Portrait of the twins, age 16 (www.corbis.com) Masha and Dasha Krivoshlyopova were born in Moscow, Russia on January 4, 1950. They were ischiopagus tripus twins (their third, vestigial leg was amputated when they were 16 or 17 years old) with their spines conjoined at 180-degree angles. Their mother was told that the girls died moments after birth, but in reality they were spirited away to a Soviet research institute for study. For the next 20 years, the sisters were subjected to cruel experiments in order to determine which anatomical systems they shared. One sister would be placed in iced water, while doctors monitored the other's body temperature, or else one would be poked with needles to see if the other cried. They were five years old when they learned to walk and required crutches to move around, since their torsos were too far apart for them to balance naturally. Although they were given special clothes to wear for press photos, such as the ones shown here, they were usually kept naked or in hospital gowns and received substandard educations.

From 1993-2003, Masha and Dasha were the oldest living conjoined twins in the world. They lived in an apartment in Moscow. Several doctors offered to separate the twins using the surgical technology now available, but they declined. One sister said, "If we weren't conjoined, we would probably still live together." On April 17, 2003, Dasha, who was an alcoholic, died of a heart attack. Masha again refused separation, but was administered a sleeping pill. She died 17 hours later.