Washington, July 7 (IANS): Explaining why women live longer than men across the world, vulnerability to heart disease is the biggest culprit behind a surge in higher death rates for men during the 20th century, says a study.

According to the team led by University of Southern California, as infectious disease prevention, improved diets and other positive health behaviours were adopted by people born during the 1800s and early 1900s, death rates plummeted but women began reaping the longevity benefits at a much faster rate.

"In the wake of this massive but uneven decrease in mortality, a review of global data points to heart disease as the culprit behind most of the excess deaths documented in adult men," said Eileen Crimmins, professor of gerontology.

"We were surprised at how the divergence in mortality between men and women, which originated as early as 1870, was concentrated in the 50 to 70 age range and faded out sharply after age 80," Crimmins said.

For the study, the team examined the lifespan of people born between 1800 and 1935 in 13 developed nations.

Focusing on mortality in adults over the age of 40, the team found that in individuals born after 1880, female death rates decreased 70 percent faster than those of males.

Even when the researchers controlled for smoking-related illnesses, cardiovascular disease appeared to still be the cause of the vast majority of excess deaths in adult men over 40 for the same time period.

"Surprisingly, smoking accounted for only 30 percent of the difference in mortality between the sexes after 1890," Crimmins added.

Further research can analyse diet and exercise activity differences between countries, deeper examination of genetics and biological vulnerability between sexes at the cell level and the relationship of these findings to brain health at later ages.

The paper appeared in the journal Proceedings of the National Academy of Sciences.