After Hurricane Maria, these lizards developed a grip that's 10 times stronger
Are we witnessing evolution in real time?
- After Hurricane Maria, anole species on the island of Dominica developed super strong grips.
- This development may be one of the fasted rates of evolutionary change ever recorded.
- Climate change will likely to result in more intense hurricanes, but not all species will adapt so quickly.
In September 2017, Hurricane Maria slammed into the island of Dominica. The category 5 storm then tore across the West Indies and up the Atlantic. Islands such as Haiti, Puerto Rico, the Dominican Republic, the Bahamas, and the U.S. Virgin Islands were devastated by the crashing storm surges and stampeding winds. Today, Puerto Rico's official death toll stands at a staggering 2,975.
We were not ready for Hurricane Maria, and we aren't preparing for the next natural disaster either. And they are coming. Weather scientists aren't sure if climate change will increase the number of hurricanes, but they expect the warmer oceans to intensify their impact. We'll need to adapt.
This said, fellow members of the animal kingdom are already acclimating. As reported by New Scientist, two species of anole lizards on Dominica have developed super strong grips in response to Hurricane Maria. Their improved cling helped the species survive, but scientists aren't sure what caused the rapid adaptation.
Hanging on for dear life
Hurricane Maria razed homes and shredded forests on the islands of Dominica and Puerto Rico. Image source: U.S. Department of Homeland Security / Wikimedia Commons)
Back in 2016, Claire Dufour, an evolutionary ecologist at Harvard, and her team visited Dominica to study two species of anoles: the native anoles and the crested anoles (the latter of which are an invasive species). They were interested in how the lizards coexisted and recorded data on their body size, toe features, and grip strength.
Then Hurricane Maria hit. The storm crushed the island's cities and left a lasting, perhaps indelible, imprint on its ecology.
Dufour and her team returned in 2018 to re-examine the anoles. The lizards they found had stronger grips than the ones they examined in 2016. Not surprising, really. One would expect stronger, fitter anoles to be more capable of surviving Maria's high winds.
What did surprise the scientists, however, was that the lizards' body size hadn't changed, nor their toe-pad size. Just their power to cling. Additionally, their grip strength averaged to an astounding 10 times stronger than previously recorded. The anoles, it seems, had rapidly evolved to meet intense environmental demands. The strong clingers managed to weather the storm and passed on their genes to the next generation.
"This study shows that hurricanes may be a previously overlooked driver of performance in Anolis lizards," Dufour told New Scientist. "This is pretty unique."
The researchers published their findings last month, May, in the Journal of Zoology.
Is it evolution in the making?
Another study, this one published in Nature, looked at anole toe-pad shapes and found that hurricanes induced changes there, too. Like Dufour's team, these researchers believe that these adaptations imply natural selection at work.
"This is a striking case of rapid evolution, which, as we can see here, can proceed exceedingly fast, even within a generation," Carol Lee, at the Center for Rapid Evolution at the University of Wisconsin at Madison, told the Atlantic. "I expect there will be many more cases like this in the future, where catastrophic events impose strong selection on populations, and where populations will need to evolve or go extinct."
Other researchers aren't as sure yet. If the lizards' newly minted grip strength and toe-pad shape are not heritable, then they have not become part of the species' genetic makeups. In which case, the changes are the result of phenotypic plasticity, meaning an organism's characteristics are flexible enough to be influenced by the environment without invoking evolution.
Both studies say additional research is needed to determine if hurricanes are overlooked evolutionary drivers or molders of elastic characteristics.
If these changes are indeed hurricane-induced natural selection, however, then "our understanding of evolutionary dynamics needs to incorporate the effects of these potentially severe selective episodes," Dufour writes.
Adapting to climate change
While the anoles may be able to adapt to the more extreme weather, other species won't be so lucky.
In a meta-analysis of more than 130 studies, Mark Urban, biologist and associate professor at the University of Connecticut, found that climate change "threaten[s] one in six species under current policies." Australia, South America, and New Zealand showed the highest extinction risks, but risks across the globe and taxonomy accelerated with increases in global temperature.
Increases in global temperatures will also allow insects and invasive species to spread to new territories, increasing the risk of insect-borne diseases and further damage to local ecosystems. And the intensity of extreme weather will continue to damage human cities and agricultural production.
As we enter hurricane season again, we'll unfortunately have more chances to see how the anoles, and people, adapt to meet the increased pressures of climate change.
What would happen if you tripled the US population? Join Matthew Yglesias and Charles Duhigg at 1pm ET on Monday, September 28.
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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