So far, in my previous blog posts I’ve talked about individual colours and how they were created and used in Ancient Egypt (see the beginning of the series here). But let us now explore a fascinating property which brings them all together – iridescence. It’s a phenomenon whereby surface colour appears to change with the angle of viewing or illumination and is caused by an optical effect rather than pigmentation. The word itself derives from the Greek goddess of the rainbow – Iris, while the Latin suffix ‘-escent’ means having a tendency towards something. A perhaps less glamorous term for iridescence, goniochromism, can also be traced back to Greek words ‘gonia’ meaning angle, and ‘chroma’ meaning colour.

Iris Carrying the Water of the River Styx to Olympus for the Gods to Swear By, Guy Head, c. 1793 – Nelson-Atkins Museum of Art (Photo: Daderot).

Iridescence is a type of structural colouration and occurs in the natural world (e.g. insects, birds) as well as in man-made materials (glass, soap bubbles, playing surface of a CD).

Blue Morpho butterfly showing off its glorious colour (Photo: Derkarts).

A brilliant example of the use of iridescence in nature can be found in the Blue Morpho butterfly (Morpho menelaus) whose upper wings appear to be bright blue. It is one of the largest butterflies in the world and can be found in South American rainforests. Those beautiful and rare butterflies use iridescence to evade predators by becoming briefly invisible! As they fly, the colour of their wings shifts between brilliant blue and brown, so against the background of the forest and sky they seem to disappear for a flash just to reappear a little further away, confusing anyone who might be trying to catch them.

Perhaps a more familiar example of iridescent colouring is mother-of-pearl, or nacre, which has long been admired and used for many decorative purposes, from jewellery to furniture, artwork to cutlery. Some specimens can even be found in the Petrie Museum collection. In nature, nacre occurs on the inner shell of some molluscs (such as abalone sea snails) or on the surface of pearls. Its purpose is once again defensive as the molluscs secrete layers of nacre on the inner surface of their shells to protect the soft layers beneath from parasites and debris. As a material, nacre is made up of tiny hexagonal platelets of aragonite, a form of calcium carbonate. The thickness of the platelets (between 300 and 1500 nm) allows them  to interfere with different wavelengths of visible light at various viewing angles, creating an iridescent effect. However, studies using Scanning Electron Microscopy (SEM) have shown that the effect is also partially caused by diffraction resulting from a high groove density of the surface.

Inside of an abalone shell (Photo: Marac).

Some plants have also evolved to use thin layers of photosynthetic structures, called iridoplasts, to bend and absorb more light in dark environments such as the lower levels of tropical forests. This causes the surface of their leaves to appear iridescent and almost glowing in the dark. For instance, peacock begonia (Begonia pavonina) from South East Asia shows a beautifully intense metallic blue as it amplifies  the small amount of visible light it receives. The iridoplasts bend the light repeatedly thus making very efficient use of long red and green wavelengths while reflecting the blue ones.

Peacock begonia (Photo: Shyamal).

Many more examples of iridescence exist in nature and this blog post could easily become a very long article if I attempted to include them all. I guess it’s very easy to assume that this phenomenon is mainly decorative and meant to create attraction, like peacock’s feathers for example. But, as we can see, there are plenty of instances where the effect serves a purpose very different to what we might originally have imagined or is an almost accidental by-product of a completely unrelated function . In my next post I will explore how one man managed to replicate natural iridescence for purely ornamental purposes, so stay tuned for Part 2!

From Great Danes and Dogue de Bordeauxs to miniature Dachshunds and Chihuahuas, man’s best friend comes in a variety of shapes and sizes, so how can they recognise fellow dogs even when they all look so different?

Dogs come in a variety of different shapes and sizes, featuring Jess the black Labrador, Jewell the miniature Dachshund, Percy the Bichon Frise, Luna the Dogue de Bordeaux, Scratch the Jack Russell Terrier, and Spud the mixed-breed. (Engager’s own photos)

The Kennel Club recognises 211 different breeds of dogs but with different coats and mixed-breeds, there are by no means 211 dog-shaped moulds. Despite this, your dog can decipher between a Bichon Frise and a lamb instantly. This is in part due to their impressive sense of smell which they use to smell the hormones secreted by other dogs. Not only do they have a large nose cavity, which contains a folded surface covered by the sensing organ that is up to 23 times larger than in humans, they also have a vomeronasal organ in the roof of their mouth for detecting smells [1]. This means dogs can smell up to 10,000 times better than humans [1].

Seven domestic dog skulls on display in the Grant Museum (Accession number: Z2909)

Dogs’ ability to recognise different chemicals through their sense of smell has been used by humans to sniff out drugs, explosives and even illnesses such as cancer and diabetes. But is this the only sense dogs rely on to recognise other canines? A study from 2013 tested nine dogs’ ability to correctly identify other dogs from pictures [2]. The dogs were shown two images: one of a dog (from a set of 3000 pictures of different breeds, including mixed-breeds) and one of a non-dog animal, which included cats, cows, rabbits, birds, reptiles and even humans. On command, the dog participant had to correctly distinguish between the images and place their paw on the picture of the dog. All nine dogs successfully chose the images of the dogs over the images of non-dogs the required 10 times out of 12. The study concluded that dogs could “form a visual category of “dog pattern”” ([2] page 647); however, it did not allow the researchers “to determine which dog morphotypes or which species were easier to discriminate” ([2] page 648). As the dogs were successful at distinguishing between dogs and other animals from photographs alone, it is clear that they don’t solely rely on a sense of smell.

Hair curlers with a hunting dog on from the Petrie Museum (Accession number: UC8529)

Although varying highly in appearance, from the colour of their coat to the length of their snout, dogs use both their senses of smell and sight to identify others. Exactly which visual cues are required is still unknown. One thing we know for certain is, regardless of how they look, they’re all good dogs!

Bibliography

[1] Miklosi, A., (2018) “The Dog: A Natural History” Ivy Press, Brighton

[2] Autier-Derian, D., Deputte, B.L., Chalvet-Monfray, K., Coulon, M., and Mounier, L., (2013) “Visual discrimination of species in dogs (Canis familiaris)” Anim Cong, 16, pp 637-651.

For budgetary reasons, UCL Culture has recently decided to terminate the Student Engager programme, which has brought PhD students into the university’s museums to share their specialist knowledge and enable greater visitor access to collections.

As we wrap up the Researchers in Museums blog, Engagers will be sharing some of their favourite memories, and providing readers with a few final details about the museums’ amazing art works, artefacts, and specimens.

Sarah’s Top Specimens

“Half of my Head is in Havana”: The Negus Collection.

Actually, it’s in UCL’s Grant Museum of Zoology. The Negus Collection is a group of bisected animal heads stored in clear Perspex containers. Have a gander at one side, and you’ll see an alligator in all his scaly glory. The other side? Well, that shows you what we might call his inner beauty. The Collection was originally assembled to study animal noses and throats. Photographs and digital models now make such preparations unnecessary. When the Grant Museum hosted a migration workshop featuring a bisected salmon head, visitors decided that the beady-eyed sushi staple should play the villain in an under-sea opera.

Crocodile (Crocodylidae; X1211)

Terrible Taxidermy: The Story of Frank

That’s what I’ve always called the Grant’s friendly pygmy orangutan. He’s an upbeat specimen, despite being a victim of some rather poor quality preparation. Taxidermists in the nineteenth century were often unfamiliar with the animals they preserved; the Horniman Museum is famous for its dramatically overstuffed walrus (no one told the taxidermist that this strange creature’s skin should lie in loose folds). Frank’s facial features are ill-defined, and his skin is splitting. It’s like he’s had both a facelift, and a few too many decades in a tanning booth. Plus, he’s an arsenic bomb. That’s right, folks. Frank is one of many early taxidermical specimens preserved using poisonous chemicals. He poses no danger unless he’s handled heavily without protective clothing. Nevertheless, don’t let those sweet brown eyes convince you to go in for a hug. At least he’s got one of those retro cool hairstyles, like the kids on Stranger Things.

Orang-utan (Pongo pygmaeus; Z490)

The Lonely Donkey

The Grant Museum has a donkey skeleton. You don’t really see this donkey, as everyone’s still a little disappointed he isn’t something else, namely, a zebra. As the Grant has always been a teaching collection, and as it also received massive transfers of specimens when London’s other university-based zoology museums closed, determining the identity and provenance of the over 60,000 collection items can sometimes be tricky. Records indicated that the Museum held two zebra skeletons. Then an expert came by to check. Turns out, it has one quagga (Amazing! Incredibly rare zebra sub-species! Only seven skeletons of the now-extinct animal in the world!) and one donkey (sigh). So, for want of display space, the sad little donkey (codename: Eeyore) gazes over the railing from the second floor. Look up next time you visit, and give him a wave.

Donkey (Equus asinus; Z233)

The Thylacine

Thylacine (nationalgeographic.com)

Like the quagga, the thylacine is a member of the dark fraternity of extinct animals. A canine-like marsupial, the last known “Tasmanian Tiger” died in 1936. Even more unfortunate is the reason for the species’ disappearance: a government bounty. The thylacine was officially designated a danger to livestock, but many scholars now argue that its extermination was part of a greater effort to undermine indigenous culture by destroying native wildlife. The Grant Museum has one of the few fluid preserved specimens in the world, but don’t expect a smile from our floating friend; the thylacine has been decapitated, possibly as part of the bounty process. One visitor who had just returned from Tasmania told me that Errol Flynn, a film star in the 1930s and 40s, grew up with thylacines in his backyard. I wonder if they liked to play fetch.

Thylacine (Thylacinus cynocephalus; Z1653)

Come find your own favourites at UCL’s Grant Museum.

Forget Anubis, Horus and Ra, Bes is the bes(t) Egyptian god around! His figure may not land him any jobs striding down our catwalks (he is short and has a large protruding stomach) but his distinctive and playful face won the hearts of Ancient Egyptians and even spread to the Roman empire, Cyprus, Syria and more. Here are 7 reasons why you should love Bes as much as the Egyptians did:

1) He protects your home
Like our modern day ‘live laugh love’ wall stickers, Ancient Egyptian families often decorated their home with images of Bes. His figure is found on a range of household objects including mirrors, cosmetic jars and even the headboard of beds where he’d protect the person sleeping.

Wooden cosmetic-spoon featuring Bes at the British Museum. Museum number EA5954.

2) He loves music and dancing
If you could only have one Egyptian god at your house party, you’d choose Bes. What better party guest than one who can provide great music and dance all night whilst simultaneously protecting the house? You can see figurines of Bes dancing at the current exhibition in the Petrie Museum called ‘Shake, Rattle and Roll: Sounds of Roman Egypt’. He is often depicted playing a tambourine or harp or dancing near other musicians, and some performers even tattooed his image on their bodies.

Dancing Bes alongside seated group of musicians in the Metropolitan Museum of Art. Accession number: 23.6.79.

3) You can wear him on your jewellery
The collection in the Petrie Museum contains many strings of beads with amulets of Bes, such as the blue faience bead of Bes’ head (read more about the bluefaiencein Arendse’s blogpost.). These were probably worn for protection but make for a great statement piece too.

Amulets of Bes in the Petrie Museum with accession numbers UC37498 (top) and UC38008 (bottom). Engager’s own photo.

4) There are vessels made in the shape of his head
It’s impossible to miss the abundance of pottery vessels in the Petrie Museum featuring Bes’ face. They’re so charming and always popular among the visitors at the museum, featuring heavily on the #PetrieMuseumInstagram hashtag.

Pottery vessel with Bes’ face decoration in the Petrie Museum. Accession number: UC8902. Engager’s own photo.

5) He makes you smile…and he’s supposed to!
When ancient Egyptian babies would unexpectedly laugh or smile, many Egyptians believed that Bes was somewhere in the room pulling funny faces. He was a protector of mothers, children and pregnant women, and wall paintings of Bes have been found in rooms that were associated with children or childbirth.

Column Capital in the form of a Bes-image in the Metropolitan Museum of Art. Accession number: 23.2.35. Engager’s own photo.

6) He had a distinctive style
As can be clearly seen on the amulets, Bes often wore a headdress made of feathers. He also was depicted wearing a lion skin cape, although after the New Kingdom he often opted for a leopard skin cape instead (very on trend!). However, the Romans adopted him as a military deity and often depicted him in their legionary costume.

Bes with a tambourine in the Metropolitan Museum of Art. Accession number: 23.6.16

From the ultimate party guest to splashing his face on vases, Bes is the best Ancient Egyptian god. Initially as a protector of the Pharaoh, Bes became the god of the people, looking after their homes and their children. He was a multifaceted god, who was a serious protector and a merry entertainer. In fact, the only temple believed to have been dedicated to Bes was next to a vineyard so he could protect the grapes and oversee the production of wine! Many relics still exist today featuring his distinctive figure. Visit the Petrie Museum where you can find many Bes related artefacts including several vases, amulets and figurines!

This is the fifth post in the Colours of Ancient Egypt series; you can read the introduction here, or all about the colour blue, red, and yellow.

In Ancient Egypt, perhaps unsurprisingly, the colour green was associated with life and vegetation. However, it was also linked with the ideas of death. In fact, Osiris, the Egyptian god of fertility, death and afterlife, was commonly portrayed as having green skin. Even scarabs, popular amulets and seals, were often green due the beetle’s symbolic connotation to rebirth and immortality.

Painted wooden stela of Neskhons, wife of the High Priest of Amun Pinedjem (II) making an offering to Osiris, identifiable by his green skin (Petrie Museum, UC14226).

Green faience scarab amulet from Amarna (Petrie Museum, UC1196).

By far the most prevalent, and likely the oldest, green pigment was made from a mineral called malachite. It is a copper carbonate and a relatively stable colourant, although sensitive to excessive heat and acid exposure. It was popular in Egyptian tomb painting from the 4^th Dynasty (c. 2613 to 2494 BC) onwards but didn’t find much use in European painting until the 15^th and 16^th centuries.

Cross-section of malachite (Image: Rob Lavinsky).

A copper acetate, called verdigris, has also been found on Egyptian art. It gives a slightly transparent bluish green, often applied over a ground of lead white or lead-tin yellow. It’s artificially produced by exposing copper plates to acetic acid, a by-product of wine-making. The reaction that follows produces a blue-green deposit, which can then be scraped off, ground, and used as a pigment. Unfortunately, verdigris is very reactive and can become dark brown or even black with ageing. However, it was identified as the primary green pigment on the headband of Queen Nefertiti’s bust, where it retains its hue.

In addition to its instability, verdigris is also moderately toxic due to its copper content. Therefore, its use gradually declined through history, to be mostly replaced by a new pigment, viridian, developed and patented in France in 1859. Viridian is both permanent and non-toxic which immediately made it a great substitute for the older green pigments.

The famous bust of Queen Nefertiti on display at the Neues Museum, Berlin (Image: Philip Pikart).

Other sources of green colour included an artificial green frit (produced the same way as blue frit or Egyptian blue, except that the lime content has to be higher than the copper content) as well as mixing Egyptian blue with yellow ochre. The latter method was occasionally used during the 12^th Dynasty (1991-1786 BC) but became popular during the Amarna period (1370-1352). For faience, copper and iron oxides were mostly used, until the discovery of yellow lead antimonate gave Egyptian artisans many more choices of hue.

Green was certainly a colour of great importance to Egyptians, although nowadays it appears overshadowed by the significance and properties of Egyptian blue. However, we can still find and admire green pigments in great condition amongst ancient Egyptian artefacts. Next time you’re visiting the Petrie Museum, check out the wall block fragment from the pyramid of King Pepy I with instructions on his ascent into heaven! Guess what colour the inscription is…;)

You may have noticed that UCL Museum’s current theme is ‘migration’, a topic that hits the headlines daily. Unstable climates and widespread political and socioeconomic unrest are forcing people to move, seeking safety and security. Migration is not a new concept in our human story, Homo sapiens initially evolved in Africa, with the population we are closely related to leaving around 60,000 years ago. This migration event led H. sapiens to encounter established Neanderthal populations in the Middle East before becoming established further into Europe and Asia. However movement outside Africa occurred prior to this as early as 300,000 kya in Morocco and 180,000 kya in the Near East. Evidence of this movement within and beyond the African Continent indicates that prehistoric migration occurred frequently in different circumstances and likely related to changes and continuity in surrounding ecology, for example climate and environment. However, migration is not strictly reserved for anatomically modern humans, other hominin species lived and moved across different landscapes; for example, although Neanderthals evolved from a common ancestor outside of Africa, they were a predominantly European species.

As part of the ‘migration’ theme the Student Engager team recently put on an put on an evening event where we discussed how our research is linked to human movement. As a researcher who focuses on aspects of human evolution, migration and people moving through landscapes is a constant consideration of mine. The behaviour of prehistoric hunter gatherers was intrinsically linked to their environment, as they relied on resource availability and survival in changing climates. During the Pleistocene, climate fluctuated significantly, and people migrated to survive. Due to a dependence on unpredictable subsistence resources, geographical features like rivers and coastlines played an important part in how hominins moved – humans can survive without food for 3 weeks but only 3-4 days without water. Food resources were also important influencing hominins to move alongside flora and fauna, for example following megafauna in order to scavenge from their prey’s carcasses (Palmqvist and Arribas 1999).

A glacial river valley in North Yorkshire. Riparian corridors and conduits were (and still are) important migratory routes for humans. They cut through difficult terrain and provide predictable resources (authors own image).

Britain is an interesting case when looking at examples of human migration as it is located on the very edge of the European continent at a northerly latitude. During the Ice Age, Britain experienced extremes of climate and regularly became inhospitable or impossible to access. The earliest evidence of humans in Britain is found at Happisburgh in Norfolk, where lithic artefacts and fauna have eroded from coastal deposits (Parfitt et al. 2010). The site is dated to > 850,000 years old, with environmental data suggesting a relatively cold climate at the time of occupation. The Happisburgh site is particularly significant as it has pushed back the estimate of human presence in Northern Europe. It is also the location of the oldest hominin footprints located outside of Africa.  In neighbouring Suffolk lies another site, Pakefield, which is dated to 700,000 years old, with fauna and environmental data suggesting a Mediterranean climate. No hominin remains have been recovered from these sites; however, the dates, human-made tools, and the size of the hominin footprints may indicate a Homo antecessor or a similar hominin (Ashton et al. 2014).

A few hundred thousand years later, we see a new player enter the scene. Homo heidlbergensis arrives at Boxgrove, Sussex. Here, hominin remains have been recovered: a tibia (shin bone) and two teeth (Roberts et al. 1994; Stringer et al. 1998). The archaeological assemblage at Boxgrove is particularly striking because the debris left behind by humans was covered rapidly by slow-flowing water and silt. This process preserved hominin activity at a high resolution, even preserving the outline of a flint knapper’s knees (got to love that “Pompeii” effect). The site is dated to around 500,000 years ago (Roberts et al. 1994).

After the relatively warm climate of H. heidlbergensis, Britain experienced a very cold glacial, known as the Anglian. As far as we know no humans were able to survive in this hostile environment. However, this glaciation was particularly important in Britain’s prehistory. Extensive ice sheets influenced the courses of several major European rivers, funnelling them into a large lake in an area now submerged by the North Sea. As the glaciation came to an end, the water level in the lake was supplemented by glacial melt water and this increased pressure caused the breach of the Weald-Artois anticline, a raised ridge of chalk stretching between England and France. For the first time Britain became an Island!

Newhaven Chalk with the Seven Sister’s Seaford Chalk formation in the distance. The Chalk of the South Coast once connected Britain to France by a land bridge that was destroyed by glacial meltwater around 450,000 years ago.

Although now an island during periods of high sea level, for much of the Pleistocene cooler climates meant Britain was linked to Europe by an area called Doggerland. Doggerland formed a terrestrial land bridge between East Anglia and the Dutch coastline and was an important routeway from the central European continent to its western fringes. People were also able to cross the Channel River, which was created by the flooding at the end of the Anglian. Around 400,000 years ago these terrestrial areas were crossed by another species of hominin, H. neanderthalensis. The first early Neanderthal fossil found in Britain was excavated at Swanscombe, Kent. It is composed of three fragments of crania, which were found separately in 1935, 1936 (Marston 1967) and 1955 (Wymer 1955). There are lots of other sites with stone tools made by Neanderthals, such as Baker’s Hole and Lynford Quarry (Ashton et al. 2016). This indicates a stable and consistent presence of these newcomers; the Neanderthals were here to stay!

Post 400,000 years Britain was visited on and off by hominins that had access via land bridges when the climate permitted. Never viewed as a destination, Britain simply represented an extent of territory that was intermittently hospitable; for example, between 160 – 80, 000 years ago the hostile environment recurred and there is no evidence for humans. Incidentally archaeologists have discovered a lot of giant bear remains from this time. It seems bears adapted well to a human-less Britain, expanding their ecological niche (bears and humans have very similar tastes) and becoming massive! H. sapiens (aka anatomically modern humans) didn’t make it to Britain until 40, 000 years ago (Higham et al. 2011) – about 800,000 years after the island saw its first human visitors. There is evidence of H. sapiens at several sites, including Kent’s Cavern and the later dated Gough’s Cave. These humans were highly mobile, adaptable, and carried a distinctive material culture (fun fact: some of them were also cannibals!).

But it isn’t until 10,000 years ago that a population of humans reach Britain and persist to survive in such a consistent way that they contribute to modern DNA. Cheddar Man, found in a cave at Cheddar Gorge, Somerset, is a very well-preserved skeleton of a person that lived in the area 10,000 years ago. Due to the high-quality nature of preservation, the skeleton of Cheddar Man retained DNA that could be used to reconstruct his genome (Brace et al. 2018). This work, published by the Natural History Museum, revealed the population he came from had a Middle Eastern origin. The phenotypic data indicates that he had dark skin and hair, and blue eyes. Comparison with the genomes of humans living today with British ancestry suggests Cheddar Man’s population contributed their DNA to ours and we retain around 10%.

A reconstruction of Cheddar Man made for the Natural History Museum by the Kennis Brothers (Image: The Natural History Museum via The Guardian)

However, a new population came to Britain in the form of the Beaker People who arrived around 4,500 years ago. The Beaker people are particularly easy to trace because they buried their dead with a specific type of pot or beaker. A large project studied the DNA of approximately 200 Beaker skeletons, concluding that these people originated in central Europe (Olalde et al. 2018). This data is supported archaeologically by the spread of the distinctive beaker burials. The DNA analysis also revealed that Beaker People had a range of skin and eye colours that wouldn’t be uncommon in Britain today. They thrived in western Europe, almost completely replacing the h. sapiens living there previously, and many modern British people are directly related to them.

So, if we total it up, that’s four different types of hominin – antecessor, heidlbergensis, neanderthalensis, sapiens – across around 850,000 years, travelling over land bridges, chalk ridges, and rivers. Following warming climates and resources or retreating from cooling climates. Human presence and absence controlled by geography, geology, sea level, and a climate that was ultimately influenced by the turning of the earth’s axis. The people most related to modern Britons arrived as migrants from Central Europe 4,500 years ago, a drop in the ocean if you consider the first hominin made stone tool dates to approximately 3 million years ago (Semaw et al. 1997). Our British society today encompasses people from all over the world demonstrating an important diversity that is reflected in its complicated human past. For most of its long (pre)history Britain was not an Island and the only hostile environments were driven by climate, not politics..

References

Arribas, Alfonso & Palmqvist, Paul. (1999). On the Ecological Connection Between Sabre-tooths and Hominids: Faunal Dispersal Events in the Lower Pleistocene and a Review of the Evidence for the First Human Arrival in Europe. Journal of Archaeological Science – J ARCHAEOL SCI. 26. 571-585. 10.1006/jasc.1998.0346.

Ashton, N., Lewis, S.G., De Groote, I., Duffy, S.M., Bates, M., Bates, R., Hoare, P., Lewis, M., Parfitt, S.A., Peglar, S. and Williams, C., 2014. Hominin footprints from early Pleistocene deposits at Happisburgh, UK. PLoS One, 9(2), p.e88329.

Brace, S., Diekmann, Y., Booth, T.J., Faltyskova, Z., Rohland, N., Mallick, S., Ferry, M., Michel, M., Oppenheimer, J., Broomandkhoshbacht, N. and Stewardson, K., 2018. Population replacement in early Neolithic Britain. BioRxiv, p.267443.

Hershkovitz, I., Weber, G.W., Quam, R., Duval, M., Grün, R., Kinsley, L., Ayalon, A., Bar-Matthews, M., Valladas, H., Mercier, N. and Arsuaga, J.L., 2018. The earliest modern humans outside Africa. Science, 359(6374), pp.456-459.

Higham, T., Compton, T., Stringer, C., Jacobi, R., Shapiro, B., Trinkaus, E., Chandler, B., Gröning, F., Collins, C., Hillson, S. and O’higgins, P., 2011. The earliest evidence for anatomically modern humans in northwestern Europe. Nature, 479(7374), p.521.

Hublin, J.J., Ben-Ncer, A., Bailey, S.E., Freidline, S.E., Neubauer, S., Skinner, M.M., Bergmann, I., Le Cabec, A., Benazzi, S., Harvati, K. and Gunz, P., 2018. New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens (vol 546, pg 289, 2017). Nature, 558(7711), pp.E6-E6.

Marston, A.T., 1937. The Swanscombe skull. The Journal of the Royal Anthropological Institute of Great Britain and Ireland, 67, pp.339-406.

Olalde, I., Brace, S., Allentoft, M.E., Armit, I., Kristiansen, K., Booth, T., Rohland, N., Mallick, S., Szécsényi-Nagy, A., Mittnik, A. and Altena, E., 2018. The Beaker phenomenon and the genomic transformation of northwest Europe. Nature, 555(7695), p.190.

Parfitt, S.A., Ashton, N.M., Lewis, S.G., Abel, R.L., Coope, G.R., Field, M.H., Gale, R., Hoare, P.G., Larkin, N.R., Lewis, M.D. and Karloukovski, V., 2010. Early Pleistocene human occupation at the edge of the boreal zone in northwest Europe. Nature, 466(7303), p.229.

Roberts, M.B., Stringer, C.B. and Parfitt, S.A., 1994. A hominid tibia from Middle Pleistocene sediments at Boxgrove, UK. Nature, 369(6478), p.311.

Semaw, Sileshi & Renne, Paul & W. K. Harris, J & S Feibel, C & Bernor, Raymond & Fesseha, N & Mowbray, K. (1997). 2.5-Million-Year-Old Stone Tools from Gona, Ethiopia. Nature. 385. 333-6. 10.1038/385333a0.

Stringer, C.B., Trinkaus, E., Roberts, M.B., Parfitt, S.A. and Macphail, R.I., 1998. The middle Pleistocene human tibia from Boxgrove. Journal of human evolution, 34(5), pp.509-547.

Wymer, J., 1955. A further fragment of the Swanscombe skull. Nature, 176(4479), p.426.

This is the fourth post in the Colours of Ancient Egypt series; here you can read the introduction, here all about the colour blue, and here about the colour red.

Due to its availability in several different forms and shades, yellow was present in many aspects of ancient Egyptian art and decoration, from painting to pottery.

Fragment of a vessel (Petrie Museum, UC25325; Photo: Anna Pokorska).

Pottery vessel containing rough pieces of pale and deep yellow pigment (Petrie Museum, UC59746).

Just as men’s skin was painted red in Egyptian painting, women’s can be distinguished by its yellow colouring, which we can see in a fragment of a statue made out of yellow jasper possibly depicting Queen Nefertiti or Queen Kiya and dated ca.1353–1336 BC.

Fragmentary head of a Queen in yellow jasper, from the 18th Dynasty (Metropolitan Museum of Art, NY).

Yellow was also used to mimic gold in works where the use of the precious metal wasn’t possible. The most prevalent yellow pigments in ancient Egypt were derived from natural ochres and had the same properties as their red equivalents — but they were by no means the only source of the colour.

Painted linen mummy shroud painted with red lead, carbon black, orpiment and Egyptian blue pigments (Petrie Museum, UC38058).

Orpiment was a common yellow pigment with a rich lemon or canary yellow shade. It is an arsenic sulphide and occurs naturally in small deposits as a product of hydrothermal veins, hot spring deposits and volcanic sublimation, although nowadays it can be easily obtained artificially. The arsenic content makes it highly toxic and the sulphur will darken lead-based pigments if used together in a mixture.

Closely related to — although not as widespread as — orpiment is an orange pigment called realgar which can often be found in the same deposits. Despite its toxicity, it was the only orange pigment available until chrome yellows and oranges were introduced in the beginning of the 19^th century. An interesting feature of realgar is that prolonged light exposure turns it into a yellow compound called pararealgar without changing its elemental composition.

In addition, Egyptians were able to synthetically produce a highly toxic lead (II) antimonate, also known as Naples yellow. It was often used as an enamel colour from about 1500BC, although it didn’t appear in painting until the Renaissance. As one of the oldest produced artificial pigments it was highly toxic and provided a warm orange shade of yellow. Interestingly, a mineral of the same chemical composition, called bindheimite, exists in nature but wasn’t used to create the pigment. Instead it was made by a calcination of a lead compound (such as lead white) with an antimony compound (e.g. potassium antimonate). A 19^th century recipe recommends mixing the ingredients, placing them over a gentle heat and then gradually increasing the temperature. After approx. 5 hrs the calcination is complete, and the resulting product can be ground in water with an ivory spatula (because iron can react with the powder and change its colour). The shade of the pigment could also be manipulated by changing the proportions of the ingredients. Lead antimonate is very stable to light exposure but due to the lead content will turn black on contact with hydrogen sulphide (e.g. in air).

Why were so many dangerous substances used as pigments for so long, especially as harmless clays were so abundant? Although their toxic effects were known, the depth and brilliance of the lead and arsenic compounds made the natural iron oxides appear rather dull and brownish in colour by comparison. In fact, even the pigments that strove to replace them — cadmium, chromium and cobalt yellows which appeared during the 19^th century — are all harmful to some extent, and it wasn’t until the development of organic pigments (based on carbon and hydrogen) that we overcame this issue!

This is the fourth and final segment in a series on incest; you can go back and read the previous segments on incest in ancient Egypt, incest in the Hapsburg family, and incest in nature.

As surprising as it may seem, consanguineous marriages are nowadays respected and practised among more than one billion of the world’s population, in particular in the Muslim countries of North Africa, Central and West Asia, and in most parts of South Asia (Jalal Abbasi-Shavazi 2008) with consanguinity rates reaching 20–50% (Hamamy 2016). It has been shown (Bittles 1994, 2001) that sociocultural factors, such as the maintenance of family structure and property, ease of marital arrangements, better relationships with in-laws, and financial advantages relating to dowry, seem to be strong contributory factors in the preference for consanguineous unions.

In countries with civil unrest, consanguineous marriages are preferred because close-kin marriage is regarded as safeguarding for personal and family. It has also been suggested that marriage dissolution and divorce is lower among cousin couples. Studies have indicated that women in first-cousin marriages are protected against intimate partner violence. In another study focussing on cases of consanguinity in Iran (Jalal Abbasi-Shavazi 2008), the authors also demonstrate that in this country the ethnicity, province and area of residence have remained by far the most important determinants of the practice of marriage to biological relatives. In contrast, the modernization variable, education, had no significant effect upon behaviour, the effect being only for those with tertiary education.

Figure 1: Global prevalence of consanguinity (Bittles 2009)

In other countries, the genetic risk associated to consanguineous relations is taken very seriously and all is done to avoid it. This is the case with Iceland. With a population of only 320.00 inhabitants, the risk of incest is really high. De facto, in Iceland everyone shares at least one family relationship. It is said that one of the most asked questions during a first date is: “Hverra manna ert þú?” Which means “ Who are you, who is your family?” To avoid any chance to end up dating your cousin, 3 engineers have recently created a smartphone app called ÍslendigaApp in which people can check the family genealogy and any family relationship with their intended in a few seconds. It even has a “bump” option which gives the info on family relationships when the partners’ phones are clashed and can even send an “incest alert” when the two partners are close family members.

At the origin of this app, there is a genealogy website called Íslendingabók (i.e. Book of Icelanders). Launched in 2010, the database lists the family relationships between Icelanders going back 1200 years. To check the information related to your family, any inhabitant of the Island only needs to provide his/her name and national identity number. Quickly, the website starts to be much more than just a catalogue of genealogy trees and people started to use it to check any possible family connections to their partner.

Here the series on Incest ends. Through the different articles of this series, I have tried to elucidate the incest taboo, find its sources, and understand its origins through different historical cases — Tutankhamun or the Habsburg family — but also through scientific cases.  All these examples have shown us that this taboo seems deeply anchored in nature and culture but that neither nature nor some cultures totally prohibited it. So where to find its source? The questioning hits some dead-end; the answers provided are always partial. Psychology has tried to stick its nose into it while some scientists are waiting for the discovery of a possible “incest” gene. While we wait for answers, I would like to ask you: “Why do you find incest disgusting?” I hope these articles gave you some food for thoughts and starting points for further questioning.

“There is nothing either good or bad, but thinking makes it so” (Hamlet by W. Shakespeare).

References

Bittles A. H. (1994). ‘The role and significance of consanguinity as a demographic variable.’ Population and Development Review 20(3):561-583.

Bittles A. H. (2001). “A Background summary of consanguineous marriage.” Center for Human Genetics, Edith Cowan University, Perth.

Bittles, A. H. and M. L. Black. “Consanguinity, Human Evolution, and Complex Diseases.” Proceedings of the National Academy of Sciences 107.Suppl 1 (2010): 1779-86. Web.

Hamamy, Hanan, and Alwan, Sura. “Chapter 18 – The Sociodemographic and Economic Correlates of Consanguineous Marriages in Highly Consanguineous Populations.” Genomics and Society, 2016, pp. 335–361.

Jalal Abbasi-Shavazi, Mohammad, et al. (2008). “modernization or cultural maintenance: the practice of consanguineous marriage in Iran.” Journal of Biosocial Science, 40(6):911–933.

Why do some objects end up in museums and others in the bin? How do people decide what’s important to keep from everyday life today?

These are questions I’ve posed as part of my research with the Heritage Futures project, both to social history curators and ordinary people. Social history curators make these decisions based on years of collections knowledge and experience, but ultimately their reasons for selecting things aren’t so different from why most people choose to hold onto important possessions.

Think of the important keepsakes in your life. The following quiz will tell you whether or not your reasons for adding to and keeping a personal collection are similar (or not) to a museum’s.

(more…)

The two most common questions I get asked about Neanderthals are ‘Why did they go extinct?’ and ‘Did we have sex with them?’ (although never phrased that directly). Neanderthals first appeared in the fossil record around 430 thousand years ago (kya) and persisted through the Mid to Late Ice Age until disappearing approximately 40 kya. They evolved outside of Africa, from existing hominin (human like) populations that had migrated there before 400 kya, and lived in Europe, the Middle East and Western Eurasia. H. neanderthalensis is very closely related to H. sapiens, who are our direct ancestors, with genetic evidence suggesting that we shared a last common ancestor until around 750–550 kya. Although this sounds like a long time ago, the earliest stone tools made by a human ancestor are around 3 million years old.

The publication of the first complete Neanderthal genome in 2010 revealed that all non-African modern humans retain approximately 2% Neanderthal DNA, indicating interbreeding between the two species. So, yes, humans did have sex with Neanderthals, probably about 60–80 kya when they left Africa and encountered established Neanderthal populations in the Middle East. But before this grosses you out, remember that most reconstructions of Neanderthals pre-2010 and particularly during the 19th century were heavily loaded with an ‘us and them’ mentality. Basically, the more ape-like the portrayal of Neanderthals, the more elite and unique humans appear. We know that this is not the case now, with a myriad of new discoveries linking Neanderthals to cultural and symbolic practices, and advanced anatomical adaptations. There is no evidence to suggest the two species would not have recognised each other as what we would call ‘humans’.

A H. neaderthalensis (right) and H. sapien (left) skulls, facing each other. Image credit: hairymuseummatt (original photo), DrMikeBaxter (derivative work) [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

As more Neanderthal genomes are studied scientists are analysing why we have retained these pieces of DNA. The initial contribution of Neanderthal DNA was likely higher at around 6% but as humans have evolved some genes were selected out. Studies  suggest that the genes we retain are related mainly to phenotypic qualities, meaning those that affect our outward appearance, for example hair and skin colour. Researchers at the Max Planck institute proposed that these genes are all linked to climate adaptation and sunlight exposure, demonstrating characteristics linked to the Neanderthal’s c. 400 kya stay in cooler climates (Dannemann and Kelso 2017).

But Anatomically Modern Humans may have inherited something much more practical from Neanderthals in the form of a genetic resistance to some viruses. Researchers have proposed that when H. sapiens left Africa they encountered viruses that their bodies were not adapted to fight. Historically we know that these kind of encounters can be fatal, think the smallpox epidemics brought by the Spanish to Mexico leading to the downfall of the Aztec civilisation. Enard and Petrov (2018) propose that by breeding with Neanderthals, who had been exposed to these pathogens for around half a million years, H. sapiens became immune and were able to survive in Europe and beyond.

In archaeology and palaeoanthropology, the traditional model of linear evolution and direct replacement of species is becoming more and more difficult to uphold, with discoveries like the Denisovans and others living during similar time spans. At this point you might could say at times the Ice Age was a bit more like Middle Earth! There is a growing openness, supported by scientific evidence, to accept more nuanced views of interaction between different human species.

References:

Dannemann, M., & Kelso, J. (2017). The contribution of Neanderthals to phenotypic variation in modern humans. The American Journal of Human Genetics, 101(4), 578-589.

Enard, D. and Petrov, D.A., 2018. Evidence that RNA viruses drove adaptive introgression between Neanderthals and modern humans. Cell, 175(2), pp.360-371.

Green, R.E., Krause, J., Briggs, A.W., Maricic, T., Stenzel, U., Kircher, M., Patterson, N., Li, H., Zhai, W., Fritz, M.H.Y. and Hansen, N.F., 2010. A draft sequence of the Neandertal genome. science, 328(5979), pp.710-722.

Slon, V., Mafessoni, F., Vernot, B., de Filippo, C., Grote, S., Viola, B., Hajdinjak, M., Peyrégne, S., Nagel, S., Brown, S. and Douka, K., 2018. The genome of the offspring of a Neanderthal mother and a Denisovan father. Nature, 561(7721), p.113.

Wolf, A.B. and Akey, J.M., 2018. Outstanding questions in the study of archaic hominin admixture. PLoS genetics, 14(5), p.e1007349.