About fair-haired mummies - 1st part

 As you know, all around the world many blond- and red-haired mummies have been found. 

Among the artificial ones, there are several from ancient Egypt (especially from the 18th and 19th dinasty, New Kingdom, such as Ramesses II and his father Seti I, Thutmose IV, Queen Tiye, Hatshepsut and Siptah), some from Tenerife, Gran Canaria and La Palma (belonging to the Guanche people) and some from the Chinchorro culture (South America). Among the natural ones, there are some of the Tarim mummies, a small part of the Chinchorro mummies, the Paracas mummies in Peru, several from Fag el-Gamous (Egypt) and one of the Gebelein mummies, also found in Egypt.  

For the artificial mummies, usually the fair hair colour is explained either with the henna or with the natron used in the mummification process.

As for the natural mummies, the fair hair colour is usually explained with unspecified post-mortem “chemical processes”.

In this two-part post, I will try to clarify the matter a bit, showing that tracing the natural hair colour of a mummy is not at all impossible.

The Princess of Xiaohe, one of the Tarim mummies

Henna

Henna is a dye made from dried, powdered leaves of Lawsonia inermis, used to dye hair and for body paint. 

The use of henna in ancient Egypt is scarcely documented. It was occasionally used in mummification, probably for ritual purposes and for its antiseptic and antimycotic effects, but no ancient source mentions henna in relation to mummification. Its use in this process has only been documented by archaeologists.

As a matter of fact, the only Egyptian source about the use of Lawsonia inermis is the Ebers Papyrus, which includes various medical uses of this plant  However, not all scholars agree on the identification of the plant referred to in this papyrus with the consonant group KPR (translitterated as kupros in Greek and cyprus in Latin), and some speculate it is actually the Cyperus rotundus.

Henna was also used to dye textiles, but that’s all. There is no reference to henna being used to dye hair in ancient Egypt. 

Another important point is that there is no reference to henna being known and used outiside of Africa, the Middle East and South Asia in ancient times. This means that the mummies in South America and Tenerife didn’t receive any treatment with it. 

Henna powder

What most people ignore is that, being henna a natural dye, it can’t make your hair fairer, because it doesn’t replace its natural color (unlike chemical dyes). Henna’s chemical agent, called lawsone, binds to hair keratin and optically adds up to hair’s natural colour. For this reason, this dye is called “tone on tone”: because henna’s orange colour superimposes over hair’s colour, thus creating a different colour (and, as a consequence, the final result will change from person to person).

For this reason, if you have dark hair you will never dye it red with henna. At the very most, you will get a reddish shade visible in the sunlight. You will dye your hair red with henna only if you have blond, light brown or white hair (more information here). Actually, if you have white hair and dye it with henna only (without mixing it with other dyeing plants) you will get an unnatural orange colour, like in the photo below. 

An elderly Bengali man in Dhaka with a beard dyed in henna

So, those who claim that the reddish hair of certain mummies is a result of henna are basically saying that all those individuals, at the time of mummification, either had white or blond/light brown hair. And those who say that “Egyptians used to dye their hair with henna” probably think that all ancient Egyptians were fair-haired.

Now, a scientific analysis of the hair can distinguish between a coloration due to henna and a natural reddish pigmentation, although the degree of certainty depends on the state of conservation of the find. Lawsone binds to hair keratin differently than natural melanin, so analysing hair with techniques such as chromatography, mass spectrometry, Raman spectroscopy, XANES, chemical imaging and the electron microscope often reveal chemical traces consistent with lawsone or its degradation products. If these markers are present, it's a strong indication of henna treatment. 

Conversely, natural red hair exhibits a characteristic distribution of phaeomelanin, the biological pigment responsible for red and copper tones. The chemical composition of phaeomelanin is different from that of henna and can be identified through appropriate analysis.

However, there is a significant difficulty with artificial mummies: after thousands of years, both lawsone and natural pigments may have degraded and therefore it's not always possible to obtain a definitive answer. For this reason, researchers tend to combine multiple lines of evidence: chemical analysis of the hair, colour distribution along the shaft (dye often leaves patterns different from natural pigmentation) and microscopic examination of melanin granules. 

In particular, the analysis of pigment in the hair shaft can be very useful, because melanin can survive for thousands of years and can be studied under the microscope or with chemical techniques.

Natron

Natron is a salt used to dry out the remains of the body prior the mummification and has often been linked to a supposed hair colour change in artificial mummies. However, in 2016, Dr Janet Davey, from the Victorian Institute of Forensic Medicine in Australia, conducted an experiment that disproved this hypothesis. You can read about it both in her paper Is ancestry, not natron, an explanation for fair haired children in Greco-Roman Egypt? and here.   

Along with a retired chemist, Alan Elliot, she prepared a quantity of synthetic natron, with which she covered 14 hair samples. 13 of them were non-treated and one was treated with synthetic beeswax (natural beeswax has been discovered on the hair of ancient Egyptian mummies). 

They remained covered for 40 days, because it is believed this was the same amount of time needed in ancient times to dry out the bodies before mummification. Well, after 40 days only one sample became slightly lighter in colour: the red one. The blacks became slightly darker and the others were unchanged, included the one treated with beeswax.

Dr Davey’s paper is interesting for another reason. Citing previous studies (which I will link at the bottom of this article), she writes  that when hair is kept in a place like a sarcophagus or a tomb, melanin doesn’t degrade and hair colour doesn’t change. She also mentions natural hair wigs found in Egyptian tombs, which, after examination, resulted to have kept their original colour.

Should this be true, it would mean that the hair colour of artificial mummies not treated with henna is the original colour at the time of mummification.

The case of Ramesses II

As you know, the mummy of Ramesses II shows red hair. Since at the time of death he was 91, this colour is most likely due to the henna used in the mummification process. However, as you can read on Wikipedia, in 1976, during an examination of the mummy, Pierre-Fernand Ceccaldi, the chief forensic scientist at the Criminal Identification Laboratory of Paris, observed that the roots of Ramesses’ hair were red and concluded that was his original hair colour. Conversely, others claim the colour red at the roots is due to henna or to the remains of resins and salts used in the mummification. 

This French article from 2009 summarises what was known at the time about Ramesses’ hair colour and henna, and doesn’t exclude that the pharaoh had indeed red hair. On the contrary, the authors of this 2023 study about the facial reconstruction of Ramesses hurry to say “However, this does not suggest that Ramesses II had red (ginger) hair when he was younger, as claimed by some authors.” They also write “Many Egyptians dyed their hair with henna” without providing any source, so I don’t think this study is very reliable.  

As we have seen, today there are ways to determine the original hair colour of a mummy treated with henna, especially because melanin is one of the most resistant biomolecules in existence. However, even if traces of eumelanin (the dark pigment) and phaeomelanin (the yellow/red pigment) should be found, this couldn’t be enough to determine the exact hair colour. 

As far as DNA is concerned, in this article we have seen that a DNA test can show if you have MC1R mutations, and which kind of mutations. Unfortunately, artificial mummies (and many natural mummies) are not the best for this kind of testing. Most of the mummification techniques included evisceration (internal organs are the best place for extracting DNA) and desiccation with natron and resin coatings, which can destroy the DNA. Besides, most of these mummies underwent recent contamination, for example because their tombs have been opened several times, or because they have been touched and manipulated by people not wearing gloves or face masks. 

A detail of Ramesses II's mummy

As of now, I’m not aware of DNA analyses conducted on the mummy of Ramesses II. In the 1970s, when the mummy was transferred to Paris for restoration and study, numerous anatomical, radiological, and forensic tests were performed (as you can read on Wikipedia). These established, among other things, that Ramesses II died at a very advanced age (around 90), suffered from arthritis, had serious dental problems, and showed signs of atherosclerosis. Hair, skin, and other samples were taken for these tests, but the primary goal was to assess the mummy's state of preservation and halt its deterioration caused by fungi and other microorganisms (did you know that for its travel to France the mummy of Ramesses was issued a passport?)

At the time, DNA analysis techniques were still in their infancy, so those samples could not be used to obtain a genetic profile as they are today. In recent decades, the technology for ancient DNA (aDNA) analysis has improved enormously. Results have been obtained on several Egyptian mummies, such as those of Tutankhamun's family and others from Abusir el-Meleq. Ramesses II, however, is not included in these published genetic studies. Perhaps the DNA was too degraded or contaminated, perhaps the researchers preferred not to perform invasive analyses on the mummy, or perhaps attempts were made that didn't produce data reliable enough for publication.

It must be kept in mind that, in order to perform certain kinds of analyses on an archaelogical find, you need to take away a piece of it, and in the case of important finds such as the mummy of Ramesses II (and others) not all samplings are approved of. Researchers prefer prioritise other studies, like ancient DNA, diseases, diet, mummification techniques. A good solution would be using a hair sample already existing and maybe kept in a laboratory (for example, the ones taken in France during the 70s, if they still exist), without cutting more hair from the mummy. Obviously, the question is: do researchers want to find out the real hair colour of Ramesses II and other pharaohs and Egyptian queens? 

In the second part, we will see what we (don’t) know about the chemical processes that can alter mummies’ hair colour. 

Some works about post-mortem hair modification cited in Dr Davey’s paper

(If you're interested in learning more about this topic, you could do some research on all those historical figures - sovereigns, rulers, saints, etc. - who have been exhumed after centuries and whose hair colour was still the same as recorded during their lifetime.)

Early Egyptian mummy hairs: Tensile strength tests, optical and scanning electron microscope observation. A paleobiological research 

Taphonomic Alterations to Hair and Nail

Interpreting biological degradative processes acting on mammalian hair in the living and the dead: which ones are taphonomic?

Structural stability of hair over three thousand years

Autopsied, Embalmed, and Preserved Human Remains: Distinguishing Features in Forensic and Historic Contexts 

Red Hair in Art: William McGregor Paxton

William McGregor Paxton (June 22, 1869 – 1941) was an American painter and instructor who embraced the Boston School paradigm and was a co-founder of The Guild of Boston Artists. He taught briefly while a student at Cowles Art School, where he met his wife Elizabeth Okie Paxton, and at the Museum of Fine Arts School in Boston. Paxton is known for his portraits, including those of two presidents—Grover Cleveland and Calvin Coolidge—and interior scenes with women, including his wife. His works are in many museums in the United States.

Lizzie, ca. 1911

Child in Sunlight (The Chinese Parasol), 1908

Glitter, 1930

A Woman with Red Hair, 1922

Reddy and the Macaw, 1918

The Yellow Jacket, 1907

Girl Combing Her Hair, 1909

The elusive redheads of Easter Island

French editionHere’s an excerpt from the Wikipedia page Rapa Nui National Park 

The earliest inhabitants of the island called it "Te Pito o TeHenua" (the navel/end of the world). The first European to discover the island was Dutch explorer Jacob Roggeveen on Easter day, 1722. As a result, he named it "Easter Island". He observed that the inhabitants were of three groups: "dark skinned, red skinned, and very pale skinned people with red hair".[15]

As you can see, after “red hair” there is the footnote 15, where this article is linked. I quote from it: 

In 1722, a Dutch explorer, Jacob Roggeveen, sighted and visited the island. This happened to be on a Sunday, Easter Sunday to be precise, and the name stuck: Easter Island (Isla de Pascua in Spanish).

What he discovered on Easter Island were three distinct groups of people, Dark skinned, Red skinned, and very Pale skinned People with red hair.

So, I began researching the original source of this statement and I found out something quite surprising. It turned out that this excerpt is not from Roggeveen’s writings, but from a book written by Carl Friederich Behrens,  a corporal during Roggeveen’s expedition. The book is Reise durch die Süd-Länder und um die Welt, published in 1737. 

Carl Friederich Behrens

Here’s the original book (click on the cover). As you can see, it was printed with the old book hand Fraktur, so it is not very easy to decipher. Anyway, it is important that we see the original. If you go to book page 87, you’ll find this passage: 

Der Coleur nach waren sie braunlich, wie ungefehr ein Spanier, doch findet man derselben einige schwarzer, auch theils ganz weiß; wie nicht minder derselben auch einige roth, gleich als wären sie von der Sonne etwas stark verbrannt.

That is:

The complexion was brownish, about the hue of a Spaniard, yet one finds some among them of a darker shade and others quite white, and no less also a few of a reddish tint as if somewhat severely tanned by the sun.

So… no mention of red hair! Here the author is clearly talking about the indigenous’ complexion, not about their hair colour, and I’m really surprised that Wikipedia cited a source with wrong information in it. Anyway, it is interesting that on Easter Island there were so many different shades of complexion.

Map from Behrens' travel report

Now, as far as this book by Behrens is concerned, something very strange happened. As you can read here:

The first edition was published in 1737 followed, among others, by a re-published edition made by German anthropologist Hans Plischke that was published in 1923. The important thing is that this version differs from the original to a great extent and the editor did not account for the changes he had introduced into the text: besides grammar and orthography modernization, he omitted certain portions, misinterpreted other ones and added some comments without marking them as his own. As a result, the narrative gives an impression of having been written by another author; Behrens appears as a person with a different character and attitude, weaker, less convincing and even less trustworthy than he really was. This article presents numerous examples of the distortions as a warning against making a scientific or an anthropological use of unreliable editions of source texts, as this may wield a negative infuence upon our view and interpretation of the culture we are analyzing.

This is very worrying, because one wonders how much we can trust modern editions/translations of old books.

So, I checked the French edition, to see if the sentence about complexion was translated correctly. Here it is (page 133 of the book): 

Ils sont en général bruns, comme les Espagnols; on en trouve cependant qui sont assez noirs, & d’autres qui sont tout-à-fait blancs. ll y en a encore, dont le teint est rougeâtre comme s'ils étoient brulés du soleil.

The sentence is exactly the same of the first German edition, so, probably the introduction of red hair instead of reddish complexion is something recent, maybe done by that website linked on the Wikipedia page of Rapa Nui National Park. 

Pakomio Maori

However, there are other sources about redheads in Easter Island.

Here’s an article written in the 90s by Robert Langdon from the Australian National University (not to be confused with Dan Brown’s character 😁), where the author talks about an alleged bue-eyed, red-haired Easter Islander called Pakomio Maori, born between 1816 and 1826 and dead in the first 1910s. Langdon writes that in 1971 he discovered 18 Easter Islanders with no known non-Easter Island ancestors who were carriers of the human leukocyte antigen (HLA) genes A29 and B12, that are especially common among Basques. All 18 islanders were the children of Pakomio Maori through his two wives. 

Pakomio Maori (source)

In his article, Langdon posits that Pakomio Maori was not a descendant of early Europeans visiting the island, although he doesn’t bring any defintive evidence, since at that time ancestry DNA tests had not yet been developed. As a consequence, we don’t know where the “Basque” genes of his children come from.

In any case, we know that traits such as blue eyes and red hair, in order to show up, need to be inherited from both parents, which would mean that Pakomio Maori would have to be the descendant of Europeans from both sides of his family. And not whatever Europeans, but Europeans carrying the mutations for red hair and blue eyes. 

Langdon also quotes early explorers describing isladers with light-coloured hair and skin and “European” facial features and in the article you’ll find photos of some European-looking Easter Islanders. One is Maria Garcia Pate Pakomio, a grand-daughter of Pakomio Maori’s, while the others are the cultural informants Juan Tepano and his mother Viriamo.

Thor Heyerdahl

Here’s the Wikipedia page about the Hanau epe, a semi-legendary people who are said to have lived in Easter Island, where they came into conflict with another people known as the Hanau momoko. I quote from the page: 

Various theories have been put forward to explain the alleged ethnic difference between the two groups. Thor Heyerdahl popularised the view that they were a South American indigenous people, who were pale skinned with red hair. Heyerdahl's Kon-Tiki expedition was designed to show that migrants from Peru could have reached Polynesia. He believed that the Hanau epe were the earliest inhabitants of the island; they created its unique monuments, which resemble similar sculptures found in the Americas, but were eventually killed off by either the Polynesians or a later wave of migrants from the Northwest coast of America.

Thor Heyerdahl was a Norwegian adventurer, ethnographer and author, know for conducting experimental voyages to test hypotheses about ancient human migrations and cultural diffusion using replica primitive watercraft.

Here’s how Wikipedia introduces him: 

Heyerdahl is notable for his Kon-Tiki expedition in 1947, in which he drifted 8,000 km (5,000 mi) across the Pacific Ocean in a primitive hand-built raft from South America to the Tuamotu Islands. The expedition was supposed to demonstrate that the legendary sun-worshiping red-haired, bearded, and white-skinned "Tiki people" from South America drifted and colonized Polynesia first, before actual Polynesian peoples. His hyperdiffusionist ideas on ancient cultures had been widely rejected by the scientific community, even before the expedition.

However, Grokipedia adds: 

Although Heyerdahl's specific diffusionist theories faced significant academic rejection for lacking corroborative genetic, linguistic, and archaeological consensus—often prioritizing independent invention narratives—his hands-on replications provided causal evidence of navigational capabilities that later findings, like transpacific crop transfers, have partially vindicated.

We’ll get back to this later.

But why Heyerdahl posited the existence of South American indigenous people with red hair? 

One reason are the mummies of Peru and Chile we have seen in this article, but we have to keep in mind that, as of now, we don’t know whether these individuals were really red-haired or not.

Another reason are the legends of red-haired and fair-skinned mythological beings in New Zealand and the uru-kehu, that we have seen in this article.

One more reason are accounts of voyagers and explorers describing red-haired people in Polynesia, as you can read in Heyerdahl’s book American Indians in the Pacific (1952), particularly in Part IV (The Complexity of Polynesians Origin). 

Clealry, in order to be sure Heyerdahl correctly translated and copied all these citations, they should be checked in their original versions. 

I copy here some of these citations.

Page 194: “A very beautiful native sat near Doña Isabel, with such red hair that Doña Isabel wished to cut off a few locks; but seeing that the native did not like it she desisted, not wishing to make her angry.” (Santa Cristina Island - Tahuata)

Page 195: “Five natives came in a canoe, the middle one vigorously bailing the water out of the vessel. His red hair came down to the waist. He was white as regards colour, beautifully shaped, the face aquiline and handsome, rather freckled and rosy, the eyes black and gracious, the forehead and eyebrows good, the nose, mouth, and lips well proportioned, with the teeth well ordered and white.” (Peregrina Island)

(both citations from The Voyages of Pedro Fernandez de Quiros)

Page 197: “… Forster (1778, p. 229) speaks of a native Tahitian who had "perfectly red hair, a fairer complexion than the rest, and was sprinkled all over with freckles". (Tahiti)

According to modern genetics, Polynesians come from two groups: Austronesians from South-East Asia and Taiwan, and Melanesians (especially Papuans).  

These “European-looking” indigenous are explained with: normal inner variation of Polynesian people, mixing between Austroneasian and Melanesian groups, independent evolution of traits such as fair skin and hair, and (obviously) subjective interpretation by European explorers.

As we have seen, both Wikipedia and Grokipedia wrote that Heyerdahl’s ideas have been rejected by the scientific community, but… it turned out he was right about contacts between South America and Polynesia, as you can read in the 2020 study Native American gene flow into Polynesia predating Easter Island settlement, by Ioannidis and colleagues, and in the article from the National Geographic DNA reveals Native American presence in Polynesia centuries before Europeans arrived. 

I won’t get into this matter, because it falls outise the topic of this post, but I want to end with this quote from Grokipedia, which, in my opinion, gives you food for thought. 

Particularly in the context of post-colonial shifts, Heyerdahl viewed the intensified rejection of diffusionism as entangled with decolonization agendas that privileged autochthonous origins to bolster indigenous self-determination, even at the expense of causal realism in migration dynamics. Mainstream institutions, exhibiting systemic preferences for narratives aligning with political sensitivities, have critiqued diffusionist claims—including his—as undermining local agency, yet Heyerdahl countered that such politicization obscured the advanced navigational prowess of ancient non-Western societies, as empirically shown through reed boat replicas navigating from Africa to the Americas in 1969 and 1970. In interviews, he underscored pursuing unvarnished truth over diplomatic consensus, warning that deference to orthodoxy stifled inquiry into humanity's interconnected prehistoric seafaring heritage.

Red Hair in Art: Thomas Cooper Gotch

Thomas Cooper Gotch (1854–1931) was an English painter and book illustrator loosely associated with the Pre-Raphaelite movement; he was the brother of John Alfred Gotch, the architect.

Gotch studied art in London and Antwerp before he married and studied in Paris with his wife, Caroline, a fellow artist. Returning to Britain, they settled into the Newlyn art colony in Cornwall. He first made paintings of natural, pastoral settings before immersing himself in the romantic, Pre-Raphaelite romantic style for which he is best known. His daughter Phyllis was often a model for the colourful depictions of young girls.

His works have been exhibited at the Royal Academy, Royal College of Art and the Paris Salon.

Self-portrait

The Heir to All Ages

Portrait of a Redhead

The Mother Enthroned

My Crown and My Sceptre

The Child Enthroned

Alleluia

A Pageant of Childhood

The Dancing Lesson

Red Hair in Art: Frank Dicksee

Sir Francis Bernard Dicksee (27 November 1853 – 17 October 1928) was an English Victorian painter and illustrator, best known for his pictures of dramatic literary, historical, and legendary scenes. He also was a noted painter of portraits of fashionable women, which helped to bring him success in his own time.

His father Thomas and his sister MArgaret were painters as well.

Red hair is featured in many of his paintings.

A Knight Being Crowned

Harmony

Chivalry

The Two Crowns

La belle dame sans merci

Passion

Stella

The Ideal or In Quest of Truth

Startled

Yseult

Red Hair in Art: Ferdinand Hodler

Ferdinand Hodler (March 14, 1853 – May 19, 1918) was a Swiss painter. He is one of the best-known Swiss painters of the nineteenth century. His early works were portraits, landscapes, and genre paintings in a realistic style. Later, he adopted a personal form of Symbolism which he called "parallelism".

Here are some of his painting featuring redheads.

Portrait of an Unknown

Portrait of Madame Loup

Spring

Spring

Head of a Red-haired Woman

Portrait of an Unknown Woman from Wien

Abendruhe

Portrait of James Vibert

Portrait of James Vibert

Portrait eines lesenden Mannes

Die Empfindung

The Dream. Cover for the novel Die Mittagsgöttin

Is red hair the result of sexual selection?

As we have seen in a previous post, in the study by Rosalind Harding and colleagues Evidence for Variable Selective Pressures at MC1R (2000) the authors argued that MC1R gene didn’t show any selective pressure.

The study by Peter Frost, published in 2006, European hair and eye color: a case of frequency-dependent sexual selection?  is a sort of reply to Harding’s paper. 

Frost writes that, without any selection, the current level of hair-colour diversity would have taken 850,000 years to develop, but modern humans have been in Europe for approximately 35,000 years according to Out of Africa II (for which I refer you to the final part of the post I linked above). So, Frost argues that there was indeed a selection: a sexual selection, which, however, acted primarily on women.

He proposes the concept of frequency-dependent sexual selection, according to which much rarer traits are more attractive and desirable and have a reproductive advantage as long as they remain rare. 

This process was stronger during the Upper Paleolithic and the last glacial period, when many men died or were absent for long periods due to long-distance hunting and extreme environmental conditions. This would have created fewer available men, less polygyny and a greater difficulty for women in finding a stable partner. In this situation, women had to compete for male partners, thus increasing the sexual selection’s pressure at more conspicuous feminine traits such as hair, eyes and skin pigmentation. Fairer traits would become a sort of visual signal, so women with these traits had an advantage in finding a partner. 

Europe during the last glacial period

This would also explain the rapid spreading of MC1R and its many mutations. Normally, more "silent" mutations (which do not change the phenotype) accumulate in genes than visible mutations. In MC1R, however, the opposite occurs: there are numerous variants that actually change hair colour. Frost interprets this as a sign that these variants have been favoured by selection (sexual selection, in this case) and not simply tolerated. The genetic structure of MC1R seems incompatible with simple random genetic drift and instead suggests a selective pressure that favoured visible hair diversity.

On the contrary, according to Frost, in many other traditional societies the situation was the opposite: thanks to a better climate, mortality rate among men was lower and they had to compete among them for women. As a consequence, sexual selection would affect men primarily. Furthermore, due to the very strong UV radiation, environmental natural selection tended to maintain more stable pigmentations.

This theory of sexual selection seems to be supported (at least in part) by other studies cited by Frost, according to which during adulthood blond hair darkens with age more slowly in women than in men, and that in all human populations women are paler than men after puberty. 

Besides, the 2008 paper Spectrophotometric Methods for Quantifying Pigmentation in Human Hair—Influence of MC1R Genotype and Environment also supports these findings, because the authors argue that hair colour varies more in women than in men and that redheads are more frequent among women. They don’t identify the genes causing this variation, but in his study Frost writes that, according to an unpublished work by Mather and colleagues, prenatal exposure to estrogen appears to be higher in individuals with blond hair or non-brown eyes. 

Many geneticists and evolutionists consider Frost’s hypothesis interesting, but not definitively proven. The main criticisms are: difficulty in empirically demonstrating prehistoric sexual preferences, speculative reconstruction of demographic relationships, possible underestimation of genetic drift and migration and risk of “adaptationism” (each trait must have a specific selective function).

Today, it is believed that skin, eye, and hair colour are likely the result of multiple combined factors, such as sexual selection, adaptation to UV rays and vitamin D, genetic drift, migrations and demographic history.

PS: as far as the last glacial period is concerned, in July 2025 a study was published which argued that even during the coldest ice ages the Arctic remained partially open, with seasonal sea ice allowing life to survive in the harshest climates. Here’s a short article and the original study.