacob, H., Paul, D., Matakidou, A., Platt, A., Runz, H., John, S., Okafo, G., Lawless, N., Plenge, R., Maranville, J., McCarthy, M., Hunkapiller, J., Ehm, M.G. and Auro, K. (2023). Major Genetic Risk Factors for Dupuytren’s Disease Are Inherited From Neandertals. Molecular Biology and Evolution, 40(6). doi:https://doi.org/10.1093/molbev/msad130.

Cooke, E. (2024). 10 unexpected ways Neanderthal DNA affects our health. [online] livescience.com. Available at: https://www.livescience.com/health/genetics/10-unexpected-ways-neanderthal-dna-affects-our-health [Accessed 11 Nov. 2024].

Deschamps, M., Laval, G., Fagny, M., Itan, Y., Abel, L., Casanova, J.-L., Patin, E. and Quintana-Murci, L. (2016). Genomic Signatures of Selective Pressures and Introgression from Archaic Hominins at Human Innate Immunity Genes. The American Journal of Human Genetics, 98(1), pp.5–21. doi:https://doi.org/10.1016/j.ajhg.2015.11.014.

Faux, P., Ding, L., Ramirez-Aristeguieta, L.M., Chacón-Duque, J.C., Comini, M., Mendoza-Revilla, J., Fuentes-Guajardo, M., Jaramillo, C., Arias, W., Hurtado, M., Villegas, V., Granja, V., Barquera, R., Everardo-Martínez, P., Quinto-Sánchez, M., Gómez-Valdés, J., Villamil-Ramírez, H., Silva de Cerqueira, C.C., Hünemeier, T. and Ramallo, V. (2023). Neanderthal introgression in SCN9A impacts mechanical pain sensitivity. Communications Biology, [online] 6(1), pp.1–12. doi:https://doi.org/10.1038/s42003-023-05286-z.

McArthur, E., Rinker, D.C. and Capra, J.A. (2021). Quantifying the contribution of Neanderthal introgression to the heritability of complex traits. Nature Communications, [online] 12(1), p.4481. doi:https://doi.org/10.1038/s41467-021-24582-y.

Pappas, S. (2023). Scientists finally solve mystery of why Europeans have less Neanderthal DNA than East Asians. [online] livescience.com. Available at: https://www.livescience.com/archaeology/mystery-of-why-europeans-have-less-neanderthal-dna-than-east-asians-finally-solved [Accessed 11 Nov. 2024].

Price, M. (2020). Africans carry surprising amount of Neanderthal DNA. [online] www.science.org. Available at: https://www.science.org/content/article/africans-carry-surprising-amount-neanderthal-dna [Accessed 11 Nov. 2024].

Sankararaman, S., Mallick, S., Dannemann, M., Prüfer, K., Kelso, J., Pääbo, S., Patterson, N. and Reich, D. (2014). The genomic landscape of Neanderthal ancestry in present-day humans. Nature, 507(7492), pp.354–357. doi:https://doi.org/10.1038/nature12961.

Simonti, C.N., Vernot, B., Bastarache, L., Bottinger, E., Carrell, D.S., Chisholm, R.L., Crosslin, D.R., Hebbring, S.J., Jarvik, G.P., Kullo, I.J., Li, R., Pathak, J., Ritchie, M.D., Roden, D.M., Verma, S.S., Tromp, G., Prato, J.D., Bush, W.S., Akey, J.M. and Denny, J.C. (2016). The phenotypic legacy of admixture between modern humans and Neandertals. Science, [online] 351(6274), pp.737–741. doi:https://doi.org/10.1126/science.aad2149.

Zeberg, H., Kelso, J. and Pääbo, S. (2020). The Neandertal Progesterone Receptor. Molecular Biology and Evolution, 37(9), pp.2655–2660. doi:https://doi.org/10.1093/molbev/msaa119. Zeberg, H. and Pääbo, S. (2021). A genomic region associated with protection against severe COVID-19 is inherited from Neandertals. Proceedings of the National Academy of Sciences, 118(9), p.e2026309118. doi:https://doi.org/10.1073/pnas.2026309118.