Neanderthals interbred with early modern humans around 40,000–60,000 years ago, and as a result, people of European (and also Asian) descent carry about 1–2% Neanderthal DNA. Some traits and genetic influences passed on to Europeans from Neanderthals include:
1. Immune system genes
Neanderthals contributed variants of genes like TLR (Toll-like receptors), which play a role in detecting pathogens and boosting immune response. This helped early humans adapt to new diseases outside Africa.
2. Skin, hair, and eye characteristics
Some genes linked to lighter skin and hair color, including red hair in some cases, are associated with Neanderthal variants. These traits may have helped early humans synthesize vitamin D in lower-light European environments.
3. Keratin production
Neanderthal genes affected keratin (a protein in skin, hair, and nails), which may have contributed to tougher skin better suited to cold environments.
4. Circadian rhythm and sleep
Some Neanderthal variants affect chronotype (morning vs. evening preference) and how people adjust to daylight, possibly helping humans adapt to the longer summer days and darker winters of Europe.
5. Mood and neurological effects
Certain Neanderthal gene variants are linked to modern-day neurological traits like depression, nicotine addiction, and even pain sensitivity, although the mechanisms aren’t fully understood.
6. Metabolism and fat storage
Some Neanderthal-derived genes may have influenced fat storage, insulin regulation, or risk of type 2 diabetes — possibly adaptations to famine-prone Ice Age environments.