Friday, 26 June 2015

Decoration in humans and other animals

A wide variety of animals decorate their outer surface. In a review paper, Graeme D. Ruxton and Martin Stevens [1] have defined a decorator as: organism that (by means of specialist behaviour and/or morphology that has been favoured by selection for that purpose) accumulates and retains environmental material that becomes attached to the exterior of the decorator.

This definition is a bit complicated as it is designed for an audience of scientists, but you get the drift. Ruxton and Stevens then give us some examples, beginning with decorator crabs (below left) that attach all sorts of materials to hooked hairs present over the body of the animal:

Several studies..have found that experimentally altering or removing decoration [from decorator crabs] increased vulnerability to predators.. ..Items used in decoration are often chemically defended plants or sessile animals, and it seems plausible that predators detect the crab but actively avoid attacking because of the repellent smell or taste from the decorations. However, not all decorations provide the animals with chemical defence, and it is likely that decoration often functions through crypsis via background matching, masquerade and/or disruption.

Another type of decoration is seen in insects that use faecal shields, an example being larvae of the tortoise beetle (above right), where faecal pellets are retained on an extension of the body, so that the solidified shield provides cover for attack by predators. The shield acts both in crypsis and as a physical defence [1], isolating the body from potential attacks; other insects use a covering of faecal material directly on the surface of the upper body. However, decoration in insects is not confined to the use of faeces: other components of "backpacks" may be cast skins from moults, or organic, and mineral, grains obtained from the surrounding environment and stuck on to the back by secretions, or held there on hairs extending from the body surface.

Decoration is also used by birds (and I am not including those, like bower birds, that make collections of bright objects remote from the animal itself). To quote Ruxton and Stevens [1]:

In birds, a range of species add substances to their feathers that alter their appearance (termed cosmetic coloration).. Staining of the feathers with soil has been observed in a number of large birds.. ..Both sexes [of the rock ptarmigan] sport all-white plumage at the start of the breeding season, as snow melts this becomes very conspicuous and females moult to produce feathers that appear to offer good camouflage. By contrast, males do not moult immediately, but smear their feathers with soil before later moulting into a brown plumage.

Free-ranging adult bearded vultures..typically have an orange colour on their underparts, neck and head conferred by iron oxide-rich soils.. .. Colour tends to be greater in (socially dominant) females than males and increases progressively from juveniles, to immatures, to sub-adults to adults.

Ruxton and Stevens conclude their review by saying [1]:

Decorating is a particularly diverse activity, and (like tool-use) it is difficult to produce an unambiguous definition that covers all cases effectively.. .. Anti-predator benefits are most commonly postulated, in contrast to humans where decoration functions strongly in social interactions.

Their last sentence set me thinking. Unless one believes in Creation, it is not possible for us to look at the behaviour of our own species without realising that much of it developed as we evolved so successfully away from the rest of the Animal Kingdom. In this post, I describe the origins of human decoration, confining myself to clothes, accessories and make-up, as these best fit the definition given above.

Humans lack a dense covering of hair over the whole body and it is likely that our first use of decoration was by draping ourselves in animal furs that were protective and helped to keep us warm. It could be argued that this enabled early humans to migrate to regions with cooler climates, something that was also facilitated by the discovery of fire, but it is unlikely that animal pelts provided camouflage against predators. Camouflage coverings are certainly important in providing crypsis in warfare and they form an important part of the clothing using by contemporary fighters (below), together with applied face paints. This is analogous to the main use of decoration used by animals but most of our clothing, in addition to its functions of keeping us warm and protected, is used in expressing social status, for mate selection, or for group identity.

Among contemporary costume, the business suit is currently de rigeur for men in many countries and in many walks of life, with only small changes in the design of a jacket and trousers. There is status in having a designer label and this is true also of all clothes, something that conveys both the quality of materials and tailoring, but also exorbitant cost. The expression of wealth in this way is important in Western Society, as is the quantity of items in an individual's collection. Surprisingly, while the business suit represents a work uniform (although casual clothes for men are more varied), women's fashion is based on variety, and it is considered acutely embarrassing to wear an outfit that is identical, or too similar, to that worn by someone else at the same social function. Despite trends in fashion, decoration in women is thus less about uniformity and more about the uniqueness of the individual. Why?

The answer to this question probably lies ancestrally in mate selection. Humans do not have a breeding season and mating can occur at any time through the year. Mate selection is based on genetic factors – the classic notion of handsome men and beautiful women pairing up – but also on decoration. Clothes are an important part of this and initial mate selection is often influenced by clothes, as these convey information about social status and identity, something that is important if mate selection is for the long-term and where breeding is likely. Of course, there are more factors than decoration involved in selection, but it forms an initial signal, with most encounters initiated by men.

In addition to the decoration provided by clothes, there are also accessories, especially used by women, and we all know individuals with a shoe and/or handbag addiction. The most similar parallel to animal decorators comes in jewellery in all its forms. This type of decoration may emphasise status, as in the integration of precious stones, or be used as a symbol of lack of availability, as in wedding rings. Similar forms of decoration are present in many tribal cultures, not just those of the Developed World, and extend to neck rings, necklaces, nose plugs and rings, ear plugs, earrings and many other forms. They are not confined to women either, as they are used by both sexes as indicators of cultures and sub-cultures, something unknown among animals other than humans.

It is ironic that one design of earrings is based on the activity of an animal decorator. Larvae of some caddis flies make cases of stones that are bound together with silk secreted by the insect. This habit has been utilised by jewellers who give larvae semi-precious stones and wait for each earring to be produced [2]. It's the only example I can think of where the activity of one decorator animal is used by another, albeit for a different purpose.

In addition to clothes and accessories, considerable attention is given to enhancing the appearance using paints and powders of various kinds. Use of ochre and ash in face and body colouration is a characteristic of some "primitive" tribal groups, but make-up in Western Culture is usually more subtle, with concentration on the face. As with clothes and accessories, there are variations but, in general, powders are used to enhance the complexion and to hide blemishes, while various products are used to decorate the eyes and lips to provide emphasis. Although men use cosmetics, women are the main users and, as with other forms of decoration, the underlying message is related to mate selection and/or belonging to a social group.  

Just as humans evolved rapidly, so did our use of decoration. It now has many forms and is constantly changing, except in tribal cultures and where national costume, or work customs and uniforms, create an identity. However, we are animals and the origin of our use of clothing, accessories and make-up lies far back in evolutionary time.

[1] Graeme D. Ruxton and Martin Stevens (2015) The evolutionary ecology of decorating behaviour. Biology Letters 11: 20150325.

Wednesday, 17 June 2015

How did humans become such unique animals?

After conducting experiments on the preferences of "semi-free-ranging" chimpanzees when presented with cooked food, Felix Warneken and Alexandra G. Rosati [1] suggested that: "The transition to a diet of cooked foods – involving the use of heat in food preparation – was a fundamental change for our species." This point was taken up in an article by Pallab Ghosh, the BBC Science Correspondent [2]:

According to Dr Warneken [and Dr Rosati], his experiments show that most of the mental skills needed to cook were there in human ancestors between 5 to 7 million years ago and so all it took for the first emergence of the culinary arts was the controlled use of fire and the ability to trust other people not to pinch our food while our back was turned..

..The motivation for the study was to investigate a controversial theory that cooking was necessary for human brains to become larger. The idea by the primatologist Prof Richard Wrangham.. that cooking enabled our ancestors to eat more protein, which helped our ancestors develop their brains.

The BBC article went on to include extracts from an interview with Professor Fred Spoor of UCL:

Cooking did not happen until 300,000 to 400,000 years ago. That is late in 7 million years of human evolution, so to put it bluntly, who cares that early humans may have liked the idea of cooked food?..

..Substantially larger brains initially emerge around 1.5 million years ago and a major leap was around 500,000 years ago.

The series of quotes led me to think about how humans developed their unique position in the Animal Kingdom, with the power to manipulate the environment to an extent quite unlike that of any other organism. I dismiss the Creationist argument that humans resulted from the invention of a supernatural force and accept that our extraordinary capacities evolved from the nucleus of possibility in our ape-like ancestors. It was the phrase "the ability to trust other people not to pinch our food while our back was turned" that had me wondering about an explanation.

Let's assume our distant ancestors lived in family groups and that they foraged for food, gathering vegetable material and hunting animals, all of which were eaten without cooking, as this method of food preparation had yet to be discovered. Families are closely related genetically and the survivorship of individuals, and thus their "selfish genes", will have been enhanced if the hunters were successful in providing plentiful food to ensure the survival of all individuals. Let's assume further that hunters from several families joined together to make hunting more efficient and make the capture of larger prey possible. Interactions between members of this larger group would have required signals – vocalisations, movements of limbs, and facial expressions – that had evolved to give clearly understood information.

After years of successful co-operative hunting, what if one group of individuals gave the signal to co-operate, but then took the catch for themselves, maybe killing some individuals in other families to ensure plenty for their own family at a low cost? The signals no longer have their original meaning and the offer to form joint hunting groups, of advantage to all participants, now carries the risk of a different, less advantageous, outcome. There was thus a need to interpret meaning in communication, with the most successful manipulators, and the best readers of false signals, having the highest chance of survival.

If there was also selection of the optimal neural pathways needed to aid interpretation, these would be fixed in the population and the process of analysing hunting signals, and signals of many other kinds, would become more and more refined. This new consciousness would extend to humans asking questions about the environment around them, forming a complex language structure to explain meaning, and, with further development of the brain, a need to ask abstract questions like: "Why are we here?”; “Is there a supernatural force?”; and “What is good and evil?”.

Or perhaps it was not like that at all?

[1] Felix Warneken and Alexandra G. Rosati (2015) Cognitive capacities for cooking in chimpanzees. Proceedings of The Royal Society B 282: 20150229.

Wednesday, 3 June 2015

Sherlock Holmes, fairies and our imagination

Sherlock Holmes is the most famous fictional detective in the World, first appearing in a series of short stories in The Strand Magazine. As a result, his inventor, Sir Arthur Conan Doyle, is afforded the respect of a near-infallible sleuth. However, there was one case reported by Conan Doyle that showed some flaws: his support for the reality of the Cottingley Fairies, named after the village in Yorkshire where they were supposedly seen.

In 1920, Conan Doyle wrote an article in The Strand Magazine [1] supporting the view that two photographs of fairies, taken by two young girls, were real and not faked. To protect the identity of the girls, he used pseudonyms in his article and thus in the captions to the two photographs (shown below). One is labelled "Alice and the fairies" (taken in July 1917) and the other "Iris and the dancing gnome" (taken in September 1917, when Frances Griffiths (Alice), who was just 10-years-old, was staying with her 16-year-old cousin Elsie Wright (Iris). Elsie used her father's recently-acquired plate camera to take the first photograph and the second was taken using the same camera, presumably by Frances. The images intrigued Conan Doyle when he saw them three years later, prompting his article. He was convinced that the fairies in the photographs were real and three further plates, taken later, gave further evidence for his conviction.

Conan Doyle summarised his views, and those of others, in his book The Coming Of The Fairies [2], that appeared in 1922 and contains the article from the Christmas 1920 edition of The Strand Magazine. Several points from the article (that I have read in the original) are worth elaborating. Much centres on a report by Mr Edward L Gardner, a member of the Executive Committee of the Theosophical Society, who met with the girls, and other members of the family, after he was shown the photographs in 1920. Mr Gardner consulted experts in photography, who confirmed that they were genuine; he visited the spots where they were taken; and he met members of the family. His conclusion was:

Extraordinary and amazing as these photographs may appear, I am now quite convinced of their entire genuineness, as indeed would everyone else be who had the same evidence of transparent honesty and simplicity that I had.

That was good enough for Conan Doyle, who, as a Spiritualist, wanted to accept the evidence at face value. However, the investigative side of his nature, so evident in Sherlock Holmes, provided a note of caution. This was his conclusion after seeing the two photographs:

There is one point of Mr Gardner's investigation that should be mentioned. It had come to our knowledge that Iris [16 year-old Elsie] could draw, and had actually at one time done some designs for a jeweller. This naturally demanded caution, though the girl's own frank nature is, I understand, a sufficient guarantee for those who know her. Mr Gardner, however, tested her powers of drawing, and found that, while she could do landscapes cleverly, the fairy figures which she had attempted, in imitation of those she had seen, were entirely uninspired, and bore no possible resemblance to those in the photograph...

Other well-authenticated cases will come along. These little folk who appear to be our neighbours, with only some small difference of vibration to separate us, will become familiar The thought of them, even when unseen, will add a charm to every brook and valley and give romantic interest to every country walk. The recognition of their existence will jolt the material twentieth-century mind out of its heavy ruts in the mud, and will make it admit that there is a glamour and a mystery to life.

Like many adherents of clairvoyance etc., Conan Doyle suggests that those with supernatural powers are able to see such apparitions when those without such skills cannot [2]. A propensity to see things is thus a prerequisite for witnessing them and this must apply to all apparitions, whether they are ghosts, little people, or even the Virgin Mary. There are still those who believe the Cottingley Fairies existed, and plenty more that have sympathy with the views expressed in the last paragraph above. However, the photographs were the result of a hoax, as revealed in an interview by Joe Cooper with Elsie and Frances a few years ago [3].

It is interesting that Conan Doyle himself was close to solving the mystery. In The Strand Magazine article he writes this about the first photograph:

..the two upheld hands of the elves [in the first photograph] seen under a high power do not appear to be human, nor does the left foot of the figure capering on the right. The hands seem furred at the edges and the fingers to be in a solid mass. This also may be due to movement and position, but it is curious that both hands give the same impression. 

The figures were cut out from a book and it was not possible to cut round each finger, so the whole hand appeared rather solid. Each figure was then fastened to  a hat pin and inserted into the ground in front of Frances. Conan Doyle's deduction did not go this far, as he wanted the fairies to be real and this overcame his doubt.

According to experts, fairies come in many forms [4,5], in addition to those, like the Cottingley Fairies, that are the common type of benevolent creatures made popular in countless illustrations and films. As Katharine Briggs remarks in a section of her book dealing with whimsy [4]:

When they were given butterfly and dragonfly wings they were reduced to almost the status of insects, and in the sheltered days of the early twentieth century every care was taken to render them unalarming.

Briggs remarks that this tradition of fairies being winged had been in existence for over 200 years and probably originated when insects were being observed and human imaginations then left to run riot. An example can be given in a quote from a correspondent in Seeing Fairies by Marjorie T. Johnson [5]:

My sister was standing near the snapdragon plant in our garden when she saw a movement on it, and a tiny fairy flew out and settled on her arm for an instant, perhaps trying to show her gratitude to my sister for putting the stake [that supported the plant] there in the first place. When I asked for a description, my sister said she didn't look more than one and a half inches high and was "silvery, with small silver wings"..

So, in the view of those that believe in fairies, where do they fit into evolution?  Conan Doyle gives us the opinion of Edward Gardner, the Theosophist:

Fairies are not born and do not die as we do, though they have their periods of outer activity and retirement. Allied to the lepidoptera, or butterfly genus, of our familiar acquaintance rather than to the mammalian line, they partake of certain characteristics that are obvious. There is little or no mentality awake—simply a gladsome, irresponsible joyousness of life that is abundantly in evidence in their enchanting abandon. The diminutive human form, so widely assumed, is doubtless due, at least in a great measure, to the powerful influence of human thought, the strongest creative power in our cycle.. ..The wings are a feature that one would hardly expect to find in conjunction with arms. In this respect the insect type, with its several limbs and two or more wings, is a nearer model. But there is no articulation and no venation, and moreover the wings are not used for flying.

In contrast, one of Marjorie Johnson's correspondents reports that "wingless fairies can soar through the air quite effortlessly" but: is possible that they [fairies] have evolved from butterflies, since they attach so much importance to the use of their wings.. .. fairies, which are fully materialized, fly like butterflies by the power of their densified wings.

Conan Doyle [1] wrote that "A.. ..general observation is that the elves are a compound of the human and the butterfly, while the gnome has more of the moth." Confusing isn't it? There seems to be agreement that fairies evolved from butterflies, but what about the fairies with dragonfly wings? What were the steps in evolution that led to these insects/creatures having the appearance of a human body? We know that it is impossible for human-like figures to fly with insect wings, just as it is for angels to fly with bird wings [6], so do those that believe in wood and water spirits, of which fairies are a part, view them as part of evolution on Earth, or as something completely supernatural, like angels? For those that do not believe in a supernatural, there is no problem, except puzzlement at the level of imagination shown by all humans in what we believe.

[1] A. Conan Doyle (1920) Faries Photographed: an epoch-making event. The Strand Magazine 60: 462-468

[2] A. Conan Doyle (1922) The Coming Of The Fairies. London, Hodder & Stoughton.

[4] Katharine Briggs (1967) The Fairies in Tradition and Literature. London, Routledge & Kegan Paul.

[5] Marjorie T. Johnson (2014) Seeing Fairies. San Antonio, Anomalist Books.