Recent genetic studies have shown that Neanderthal DNA spanning at least 20% of their ancient genome survives in modern humans of non-African ancestry. If you are of European or Asian heritage, then around 2% of your genome originated from Neanderthals.

This legacy was picked up from 60 – 80,000 years ago, when successive waves of modern humans began migrating from Africa into Asia and Europe, encountering and interbreeding with their Neanderthal cousins who had evolved there from around 250,000 years ago.

Their hybrid children bore genes from both lineages, but eventually modern human genes diluted Neanderthal genes to the extent that the species seemed to disappear from the archaeological record around 30,000 years ago.

Those Neanderthal genetic mutations which were not beneficial to modern humans were partially swept out by natural selection over time. The remnants are alive in the genomes of Europeans and Asians today. If you exhibit any of the following traits, they may just be an echo of your inner Neanderthal:

1. Occipital bun

The occipital bun was a knot of rounded bone at the back of the Neanderthal skull and may have been an adaptation for the attachment of their massive neck and jaw muscles. Vestiges of the occipital bun were common in early modern European skulls, but are relatively rare among Europeans today.

(Image and cool haircut courtesy of Kenji)

2. Elongated skull

Modern human faces tend to be small and tucked into the lower half of the head under a rounded brain case. The Neanderthal face tended to be larger, with a brain case set back in a longer skull. An elongated skull may hint at a Neanderthal inheritance and is particularly common in the British Isles, Scandinavia and Iberia.

3. Space behind the wisdom teeth

Neanderthals had jaws large enough to comfortably house all of their teeth, even having a gap behind their wisdom teeth. If, as commonly occurs, any of your wisdom teeth have become impacted or haven’t erupted at all, it may be because your evolved smaller jaw doesn’t have the space to cope with these vestiges of our foliage-chewing past. If you have all 4 wisdom teeth with space to spare, you may have a Neanderthal ancestor to thank.

4. Supraorbital ridge or brow ridge

The brow ridge is a bony ridge located above the eye sockets of all primates which reinforces the weaker bones of the face. The pronounced brow ridge that Neanderthals shared with other archaic human species, such as Homo erectus, shrank when modern humans evolved – but did not disappear entirely.

In terms of racial classifications used in forensic anthropology, Professor Caroline Wilkinson said that Australoids have the largest brow ridges, Caucasoids have the second largest, Negroids have the third largest and Mongoloids are “absent brow ridges“.

Genetic studies suggest that the ancestors of these populations all interbred with some archaic human species or other at some point in the past. In the case of Australoids and Mongoloids, most carry both Neanderthal and Denisovan DNA in their genomes.

5. Broad, projecting nose

The angle of the Neanderthal nose bone projected out with a wide opening, making it a large and prominent facial feature. It could be an influence on the modern human aquiline nose prevalent in the Neanderthal hotspots of southern Europe and the Near East, and amongst native North Americans whose genetic source has been traced to the Altai mountains of East/Central Asia.

6. Little or no protruding chin

The Neanderthals’ large jaw and protruding mid-face meant that they had a weak, or receding chin. The receding chin in modern humans is normally a congenital condition. It ran in the family of the ancient Egyptian pharaohs of the 18th dynasty, to which Tutankhamun (1341 BC – 1323 BC) belonged. A reconstruction of Tutankhamun’s features in 2005, based on CT analysis of his skull, captured his weak chin and overbite. Although his racial identity is debated, anthropologists reconstructed his appearance as a Caucasoid North African. They also concluded that his elongated skull was a normal anthropological variation, not a result of disease or congenital abnormality.

7. Rosy cheeks

Neanderthals had a large mental foramen in their mandible for facial blood supply, meaning that their side jaws and cheeks were well supplied with blood. The result was a reddening of the cheeks, familiar to Eurasians inhabiting the northern latitudes when the weather is cold or doing physical exercise.

8. Wide fingers and thumbs

A comparison of Neanderthal and average modern human finger bones shows how much more robust Neanderthal hands were – especially the tips (distal phalanges).

In fact, research suggests that the slenderness of modern human hands helped to give us the advantage over Neanderthals. While Neanderthals had much greater hand strength, our precision grip gave us the technological and cultural leap in developing more sophisticated tools and art.

Of course, there is a huge amount of modern human variation in hand and finger size. Russian arm wrestling champion Denis Cyplenkov may be a Neanderthal throwback in the hand department – his party trick is crushing walnuts between his massive fingers.

9. Straight, thick hair

Genetic analysis has revealed that 70% of modern East Asians inherited Neanderthal mutations in genes involved in the production of keratin filaments, which may be responsible for straightening and thickening hair.

There is a lot of variation in the shape and texture of modern human hair. Broadly speaking, African hair is mainly coiled and dry; Asian hair is straighter and thicker; and European hair is somewhere in between.

A Neanderthal inheritance of straight, thick hair may have helped modern humans to adapt to non-African environments; straighter hair tends to be oily and thicker hair is insulating, which would have been an advantage in colder northern latitudes.

10. Insulating skin

The same Neanderthal keratin mutations which affect hair also affect skin, making it more insulating and better adapted to colder environments.

The overall thickness of the stratum corneum, or outermost layer of skin, is generally similar among all modern humans. Although African skin has been shown to be made up of more layers when compared with the skin of Eurasians, it seems more compact. The less compacted layers of Eurasian skin may be an insulating adaptation.

11. Fair skin and freckles

Neanderthals, who ranged from Western Europe to Central Asia, probably had the same distribution of skin color as modern humans, including fair skin and freckles. Fair skin is an advantage at northern latitudes because it is more efficient at generating vitamin D from weak sunlight. Freckles are clusters of cells that overproduce melanin granules; they are triggered by exposure to sunlight and are most noticeable on pale skin. BNC2 is one of several skin color genes and it influences saturation of skin color and freckling. It is a Neanderthal gene and is found in Eurasian populations, most commonly in Europeans (70% have at least one copy of the Neanderthal version).

12. Red hair

Neanderthals also likely had the same distribution of hair color as modern Eurasian populations, including a spectrum of red hair from auburn to brilliant red to strawberry blond.

Between 2% and 6% of modern northwestern Europeans have red hair, compared with an average of around 0.6% of the world’s population as a whole. In the British Isles the numbers are much higher. In Scotland around 13% of the population have red hair, but over 30% are unknowing carriers of the redhead gene. In Ireland about 10% have red hair, but as many as 46% are carriers. Genetic red hair is rarer In Asia, but can be found in the Near and Middle East.

One of the mutations in the main gene for modern human hair color appears to be of Neanderthal origin and may have helped European hair color to diversify by providing raw material for selection to act on.

13. Large eyes

The large eye sockets in Neanderthal skulls indicate that they had large eyeballs to fill them. Antroplogists have suggested that they required larger eyes to enable them to see in the weaker sunlight of the northern latitudes.

Some further suggest that they devoted more brain power to processing visual input than to higher-level processing, and this is partly why modern humans had the evolutionary edge on them.

Ukrainian model Masha Tyelna’s large natural eyes may be a hint of this ancestry, or at least more accurately reflect the proportionate size of Neanderthal eyes.

14. Immunity against Eurasian pathogens

Having evolved in Eurasia over hundreds of thousands of years, Neanderthals developed the HLA receptor that provided them with immunity against the many local pathogens that lurked in the forests, rivers and caves of Europe and Asia. There was a distinct evolutionary advantage for the newly arrived modern humans from Africa to inherit this receptor.

While this inheritance conferred an immunity advantage to modern Eurasians, it also made them more prone to some autoimmune reactions. It isn’t yet known if Neanderthals suffered from these diseases themselves, or if these mutations affected only modern humans when they were implanted into our genetic code:

15. Increased risk of Type 2 diabetes

Type 2 diabetes develops when the body is unable to produce enough workable insulin – the hormone that helps release the glucose in your blood to give you energy. Type 2 diabetes usually appears in people over the age of 40, though in South Asian people, who are at greater risk, it often appears from the age of 25. It is treated with a healthy diet and increased physical activity, plus medication and/or insulin as required.

16. Increased risk of Crohn’s disease

Crohn’s disease is a type of inflammatory bowel disease that may affect any part of the gastrointestinal tract in genetically susceptible individuals. It leads the body’s immune system to attack the gastrointestinal tract, possibly directed at microbial antigens. Crohn’s disease affects about 3.2 per 1,000 people in Europe and North America, but is less common in Asia.

17. Increased risk of lupus

Lupus is an autoimmune disease in which the body’s immune system mistakenly attacks normal, healthy tissue. It can affect the skin, joints, kidneys, brain, and other organs. It affects around 53 per 100,000 in the US and around 40 per 100,000 people in Northern Europe, but it occurs more frequently and with greater severity among those of non-European descent.

18. Increased risk of biliary cirrhosis

Primary biliary cirrhosis is an autoimmune disease of the liver marked by the slow progressive destruction of the liver’s small bile ducts. When these ducts are damaged, bile builds up in the liver and over time damages the tissue. It may affect up to 1 in 4,000 people in North America and Europe, but appears to be much less common in Africa. The ratio of female:male sufferers is at least 9:1.

19. Difficulty with nicotine addiction

Neanderthals did not (as far as we know!) smoke cigarettes, but one of the gene variants they passed on to modern humans is associated with the difficulty in trying to stop smoking. What particular function this mutation originally had in Neanderthals is a mystery.

20. Increased risk of long-term depression?

Major depression is characterized by a pervasive and persistent low mood that is accompanied by low self-esteem and by a loss of interest or pleasure in normally enjoyable activities.

There is much debate about the nature vs nurture causes of depression in modern society, but the potential link to the inherited Neanderthal HLA receptor is one of the more fascinating possibilities.

There is no suggestion that Neanderthals themselves suffered from mental disorders like depression. In fact, DNA evidence suggests that they didn’t. The genetc triggers which contribute to these ailments were essentially ‘turned off’ in the Neanderthal genome. Some were ‘turned on’ in the modern human genome when we inherited the Neanderthal HLA receptor.

To pin the causes of depression on our Neanderthal ancestors may well be overblowing the potency of their contribution. For example, a counselling psychologist may see depression not as a biochemical disorder but as “a species-wide evolved suite of emotional programs that are mostly activated by a perception, almost always over-negative, of a major decline in personal usefulness, that can sometimes be linked to guilt, shame or perceived rejection”.

Depression may have started in our hunter-gatherer past (the way we have lived for at least 90% of our history). When an aging hunter (who would have been old by his early 30s) began to lose his speed and agility, his feelings of uselessness and alienation from his tribe may have been a prompt for the tribe to rally round and support him. Similar feelings may have haunted the aging female (again, in her 30s) in the face of her declining fertility prior to menopause. Investing in the survival of her grandchildren may have given her a sense of purpose (and an evolutionary edge).

Interestingly, studies of modern populations have consistently shown major depression to be about twice as common in women as in men. They also show that people are most likely to suffer their first depressive episode between the ages of 30 and 40.

While depression is indeed a species-wide problem for modern humans, affecting over 5% of the world’s population, some populations feel more depressed than others. According to the US Census Bureau and the Center for Disease Control and Prevention, the top 10, by percentage of population, are:

(10) Italy – 3.8%

(9) Mexico – 4.8%

(8) Spain – 4.9%

(7) Belgium – 6.2%

(6) Lebanon – 6.6%

(5) Colombia – 6.8%

(4) Netherlands – 6.9%

(3) France – 8.5%

(2) Ukraine – 9.1%

(1) United States – 9.6%

There are very good reasons – politically, economically, and socially – why these countries are top of the league table for depression, but it is interesting how all of their populations now sit in the old Neanderthal range (or were transplanted to America by European colonisation).

Sources: Sci-News, Discovery, New Scientist, Eupedia, Netwellness