BioQuakes

AP Biology class blog for discussing current research in Biology

Evolution of Human Lifespans

human_evolution_scheme

(Locutus Borg, Wikimedia Commons)

Humans have started living longer and healthier lives. According to research conducted by various international teams, the last two centuries have had a greater percent increase in human lifespan than the past millions of years did.

The research teams compared the average lifespan of the most developed societies to the average lifespan of modern-day hunter-gatherer populations, which most closely resemble the lifespan and lifestyle of early humans. The researchers found that developed countries, such as Sweden, have average lifespans of eighty years now (an increase from the mid-thirties range it was in 200 years ago). On the other hand, hunter-gatherer populations such as the Hadza in Tanzania live only ten to twenty years longer than wild primates.

Such drastic improvements in human longevity are attributed to the advent of several post-industrial era features, including modern medicine and supermarkets. However, males trail behind females in terms of lifespan by at least three to four years– something that has not changed since the beginning of primate history.

The exact reason for the lifespan gender gap is unknown. Some hypotheses propose that males are more at-risk because they carry one X-chromosome and one Y-chromosome, as opposed to the females’ two X-chromosomes, which makes males more susceptible to disease. Another possible explanation centers around harmful male-related behavior, such as fighting. What do you think is the most likely reason for the gender gap?

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1 Comment

  1. evansymes

    Cool article SEJEOLOGY, very informative and interesting. One point I noticed that you didn’t mention is the effect of infant mortality of average life expectancy. In this article – https://priceonomics.com/why-life-expectancy-is-misleading/ – by Priceonomics, it is stated that “Life expectancy statistics as we commonly see them, then, are strongly shaped by infant mortality rates”. I’m curious as to how similar the birthing methods of the modern hunter-gatherer societies referenced in your study compare to those of the past. I’m also curious as to how the discrepancy between life expectancies would change if infant mortalities are removed from the equation. Maybe modern hunter-gatherer societies don’t actually have longer lives, but are merely less likely to die in their infancy. Maybe not as much has changed as we think.

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