Henna or not henna, that is the question - 1st part

INDEX
1st part: The mummy of Asru
2nd part:
3rd part:

In the first part of my article about fair-haired mummies there is a short paragrapgh about henna, which I suggest you to read before this one.
There, I pointed out that no Egyptian source mentions henna in relation to mummification or hair dyeing, and that the only alleged Egyptian source mentioning the plant today known as Lawsonia inermis is the Ebers papyrus, but probably the plant called HNW in this papyrus is not Lawsonia.
So, basically, the use of henna in ancient Egypt is scarcely documented.
I also pointed out a thing that is usually overlooked when speaking of henna. Henna, being a natural dye, can only dye tone on tone, that is, its colour adds up to the colour of your hair. This means that if you have dark hair you will never dye it red with henna. At the very most you will get copper shades, but if you want a colour like the one of natural red hair, you need to have light-coloured hair. Also, depending on the shade of red you want, you will probably need to mix henna with darker herbs.

In this article (which will be probably split into three parts) we are going to examine three studies claiming to have identified traces of henna on the hair of Egyptian mummies and we will see that, actually, they don’t provide the necessary evidence.
After that, I will briefly talk about a French article on henna, which, in my opinion, is interesting on many levels and which can help to clarify the matter.




THE MUMMY OF ASRU (circa 700 BC)
The mummy of Asru and the two associated coffins were presented to the Manchester museum in 1825. They were the first Egyptian antiquities to enter the collection.
Their exact provenance is unknown, but probably they originated at the Egyptian capital of Thebes (modern Luxor). Inscriptions on the coffin provided the information that the owner was named Asru, her mother was Ta-du-Amen and she was a temple chantress. Her duties involved singing to accompany the sacred rituals to the god Amun.
Scientific studies revealed that Asru was 50 or 60 when she died, probably around 700 BC.
As you can see, she comes from the same city as Takabuti and is dated to the same period. 

Coffin of Asru

 

In 2003 an analysis of Asru was published: Asru, an Ancient Egyptian Temple Chantress, by Rosalie Ann David and V. Garner (we have already met David in the article about Takabuti). I’m going to quote some passages:

2.3.2. The identification of henna
Evidence of the use of henna has been found on a sample of hair attached to tissue taken from Asru's scalp. The following procedure was used to investigate this sample using several distinct stages.
Optical microscopy was used to examine the hair sample, and the optical image showed a portion with obvious red colour that was lacking in the rest of the hair, where there appeared to be no pigmentation. This posed the question whether the colour was due to the addition of a colouring agent. for example henna. or to the bleaching of a naturally coloured red hair. In either case, it appeared that the two sections of contrasting pigmentation were the result of the postmortem hair growth: the colour had been absorbed into the hair during life, and new unstained hair had grown after death. When the hair was viewed using the Bio-Rad lR Microscope/Spectrometer, the red portion had additional signals assigned to aromatic and phenolic compounds that were lacking in the non-coloured portion. […]
Application of this technique to the hair sample demonstrated the presence of terpenoid compounds including cadalin and podocarpin, known constituents of vegetation extracts such as henna. […]
The ancient Egyptians are known to have used henna in several ways. The odiferous
pink or cream-coloured flowers of the shrub (Lawsonia illermis L.) [21] may have been added to the perfume of some ointments and, for both the living and the dead, the leaves may have been used to stain the palms of hands, soles of feet, and toenails and fingernails [22].
Henna was used by the Romans to dye their hair red, and the custom is still widespread amongst women in Islamic countries today. The hair of some Egyptian mummies is also evidently dyed red, but the project on Asru's hair sample is the first time that spectrometric studies have been undertaken in order to demonstrate conclusively that the dye was henna.

Basically, organic material was found on the red-coloured portion of hair, while on the white hair grown after death (post-mortem hair growth is not unusual) there was no organic material.

Now, please note the wording. The authors write: “Application of this technique to the hair sample demonstrated the presence of terpenoid compounds including cadalin and podocarpin, known constituents of vegetation extracts such as henna.”
They are not saying that these compunds are exclusive of henna. On the contrary, they are saying these compounds can be found in several vegetation extracts and henna is one of them. Besides, they don’t list all the terpenoid compounds they found: why?

But let’s have a look at the compounds they mention, cadalin and podocarpin.

Cadalin
For starters, the real name of cadalin is cadelene and is found in essential oils of many higher plants. Here’s the list of the plants that contain cadalene and, as you can verify by yourselves, Lawsonia inermis is not listed.
Cadalene has been found is some human remains from Egypt and has been linked to the Atlas cedar, a species of coniferous tree (see here and here). It has also been found on ancient Egyptian pleated textiles along with other elements, suggesting a conifer oil, probably juniper oil.
Interestinlgy, cadalene is found in the essential oil of Lawsonia inermis, but a compound identified in the essential oil cannot automatically be considered a marker of the dyeing paste. Besides, compositions of Lawsonia inermis essential oil may vary.
In any case, the presence of cadalene may be explained with a precursor present in the plant which transformed into cadalene during heating or pyrolysis and, as a matter of fact, the hair sample from Asru did undergo pyrolysis, as the authors explain in the study: 

A minute sample of the coloured hair (1-2 mg) was investigated by MSSV-GC-MS (MicroScale Sealed Vessel pyrolysis coupled to high resolution Gas Chromatography Mass Spectrometry). In this technique that was developed for the investigation of organic residues in geological materials, the sample is sealed in a silica tube and heated at 300 C [300 °C = 572 °F] for twenty-four hours; any polymeric material undergoes thermal scission to form volatile organic compounds that are released as the tube is opened and transferred in a stream of helium and cryofocussed using liquid nitrogen so that they can be analysed by conventional GC-MS.

(For more information about GC-MS see here).
So, cadalene can be a transformation product of terpene precursors during these thermal processes. To interpret this correctly, one would need to know the behavior of the various henna components under the same pyrolysis conditions.

 

Podocarpin
Apparently, a thing called podocarpin doesn’t exist.
There is the podocarpic acid and the podocarpane, both isolated from species like Podocarpus totara and Dacrycarpus dacrydioides. Podocarpus is a large genus of conifers, the most numerous and widely distributed of the family Podocarpaceae. So, no Lawsonia inermis.
I only found two plants with both cadalene and podocarpane.
One is the Taiwania cryptomerioides, a large coniferous tree in the cypress family Cupressaceae (here are its compounds), and, as you can infer from its name, the genus is named after Taiwan and the plant grows in Asia.
The other is the savin juniper (Juniperus sabina), which is native to the mountains of central and southern Europe and western and central Asia, typically growing at elevations of 1,000–3,300 metres (3,300–10,800 feet, here are its compounds).
None of them is a hair dye. 

Reconstructed head of Asru by Richard Neave (source)

 

 

And the lawsone?
Some of you may have noticed something conspicuous by its absence: the lawsone. Lawsone, also known as hennotannic acid, is a red-orange dye present in the leaves of Lawsonia inermis, as well as in the common walnut and water hyacinth. So, one would expect to find traces of it in hair dyed with henna.
However, the absence of lawsone in an ancient find is not a definitive proof that henna was not used. Over the millennia, the compound could have degraded, or it might be present in quantities below the detection threshold. For instance, in this 2024 study focused on identifying natural dyes in medieval Islamic manuscripts, the presence of lawsone was considered reliable in only four of the samples. This demonstrates that degradation can indeed make it difficult to identify henna in archaeological finds, even when sophisticated analytical techniques are employed.
In any case, the authors of the study on Asru should have explained whether they looked for lawsone and, if so, provided possible reasons why they did not find it.

 

Why citing unreliable sources?
If you read again the passage from the study I have quoted in the beginning, you will see there are two footnotes, 21 and 22: 21 refers to 1962 book Ancient Egyptian Materials and Industries, by A. Lucas, and 22 to the 1989 book An Ancient Egyptian Herbal, by Lise Manniche. 
Well, if you search both of them for the word “henna”, you will see a stream of “it is suggested… possibly… probably…”. I’m going to give some example, but you can see the rest by yourselves.

From Ancient Egyptian Materials and Industries (my bold type).

Page 87: In connexion with henna it may be mentioned that the leaves were possibly used in ancient Egypt, much as they are to-day, in the form of a paste to colour the palms of the hands, the soles of the feet, the nails and the hair. Thus, the Romans certainly employed henna, an Egyptian shrub, for colouring the hair, and probably therefore the Egyptians also, and Elliot Smith describes the hair of the mummy of Henttawi (Eighteenth Dynasty) as being dyed a brilliant reddish colour, which he suggests was done with henna.
Page 234: The materials mentioned by Herodotus and Diodorus as having been employed in the mummification process, as also certain materials stated by Pliny to have been used by the Egyptians for embalming and those found in recent times in connexion with mummies, taking them in alphabetical order, are: beeswax, bitumen, cassia, cedar oil, cedri succus, cedrium, cinnamon, gum, henna, juniper berries, natron, ointments, onions, palm wine, resins (including gum-resins and balsams), salt, sawdust, spices and wood tar or wood pitch, all of which may now be considered.

This last passage may give the idea that, in previous pages of the book, henna was mentioned in relation to the works by either Herodotus or Diodorus or Pliny, but that’s not true. None of these authors mentions henna in their works about Egyptian mummification and, as I wrote in this article I have already mentioned, no ancient source whatsoever mentions henna in relation to mummification.


From An Ancient Egyptian Herbal (my bold type).

Page 37: Red dye was extracted from the roots of Alkanna tinctoria, Rubia tinctorum (madder) and the flowers of Carthamus tinctorius. lt is possible that henna was used as well.
Page 47: Sorne Egyptians appear to have dyed their fingernails, but the nature of the red colour used is unknown. lt may have been henna.
Page 114: The leaves have been found in tombs of the Late Period and of Ptolemaic date, but the actual use of the plant as a colouring agent is somewhat disputed.
Although there is evidence that the Egyptians coloured their finger-nails, there is no proof that they used henna to do so. Sorne mummies were found to have
their hair dyed red, and henna may have been used for this.

So, you see how it works. Authors cite books to support their thesis, but when you verify these sources, you find out they don’t support said thesis. 

What is lacking in this study
The authors write: 

This finding was the starting point for an extended project at Manchester which has examined samples from other sources 123], with the aims of detecting the presence of henna in ancient Egyptian hair, using MSSV-GC-MS and comparing ancient and modern dyed samples to ascertain the differences between them.

If they compared ancient and modern dyed samples, where are the figures showing the results of the comparison? The only figure in this study refers to the palm wine used in the mummification process.
Basically, what is missing is the evidence of the following passages.
First of all, they needed to prepare authentic Lawsonia inermis leaves, a dyeing paste obtained from macerated leaves, and modern hair dyed with this paste, possibly including both untreated hair and hair treated with other plant-based dyes.
Then, they needed to subject the reference samples to the same MSSV-GC-MS treatment used for Asru’s hair, identifying which compounds are actually produced following heating to 300 °C.
Then, they needed to compare the profile of Asru’s hair with the experimental profiles, verifying the compounds through retention times, mass spectra, and, where possible, authentic standards.
Finally they needed to determine whether the observed profile effectively distinguishes henna from other plant-based dyes and from naturally red hair.

 

Egyptian mummies and modern science
In the 2008 book by Rosalie David Egyptian mummies and modern science we find the plate below with the following caption:

Visible light and infrared images of a hair from the mummy of Asru. Top left: hair (colourless) with darker coating. Bottom left: Infrared image over entire infrared spectrum, showing organic material unevenly coating the hair (red colour indicates highest infrared activity). Top right: infrared image over the range 1,600–1,700 cm -1 only, indicative of the concentration of C=O on the hair. Bottom right: Anticipated infrared absorbtion area if hair was coated with plant oils.

However, this plate is not a proof of henna, because the caption only mentions “organic material” and “plant oils”, and the red and yellow colours indicate a higher activity or infrared answer.


On page 145 of the book we read: 

Shown in Plate XVI are optical and IR images of a hair from the twentyfifth Dynasty mummy of Asru, a chantress from the Temple of Amun at Karnak. The lumpy nature of the optical picture, echoed by the average IR
picture, is considered to be due to a paste of oils and dyes applied to the scalp and hair. This theory is borne out by the uneven orange colouring on the hair, suggestive of henna.
The active ingredient in henna is hydoxynaphthoquinone, a light yellow crystalline compound when pure. In henna, it complexes and oxidises to produce the characteristic orange colour. The uneven coating on the hair suggests it was applied after death as part of the ritual preparation process rather than as a cosmetic during life, an identical interpretation to that obtained from another mummy (Plate XV). Mapping the 1,600 to 1,700- cm−1 C=O and aromatic carbon region produces an image with bright spots roughly corresponding to the orange areas in the optical picture, not inconsistent with the application of the aromatic oil/henna mix.

As usual, we have the typical wording “suggestive of henna” and “not inconsistent with henna mix”, but zero scientific evidence.
Besides, here they say “The uneven coating on the hair suggests it was applied after death as part of the ritual preparation process rather than as a cosmetic during life”, while in the 2003 study they wrote “The colour had been absorbed into the hair during life, and new unstained hair had grown after death.”

Just to make a comparison, this is a study about red colourants in archaeological textiles from pharaonic Egypt, and if you scroll it you will see several tables and figures with the results of the analyses.

Basically, the authors of the study on Asru are asking us to take their word for it, but this is science, not religion.
Just to be clear, I’m not saying henna was not found on the hair of this mummy. I’m only saying the study by David and Garner doesn’t provide the necessary evidence.

My idea is that cadalene, podocarpic acid/podocarpane and the red colour on Asru’s white hair might come from three different sources. For example, it is possible that one or more substances used during mummification were put on the mummy’s white hair (juniper resin was known for having anti-bacterial and insecticidal properties) and, over the millennia, this substance or substances coloured the white hair red.
Or, it is also possible that Asru used hair products, maybe a “gel” like the one of Takabuti, or something to avoid lice, and this product gave her hair a reddish hue after death (the Ebers Papyrus describes a remedy for lice prepared from date flour).

In the next part we will examine two more studies.

One more red-haired mummy from Egypt: Takabuti

Takabuti was an ancient Egyptian woman who lived in Thebes (modern Luxor) around 660 BC and died between the ages of twenty and thirty. Her mummy and coffin are in the Ulster Museum in Belfast, Northern Ireland. The coffin was opened and the mummy unrolled on 27 January 1835, and the leading Egyptologist Edward Hincks deciphered the hieroglyphs, revealing that she was a noblewoman and the mistress of a great house.
Takabuti was killed by an axe, probably while she was attempting to escape from her assailant. The wound was found in her upper left shoulder, and was more than likely instantaneously fatal. It was also found that Takabuti possessed two very rare mutations: an extra tooth and an extra vertebra.

The coffin and mummy and Takabuti

In 2020, the University of Manchester's KNH Centre analysed Takabuti's mitochondrial DNA (mtDNA) and determined it was H4a1. This is a European haplogroup, and in the archaeological record it has previously been reported in Guanche remains from the Canary Islands, in Bell Beaker and Únětice remains from Germany and in an individual from early Bronze Age Bulgaria. The oldest reported H4a1 samples are from Cardial Neolithic contexts in Spain and Portugal, dating from c. 5300 BC. Today, this subclade is relatively rare in modern populations, while haplogroup H is the most common mtDNA clade in Europe. As you can read here, H4 “is often found in the Iberian Peninsula, Britain and Ireland at levels between 1 and 5% of the population. It is associated with Neolithic migrations. H4 and H13, along with H2 account for 42% of the hg H lineages in Egypt.”
Interestingly, haplogroup H has been observed among ancient Egyptian mummies excavated at the Abusir el-Meleq archaeological site in Middle Egypt, which date from the pre-Ptolemaic/late New Kingdom and Ptolemaic periods. Additionally, haplogroup H has been found among specimens at the mainland cemetery in Kulubnarti, Sudan, which date from the Early Christian period (AD 550–800).


THE MYSTERY OF TAKABUTI'S HAIR COLOUR
As for Takabuti’s hair colour, the Wikipedia page I linked at the beginning of the article states that the mummy’s hair is auburn, although now (as you can see in the photos below) the colour is more of a yellow-orange.

 

Source

 

However (as you can read here), when the coffin was first opened, the hair was reported to be auburn and a strand was taken and put into a box. This strand (photo below) is said to be still auburn. In the photo, because of the glass, the colour is not very clear, but it looks indeed like a dark red/auburn. The change in colour of the mummy’s hair is attributed to the long exposure to the air since the time of the unwrapping. 

 

Now, the plot thickens and we will see the same pattern we already saw in the five-part article about fair-haired mummies.


First of all, in 2011 a study about Takabuti’s (and other mummies’) hair was published: Ancient Egyptian hair gel: new insight into ancient Egyptian mummification procedures through chemical analysis,  by Natalie C. McCreesh, Andrew P. Gize and Rosalie Ann David.
Hair was analysed with some of the techniques we saw here, such as gas cromatography-mass spectrometry and microscopy, and researchers found out that, in the case of Takabuti, a fatty substance was used to coat the hair, which was interpreted as a product that was used in life to style the hair (similar to a modern day ‘hair gel’ or fixative). It was made up of camphor, tetradecanoic acid, phthalate ester, hexadecanoic acid, octadecanoic acid, dehydroabietic acid, methyl ester, phthalate ester, cholesterol and silicone grease.
No analysis was performed to determine the natural hair colour.

 

In the 2016 book Women in Antiquity: Real Women Across the Ancient World,  
Rosalie David (one of the authors of the 2011 study) writes (page 190): 

Another analytical study was carried out on hair taken from the mummy of Takabuti, a high-
ranking woman who lived at Thebes, c.660 bce (the mummy is now in the Ulster Museum, Belfast (UK)). This demonstrated that the reddish-blonde colour was a result of degradation, not natural pigment or the use of dye. It was also possible to show that the woman’s elaborate hairstyle, which incorporated artificial curls, had been coated with a hair-gel composed of fat mixed with camphor; 63 similar styling products have been found on mummies elsewhere. 64

As you can see, there are two footnotes, 63 and 64, but none of them clarify which study demonstrated that the reddish-blonde colour was a result of degradation (and degradation of what? Keratin or melanin?). The footnote 63 says “Personal communication, N. McCreesh”, while the 64 refers to the 2011 study.
Now, in 2009 Natalie McCreesh published the doctoral thesis Ritual anointing: analyses of hair and coffin coatings in ancient Egypt, of which only the abstract is available. Here we read: 

Another significant finding was that the red coloured hair often seen on mummified remains was caused by the embalming material and degradation of the hair, not by henna dye as has been previously suggested.

This thesis is also mentioned in the book Être vieux en Égypte aux époques lagide et impériale. On page 199 we read (I translate from French): 

The use of henna has often been proposed to explain the reddish color observed on the nails and hair of certain mummies. However, this hypothesis has been challenged in favor of a coloration attributed to embalming products. McCreesh recently conducted research on the ritual anointing of the body and funerary equipment as part of her thesis. Her results show that the red coloration of the hair on the mummies she studied does not stem from the use of henna. The oxidation of products applied during the treatment of the deceased’s body—specifically incense—could be the cause. 

At the end of this paragraph there is the footnote 1004, where the author cites McCreesh’s thesis and writes: “I warmly thank Dr. N. McCreesh for granting me access to her as-yet unpublished work, as well as for the other references she kindly provided.”
So, basically, the work demonstrating that the red hair often seen in mummies COULD be due to the oxidation of products applied during mummification is not available….

 

In 2021, the newsletter of the Ulster Archaeological Society states about Takabuti (page 11, April Lecture by Duncan Berryman): “Analysis of her hair showed that it was naturally auburn”, but unfortunately the author doesn’t say which analysis he is referring to.

Always in 2021, Rosalie David wrote one more book, The Life and Time of Takabuti in Ancient Egypt. I quote from page 58:  

Also noted during the unwrapping of the mummy was the large number of beetles that had penetrated the wrappings, attacking the body, especially the head, and more so on the sides. […] The mummy was fumigated with Phosphine gas in 1987 for conservation. […] The colour of ancient hair is often affected by degradation and mummification procedures, and cannot be presumed to represent its original colour.

Both hair from the mummy and the auburn strand taken in 1835 were analysed with light microscopy and environmental scanning electron microscopy (ESEM), and with gas cromatography-mass spectrometry (GC-MS).
On page 61 we read: “Pigment retained at the root of the hair indicated the original hair colour to be dark. Cross sections of the hair indicated it to be Caucasian in shape.”

What can we say about these passages?
The first thing that comes to my mind is that researchers keep repeating the usual mantra that the red colour is due to degradation without providing any evidence of that, and this is the opposite of what is called “the scientific method”. And I’m not saying that Takabuti’s hair is not degraded. I’m saying we don’t have any evidence that the auburn colour seen in 1835 was due to melanin or keratin products of degradation. Also, these researchers don’t seem to be interested in ascertain the natural colour of mummies’ hair, in spite of the many techniques available.
Secondly, on the one hand we are constantly told that we cannnot tell the real hair colour of a mummy by simply watching its hair, but on the other this researcher, after seeing Takabuti’s hair roots are “dark”, states that the original hair colour was dark.
And anyway, what does “dark” mean in this case? Because if you watch again the photo of the strand kept in the box, you’ll see it looks quite darkish. It is not a light colour.
And how come in the case of Takabuti the colour of hair roots is considered a proof of her natural hair colour, while in the case of Ramesses II the colour of his hair roots (which is red) is not a proof of his natural hair colour?
Furthermore, there are studies about hair roots getting darker post-mortem.
In 2018 A study of the intrinsic variability and the effect of environmental conditions on the formation of a postmortem root band was published and in 2023 The rate and quality of post-mortem hair root changes in relation to melanin content.
In particular, the 2018 study is about the so-called postmortem root band (PMRB), which is defined as “an opaque ellipsoidal band composed of a collection of parallel elongated air/gas spaces and is approximately 0.5 mm above the root bulb and about 2 mm below the skin surface” which can appear in the root of hairs attached to remains during decomposition. According to the study, an aqueous environment and microbial activity are essential for the formation of PMRB-like features. Clearly, the mummy of Takabuti did not come in contact with water, but since at the moment of unwrapping beetles were found, it is possible that microbes were there too. The interaction with the “hair gel” should be taken into consideration as well.
Besides, the authors write PMRBs can appear antemortem (before the death) as well.
As far as I could understand, researchers did not analyse the roots to verify the nature of the dark colour.

Lastly, in 2023 a new analysis on Takabuti was performed, published under the title Enhancing mummy ‘palaeobiographies’ through the use of
multidisciplinary techniques and approaches and, as you can see, we find Rosalie David among the authors. The mummy was examined with several techniques. I quote from the introduction: 

Here we re-examine Takabuti’s mummy to evidence the scope of combining computerised interrogation of CT imaging, an MIP (image intensifier-guided needle biopsy), coupled with analytical technologies (genomics, proteomics, light and electron microscopy, inorganic and organic analysis and radiocarbon dating) and existing Egyptological data, to extend previous understanding of her background, life events and preparation for the afterlife. We describe a toolkit for examining hard and soft tissues and define its scope, allowing not only an “osteo- biography” to be produced but also a more holistic “palaeobiography” that brings enhanced insights about an individual.

No analysis of hair colour. 

 

So, to cut a long story short, here we have a very confused and contradictory situation, but the fact remains that Takabuti’s hair has not been analysed to ascertain the natural hair colour, in spite of the mummy having been analysed twice and with the most modern techniques. And, as usual, researchers go on repeating unproven theories about degradation to explain the red hair colour.
The usual with potatoes, as we would say in Italy.😄

 

Red-haired ancient tribes: the Wusun

The Wusun were an ancient semi-nomadic steppe people mentioned in Chinese records from the 2nd century BC to the 5th century AD. They are generally believed to be an Indo-European people who spoke a language belonging to the Indo-Iranian branch.
The Wusun originally lived between the Qilian Mountains and Dunhuang (Gansu) near the Yuezhi people.

The Wusun and neighbouring polities circa 200 BC, before their westward migration

 

Around 173 BC, the Yuezhi attacked the Wusun and killed their king Nandoumi. According to the legend, Nandoumi's infant son Liejiaomi was left in the wild. He was miraculously saved from hunger being suckled by a she-wolf, and fed meat by ravens. Since this myth shares similarities with those of the Hittites, the Zhou Chinese, the Scythians, the Romans, the Goguryeo, Turks, Mongols and Dzungars, scholars have suggested that the Wusun, Sogdians, or both could represent an Indo-Aryan influence.
In 162 BC, the Yuezhi were finally defeated by the Xiongnu (a tribal confederation of nomadic peoples), after which they fled Gansu, a province in Northwestern China. After the Yuezhi retreat, the Wusun settled in Gansu, as vassals of the Xiongnu.
The Xiongnu ruler was impressed with Liejiaomi, considering him a supernatural being, and adopted the child. When the child grew up, he was appointed leader of the Wusun and a Xiongnu general. Thanks to his leadership, the Wusun took over the Ili Valley. After settling in the Ili Valley, the Wusun became so strong that the Han were compelled to win their friendship in alliance. Liejiaomi finally agreed to the alliance, sending tributary horses and accepting Princess Xijun as his wife. Since Liejiaomi was already an old man, Xijun was married to his successor Cenzou.

Xijun wrote a famous poem, the Beichouge, in which she complains about her exile in the land of the "barbarians":

My family sent me off to be married on the other side of heaven. They sent me a long way to a strange land, to the king of Wusun. A domed lodging is my dwelling place with walls of felt. Meat is my food, with fermented milk as the sauce. I live with constant thoughts of my home, my heart is full of sorrow. I wish I were a golden swan, returning to my home country.

Later location of the Wusun after their migration to the Ili Valley at the time of Princess Xijun

Around 80 BC, the Wusun were attacked by the Xiongnu, who inflicted a devastating defeat upon them. In 72 BC, Kunmi, chief of the Wusun, requested assistance from the Han against the Xiongnu. After their crushing victory against the latter, the Wusun increased in strength, achieving significant influence over the city-states of the Tarim Basin.
In the 5th century AD, the Wusun were pressured by the Rouran and may have migrated to the Pamir Mountains. They are last mentioned in Chinese historical sources in 436 AD, when a Chinese envoy was sent to their country and the Wusun reciprocated.


Wusun’s physical appearance

The Book of Han and Shiji do not make any special note of the physical appearance of the Wusun. The first description of the Wusun's physical appearance is found in a Western Han dynasty book of divination, the Forest of Changes by Jiaoshi Yilin, which describes the women of the Wusun as 

"with deep eyesockets, dark, ugly: their preferences are different, past their prime [still] without spouse."

A later 7th century commentary to the Book of Han by Yan Shigu says:

Among the barbarians (戎; Róng) in the Western Regions, the look of the Wusun is the most unusual. The present barbarians (胡人; húrén) who have green eyes and red hair, and look like macaque monkeys, are the offspring of this people.

In Chinese: 烏孫於西域諸戎其形最異。今之胡人青眼、赤須，狀類獼猴者，本其種也。

A Chinese depiction of the Wusun, from Gujin Tushu Jicheng, 18th century.

 

The above English translation is the one we find on Wikipedia, but, apparently, it is not entirely correct, because in the original Chinese the author is not talking about the hair on the head, but about the beard. Also, the term referring to eye colour does not mean only green, but it can be used for all light-coloured eyes (blue/green).
Besides, it is important to understand that here Yan Shigu is not describing the Wusun, but some groups belonging to the peoples called “barbarians” by the Chinese of his time. These groups, according to the author, are the offspring of the Wusun.
So, a better translation would be 

Among the barbarians (戎; Róng) in the Western Regions, the look of the Wusun is the most unusual. Those among the present barbarians (胡人; húrén) who have light-coloured eyes and a red beard, and look like macaque monkeys, are the offspring of this people.

So we have:
青眼、赤須
qīng yǎn, chì xū

where:
• 青 (qīng) = blue, light blue, green
• 眼 (yǎn) = eye, eyes
• 赤 (chi) = red, reddish
• 須 (xū) = beard, moustaches, facial hair

While the red hair on the head would be 赤髮= chì fà.

As for the comparison with the macaque monkey, it is clearly a reference to the Caucasoid peoples being more hairy than peoples from other races. 

Average male body hair in indigenous populations

 

Connection with the Yenisei Kyrgyz
In this previous article we talked about another ancient tribe of central Asia described as red-haired in Chinese records, the Yenisei Kyrgyz.
According to Russian historian Nikolai Aristov (1847 - 1903), a part of the ancient Kyrgyz had remained in the Yenisei, while another migrated southwards. This group was later called Wusun in Chinese records (more information here). Modern archaeological research, however, highlights the close relationship between Wusun and Yenisei Kyrgyz, but scholars don’t go as far as to say they were the same people.
In 2018, a DNA analysis was performed on the remains of four Wusun individuals. The only Y-DNA found was R1a1a-Z93 and as we have seen in the article about the Kyrgyz, the R1a haplogroup is common in Eurasia, extending from Scandinavia and Central Europe to Central Asia, Siberia and South Asia, and the question of the origins of R1a1a is relevant to the ongoing debate concerning the urheimat of the Proto-Indo-European people.

Haplogroup R1a distribution

 

As for the mtDNA (passed from mother to children), four haplogroups have been found: C4a1, HV6, J1c5a and U5b2c.
The Wusun were suggested to be descended from Western Steppe Herders (at a proportion of 47%), who admixed with peoples related to the Bactria–Margiana Archaeological Complex (32%) and Late Bronze Age herders (Ancient North-East Asians, 21%). 

 

More articles about ancient red-haired tribes:
the Budini 
the Rutuli 
the Ngāti Hotu 
the island of Toprabane 
the Schytians 
Easter Island 
Genghis Khan 
Various tribes  

Jesus had red hair, now we have proof of it. Or do we?

In 2017, the authors of the study about the DNA analysis of Napoleon Bonaparte published an analysis of a small fragment of hair found on the Shroud of Turin, a fragment of hair which, apparently, was reddish-blond.
The study is Scanning Electron Microscopic Characterization and Elemental Analysis of One Hair Located on the Face of the Turin Shroud, by Gérard Lucotte e Thierry Thomasset. 
Now, obviously, we all know that debates about the authenticity of the Shroud are still ongoing, and we don’t know who this fragment of hair came from. However, since it is probably reddish, and (as far as I could understand) this is the only human hair found on the Shroud, I thought you might be interested.
Besides, if you follow this blog, you know that there are many paintings depicting Jesus (and often the Virgin Mary as well) with red hair, and you must admit this is quite curious: why choosing the rarest hair colour on earth? Did painters have no trouble finding sitters with this hair colour?

The hair fragment (called b1) is 14 × 9 μ (micrometers) and was found in 1978 between the eyebrows of the face, in a red spot deemed to be a blood spot (although others claim it was found in 1988). 

On the top of the image, the area where the fragment was found

The authors call it “down hair”, that is, a normal body hair, because they found it to be thinnest than a facial hair or a hair from the head or from the eyebrows. They write it is ten times thinner than a beard or an eyebrow hair.
They analysed it with some of techniques we saw in this article, namely the scanning electron microscope (SEM) and the energy-dispersive X-ray spectroscopy (EDX).

Under the electron microscope, the authors observed the cuticle scales, that is, the overlapping structures that form the outer coating of the hair.
In the fragment, the distance between successive rows of scales is approximately 2 μm, but according to the authors' comparison, this characteristic more closely resembles a strand of beard than their sample. However, since the diameter is so thin, they conclude the fragment is a down hair.

Through EDX analysis, carbon, oxygen, a small amount of sulfur and a small amount of calcium were found.
Carbon and oxygen are consistent with the organic component of the hair. Sulfur, on the other hand, is interpreted by the authors as a component of keratin, the primary structural protein in hair. Notably, cysteine molecules can form disulfide bridges with one another and these bonds contribute to the three-dimensional structure and strength of keratin. It is precisely this characteristic that makes hair relatively strong.
The authors note that the sulfur peak in this fragment is quite low (3%) compared to that observed in the modern human hairs used for comparison, therefore they argue the hair's sulfur content may have decreased during the preservation process.
As for the small calcium peak, the authors state that it likely corresponds to a residual calcium deposit on the fragment's surface, rather than the fundamental composition of the hair itself.
They also found copper at both ends of the fragment, attributing this to the fact that the hair was likely cut with a copper or bronze blade.

As for the colour, the authors identify 25 melanosomes on the surface of the fragment: 8 classified as MS1, associated with eumelanin, and 17 as MS2, associated with phaeomelanin. The ratio is therefore approximately 1:2, so they conclude that the fragment was reddish-blond.
According to the studies by Ito and Wakamatsu (like this one), in blond hair the ratio eumelanin/phaeomelanin is 5:1, while for red hair is about 0,8:1, so the colour of the fragment could have really been some sort of reddish-blond, strawberry blond.
If this was a body hair, it is possible the person it belonged to was a redhead, since usually redheads have reddish-blond body hairs. 

 

Schematic representation of the melanosome distributions in the fragment; 1 and 2 numbers concern M1 and M2 melanosome types, respectively

 

Napoleon had red hair, now we have proof of it. Or do we?

On our partner blog Famous Redheads in History we have this post about Napoleon Bonaparte (1769-1821). In it, we linked several sources describing him as having reddish or chestnut hair. Here are a couple of examples:

- "The hair on his head was not black, but dark reddish-blond; his eyebrows and eyelashes were much darker than the colour of his hair, and his blue eyes, set off by the almost black lashes, gave him a most pleasing expression."
"His very fine chestnut hair, which, until the time of the expedition to Egypt, he had worn long, cut square and covering his ears, was clipped short."

The post also features the photos of two locks of hair.
Red hair is also visible in some portraits, especially (but not only) portraits of Napoleon as a young man. 

Lock of hair from 1817 (source)

 

Now, apparently, we have more solid evidence.
In July 2021 a study was published with the genomic analysis of some phenotypic traits of Napoleon: Napoleon the First, a Corsican with Pale Skin, Clear Eyes and Red Hair: DNA Evidence for these Phenotypic Traits, by Gérard Lucotte, Jacques Macé and Thierry Thomasset.
DNA was extracted from an authenticated lock of hair from 1811.
For the skin colour, the authors studied the F374L polymorphism of the membrane associated transporter protein (MATP) gene (also known as solute carrier family 45 member 2, SLC45A2) and found out Napoleon was homozygous FF for this polymorphism, so he must have had pale skin.
(A cell is said to be homozygous for a particular gene when identical alleles of the gene are present on both homologous chromosomes.)

Bonaparte on the Arcole Bridge on 17 November 1796,  by Antoine-Jean Gros, 1801

 

For eye colour, authors studied the rs12913832 polymorphism near the OCA2 gene. Napoleon resulted to be homozygous CC, so he most likely had blue eyes.
(Please note that on the SNPedia page I’ve linked you’ll find GG instead of CC, but it’s the same thing.)
For hair colour, the whole MC1R gene was sequenced and authors found out Napoleon was heterozygous CG for the rs1805009 polymorphism, corresponding to the D294H mutation. As we have seen in this article, the D294H mutation is considered one of the “strong” (high penetrance) mutations for red hair, but (and authors don’t highlight that) since Napoleon was heterozygous and not homozygous for it, he had a lower chance of red hair than someone with a homozygous mutation. 

Authors wrote they sequenced the whole MC1R gene, but unfortunately they don’t tell us if Napoleon also had low penetrance mutations, which can raise the chances of having red hair in case you have heterozygous mutations. Nor they tell us about Napoleon’s other polymorphisms influencing hair colour. We have to keep in mind that many phenotypic traits are polygenic, which means they are the result of the interaction of multiple genes, even when a single factor (like a certain mutation) may give that trait a particular direction. 

First Consul Bonaparte, by Antoine-Jean Gros (detail), c. 1802

 

Lastly, they analysed Napoleon’s lock of hair with the scanning electron microscope (which we have mentioned here) to study melanosomes. As we saw in the article I have just linked, melanosomes containig eumelanin are ellipsoidal, while malanosomes containing phaeomelanin are spherical. They write: “As the surface area of the piece is more covered by pheomelanin melanosomes than by the eumelanine melanosomes, the colour of the corresponding hair is effectively yellow-brown, so red.”
Unfortunately, they didn’t use the Raman spectroscopy, which can measure the amounts of melanins, thus giving a more precise answer as far as hair colour is concerned.

In any case, if we put all together, I guess we can safely say Napoleon had at least reddish hair. Probably in his youth the red was lighter and darkened in his old age, although in the drawing below, made in Saint Helena, his hair is still red.
We know very well that hair tends to darken in adulthood, and in the case of Napoleon that would be also consistent with his heterozygous mutation. Besides, he suffered from several health issues and this may have influenced his hair colour too.

However, even after this study, both Wikipedia and Grokipedia, in the paragraphs about Napoleon’s appearance, write he had black hair and dark complexion, quoting the same description. Basically, among the many descriptions of Napoleon, they both chose the same, and they both chose the one depicting him with dark colours! What a coincidence… Since he was of Italian origins, he must have had black hair, black eyes and a dark complexion. At least Grokipedia denied the myth of his shortness.
All in all, more red hair erased from history, but not from this blog!

 

Napoleon in Saint Helena, from the book Napoléon à Sainte-Hélène (2018) by C. E. Vial 

About fair-haired mummies - 5th part

Index
1st part: henna, natron and Ramesses II 
2nd part: bog bodies and photo-oxidation 
3rd part: Tarim and Paracas mummies 
4th part: Egypt and Sudan 
5th part: techniques for tracing the original colour of archaeological hair, hypotheses about the origin of red/blond archaeological hair

This 5th and last part is going to be a bit more technical than the previous ones, but I think it is important that we have a clear picture of the situation. That is, it is important we see that techniques for hair colour analysis do exist, while, on the contrary, we don’t have any evidence supporting the various hypotheses about the origin of red/blond archaeological hair. 

 

TECHNIQUES FOR TRACING THE ORIGINAL COLOUR OF ARCHAEOLOGICAL HAIR

As you will see, only some of these techniques allow us to directly measure the amount of eumelanin and phaeomelanin in hair. The others too are important, however, because they allow us to determine if the hair contains dyes or other pigments, traces of minerals present in the soil or burial, degradation products, etc. Consequently, using three or four of these techniques in combination can achieve good results, although, obviously, we can't always be sure of a definitive answer as far as archaeological hair is concerned.
Furthermore, these techniques are either non-destructive or minimally destructive, which means they can also be used on important finds such as pharaonic mummies.

Without sampling

Raman spectroscopy
As of now, Raman spectroscopy is one of the few tools to detect and distinguish melanins, as you can read in these three studies by Ismael Galvàn and colleagues: Raman spectroscopy as a non-invasive technique for the quantification of melanins in feathers and hairs, Dispersive Raman spectroscopy allows the identification and quantification of melanin types and Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy. 
The laser interacts with the hair molecules and produces a spectrum containing information on keratin, disulfide bonds and even pigments. Experimentally, it has been demonstrated that Raman spectra can correlate with the amount of eumelanin and phaeomelanin present in hair.
Since it is non destructive, Raman has already been used for various analyses on historical hair (see here).
However, a Raman spectrum of mummified hair doesn't automatically equate to a photograph of its original colour, because the hair may have been altered by the environment, mummification, cosmetics, oils, resins or dyes. Therefore, it would be useful to combine Raman with other techniques.


Fourier-transform infrared spectroscopy
The Fourier transform infrared spectroscopy (FTIR), included micro-FTIR and synchroton FTIR, allows for the analysis of molecular composition without necessarily sampling material. It has been used directly on ancient hair to assess keratin preservation, protein degradation, chemical modifications and substances from the environment or mummification.
For example, as you can read in this study, this technique has already been used to analyse the state of the hair of two Egyptian mummies.
Another study analysed ancient hair from the Roman period, to characterise its state of conservation and the alterations of the organic elements (see here).
Athough performed with sampling, I think this 2018 study is important too. By using nano-FTIR and scanning transmission electron microscopy (STEM), the authors analysed sheep hairs melanosomes. They were able to directly distinguish, in situ (i. e. in the single hair), the vibrational characteristics associated with eumelanin and phaeomelanin, without resorting to chemical extraction. Some of the hairs were white (without melanosomes) and others black. In white hairs, they were able to indentify keratin, while in black hairs they could associate specific vibrational bands with melanosomes of eumelanin and phaeomelanin, thus distinguishing the chemical fingerprint of the two melanosomes.
So, althought this technique can’t measure the amounts of melanins, it can give us important information about the modifications that hair has undergone over centuries and millennia and about melanosomes.


Hyperspectral and multispectral imaging
Hyperspectral imaging collects and processes information from across the electromagnetic spectrum. The goal of hyperspectral imaging is to obtain the spectrum for each pixel in the image of a scene, with the purpose of finding objects, identifying materials or detecting processes
When applied to hairs, it can help distinguish pigments, dye residues, foreign materials, areas of different composition and surface alterations. Basically, it can give an excellent and completely non-invasive preliminary mapping.

 

X-ray fluorescence
X-ray fluorescence is another non-destructive technique which detects chemical elements, like iron, copper, lead, arsenic, etc. Along with scanning electron microscopy and energy dispersive X-ray spectroscopy, it has been used on two Andean mummies.

 

With sampling 

High-performance liquid chromatography
High-performance liquid chromatography (HPLC) is a chromatography technique in analytical chemistry used to separate, identify, and quantify specific components in mixtures. The mixtures can originate from food, chemicals, pharmaceuticals, biological, environmental, agriculture, etc., in which the sample analysed is either a liquid or has been dissolved into a liquid.
Melanin is an extremely complex polymer and difficult to analyse directly, but through a standardised chemical reaction it produces certain relatively simple and characteristic molecules, such as PTCA, PDCA, TTCA, etc., which can be separated by HPLC.
For example, eumelanin produces PTCA, PDCA and PteCA, while phaeomelanin produces TTCA and TDCA.
Therefore, we don't directly measure how much melanin there is: we measure how much marker product is formed from melanin. A higher amount of PTCA indicates a higher amount of certain eumelanin structures, while TTCA is an important marker of the benzothiazole component of phaeomelanin.
Obviously, the whole process may be more difficult with archaeological hair.
Here’s an article on the subject. 


Mass spectrometry imaging
Mass spectrometry imaging (MSI) can be performed on a section of a single hair, obtaining a true chemical map. In modern hair, it has been possible to directly visualise the melanin granules and distinguish them from the cuticle, cortex, and medulla (see here).
It also allows mapping numerous chemical species along and through a single hair shaft (see here).  
The problem is that the most powerful versions of MSI are microdestructive: the hair generally needs to be sectioned and/or subjected to surface preparation.


X-ray Absorption Near Edge Structure (XANES)
XANES measures how an element absorbs X-rays near its absorption threshold and can provide information about its chemical state and coordination environment.
It has already been used, along with EXAFS (extended X-ray absorption fine structure), in the study of Egyptian mummies' hair. In particular, experiments on zinc showed differences between ancient and modern hair, suggesting that some of the zinc was of exogenous origin or had a different chemical environment than biological zinc. (see here)
However, this technique can’t determine directly hair colour. Melanin is a complex organic system, and colour doesn't simply depend on an element that XANES can identify as "black" or "red." XANES can, though, tell us if the element (pigment) we see is the result of mummification or other port-mortme treatments.
 

Scanning electron microscopy and Transmission electron microscopy
The scanning electron microscope (SEM) allows us to observe the surface and microstructure of hair at very high magnifications. With it, we can analyse the state of preservation and alterations of the cuticle, the cortex and medulla, the distribution and morphology of melanosomes and any mineral deposits or contaminants that have penetrated the hair.
Combining SEM with EDX (energy-dispersive X-ray spectroscopy) we can distinguish organic material from mineral deposits, identify elements from the soil or burial environment, recognise any pigments or contaminants and understand whether a colour change is likely endogenous or due to mineralisation/contamination.
However, if our goal is to study melanosomes, the transmission electron microscopy (TEM) could be even more informative than SEM.
For example, in the 1993 study Detection of eumelanogenic and pheomelanogenic melanosomes in the same normal human melanocyte, by M. Inazu and Y. Mishima, melanosomes were analysed with high-voltage transmission electron microscopy (HV-TEM) and EDX. Melanosomes producing the two melanins are different: phaeomelanosomes are spherical, while eumelanosomes are ellipsoidal/lamellar. By using HV-TEM, the authors of this study confirmed this different morphology. By using EDX, they found sulfur in spherical melanosomes, but not in ellipsoidal ones, and sulfur is typical of phaeomelanin. Lastly, they treated melanosomes with sodium hydroxide (NaOH) and found that the internal structure of the spheroidal melanosomes was dissolved, while that of the ellipsoidal melanosomes was not altered. This provided a further physicochemical difference between the two melanosomes.


Liquid chromatography–mass spectrometry
Liquid chromatography, combined with mass spectrometry (LC-MS) can tell us which melanin products are chemically present in hair and in what ratio, and this can tell us, indirectly, which melanin was originally mostly present.
This review on colour reconstruction in fossil material emphasises that the chemical markers of eu- and phaeomelanin are well characterized by HPLC/MS, but that diagenetic transformations of melanin in ancient finds still constitute a major problem. However, the SEM/EDX and controls on archaeological hair of different ages and conservation conditions can solve in part this problem. Along with others, this technique has been used for several analyses on an Egyptian mummy.  

 

Pyrolysis-gas chromatography–mass spectrometry (Py-GC-MS)
Pyrolysis–gas chromatography–mass spectrometry is a method of chemical analysis in which the sample is heated to decomposition to produce smaller molecules that are separated by gas chromatography and detected using mass spectrometry.
With archaeological hairs, the sample is rapidly heated in the absence or near-absence of oxygen. Melanin, being a polymer, breaks down into smaller molecules. These products are then separated by GC and identified by MS. The composition of the resulting products can provide information on the presence and state of melanin.
So, basically, GC-MS does not directly "see" the intact eumelanin or phaeomelanin molecule, but only identifies characteristic degradation products.

 

DNA phenotyping - HIrisPlex-S
DNA phenotyping is the process of predicting an organism's phenotype using only genetic information collected from genotyping or DNA sequencing. This term, also known as molecular photofitting, is primarily used to refer to the prediction of a person's physical appearance and/or biogeographic ancestry for forensic purposes.
With this technique, significant genetic variants associated with a particular trait are discovered using a genome-wide association study (GWAS) approach, in which hundreds of thousands or millions of single-nucleotide polymorphisms (SNP) are tested for their association with each trait of interest. Predictive modeling is then used to build a mathematical model for making trait predictions about new subjects.
One online tool available to the public and law enforcement is the HIrisPlex-S Webtool. This system uses SNPs that are linked to human pigmentation to predict an individual's phenotype.
In the case of ancient human remains, the main issue for analysis is not just how much DNA is left, but how much endogenous human DNA is recoverable compared to modern contamination.
As I said, this method was originally developed for modern/forensic DNA, while in ancient DNA we often find fragmented DNA, postmortem damage, low coverage and possible modern contamination. It's not enough to find a SNP: we must be sure that the observed allele is truly that of the ancient individual and not the result of postmortem damage or contamination.
In this 2013 study authors extracted the DNA from twenty-one teeth between 1 and approximately 800 years of age and from 5 contemporary bones, and then analysed them using the HIrisPlex system. I quote from the abstract: 

Twenty-three out of 26 bone DNA extracts yielded the full 24 SNP HIrisPlex profile, therefore successfully allowing model-based eye and hair colour prediction. HIrisPlex analysis of a tooth from the Polish general Władysław Sikorski (1881 to 1943) revealed blue eye colour and blond hair colour, which was positively verified from reliable documentation. The partial profiles collected in the remaining three cases (two contemporary samples and a 14th century sample) were sufficient for eye colour prediction. 

Besides, a paper published in February 2026 developed a missing data imputation method for HIrisPlex-S, demonstrating that under certain conditions, predictions can be obtained even from ancient genomes with extremely low coverage, on the order of 0.1–0.5×.
In 2025, the first high-quality genome of an individual from Nuwayrat (Old Kingdom of Egypt), was published. From the genetic analysis, the authors predicted brown eyes, brown hair and dark/black skin pigmentation (see here and here). DNA was extracted from seven teeth.
However, this very work underscores how anomalous the result is: authors explicitly write that, until then, poor DNA preservation had prevented whole-genome sequencing in Dynastic Egypt. There's also a very important detail: the find was exceptionally well preserved. The body was placed in a large pottery vessel inside a rock-cut tomb and authors believe that this particular burial may have favoured DNA preservation.
So, caution is warranted: another recent study (from 2025) shows that HIrisPlex-S predictions can become unstable when coverage drops too low. In particular, below about 8×, some approaches can produce large errors.

Here are a couple of articles discussing some of the techniques we have just seen:

- Research Techniques Made Simple: Cell Biology Methods for the Analysis of Pigmentation  
- From Extraction to Advanced Analytical Methods: The Challenges of Melanin Analysis 

 

HYPOTHES ABOUT THE ORIGIN OF RED/BLOND ARCHAEOLOGICAL HAIR
It is important to keep in mind that none of these hypotheses has ever been directly tested on red- and blond-haired mummies. For this reason, I’m not saying they are wrong: I’m just saying they are only educated guesses, and passing off mere educated guesses as proven facts is scientifically incorrect.
So, basically, we need to find a process that can 1) explain both red and blond hair and 2) occur in places as different as the Tarim Basin, Egypt and South America.

Photo-oxidation
see part 2

Melanin oxidation/degradation
As you have seen in the previous parts of this article, melanin (and specifically eumelanin) oxidation/degradation is one the preferred hypotheses to explain blond and red archaeological hair, although 1) there is no evidence that melanin oxidation turns archaeological hair red or blond, and 2) there is no evidence this red/blond archaeological hair is due to melanin oxidation.
(Please note that here "degradation" is a sort of umbrella word: it means that the chemical structure of melanin is altered or fragmented and this can occur through various mechanisms.)

As far as melanin oxidation is concerned, we know for certain it can occur in two situations (apart from photo-oxidation, obviously). One is the bleaching with hydrogen peroxide (which I have already mentioned in previous parts) and another one comes from this study with ozonated water, although authors write that “Changes in shine and colour were minimal.” There is also this study on Japanese swimmers’ hair, but authors conclude that “discoloration was mainly due to cuticle damage by friction with water”, and, although they write that hypochlorous acid in the swimming pool water can oxidise melanosomes, this is only a concurrent factor.

As you probably know, one of the main oxidising agents is oxigen (here’s a list of the most common oxidizing agents), which means that oxidation can occur underground as well, for example because of residual atmospheric oxygen in the pores of the soil, in the burial materials or in the cavity in which the body is laid, or because of water/humidity and microorganisms.
However, the mummies and skeletons we are talking about not only have been found in very dry environments (so, most likely, there was very little or no humidity at all), but many of the bodies were laid to rest wrapped in several layers of textiles, just like the so-called “mummy bundles” of Paracas, or the Gebelein Man. In such a situation, it is unlikely that melanin can oxidise, and in any case, if oxidation occurred, we should find some traces of it on textiles as well. On the contrary, the textiles found in Paracas burials were in excellent conditions, so excellent that many of them were stolen by tomb looters. Furthermore, if oxidation occurred and we assume this is the cause of red hair, all the mummies found in the same place should have red hair. 

Some argue that oxidation could have occurred when the mummies were removed from their burial sites: contact with oxygen in the open air would have oxidised the melanin, causing the hair colour to change. If this were the case, however, archaeologists should have noticed it. Others argue that contact with oxygen (and therefore oxidation) could have occurred due to tomb looters. In this case, however, it would be necessary to demonstrate that all the mummies with red hair come from burials that were disturbed by tomb looters.
In some of the previous parts (for example in the 2nd part, speaking of bog bodies) we have seen that dark, brown and blond hair have very small amounts of phaeomelanin, so, even if all eumelanin should disappear (through oxidation or other forms of degradation), the remaining phaeomelanin wouldn’t be enough to turn hair red. Probably this is reason why some speak of “products of degradation”. That is, products are left as a result of eumelanin oxidation/degradation and this products could turn hair red. 

Deposits of iron and other minerals oxides
Minerals in the soil (such as iron or copper) are sometimes implicated in explaining red or blond hair in mummies and skeletons, but here two aspects of the issue need to be distinguished.
The fact that iron oxide (or other minerals) can produce a visible and very intense colour on a keratin fiber, without altering the internal biological pigment, is now well documented. See, for example, the experiment with the bearded vultures: 

The rufous colouring on the feathers of the under parts of adult bearded vultures Gypaetus barbatus, studied by scanning electron microscopy, energy-dispersive X-ray microanalysis and X-ray diffraction analysis, is caused by an external deposit of iron oxide in the ferrihydrite state. Unstained feathers, e.g. in captive birds, are pure white. 

Subsequent studies have experimentally observed the behavior of bearded vultures in captivity: when baths containing red/ferruginous soil were provided, the animals willingly immersed themselves, and their feathers took on a rich orange hue (see one more study here).
However, we don’t have any evidence that the red and blond hair of mummies and skeletons is caused by minerals in the soil. We only have evidence that, in certain cases, minerals were found on archaeological hair.

 
For example, here we have a study on the hair of two Andean mummies. 
The hair was analysed with some of the techniques we just saw (scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray fluorescence spectroscopy. Fourier transformed infra-red spectroscopy), but NOT to ascertain its original colour. Researchers found out that for one of the mummies (PLM7_T305) a 3,5% of iron was found on its reddish hair. After treatment with ultrapure water, dichloromethane/methanol and acetone, the iron levels dropped to approximately 100 ppm. EDS mapping also showed that the iron was distributed across the surface. From these observations, researchers deduced that the red coloration was due to the use of hematite, an iron-based red pigment. However, strangely enough, the study doesn’t say which colour the hair sample turned after the treatment with ultrapure water, acetone, etc. and, as I said, researchers didn’t attempt to assess the levels of melanins in hair. 

Another interesting study is the one on the relics of “Mary Magdalene” (kept in Provence, France), which consist of a dry skull and a lock of hair of brown colour.
Researchers analysed the hair with optical microscope, scanning electron microscope and helium ion microscope in order to assess melanin concentration and aspect of melanosomeThey observed microscopic characteristics of pigments consistent with dark brown hair. Along with localised red pigmentation features in some portions. The meaning of this red pigmentation is not very clear, however, because researchers didn’t use any of the techniques for the chemical analysis of melanin. The techniques they used were aimed to find mineral deposits and, in fact, they found significant superficial diatomaceous deposit, probably used as a prevention method against lice. 
On the same year, 2019, another study on the hair of “Mary Magdalene” was published. I quote from the abstract: 

As a new contribution to the scientific knowledge of Holy Maria-Magdalena’s remains, we have studied by SEM-EDX some mineral particles and micro-organism debris adhering to her hair. We found on it mineral particles of gypsum, aragonite and salt, algae fragments, microorganism as diatoms, coccoliths and tintinnides, and micro-debris of Crustaceans. Such marine micro-remains indicate a past close contact of the hair with sea water. 

Many mineral particles of barytine were also found on or near the surfaces of the hairs, which, according to researchers, originated from the ceiling of the Sainte-Baume cave. Not even this time a chemical analysis of melanin was performed.
However, since (as I said in the previous paragraph) many of the mummies we are talking about were found wrapped in layers of textiles, I doubt that in such a condition a contamination from minerals in the soil can occur. 

Keratin/tyrosine degradation/oxidation
As I said before, "degradation" is a sort of umbrella word: it means that the chemical structure of keratin is altered or fragmented. This can occur through various mechanisms: oxidation, hydrolysis, photodegradation, enzymatic/microbial attack, reactions with acids or bases and other chemical reactions.
Keratin is one of the components of hair (but also of scales, nails, feathers, horns, etc.).
Tyrosine is one of the 20 standard amino acids that are used by cells to synthesize proteins and is also the precursor to melanin. 

As we have seen in previous parts, the products of degradation and oxidation of these two elements are sometimes used to explain the fair-haired mummies, and not only fair-haired mummies, but even… red-haired mammoths!
This 2014 study by Silvana Tridico and colleagues is about the hairs of wolly mammoths and wollly rhinoceros. At one point, authors write "The majority of overhairs and thicker guard hairs from the woolly mammoths and woolly rhino were vivid red/orange colour or ‘fox red’ as described by Krefft (1969)” and argue this colour may be in part due to melanin oxidation. However, they find out that also some hairs lacking melanin granules (i. e. they were originally white) had the same red/orange coloration. One of the sources cited (Krefft 1969) attributes this colour to photo-oxidation, but then researchers find “red/orange debris” on some of these red (originally white) hairs, and conclude this is due to a fungal deposit. The techniques they used to analyse hairs samples are scanning electron microscopy (SEM) and confocal microscopy, which means they didn’t perform a chemical analysis of eumelanin and phaeomelanin to trace the original colour. They don’t even verify if melanin was really oxidated.  

So, we have here the usual situation: they wonder why these animals’ hairs are red, they make hypotheses about the oxidation of this and that, but don’t do the only thing that could, maybe, give an answer.
Besides (as you can read here) in 2006 a mutation of MC1R was found on a 43,000-year-old woolly mammoth. The author writes “… the reduction in activity of the Arg67Cys variant would be sufficient to result in substantially lighter hair color…it is possible that mammoth populations were polymorphic with regard to hair color, harboring both dark- and light-haired individuals." So, it is perfectly possible that the red hairs Tridico and colleagues were analysing were naturally red (apart from the ones without pigment granules).


Conclusions
The conclusions we can draw seem very clear to me. Although scientists today possess all the tools to analyse archaeological hair in terms of colour, they do not seem interested in doing so, preferring instead to keep repeating hypotheses that have never been proven.
We have seen that it is not a matter of funding, since these same tools have been used to conduct other types of hair analyses.
It’s not even a matter of damaging important finds, since many of these tools are either non-destructive or minimally destructive, and in any case we have seen that, whenever necessary, samples are taken from mummies and skeletons.
At this point, all we can do is wait and hope that someone decides to do the only sensible thing to clear up the mystery.