Possibly reflecting the resilience of the human spirit, Holocaust survivors live longer than comparable people who did not experience the Shoah, a new study by researchers in Haifa and Leiden universities revealed.

The study, published July 24 in online scientific journal PLOS ONE, found that male Jewish Holocaust survivors lived on average 14 months longer than Jews who immigrated to Israel before the Second World War and that the older they were when they experienced the trauma, the longer they lived.

The surprising findings were based on researchers’ analysis of data gathered from Israel’s National Insurance Institute on 55,220 Polish immigrants. Using 2011 numbers, the researchers compared 13,766 immigrants who arrived in Israel before 1939 (the control group) to 41,454 people who immigrated between from 1945 to 1950 (Holocaust survivors). In order to offer comparable results, in both groups the researchers selected only people who were aged between 4 and 20 in 1939.

The study did not differentiate between different Holocaust experiences because “it was assumed that any Jew who was in Europe between the years 1939–1945, and in Poland in particular, should be defined as a Holocaust survivor, because no matter what the specific nature of the experience was (e.g., concentration camp, hiding in convents or elsewhere) normal life was in jeopardy.”

“Given the damaging living conditions of Holocaust survivors during part of their lives, we expected to find that the risk of Holocaust survivors to die younger is greater than that of comparisons without Holocaust background,” wrote the authors in their introduction. But overall, the survivors’ life expectancy was 6.5 months longer than those who left Poland before the war.

The analysis revealed little difference between women in the two groups. But the difference among men was significant, with Holocaust survivors living between 10 and 18 months longer.

The study found that the older the surviving men were at the time of the Holocaust, the bigger the life expectancy discrepancy between them and those who left Poland before the war.

“Men who were 10-15 years old during the war and in their early adolescence had a 10 month longer life-expectancy compared to the control group. Men who lived through the Holocaust when they were 16-20, had an even bigger difference in life-expectancy, 18 months longer than their peers with no Holocaust experience,” study leader Avi Sagi-Schwartz, head of the Center for the Study of Child Development at the University of Haifa in Israel, said in a university news release.

“Such findings may highlight the resilience of survivors of severe trauma, even when they endured psychological, nutritional, and sanitary adversity, often with exposure to contaminating diseases without accessibility to health services,” said Sagi-Schwartz.

The researchers offered two explanations for their surprising findings. They suggested the survivors may have experienced post-traumatic growth — their traumatic experiences and psychological distress during the Holocaust encouraging them to develop personal skills and insights into a deeper appreciation for life that, in turn, actually lengthened their lives.

Alternatively, they posited that those who were “vulnerable to life-threatening conditions” were more likely to have died in the camps and the survivors who got through the trauma may have done so because of genetic, physical or psychological factors, which may have prepared them to live to an old age.

The authors noted that “albeit not dying at a younger age, Holocaust survivors may have experienced lower quality of life, for example, higher rates of invalidity or non-fatal illnesses.”

“The results of this research give us hope and teach us quite a bit about the resilience of the human spirit when faced with brutal and traumatic events,” Sagi-Schwartz said.