Lady Meerkats Make More Testosterone Than Males

Two female meerkats, mid-beef. Image Credit: Charli Davies, Duke University

They’re unpleasant. They’re uncooperative. And they’re unwilling to share.* Testosterone-fueled bad behavior is as common in meerkats as it is among other animals. But there’s one major difference: In meerkat society, scientists say, it’s the females doing the misbehaving. A report on their misconduct, and its implications for their health, was published in the journal Scientific Reports.

Meerkats are intensely social animals. They live in tight-knit groups of up to 40 or 50 animals and do everything collectively, from hunting and sleeping to raising pups. They maintain order through a strict hierarchy led by a fierce matriarch and her subordinates. Meerkat matriarchs are notoriously self-involved, but other females are not much sweeter. They, and not the males, are the growlers, the biters, the brawlers, the food-swipers, and the warmongers—all identities traditionally associated with high levels of testosterone.

To find out if the females’ bad attitudes were linked to this so-called male hormone, researchers collected blood and poop samples from 93 wild meerkat males and 91 females on the Kuruman River Reserve in South Africa. The meerkats there are habituated to scientists, which made it no big deal for the team to catch them, anesthetize them, and take a little blood. They’re also clearly tagged with individual dye markings, which made it easier for the researchers to tell who was chasing (or being chased by) whom.

They're going to a rumble. (No, really. They are.) Image Credit: Kendra Smyth, Duke University

As anticipated, the blood tests showed a stark difference in hormone levels between male and female meerkats. The females’ blood boasted much more testosterone than the males’ blood did—in some cases almost double. Levels of testosterone and related hormones in females were closely linked with their place in the hierarchy. This was less true for males, whose hormones were more likely to fluctuate during mating periods.

A testosterone-charged life doesn’t come without its costs. For meerkats, as with other animals, this may mean a compromised immune system. They combed through the meerkats’ feces and counted the number of parasite eggs they found in each sample. The higher a female’s testosterone level, the higher her parasite count—and the weaker her immune response.

Riding high on testosterone may not make a lady meerkat popular, and it may not make her healthier, but all that jerk behavior could just give her—and her kids—a competitive edge.

*National Geographic appears to have gone for a slightly different tagline.
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Slow Motion Is the Only Way to Appreciate a Chameleon’s Lightning-Fast Tongue

From the unusual way they walk, to their ability to change color, the evolutionary adaptations of chameleons are pretty bizarre, and some of them remain mysterious even to scientists. Their super-powered tongues, for instance, can dart out so quickly that the movement can barely be seen with the naked eye. But modern high-speed cameras have enabled researchers at the University of South Dakota to observe this appendage at work like never before. The video below, shared over at The Kid Should See This, includes some of that groundbreaking footage, and it's pretty amazing to watch.

Shooting at 3000 frames per second, the camera was able to capture every split-second aspect of the chameleon's tongue strike. Slowed down, the video allows you to see how every component of the process works in harmony: First, muscles in the lizard’s tongue contract like the string of a bow. Then, when that tension is released, the bony base of the tongue shoots forward, pushing the sticky, elastic part toward the chameleon’s prey.

According to Christopher Anderson, one of the scientists who conducted the high-speed camera research, larger chameleons can catapult their tongues forward at distances of one to two times their body length. For smaller chameleons, this distance can reach up to two and a half times their body length. “Small chameleons need to be able to eat more food for their body size than large chameleons,” he tells bioGraphic in the video, “and so by being able to project their tongues proportionately further than these large species, they basically are opening up additional feeding opportunities to themselves that they wouldn’t have if they had a shorter tongue.”

To see one of nature’s greatest hunting tools in action, check out the full video below.

[h/t The Kid Should See This]

There May Be an Ancient Reason Why Your Dog Eats Poop

Dogs aren't known for their picky taste in food, but some pups go beyond the normal trash hunting and start rooting around in poop, whether it be their own or a friend's. Just why dogs exhibit this behavior is a scientific mystery. Only some dogs do it, and researchers aren't quite sure where the impulse comes from. But if your dog is a poop eater, it's nearly impossible to steer them away from their favorite feces.

A new study in the journal Veterinary Medicine and Science, spotted by The Washington Post, presents a new theory for what scientists call "canine conspecific coprophagy," or dogs eating dog poop.

In online surveys about domestic dogs' poop-eating habits completed by thousands of pet owners, the researchers found no link between eating poop and a dog's sex, house training, compulsive behavior, or the style of mothering they received as puppies. However, they did find one common link between the poop eaters. Most tended to eat only poop that was less than two days old. According to their data, 85 percent of poop-eaters only go for the fresh stuff.

That timeline is important because it tracks with the lifespan of parasites. And this led the researchers to the following hypothesis: that eating poop is a holdover behavior from domestic dogs' ancestors, who may have had a decent reason to tuck into their friends' poop.

Since their poop has a high chance of containing intestinal parasites, wolves poop far from their dens. But if a sick wolf doesn't quite make it out of the den in time, they might do their business too close to home. A healthier wolf might eat this poop, but the parasite eggs wouldn't have hatched within the first day or two of the feces being dropped. Thus, the healthy wolf would carry the risk of infection away from the den, depositing the eggs they had consumed away in their own, subsequent bowel movements at an appropriate distance before the eggs had the chance to hatch into larvae and transmit the parasite to the pack.

Domestic dogs may just be enacting this behavior instinctively—only for them, there isn't as much danger of them picking up a parasite at home. However, the theory isn't foolproof. The surveys also found that so-called "greedy eaters" were more likely to eat feces than dogs who aren't quite so intense about food. So yes, it could still be about a poop-loving palate.

But really, it's much more pleasant to think about the behavior as a parasite-protection measure than our best pals foraging for a delicious fecal snack. 

[h/t The Washington Post]


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