Can Biological Theories Explain Rolex Watches in Addition to Peacocks Tails?

Can biological theories explain Rolex watches in addition to peacock's tails?

As humans, we do many things which are not instrumentally useful in an evolutionary sense: we dance, get drunk, create art, listen to music, and dress up in expensive clothing, amongst other things. These exhibitions of "useless" behaviours cannot be accounted for simply because we are reported to be in an evolutionary disequilibrium (Kirk et al, 2001); even our ancestors exhibited many of these "useless" behaviours. Aborigines have been painting on rocks for at least 50,000 years, and using make up for twice that long; and painting, jewellery and musical instruments have been around for 35,000 years in Europe alone (Pinker, 2002). Indeed, many animal species engage in analogous activities, especially in the contexts of courtship displays and status contests. But how do we explain these seemingly useless behaviours, seen not only in humans, but across the animal world? Darwin (1871) concluded that natural selection was powerless to account for such apparently pointless splendour, particularly when faced with the evolution of excessively elaborate adornments such as the peacock's tail (Petrie et al., 1991). His solution was the theory of sexual selection, which is the selection for traits which are solely concerned with increasing mating success.

In many animal species, male traits have been subject to stronger sexual selection than female traits. Males of these species tend to compete for females and mate indiscriminately, whereas females are fastidiously choosier. This sex difference is attributably to the fact that males produce large amounts of 'cheap' sperm and females produce much larger, more valuable eggs and their parental investment is usually larger (Trivers, 1972). As a result of sexual selection, males of these species have adapted secondary sexual traits that are maladaptive. Zahavi's (1975) handicap hypothesis of sexual selection has increasingly come to dominate discussions about the evolution of these seemingly maladaptive secondary sexual traits (Andersson, 1994). Zahavi's theory predicts that female preferences have evolved for exaggerated sexual ornaments which signal male genetic quality, and these ornaments have coevolved to be larger and more costly. A variety of mechanisms have been proposed as advertisements of genetic calibre (e.g. antlers depicting calcium reserves (Trivers, 1985); bright feather colouration indicating parasite resistance (Hamilton and Zuk, 1982)). Classic experimental studies of this include Andersson's (1982) long-tailed widow bird, which showed that males with longer tails had significantly higher mating success; and the elaborate display of the song of the European sedge warbler (Catchpole, 1980) which shows that males with the most elaborate songs are the first to acquire mates.

Zahavi (1975, 1977, 1997) used the peacock's long tail to illustrate his theory. The peacock's tail is a handicap in day to day survival, a point that few would dispute. According to his theory, the deleterious structure that is the peacock's tail does, in fact, constitute as a valid indicator that the signalling animal is being honest in its claim of superiority, precisely because the trait is a handicap. By having a large, cumbersome tail that is grown over months where food is scarce, the peacock is advertising that he managed to find food and avoid predators, despite such a burden, proving that he is a high quality mate. The bigger the handicap, the more rigorous test he has passed.

But how can we extend Zahavi's theory to explain the useless behaviour exhibited by humans cross-culturally and throughout history? Zahavi's handicap theory shows us that useless or, more importantly, costly things can be paradoxically highly useful for a certain purpose: evaluating the assets of the bearer. This point was first made by Thornstein Veblen (1899) in his Theory of the Leisure Class where he wrote that the psychology of taste is driven by three "pecuniary canons": conspicuous consumption, conspicuous leisure and conspicuous waste. Conspicuous consumption and abstinence from work are the two ways the leisure class can distinguish itself from the labour class, with conspicuous waste being the main feature. Leisure is a waste of time and conspicuous consumption is a waste of money so Veblen came to the conclusion that all this waste is, in fact, a measure of social status. In order to distinguish themselves from others, people need to consume and advertise to display their wealth. This is an enduring battle for prestige where people who show off expensive jewels, Rolex watches, sports cars or works of art gain status because the signal cannot be faked. Miller (1999) called this the Sennheiser Effect; where top of the range products are the equivalent peacock's tails of humans. Their price is a benefit, not a cost.

Women, more than men, prefer mates that have a good earning potential (Buss, 1985, 1989) and by displaying wealth via conspicuous waste men increase their chances of mating by effectively saying 'I have plenty of money to support you and your children.' There is empirical support for these ideas; Essock-Vitale (1984) found that the Forbes 400, a modern equivalent of Veblen's leisure class, had significantly higher reproductive success compared with the general American population, and a positive correlation has been found between the resources possessed by a male and the reproductive success of his wife in the Kipsigis of Kenya (Borgerhoff Mulder, 1987).

The strive for social status in humans is biologically rooted. All human languages contain words referring to honour and status (Somit & Peterson, 1997) and it is cross-culturally and cross-temporarily valued as an important determinant in mate choice (Buss, 1989). Therefore, to be able to distinguish between signals of status are highly advantageous biologically and therefore subject to positive selection (Buss, 1989, 1994; Ellis, 1992). Men compete with other men for signals of status and the handicap principle can be applied to much costly or dangerous human behaviour aimed at achieving status or at sexual benefits in particular. Kwakiutl, American Indians of the Northwest seek status by performing an elaborate giveaway feast called potlatch rituals in which rival chiefs give away their property, or in extreme cases, burn down their own houses. The handicap principle explains the potlatch (Boone, 1998) as the chief who gave away his property was engaged in a form of costly signalling: sending a message to other chiefs that he was so rich that these things didn't matter. He could easily recover from such losses.

The deliberate and often painful modification of the human body, through tattooing or scarification