However, they were not the first - Mary and Eliza Chulkhurst, known as the Biddenden maids after the Kent village in which they were born in1100, are the earliest recorded example - and cases, though rare, still occur. Eleven-month-old Nepalese babies, Goh and Jamuna Shrestha, joined at the head, were separated in a 90-hour operation earlier this month.
When Eng and Chang were born, the midwives fled in horror, believing them to be monsters. But their mother looked after them and made them exercise to stretch the short ligament connecting them until they were able to stand side by side instead of face to face. They visited the King of Siam, Rama III, who resisted calls from the superstitious citizens that they be put to death. They learned to run, swim and handle a boat, and after their father died they continued his business of breeding ducks and selling eggs.
When they were 14, Scottish merchant Robert Hunter saw the twins swimming in a river. Thinking he had witnessed a strange new mammal, he followed them and eventually, for a sum of money, persuaded their mother to let them travel with him to the United States. As the "Siamese double boys", they appeared in theatres, performing gymnastics, playing badminton and offering to lift members of the audience. They travelled widely in the US and Europe - except France, where the authoritie refused them entry on the grounds that they might influence pregnant women to bear similar "monstrosities".
By their twenties they were living well on the proceeds of these freak shows and had settled in North Carolina as farmers, becoming American citizens and adopting the surname of a friend. They married sisters, Adelaide and Sarah Yates, although Eng had to woo Sarah for several years before she agreed to their unusual union, and between them they fathered 21 children, none of whom were twins.
Today, it would be a relatively simple medical procedure to disjoin them, but 19th century surgeons, without anaesthetic or antibiotics, refused the twins' requests to be separated. They did not share any internal organs although their nervous systems were linked, and when one was tickled the other would jump.
In cartoons of the day the Bunker twins became symbolic of the two sides in the American Civil War - joined yet wanting independence - and their existence posed legal dilemmas. When Chang punched a member of their audience a judge refused to imprison him because it would have meant jailing an innocent man, Eng.
Chang became a Roman Catholic and a heavy drinker, while Eng was a Baptist teetotaller. Despite their condition they enjoyed relatively good health until 1870 when Chang suffered a stroke. Four years later he had another and died, aged 64. Within a few hours, Eng, too, died.
HARVEY McGAVIN. Photograph from Hulton Getty.
Social history of conjoined twins: http:zygote.swarthmore.educleave4b.html
Novel based on their story: www.changandeng.com General site: www.twinstuff.com