The Siamese is one of the first distinctly recognised breeds of Oriental cat. The exact origins of the breed are unknown, but it is believed to be from Southeast Asia, and is said to be descended from the sacred temple cats of Siam (now Thailand). In Thailand, where they are one of several native breeds, they are called Wichien-maat (วิเชียรมาศ, a name meaning "Moon diamond"). In the twentieth century the cats became one of the most popular breeds in Europe and North America.

The Siamese or 'Moon Diamond'

Siamese generally have a creamy colouration to their under fur with similar coloured points on their snouts, ears, paws and lower legs and tails. The pointed pattern is a form of partial albinism, resulting from a mutation in the melanin producing enzyme within the cats metabolism. The mutated enzyme is heat-sensitive; it fails to work at normal body temperatures, but becomes active in cooler areas of the skin. This results in dark colouration in the coolest parts of the cat's body, including the extremities and the face, which is cooled by the passage of air through the sinuses.

All Siamese kittens, although pure cream or white at birth, develop visible points in the first few months of life in colder parts of their body. By the time a kitten is four weeks old the points should be clearly distinguishable enough to recognise which colour they are. Siamese cats tend to darken with age, and generally adult Siamese living in warm climates have lighter coats than those in cool climates.

Originally the vast majority of Siamese had seal (extremely dark brown, almost black) points, but occasionally Siamese were born with blue (or light grey) points, genetically a dilution of seal point; chocolate (light brown) points, a genetic variation of seal point; or lilac (pale warm gray) points, genetically a diluted chocolate. These colours were at first considered "inferior" seal points, and were not qualified for showing or breeding. Each of these shades were eventually accepted by the breed associations, and became more common through breeding programmes specifically aimed at producing these colours. Later, 'outcrosses' with other breeds developed Siamese-mix cats with points in other cat colours and patterns including red point, lynx (tabby) point, and tortoise-shell ("tortie") point.

Here in the United Kingdom, all pointed Siamese-style cats are considered to be part of the Siamese breed. In the United States, the major cat registry, the Cat Fanciers' Association, considers only the four original colourations as Siamese: seal point, blue point, chocolate point, and lilac point. Oriental cats with colourpoints in colours or patterns aside from these four are considered Colourpoint Shorthairs in the American cat fancy.

Siamese cats may demonstrate the once common cross-eyed trait that has been largely been eliminated today through selective breeding.Siamese also have almond-shaped, bright blue eyes and short, flat-lying coats. Many Siamese cats from Thailand had a kink in their tails but over the years this trait has been considered to be a flaw and breeders have largely eradicated it, although it persists among street cats in Thailand. Many early Siamese were cross-eyed to compensate for the abnormal uncrossed wiring of the optic chiasm, which is produced by the same albino allele (or gene) that produces coloured points. Like the kinked tails, the crossed eyes have been seen as a fault and through selective breeding, the trait is far less common today.

Temperament

Siamese are affectionate and intelligent cats, renowned for their social nature. They enjoy being with people and are sometimes described as "extroverts". They are extremely vocal, with a loud, low-pitched voice – known as "Meezer", from which they get one of their nicknames – that has been compared to the cries of a human baby, and persistent in demanding attention. They also have a great need for human companionship. Often they bond strongly to a single person. These cats are typically active and playful, even as adults.
The social orientation of Siamese cats may be related to their lessened ability to live independently of humans. Siamese coat colouration is appealing to humans, but is ineffective for camouflage purposes. They are less active at night than most cats, possibly because their blue eyes lack a tapetum lucidum, a structure which amplifies dim light in the eyes of other cats. Like blue-eyed white cats, they may also have reduced hearing ability. Therefore, being dependent on humans may have been a survival trait for ancestors of the Siamese.

History

Siamese cats have existed for centuries in Thailand (formerly Siam). The pointed cat known in the West as "Siamese" is one of several breeds of cats from Siam described and illustrated in manuscripts called "Tamra Maew" (Cat Poems), estimated to have been written in the 1700s.
The breed was first seen outside their Asian home in 1884, when the British Counsul-General in Bangkok, Edward Blencowe Gould (1847-1916) brought a breeding pair of the cats, Pho and Mia, back to Britain as a gift for his sister, Lilian Jane Veley (who went on to be co-founder of the Siamese Cat Club in 1901). Just one year later, three kittens were produced by Pho and Mia. These kittens – Duen Ngai, Kalohom, and Khromata – and their parents were shown at the Crystal Palace Show in 1885, where they made a huge impression because of their unique appearance and distinct behavior. Unfortunately, all three of the kittens died soon after the show. The reason for their deaths is not documented.
The following year another pair (with kittens) were imported by a Mrs. Vyvyan and her sister. Compared to the British Shorthair and Persian cats that were familiar to most Britons, these Siamese imports were longer and less "cobby" in body, had heads that were less round with wedge-shaped muzzles and had larger ears. These differences and the pointed coat pattern which had not been seen before by Westerners, produced a strong impression--one early viewer described them as "an unnatural nightmare of a cat". But these striking cats also won some devoted fans and over the next several years fanciers imported a small number of cats, which together these formed the base breeding pool for the entire breed in Britain. It is believed that most Siamese in Britain today are descended from about eleven of these original imports. Several sources give Gould's brother Owen Nutcombe Gould (1857-1929) as the British Consul-General in Bangkok, but Owen was only 27 in 1884 and not known to be in Bangkok. In their early days in Britain they were called the "Royal Cat of Siam", reflecting reports that they had previously been kept only by Siamese royalty. Later research has not shown evidence of any organised royal breeding programme in Siam.

The original Siamese imports were, like their descendants in Thailand today, medium-sized, rather long-bodied, muscular, graceful cats with moderately wedge-shaped heads and ears that were comparatively large but in proportion to the size of the head. The cats ranged from rather substantial to rather slender but were not extreme in either way.

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In the 1950s - 1960s, as the Siamese was increasing in popularity, many breeders and cat show judges began to favor the more slender look and as a result of generations of selective breeding, created increasingly long, fine-boned, narrow-headed cats; eventually the modern show Siamese was bred to be extremely elongated, with thin, tubular bodies, long, slender legs, a whip-thin tail and long, narrow, wedge-shaped heads topped by extremely large, wide-set ears. The major cat organisations altered language and/or interpretation of their official breed standards to favor this newer streamlined type of Siamese, and the minority of breeders who stayed with the original style found that their cats were no longer competitive in the show ring.

By the mid-1980s, cats of the original style had disappeared from cat shows, but a few breeders, particularly in the UK, continued to breed and register them, resulting in today's two types of Siamese – the modern "show-style" Siamese, and the "traditional" Siamese, both descended from the same distant ancestors, but with few or no recent ancestors in common. In the late 1980s, breeders and fans of the older style of Siamese organised in order to preserve old, genetically healthy lines from extinction, educate the public about the breed's history and provide information on where people could buy kittens of the more moderate type. Several different breeders' organisations have developed, with differing breed standards and requirements (such as whether or not cats must have documented proof of ancestry from an internationally recognised registry). Partially due to such disagreements, there are several different names used for the cats, including "Traditional Siamese", "Old Style Siamese", "Classic siamese" and "Appleheads" (originally a derogatory nickname coined by modern-type Siamese breeders as an exaggerated description of less extremely wedge-shaped heads). The popularity of the older body style has also led to pointed mixed-breed cats that may have few or no Siamese ancestors being sold as "Traditional Siamese" to uninformed buyers, further increasing confusion over what a "real" Siamese looks like.

Other breeds derived from the Siamese

• Balinese – a longhaired Siamese. In the largest US registry, the Cat Fanciers Association (CFA), limited to the four traditional Siamese coat colours of seal point, blue point (a dilute of seal point), chocolate point and lilac point (a dilute of chocolate point). Other registries in the US and worldwide recognise a greater diversity of colours.
• Burmese is a breed of domesticated cats descended from a specific cat, 'Wong Mau', who was found in Burma in 1930 by Dr. Joseph G. Thompson. She was brought to San Francisco, California, where she was bred with Siamese. While technically not derived from Siamese, the breed was considered to be a form of Siamese for many years, leading to cross-breeding.
• Colourpoint Shorthair – a Siamese-type cat registered in CFA with pointed coat colours aside from the traditional CFA Siamese coat colours; originally developed by crosses with other shorthair cats. Considered to be part of the Siamese breed in all other cat associations, but considered a separate breed in CFA. Variations can include Lynx Points and Tortie Points.
• Himalayan - Long-haired breed originally derived from crosses of Persians to Siamese and pointed domestic longhair cats in order to introduce the point markings and the colours chocolate and lilac. After these initial crosses were used to introduce the colours, further breed development was performed by crossing these cats only to the Persian breed. In Europe they are referred to as colourpoint Persians. In CFA they are a colour division of the Persian breed.
• Javanese – a longhaired version of the Colourpoint Shorthair in CFA. In Europe, an obsolete term for the longhaired version of the Oriental Shorthair.
• Ocicat – a spotted cat originally produced by a cross between Siamese and Abyssinian.
• Old Style Siamese – The Old-Style Siamese (OSS) also known as Thai, are the original type of cats from Thailand, brought to America on January 3, 1879 as a gift from the American consul in Bangkok to the President's wife, Mrs. Lucy Webb Hayes, and are still bred and seen in Thailand today.
• Oriental Shorthair – a Siamese-style cat in non-pointed coat patterns and colours, including solid, tabby, silver/smoke, and tortoise-shell.
• Oriental Longhair – a longhaired version of the Oriental Shorthair.
• Serengeti Cat – a spotted breed created to resemble the Serval, from Siamese, Oriental Shorthair, and Bengal crosses.
• Snowshoe – a cream and white breed with blue eyes and some points that was produced through the cross-breeding of the Siamese and bi-coloured American Shorthair in the 1960s.
• Tonkinese – a cross between a Siamese cat and a Burmese. The Tonkinese are "pointed" cats but their bodies are of a darker colour than the Siamese.
• Thai Cat – a pointed cat also called the Thaikatzen which represents the early 20th century Siamese, and can (it is said) still be found in Thailand catteries.