Male Animals Are More Sickly Than Females Tim Sandle - Digital Journal | |
go to original August 6, 2015 |
Which is the sickliest sex? Males or females? Across the animal kingdom is seems that males are more troubled with ill-health than females.
In human societies, females tend to have a longer life-expectancy than males. The same appears to be so across most types of animals. The reason for this, researchers speculate, is because males expend a high-level of energy in the competition to reproduce, often coming up against other males. This leads to the immune system weakening, which means that, in the wild, male animals are more prone to infectious diseases and thus the tendency for an earlier death results. The primary risk to many male animals is parasitic infection.
The research goes onto explain that there is a difference in behavior between male and female animals, which affects energy levels. Males need to invest energy in attracting mates. This can be, depending on the animal, singing, changing color, engaging in courtship rituals, fighting other males and so forth.
To test this further, the Mexican researchers studied dragonflies and they found that lipid levels (sources of energy stored as fat in muscles) is higher in females than in males. Moving up the scale, a similar pattern is seen with lions. In the wild, males seldom live longer than 14 years. This is because injuries from continual fighting with rival males lower longevity. Females can live up to 20 years.
The research forms part of the field of evolutionary ecology and it was conducted at the Institute of Ecology at the National University of Mexico (UNAM). The findings have yet to be published in a journal.
Read the rest at Digital Journal
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