Humans have made great strides in increasing their longevity the past two centuries, but the gap in lifespan between men and women remains about the same. Do researchers know why?

Hey men, there’s good news and bad news.

The good news is we’re living decades longer than we were just a couple centuries ago.

The bad news is the gap between how long men live and how long women live is still about the same.

An international team of researchers published a study on Monday in the Proceedings of the National Academy of Sciences.

In it, they detailed the great strides that humans have made in longevity the past 200 years, even compared to other primates such as monkeys and apes.

However, they noted, women are still outliving men by about five years, the same gap that was present in the early 1800s.

That gap between male and female lifespans is also found in other primate species.

And researchers aren’t entirely sure why.

“It’s puzzling. If we can make life last so long, why can’t we shrink the male-female gap?” study co-author Susan Alberts, a biology professor at Duke University, said in a press release.

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The researchers from the United States, Germany, Denmark, Canada, and Kenya compiled the birth and death records of more than 1 million people from the 1700s to the present.

The study included people from industrialized countries, people born before the Industrial Age, and modern hunter-gathers.

They compared the human data with lifespan records from six species of wild primates that have been studied from three to five decades.

The researchers said the data shows humans are making more rapid gains in longevity than other species on the primate family tree.

For example, the life expectancy for people in Sweden has jumped from the mid-30s in the early 1800s to more than 80 years today. That’s more than double in a 200-year span.

Researchers attribute the leap in lifespans to modern medicine and public health facilities. In particular, they note, childbirth deaths and childhood diseases have been greatly reduced.

“We’ve made a bigger journey in lengthening our lifespan over the last few hundred years than we did over millions of years of evolutionary history,” Alberts said.

However, the gap between men and women hasn’t changed much.

Worldwide, the average lifespan is about 71 years. Men, though, live an average of 68 years while women live an average of 73 years.

In the United States, the average lifespan is almost 79 years. Men live on average about 76 years while woman live an average of 81 years.

Researchers said a similar proportional gap exists between females and males in almost every wild primate population they studied.

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Alberts and the other researchers say there is probably a genetic component to the gap in male and female longevity.

They surmise it might lie in the X chromosome. Women have two of them while men only have one.

The solitary X chromosome in men may not be enough to compensate for any gene variants in that single chromosome.

Alberts said that wars and other aggressive behavior by men may also be a factor.

However, Dr. Jamin Brahmbhatt, a urology surgeon at The PUR Clinic at Orlando Health’s South Lake Hospital in Florida, thinks there may be more to it than that.

Brahmbhatt told Healthline a big factor may be that men simply don’t take care of themselves as well as women do.

They don’t eat as well and they don’t go to the doctor nearly as often as women do.

“Men simply don’t prioritize their health,” Brahmbhatt said.

The surgeon believes that this behavior may have its roots in childbirth.

He said women usually go through pregnancy in the first few decades of their life. They develop a pattern early of going to the doctor and taking care of their health.

Most men don’t do that until they are perhaps beyond 50 or 60 years of age.

Brahmbhatt said there is only so much you can do about genetics, but there is a lot you can do about behavior.

“You have to live with the cards you are dealt, but there are things around you that you can control,” he said.

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