A Soviet physiologist named Pyotr Anokhin dedicated his career to conducting experiments that sought to pinpoint the different functions of the human circulatory and central nervous systems, specifically when a person was sleep-deprived, subjected to extreme temperature changes, or denied sustenance. So, when conjoined twins Masha and Dasha were born in Moscow in 1950 possessing one body that contained a joint circulatory system and two separate nervous systems, Anokhin saw them as the perfect subjects for his future experimentation. 

Shortly after they were born, the twins were taken from their mother, who was told they had died of pneumonia just after birth. In reality, the sisters were transported to a nearby medical institute in Moscow where they became the subjects of extensive, life-altering experiments.

Since Masha and Dasha shared the same circulatory system but had separate nervous systems, scientists were particularly interested in testing each twin’s reaction (or lack thereof) to the other twin’s physical distress. The experiments they conducted involved tactics like covering one twin in ice while the other twin would be carefully observed for a reaction. Similar experiments were also conducted with extreme heat and painful stimuli. They were also reportedly injected with radioactive iodine to see if the substance would make its way from one sister’s bloodstream into the other’s. In another experiment, one twin was fed while the other starved, in an attempt to measure the gastric juices of both using tubes inserted into their stomachs.

The girls are also believed to have been electrocuted, and to have been deprived of sleep, particularly during their formative years, from birth to around age 12.

Just after they were born, the twins were sent to the Institute of Experimental Medicine in Moscow. Six months later, the doctor who had been experimenting on the girls was exiled and the twins were subsequently moved to the Academy of Medical Sciences Pediatric Institute – where the experiments were continued by other scientists.

At 6 years old, the girls were moved to Scientific National Institute of Prosthetics in Moscow, where they learned how to walk and read. Eight years later, the girls were moved to a boarding school for people with disabilities, before moving into an institution that cared for veterans. 

While the girls were living at the medical institute, the USSR Academy of Medical Sciences filmed many of their interactions with Masha and Dasha, from their infancy well into their early childhood years. The resulting film documents each of the twins being probed with various stimulus tools to measure the reaction of the ‘unharmed’ sister. The footage also shows them learning how to put on socks and use crutches for walking.

Masha became noticeably disobedient as soon as Soviet scientists began trying to measure the motor skills of the twins as toddlers. While Dasha would lift the leg she controlled in response to a nurse’s request to put socks on her, Masha would ignore the caregiver and even throw the sock away aggressively. As a result, Dasha quickly learned how to put socks on herself while Masha was unable – or unwilling – to concentrate on the task long enough to get it done.

As the sisters grew older, they became friends with a woman named Juliet Butler, who claims Masha would scream threats at Dasha while physically attacking her. Butler also noted that Masha often refused to let Dasha speak for herself in many of the trio’s conversations, and alleged that Masha compulsively lied and showed narcissistic tendencies.

Even when they were children, Dasha was far more compliant and emotionally vibrant than Masha. Experiments that called for cooperation from the girls always showed a marked difference in the sisters’ attention spans, motor skill development, and interest in other people.

As a toddler, Dasha was always the first to pass motor coordination tests and complete requested tasks. When asked to squeeze a bulb in response to seeing lights, for instance, Dasha would always react first and keep her mind focused on the task, while Masha was almost always argumentative and distracted.

As they grew older, Dasha continued to seek companionship and romance away from her sister, while Masha would stubbornly push people away.

According to Juliet Butler, a friend of the twins who wrote multiple books about their lives, Masha began beating and abusing Dasha while they were still in institutionalized care. Recounting an incident that occurred when the girls were 11, she told the Ottawa Citizen that Masha beat Dasha until her nose was bleeding, threatening to kill her.

Dasha’s only response was to attempt to clean up the blood once her sister fell asleep, in hopes that the hospital staff wouldn’t know what was happening.

When Dasha fell in love with a fellow student named Slava while attending the School for Invalids, Masha became enraged. As she grew older, Masha had become very controlling and manipulative, pushing people away, lying, and exhibiting other troubling signs of psychopathy.

Masha disapproved of Dasha’s relationship with Slava, and would even physically attack him at times. Masha preferred to avoid romantic relationships, but reportedly enjoyed watching movies with beautiful women in them. Maybe they just had different tastes.. Distressed by her inability to pursue love interests and the violently controlling nature of her sister, Dasha attempted to hang herself at the age of 18.

In more ways than one, Dasha was unable to live her life the way she wanted, as Masha managed to assert control over nearly every aspect of both of their lives. They had to keep their hair short and boyish, their clothes plain and androgynous, and there was never an opportunity for an outsider to enter Dasha’s life and provide the romance and affection she desperately craved.

Once the sisters were released from the hospitals and asylums they had been forcibly admitted to, Dasha began to drink alcohol regularly. On several occasions, she allegedly drank to excess in hopes that, through their shared bloodstream, Masha would get drunk enough to be unable to physically abuse her or verbally accost strangers that looked their way.

Years later, their mother Yekaterina managed to reconnect with Masha and Dasha and attempted to form a relationship with them. Unfortunately, Masha ran their mother off after only four years of reconciliation, returning the girls to a life of isolation.

Tragic Death

After spending over 53 years together, on April 17, 2003, Masha suffered from a deadly heart attack that left Dasha in a particularly vulnerable state. Unsure of what to do, doctors initially told Dasha that her sister was simply sleeping. “Dasha of course would have known the moment Masha’s heart stopped beating,” recalled a woman who was a long-time friend of the sisters.

Despite doctors suggesting she be promptly separated from her sister’s body, Dasha refused. Within 17 hours, Dasha died from blood poisoning, as her body had been slowly contaminated by the toxins that were being given off by her sister’s corpse.