The gender gap for life expectancy is fading, and by 2030 experts predict that adult males will have the same life expectancy as females for the first time in recorded history.

Professor Les Mayhew, an adviser for the UK Office for National Statistics, said that the difference in life expectancy between men and women peaked at nearly six years in the 1970s, and while life expectancy is becoming longer for both sexes, rates for men are increasing faster as more men opt for healthier lifestyles and move away from hazardous occupations toward office-based jobs.

Traditionally males have always had a shorter life expectancy, even before they’re born and in their first year of life.  A similar gap has been observed in animals, suggesting that some underlying genetic factors were responsible for sentencing men to an earlier death.   

While the gender gap for life expectancy had been relatively narrow since records of life expectancy in the UK began in 1841, the gap began widening as more men started smoking and peaked at six years in the 1970s. 

"One of the main reasons, I think, is the trend in the prevalence of smoking. Smoking took off after 1920 in the male population and at its high about 80% of males smoked,” Mayhew said, according to BBC. "This was reflected in more divergence in the life expectancy, so by the time you get to about 1970 it was at its peak - the difference in life expectancy was about 5.7 years."

Based on his calculations, if the current trend of male life expectancy continues to increase more rapidly than their female counterparts, both sexes would be living to the age of 87 in 2030. 

"What's interesting at the moment is that in the last 20 years or so, male life expectancy at 30 has jumped by about six years and if it jumps by the same amount in the next 20 years it will converge with female life expectancy," he explained to BBC.

Mayhew believes that there will soon be a reversal in the current trend in male and female life expectancy as men shift away from their macho lifestyles towards healthier ones, which have been traditionally more favored by women.

Rates of lung cancer have been increasing in women, whereas rates of the disease have been falling fast in men, and while heart attacks are three times more common in men, heart problems are much easier to treat than in the past. 

Mayhew’s estimates, based on findings due to be published by City University’s Cass Business School, that a boy born in 2000 will from the age of 30 have the same life expectancy as a girl who is of the same age, are different from the official statistics from the UK Office for National Statistics predictions, which estimates that there will still be a gap of three and a half years.

Mayhew notes that his predictions only apply to boys living in England and Wales and only once they have turned 30, as young men are generally more risky than young women and more likely to die in sport and automobile accidents. 

He believes that the Office for National Statistics is too conservative and notes that men are catching up in life expectancy in other countries too. For instance, he predicts that in Sweden a 30-year old man will have the same number of years left as a woman of the same age in 2024, six years earlier than he projected for England or Wales. 

"In virtually all countries in the world, women do have a slight advantage," Professor David Leon, from the London School of Hygiene and Tropical Medicine, said, according to BBC.

Leon said that the gap was certainly closing in some countries, but countries with lower rates of life expectancy, like ones in sub-Saharan Africa, there were very little differences between men and women because of the prevalence of infectious diseases which "are not picky about men and women", he said.

However in Eastern European countries, where infectious diseases are much less of a problem, "there is a much bigger difference, mostly dominated by lifestyle factors," Leon said.

Leon pointed out that at one point in the 1990s, the gender life expectancy gap expanded by 13 years, which he said was an "absolutely massive" difference in a "very gendered society".

He said that countries like the UK, where the gap in life expectancies is rapidly closing, men are becoming “a bit better behaved” as women “are adopting male life expectancies,” according to BBC.