In species which reproduce sexually, sexual attraction is attraction to other members of the same species for reproduction. This type of attraction is a very important survival factor.
Sexual attraction in animals
Sexual attractiveness in non-human animals depends on a wide variety of factors. Often, there is some element of the animal's body which is adapted to be sexually attractive to the opposite sex: the bright plumage and crests of some species of birds, for example. In many species, there are behaviors which appear to be adapted for sexual display. Some of these attributes seem to be adapted to demonstrate fitness and health, for example by demonstrating the ability to sustain an "expensive" feature with no other apparent survival function. The adaptation takes place in the displaying gender in parallel to the development of the prefenece in the other gender. It is possible for the adaptation to be so expensive in terms of fitness that it causes major survival problems (see game theory), especially where, as in moose, a direct competitive element is involved.
Frequently (especially in insects) chemical signals are used to generate sexual interest and to locate potential mates. These signals, known as pheromones, can produce a profound effect upon an animal's behaviour even when present in very minute quantities.
Common elements of sexual attraction in humans
Typically, sexual attraction refers to a person being drawn to another in order to have a sexual relationship.
Sexual attractiveness of a person to another person depends on both persons; to some extent there is universal agreement as to what is sexually attractive among a species, but individuals have subjective opinions as well.
Much of human sexual attractiveness is governed by physical attractiveness. This involves the senses, in the beginning especially:
- visual perception (how the other looks)
- audition (how the other sounds, mainly the voice; what may also vary widely is how noisily somebody walks (also depending on the footwear), but this is not necessarily a big factor for sexual attraction, either way)
- olfaction (how the other smells, naturally or artificially; the wrong smell may be repulsive).
(disputed — see talk page) Some studies suggest that the source of the physical attraction of a human male to a human female is dependent upon a proportion between the width of the hips and the width of the waist (see Golden ratio).
As with animals, pheromones may also enter into the picture, though less significantly than in the case of animals. Theoretically, the "wrong" pheromone smell may cause someone to be disliked, even when they would otherwise appear attractive. Frequently a pleasant smelling perfume is used to encourage the member of the opposite sex to more deeply inhale the air surrounding its wearer, increasing the probability that the pheromones from the individual will also be inhaled. The importance of pheromones in human relationships is probably limited and widely disputed (http://www.straightdope.com/classics/a2_206.html), although it appears to have some scientific basis (http://www.sciam.com/article.cfm?articleID=0007F9B4-B6D4-1C60-B882809EC588ED9F&sc=I100322).
A sexually attractive visual appearance in humans generally involves:
- a general body shape and appearance sanctioned by the local culture.
- a lack of visible disease or deformity.
- a high degree of mirror symmetry between the left and right sides of the body, particularly of the face.
- pleasing bodily posture.
However, these factors are complicated by many other factors. There may sometimes be a focus on particular features of the body, such as breasts, legs, hair, or musculature.
Factors determining sexual attraction of women
A strong aspect to sexual attraction is proportion. It is typical for a plastic surgeon to correct an error of proportion, such as making a nose that is too big smaller (via rhinoplasty), or making breasts that are too small larger via breast implants.
One idea of physical beauty regarding the breasts of women is that the best shape approaches the shape of a three dimensional parabola (which is called a Paraboloid of revolution) as opposed to a hyperbola, or a sphere. Conversely, the shape of the buttocks of an attractive person (male or female) tends to resemble the shape of a cardioid, which is the inverse transform of a parabola.
The appearance of health also plays a part in physical attraction. Often, women with long hair appear more beautiful as the ability to grow long healthy looking hair is an indication of continuous health of the individual growing it. Another indication of health of an individual is the ability to grow long, strong, fingernails. Therefore, artificial nails and manicures have become widely popular in late 20th century with women.
Factors determining sexual attraction of men
Sexual attraction for man by a woman is determined largely by the height of the man. For the woman, the man should be at least a few inches taller than her in order for her to be sexually attracted to him. It would be preferable if the man is at least a little above the average in height in the given population of males. This implies that women look for signs of social dominance and power as factors that determine male beauty. Women get attracted to men who display possession of resources and wealth, shows influence in social group, and display a promise or prospect of upward social mobility.
Males demonstrate attractiveness by, sometimes, demonstrating their levels of the hormone testosterone by growing larger and well-defined muscles through exercise.
At various times in history and throughout various cultures and sub-cultures the growth, maintenance and display of facial or body hair produced as a by-product of testosterone activity within male bodies has been considered a primary characteristic of sexual attractiveness, and of a display of masculinity in general. Cultural development seems to oscillate through multi-generational cycles from one pole to another: extreme hair growth, especially of facial hair accompanied by elaborate grooming rituals is often followed within a couple of generations by a widespread antipathy to body hair and the widespread adoption of depilatory practices.
The causal mechanism for this oscillation has not been established but differences in the simultaneous characterisation of body hair attractiveness within a culture between different social classes may indicate that the dynamic force driving the diffusion of differing male body hair social practices is in fact mate selection by females. Sociological and genetic studies in developed nations have indicated that in general females tend to mate with males of a slightly higher socioeconomic status. Therefore there are several loci of female attraction to male body hair "chasing" each other through society in a roughly vertical direction. Thus particular male attitudes to their body and facial hair within a social stratum are generated largely by the attitudes extant within women of a slightly lower socioeconomic status.
Personality and sexual attractiveness
Provided that all of the above listed aspects are reasonably normal, there is no requirement for great physical beauty for a person to be sexually attractive, and personality and good manners can come to the fore. In many cases, people with good personality can be strikingly sexually attractive, even if they are superficially sexually unattractive in appearance. The personality characteristics of a dominant male may override any other logical or superficial flaws.
Imprinting and sexual attraction
The Westermarck effect was discovered by anthropologist Edward Westermarck. When two people live in domestic proximity during the first 30 months in the life of either one, both are desensitized to later close sexual attraction and bonding.
Many people exhibit high levels of sexual fetishism, and are sexually aroused by other stimuli not normally associated with sexual arousal. The degree to which such fetishism exists or has existed in different cultures is controversial.
Often the result of a sexual attraction is sexual arousal.