While there is significant variation in anatomical proportions between people, there are many references to body proportions that are intended to be canonical, either in art, measurement, or medicine.
In measurement, body proportions are often used to relate two or more measurements based on the body. A cubit, for instance, is supposed to be six palms. A span is taken to be 9 inches and was previously considered as half a cubit. While convenient, these ratios may not reflect the physiognomic variation of the individuals using them.
Similarly, in art, body proportions are the study of relation of human or animal body parts to each other and to the whole. These ratios are used in depictions of the figure (to varying degrees naturalistic, idealized or stylized), and may become part of an aesthetic canon within a culture.
It is important in figure drawing to draw the human figure in proportion. Though there are subtle differences between individuals, human proportions fit within a fairly standard range, though artists have historically tried to create idealised standards, which have varied considerably over different periods and regions. In modern figure drawing, the basic unit of measurement is the 'head', which is the distance from the top of the head to the chin. This unit of measurement is reasonably standard, and has long been used by artists to establish the proportions of the human figure. Ancient Egyptian art used a canon of proportion based on the "fist", measured across the knuckles, with 18 fists from the ground to the hairline on the forehead. This was already established by the Narmer Palette from about the 31st century BC, and remained in use until at least the conquest by Alexander the Great some 3,000 years later.
A study using Polish participants by Sorokowski found 5% longer legs than an individual used as a reference was considered most attractive. The study concluded this preference might stem from the influence of leggy runway models. The Sorokowski study was criticized for using a picture of the same person with digitally altered leg lengths which Marco Bertamini[who?] felt were unrealistic.
Another study using British and American participants, found mid-ranging leg-to-body ratios to be most ideal.
A study by Swami et al. of American men and women showed a preference for men with legs as long as the rest of their body and women with 40%[clarification needed] longer legs than the rest of their body. The researcher concluded that this preference might be influenced by American culture where long-legged women are portrayed as more attractive. The Swami et al. study was criticized for using a picture of the same person with digitally altered leg lengths which Marco Bertamini felt were unrealistic. Bertamini also criticized the Swami study for only changing the leg length while keeping the arm length constant. Bertamini's own study which used stick figures mirrored Swami's study, however, by finding a preference for leggier women.
Another common measurement of related to leg-to-body ratio is sitting-height ratio (SHR). Sitting height ratio is the ratio of the head plus spine length to total height which is highly correlated to leg-to-body ratio. SHR has been found to be very different between individuals of different ancestry. It has been reported that individuals with African ancestry have on average longer leg length, i.e. lower SHR than individuals of European ancestry. A study in 2015 revealed that this difference is mainly due to genetic differences and the SHR difference between African and European individuals is as large as 1 standard deviation.
A 1999 study found that "the (action) figures have grown much more muscular over time, with many contemporary figures far exceeding the muscularity of even the largest human bodybuilders," reflecting an American cultural ideal of a super muscular man. Also, female dolls reflect the cultural ideal of thinness in women.
The ancient Greek sculptor Polykleitos (c.450-420 BC), known for his ideally proportioned bronze Doryphoros, wrote an influential Canon describing the proportions to be followed in sculpture. The Canon applies the basic mathematical concepts of Greek geometry, such as the ratio, proportion, and symmetria (Greek for "harmonious proportions") creating a system capable of describing the human form through a series of continuous geometric progressions. Polykleitos uses the distal phalanx of the little finger as the basic module for determining the proportions of the human body, scaling this length up repeatedly by to obtain the ideal size of the other phalanges, the hand, forearm, and upper arm in turn.
Leonardo da Vinci believed that the ideal human proportions were determined by the harmonious proportions that he believed governed the universe, such that the ideal man would fit cleanly into a circle as depicted in his famed drawing of Vitruvian man (c. 1492).
Leonardo's recorded information was about relative body proportions - with comparisons of hand, foot, and other feature's lengths to other body parts - more than to actual measurements. He was a prodigious note writer and small sketch draftsman. After 1490, he left voluminous manuscripts including studies on proportions. These were later collected and translated into English by Jean Paul Richter and published in 1883.
Avard T. Fairbanks taught in five universities. His proportions study was used for college instruction. The main male and female illustrations (1936) were drawn to accompany Leonardo's system of relative proportions. He erected more than 100 public monuments over the course of his 75 year career. His son, Eugene F. Fairbanks published books based on this study and his own study of children's proportions.
Drawings by Avard T. Fairbanks developed during his teaching career. This image was used in Eugene F. Fairbanks' book on Human Proportions for Artists.
All were head shots of the same person with different distances from eyes to mouth or between the eyes. She was at her most attractive when the space between her pupils was just under half, or 46 per cent, of the width of her face from ear to ear. The other perfect dimension was when the distance between her eyes and mouth was just over a third, or 36 per cent, of the overall length of her face from hairline to chin. ...