The gap between the average male and female life expectancy of given population group is alternately labeled as Life Expectancy Gender Gap (LEGG) or Gender Gap in Life Expectancy (GGLE). Going forward I will be using the LEGG acronym.

The lost years

The first important thing to know about the LEGG is that its impact is, without an exaggeration, enormous. Let's take for example the US, with a LEGG of 5.8 years at the average predicted age for men and women 73.5 and 79.3 years respectively. Do you see the enormity? No, you don't?

Ok, let's put things into perspective - how do you measure an impact of early death? With Years of Potential Life Lost (YPLL). This measure is based on an estimate of years a person would have lived if they had not died prematurely. It is usually reported in years per 100,000 people and the reference "mature" age should correspond roughly to the life expectancy of the population and is now usually given as 75 years. Now, men and women in the US lose some 8,265 and 4,862 potential years of life per 100,000. Given the population as 332 millions, men lose some 5,648,980 more years of potential life than women. Do you see the enormity now? Not yet?

During the roughly 3.5 years of WW2 the US lost some 407,300 military and 12,100 civilian lives. With an average life expectancy back then cca 68 years, and a guestimated average age at the time of death 21 years, every killed American lost some 47 years. That means the US as a whole lost some 5,640,000 potential years of life every year of the war.

In other words, there is an invisible perpetual war that kills as many men every year as WW2. Do you see the enormity of the LEGG now? I think you do.

The causes

The second important think to know about the LEGG is that nobody seem to care. Biologists, statisticians, politicians, Wikipedians - not even men's rights activists - nobody seems to be franticly looking for the causes and proposing policies to stop this haemorrhage of men's lives. Let me summarise what Wikipedia has to says about it:

• It is the life style - men drink more, smoke more and eat crap. There is nothing we can do or should do.
• And it is also the biology - men lack the protective double X chromosome and have higher rate of mitochondrial mutations. We see this across all mammalian species. There is nothing we can do or should do.
• Females have have higher mortality as foetuses but lover mortality as premature babies. That is why male babies and boys dies of diseases much more than girls. There is nothing we can do or should do.

(Speaking of Wikipedia, it has dedicated articles for many things, including the Orgasm gender gap, but it does not have a dedicated article for the LEGG.)

To my surprise I have not been able to find any further information, neither on biology forums, nor on Google Scholar. Studies usually focus on one cause or divide the mechanisms into social and biological but there our knowledge seem to end. I am not a statistician nor a biologist but I know how to use excel and at this point I was so frustrated that I decided to "do my own research".

"The research"

1/

My first observation was that there is a huge variance between developed countries with similar GDP and life expectancy. Example:

• 2021 Norway - LE: 83.16 years, LEGG: 3,0 years
• 2021 France - LE: 82.32 years, LEGG: 6,2 years

Conclusion: At least 50% of the gap is not caused by male/female biological differences.

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2/

Next, I knew where to find Eurostat data on causes of death - unfortunately only from 2010 - and I filtered out everything mechanical: suicides, assaults, accidents (men suffer 90% of all work related fatal accidents) and drug and alcohol overdoses. The LEGG shrunk significantly:

• 2010 Norway - all LEGG: 4.54 | non-mechanical LEGG: 3,51, decrease by 29.5%
• 2010 France - all LEGG: 7.14 | non-mechanical LEGG: 6.19, decrease by 15.3%

Conclusion: 15% - 30% of the gap is caused by non-biological (preventable) external factors.

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3/

Then I was curious how much of the LEGG is caused by mortality differences of infants and children so I calculated non-mechanical LEGG at 20 years, as opposed to LEGG at birth. The difference is negligible:

• 2010 Norway - non-mechanical LEGG at birth: 3,51, non-mechanical LEGG at 20: 3.37, difference: 3.8%
• 2010 France - non-mechanical LEGG at birth: 6.19, non-mechanical LEGG at 20: 6.07, difference: 1.7%

Conclusion: The impact of fetus/baby mortality is negligible.

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4/

Next, I did one more napkin calculation. Assuming that smoking reduces the life expectancy on average by 10 yers and smoking rate among French men and women are 0.349 and 0.319 and smoking rate among Norwegian men and women are 0.17 and 0.154, I reduced the LEGG further:

• 2010 Norway - all LEGG: 4.54 | non-mechanical, non-smoking LEGG: 3,35, decrease by 35.7%
• 2010 France - all LEGG: 7.14 | non-mechanical, non-smoking LEGG: 5.89, decrease by 21.2%

Conclusion: Other non-biological factors clearly play a role. Men famously visit doctors only half as often as women. Men lead in drugs and alcohol abuse, men lead in obesity and processed meat consumption. Man also do most paid work so there is work related stress and exposure.

It should not be a rocket science to isolate these factors. Actually, it would amount to a very cool paper with thousands of citations. So where is this paper?

The good

Apparently I am bad at googling papers - luckily some friends pointed me to some actual research. This paper mentions in passing that external causes (accidents, self-harm) caused 21.2% of the LEGG in Sweden in 2014 (my Excel calculation is in the ballpark!). Further studies attribute 75%+ of the LEGG to non-biological factors (e.g., behavior, life style, social roles) (Luy and Wegner-Siegmundt 2015; Oksuzyan et al. 2008), with higher mortality risk among men due to smoking, hazardous alcohol consumption, substance abuse and occupational risks (Loef and Walach 2012; Oksuzyan et al. 2008). A paper Causes of Male Excess Mortality: Insights from Cloistered Populations examines 11,000 Bavarian monks and nuns living in "very nearly identical behavioral and environmental conditions" with nuns having only a "slight advantage" in life expectancy.

The bad and the ugly

Social and biological mechanisms out there are causing men to lose life equivalent to WW2 every year. We should be creating policies to stop this haemorrhage. We should be targeting men specifically with anti-smoking campaigns while improving their access to preventive health care.

Instead, the UN's quietly manipulates the Gender Development Index by removing 5 years from the LEGG, arguing that men living 5 years shorter is justified by biology. The Global Gender Gap Report published annually by the World Economic Forum does something similar, arguing that if women live at least 6% longer than men then equality is achieved.

As a consequence, women is Norway living only 3 years longer than men is interpreted as oppression.