Scientists extend mice lifespan 12% by tweaking telomeres
The team seems to have found a way to extend animal lifespan without genetic modification.
- Using specially cultivated embryonic stem cells, scientists generated mice whose cells had extra-long telomeres.
- Telomeres are stretches of DNA at the ends of chromosomes that help protect the genetic information inside.
- Lengthening telomeres in embryonic stem cells could pave the way toward slowing aging without genetic modification.
Scientists successfully extended the average lifespan of mice by breeding them using embryonic stem cells with extra-long telomeres. The findings are significant because the researchers managed to extend lifespan without genetic modification, and they also shed light on the aging process and techniques that might someday slow it.
The study — published October 17 in Nature Communications — focuses on telomeres, which are stretches of DNA found at the end of chromosomes.
Because telomeres protect the genetic material inside chromosomes, they've been likened to the plastic tips on the ends of shoelaces. But telomeres have also been compared to bomb fuses, or "molecular clocks," because they become shorter each time a cell divides, eventually shrinking so much that the cell dies or stops dividing. This shortening of our telomeres is associated with aging, cancer, and death.
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"Telomere shortening is considered one of the hallmarks of aging as short telomeres are sufficient to cause organismal aging and decreased lifespan," the researchers wrote. "Telomere length is determined genetically and both average telomere length and the rate of telomere shortening varies between species. In this regard, humans are born with shorter telomeres than mice, but mice telomeres shorten 100-times faster than humans."
For years, scientists have been exploring how lengthening telomeres might help stave off disease and aging in animals, and, perhaps someday, in humans. But these attempts have all involved genetic modification. In the new study, a team of researchers at the Spanish National Cancer Research Center left induced stem cells to multiply in a petri dish, a process which eventually results in cells that have extra-long telomeres, as researchers first discovered in 2009.
Using these specially cultivated embryonic stem cells, the team generated mice with extra-long telomeres. Compared to a control group, these mice experienced "significant increase of 12.74 percent in median longevity", showed no cognitive defects and were less likely to develop cancer and obesity.
"This finding supports the idea that, when it comes to determining longevity, genes are not the only thing to consider," says molecular biologist Maria Blasco, from the Spanish National Cancer Research Centre (CNIO). "There is margin for extending life without altering the genes."
Is lengthening telomeres the secret to slowing aging in humans?
Shorter telomeres are linked to a shorter lifespan in humans. And although we're unlikely to see any experiments involving that are similar to the recent study, there are some steps you can take to lengthen your telomeres and increase your chances at a longer life. The main step: endurance exercise.
A 2018 study published in the European Heart Journal found that telomerase activity spikes in people who regularly do endurance exercises, defined as 45 minutes of continuous running. Interestingly, this effect was not observed in people who lifted weights or walked for 45 minutes. The results echoed those of a similar 2017 study, which found that people who ran regularly appeared to be biologically younger than those who didn't. But it takes some effort.
"If you want to see a real difference in slowing your biological aging, it appears that a little exercise won't cut it," study author Larry Tucker told Science Daily. "You have to work out regularly at high levels."
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Whether or not women think beards are sexy has to do with "moral disgust"
- A new study found that women perceive men with facial hair to be more attractive as well as physically and socially dominant.
- Women tend to associate more masculine faces with physical strength, social assertiveness, and formidability.
- Women who display higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, are more likely to prefer hairy faces.
Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
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