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.

All Siamese have a creamy base coat with coloured points on their snouts, ears, paws and lower legs, tails and (in males) scrota. The pointed pattern is a form of partial albinism, resulting from a mutation in tyrosinase, an enzyme involved in melanin production. 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 (a cool grey) points, genetically a dilution of seal point; chocolate (lighter 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. 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.
This Siamese cat demonstrates the once common cross-eyed traits that has been largly eliminated today through selective breeding.
Siamese 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 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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