Man Flu is no myth

[JimandChristy 1,689]

Men's ability to turn a sniffle into flu and a headache into a migraine has long been a source of irritation to wives and girlfriends.

But the new research suggests that they are not faking it and that they suffer diseases more seriously and for longer.

Scientists believe it is the male predilection for a "live fast, die young" lifestyle that means in evolutionary terms they have failed to build up their immune systems like females.

That means that they not only catch more diseases but they tend to suffer more seriously, and for longer, from them.

A team at the University of Cambridge came up with the theory by applying a mathematical model to the various factors that characterise males and females.

It predicts that the adventurous lifestyle of the male means that they are more exposed to disease but paradoxically this reduces their immunity.

The reason is that they invest more energy in maintaining the ability to reproduce while ill and also take the view they will be reinfected quickly so do not need to have such a strong immune system.

Dr Olivier Restif, of the University of Cambridge, said: "In many cases, males tend to be more prone to get infected or less able to clear infection.

"Proposed mechanisms include interference between male hormones and immunity, as well as risk-taking behaviour.

Men compete more with each other than females do, because of the male strategy to "live hard, die young' which means they may invest less in immunity.

Dr Restif and colleague Dr William Amos assessed how the evolution of male and female immune defences is affected by differences between the sexes.

Dr Restif said: "An increase in male susceptibility or exposure to infection favours the spread of the pathogen in the whole population and therefore tends to select for higher resistance or tolerance in both sexes if the cost of immunity is essential.

"But above a certain level of exposure, the benefit of rapid recovery in males decreases owing to constant reinfection.

"This selects for lower resistance in males, ultimately leading to the counterintuitive situation where males with higher susceptibility or exposure to infection than females evolve lower immunocompetence."

The finding published in Proceedings of the Royal Society B: Biological Sciences suggests that 'man flu' is not a myth.

Across a range of animal species, males tend to be the "weaker sex" in relation to immune defences, usually because of hormonal differences.

Dr Restif said: "Our results show that, under a range of genetic and ecological constraints, males and females can evolve different levels of immune defences, sometimes at odds with intuitive expectations."

He said that maintaining the ability to mate was more important to men than getting better, yet for women it was the other way around.

"Under this scenario, the model predicts that overall, females should try to clear infection rapidly, regardless of the relative risk of catching infection," he said.

"In contrast, males are selected to decrease their immune defences and remain sexually active during infection if their exposure to infection is high."

"On the other hand, even if males have a strong immune system that clears infection, they will become reinfected rapidly, so the effective benefit of immunity is low."

http://www.telegraph.co.uk/health/healthnews/7505207/Man-flu-is-no-myth-as-scientists-prove-men-suffer-more-from-disease.html

[SMR 368]

Men's ability to turn a sniffle into flu and a headache into a migraine has long been a source of irritation to wives and girlfriends.

But the new research suggests that they are not faking it and that they suffer diseases more seriously and for longer.

Scientists believe it is the male predilection for a "live fast, die young" lifestyle that means in evolutionary terms they have failed to build up their immune systems like females.

That means that they not only catch more diseases but they tend to suffer more seriously, and for longer, from them.

A team at the University of Cambridge came up with the theory by applying a mathematical model to the various factors that characterise males and females.

It predicts that the adventurous lifestyle of the male means that they are more exposed to disease but paradoxically this reduces their immunity.

The reason is that they invest more energy in maintaining the ability to reproduce while ill and also take the view they will be reinfected quickly so do not need to have such a strong immune system.

Dr Olivier Restif, of the University of Cambridge, said: "In many cases, males tend to be more prone to get infected or less able to clear infection.

"Proposed mechanisms include interference between male hormones and immunity, as well as risk-taking behaviour.

Men compete more with each other than females do, because of the male strategy to "live hard, die young' which means they may invest less in immunity.

Dr Restif and colleague Dr William Amos assessed how the evolution of male and female immune defences is affected by differences between the sexes.

Dr Restif said: "An increase in male susceptibility or exposure to infection favours the spread of the pathogen in the whole population and therefore tends to select for higher resistance or tolerance in both sexes if the cost of immunity is essential.

"But above a certain level of exposure, the benefit of rapid recovery in males decreases owing to constant reinfection.

"This selects for lower resistance in males, ultimately leading to the counterintuitive situation where males with higher susceptibility or exposure to infection than females evolve lower immunocompetence."

The finding published in Proceedings of the Royal Society B: Biological Sciences suggests that 'man flu' is not a myth.

Across a range of animal species, males tend to be the "weaker sex" in relation to immune defences, usually because of hormonal differences.

Dr Restif said: "Our results show that, under a range of genetic and ecological constraints, males and females can evolve different levels of immune defences, sometimes at odds with intuitive expectations."

He said that maintaining the ability to mate was more important to men than getting better, yet for women it was the other way around.

"Under this scenario, the model predicts that overall, females should try to clear infection rapidly, regardless of the relative risk of catching infection," he said.

"In contrast, males are selected to decrease their immune defences and remain sexually active during infection if their exposure to infection is high."

"On the other hand, even if males have a strong immune system that clears infection, they will become reinfected rapidly, so the effective benefit of immunity is low."

http://www.telegraph.co.uk/health/healthnews/7505207/Man-flu-is-no-myth-as-scientists-prove-men-suffer-more-from-disease.html

Various factors may make men more susceptible to disease than women and it may be true that immune defense is more important evolutionarily for men than for women. But I find the assertion that men with stronger immune systems are disadvantaged to be erroneous, not only intuitively, but also logically.

My main reason for this is that the ability to have sex is only a small component of the evolutionary fitness of male humans. Other factors include the ability of the man to attract mates, the ability to gather resources to provide for mates and offspring, the ability to protect mates and offspring, the ability to survive long enough to raise offspring, and the basic ability to survive until sexual maturity. All of these are critical to evolutionary fitness and are very negatively affected in the event of disease.

It seems to me that the major fallacy of this argument is that even if men are programmed to "live fast and die young," fast is a relative term. We are talking about a minimum of 20 years. More realistically, a man's fitness increases as he survives longer at least until the age of 40 and probably until 60 or more. The reality is that an inability to fight off an infection means death. Death causes a drastic decrease in evolutionary fitness.

The article seems unclear, but perhaps the assertion is simply that for men, the ability to continue to function while sick is more important than the ability to recover to full capacity quickly. That may be true, but eventual recovery is still an essential component to evolutionary fitness.