During the Christmas season, homes are festooned with all sorts of decorations. But if we look around when they come down, we’ll notice the more modest ways we adorn our living spaces — with pictures, flowers and fabrics. We also decorate our bodies with makeup, jewellery, clothes and more. We rarely pause to consider the importance and ubiquity of this commonplace practice. In fact, our obsession with embellishment can be seen across all civilisations, societies, and periods. We are the species that puts flowers in its hair and paints itself.

The use of jewellery is ancient. Perforated seashells, presumably worn as necklaces or bracelets, have been found in graves more than 130,000 years old. Gold and silver were widely sought and traded across much of the ancient world, along with jade, amber, coral, pearl and obsidian. Some 3,400 years ago there was already a huge commercial market in glass beads; over the following millennia, these were exported over much of the world.

The application of makeup and body paint also has a long history. More than 100,000 years ago, our ancestors collected bright red shades of ochre. The Greeks and Romans continued to trade in scents, lotions and cosmetics across ancient Egypt and the Middle East. From Roman cosmetics to the scents and makeup in ancient India and Asia, the application of makeup and body paint has a long history. The mummified remains of Egyptian priestesses from 4,000 years ago bear tattoos (instruments for tattooing date back some 20,000 years), and there is also a long tradition of tattooing in Asia and the Pacific.

The use of self-decoration is not only ancient but nearly universal. Few individuals completely shun aesthetic embellishments. We have shaped our self-presentation and social interactions around practices that enhance us with carefully chosen aesthetic adornments. More than morality, religion, or art, the desire for bodily adornment is a common signature among our species.

Decoration involves making things that are aesthetically pleasing by augmenting their beauty or sublimity. Typically, decoration is intentional. The audience is supposed to notice the beautifying intention, the effort expended, and the improvement achieved. Adorning practices can become institutionalised, and in those cases the relevant intention and response is only implicit. A vase of flowers decorates a hotel’s front desk, even if it isn’t admired by those checking in, for example.

Many decorations have no meaning. Their sole function is to add beauty. But others, especially those connected to the body, convey important social messages while retaining their underlying aesthetic purpose. They indicate age, sex, gender, class, wealth, social status, religion and occupation. They commemorate our achievements or memorisalise our losses. Our decorations also mark special occasions, such as Christmas, and they can indicate our social affiliations. Religious groups, for example, often wear distinctive attire.

Adornments identify and situate the people who bear them and the things they care about. By their adornments, we can get a fair idea of who we are dealing with and what they value – helping us to interact with each other. But decorations can also be used to send deliberately misleading messages. Someone might wear clothes they can’t readily afford, thereby intimating status or wealth that they lack.

Since reproduction plays an important role in most people’s lives, decorations often send signals about our circumstances as possible mates. Though gender-based generalisations are crude, and should be applied with caution, we can see across history how each sex has catered to the preferences of the other in the adornments it favours, with women using makeup to simulate youthfulness (synonymous with fertility) and men decorating themselves with adornments that signal status and wealth.

To the extent that wealth and reputation can be lost or gained, men’s decorations tend to be impermanent. In many tribal and traditional societies, decorations worn by men frequently take the form of body paint or insignia, while women’s bodies are decorated with marks that are more permanent to communicate puberty, marriage and childbirth.

We can also predict that people will be inclined to distrust the reliability of the signals sent by the other’s adornments. This is particularly apparent in men’s ambivalence toward women’s decorations throughout history. Men are drawn to women who employ makeup, but are highly critical of what is regarded as its overuse. To mention just one case, an edict issued in England during the sixteenth-century observed that “any woman who through the use of false hair, Spanish hair pads, make-up, false hips, steel busks, panniers, high-heeled shoes or other devices, leads a subject of her majesty into marriage, shall be punished with the penalties of witchcraft.” And it isn’t as if the association of makeup with vanity, immodesty, and vice has been entirely left behind in modern times.

There are many exceptions to these observations. This is to be expected since decorations can be used to send many other kinds of messages, and we should also challenge the implicit gender-stereotyping such views assume. Reducing female beauty to youthful sexual attractiveness dismisses the many other human beauties that we value, such as those of graceful elegance or athletic prowess. Meanwhile, the ideas that the male parental role is that of provider and that mothers cannot possess status or wealth in their own right might be unfortunate consequences of socialised patriarchy rather than of biology. Besides, even if some decorative practices were once concerned primarily with mate attraction, they were long ago co-opted to broader social practises of self-presentation and social identity. It isn’t as if people give up their styles of ornamentation after mates have been found or children birthed.

It’s also important to notice the cultural relativity of many judgments both of beauty and of the effects produced by bodily decoration. Widespread indigenous adornment practices include tattooing, piercings, scarification, ear and lip plugs, neck coils, and labrets. (The latter are piercings, usually from the interior of the mouth, that support ornaments, such as veils of beads, that hang on the outside of the face.) While some of these occur also in Westernised societies, they have often been viewed negatively. Tattoos, for instance, were not always be employed as adornments, but instead used to brand slaves and punish criminals.

Tattoos and scars, especially on the face, are sometimes repellent to people with cultural traditions deriving from religions in which people are said to be made in God’s image. But some other groups regard people as unfinished or uncivilised until their bodies have been marked. Many African peoples consider beauty to be an effect of scarification, not innate. Scars may serve as tribal insignia or as marks of achievements alongside their beautifying function. The same is true for tattoos. Some New Guineans regard a person as “raw” if they aren’t tattooed. Many peoples adopt tattoos for their beautifying effects. And when tattoos serve other purposes, aesthetic enhancement is a subsidiary function that is widely acknowledged.

This cultural relativity is apparent also where people draw the line between bodily adornment and regular bodily maintenance. In one society, the removal of body hair might amount to regular bodily maintenance. In another, it could be viewed as body adornment, insofar as it is a form of aesthetic improvement, or even thought of as abnormal.

In exceptional cases, decoration goes far beyond aesthetic augmentation. Indeed, it transfigures the bearer’s identity. Consider a jewel-encrusted sword with a gold blade. It can no longer function as a fighting weapon, though it might now become a ceremonial item. In a similar fashion, the body, rather than being highlighted via its adornments, can be demoted to the status of a canvas that supports them. The body’s owner disappears under the patina of decoration that is applied to them. Here, ornamentation aspires to the status of art – it, and not the bearer, is the intended focus.

Christmas lights can be so elaborate that they transform ordinary homes into kaleidoscopic castles. We might think of these like a bejewelled sword, or as examples of decorative art. But no matter how you dress-up your home over Christmas, the diverse ways we decorate ourselves and our surroundings make one thing clear: adornment is the mark of the human.

Stephen Davies is Distinguished Professor of Philosophy at the University of Auckland. He is the author of Adornment: What Self-decoration Tells Us About Who We Are.

This article is part of the Agora series, a collaboration between the New Statesman and Aaron James Wendland, Professor of Philosophy at the Higher School of Economics. He tweets @ajwendland.