Posts Tagged ‘social behavior’


A vampire bat carrying a proximity sensor to study its social behavior in the wild.

By Jessie Young

Vampire bats may be bloodsucking creatures of the night — but they also form strong friendships and help each other out in times of need, a study has found.

The study, published in the journal Current Biology on Thursday, found that vampire bats who formed social bonds in captivity maintained those bonds even after they were released back into the wild.

This is significant because it’s often difficult to tell whether “partner fidelity” in animal relationships is due to the immediate costs and benefits of helping each other, or due to some shared relationship history. But in this experiment, the bats remembered and helped each other in two drastically different environments, even when they didn’t have to.

The study, conducted by researchers at Ohio State University, housed 23 wild female vampire bats and their captive-born offspring for almost two years. To encourage them to help each other and to measure these relationships, researchers withheld food from some individual bats “to induce social grooming and regurgitated food sharing.”

They found that the bats who didn’t receive food had a higher probability of being groomed and fed by other bats. This kind of cooperation is particularly rare between vampire bats that aren’t related because they have to pay a cost to help their peers — to feed each other, they have to regurgitate their own meals.

“It’s pretty rare outside of humans to have behaviors where I’m paying an obvious cost to help you and you’re not related to me,” said Gerald Carter, one of the study’s lead authors, in the press release.

Then, the bats were released back into their original roost, wearing small sensors to monitor their behavior. Even though they were now part of a bigger group with other bats who hadn’t been part of the experiment, the “test” bats who had lived together in the lab stuck together — they had higher levels of social grooming, food sharing, and close contact with each other.

The fact that the bats continued their friendships in the wild was “a sign that the relationships weren’t borne only of convenience while they lived together in a cage,” said the study’s press release.

“It’s kind of analogous to being friends in high school,” said Carter. “After you graduate, and you’re released out of this structured environment, do you continue to stay in touch with those people, or do you lose touch with them? It depends on personality types and the kinds of experiences you shared. That’s essentially what we were after with this study.”

The study concluded that, much like humans, vampire bat friendships are generally strengthened by their shared past experiences.

However, sometimes humans drift apart after high school — and similarly, not all the lab bat friendships survived in the wild. In particular, the captive-born offspring had bite marks after returning to the wild colony, and they eventually left the roost. The study suggested they might have tried to fly back to their place of birth — the lab — or perhaps failed to develop natural wild bat behaviors.

https://www.cnn.com/2019/10/31/world/vampire-bats-friends-intl-hnk-scli-scn/index.html?utm_source=The+Good+Stuff&utm_campaign=91b09c3d68-EMAIL_CAMPAIGN_2019_10_30_05_15&utm_medium=email&utm_term=0_4cbecb3309-91b09c3d68-103653961

By Katie Camero

Watching a movie with a friend can make you feel closer to that person, and more likely to hang out with them in the future. The same, it turns out, is true of chimpanzees.

Researchers analyzed 36 pairs of chimpanzees in the Ngamba Island Chimpanzee Sanctuary in Uganda. They led the apes—two at a time—into two adjacent, caged rooms with a closed door between them. The scientists then played several 1-minute videos of baby chimps swinging on tree branches on a computer screen. In one trial, the apes watched one screen placed outside of their rooms together. In the other trial, the team added a screen and put a plastic barrier in between them, blocking the apes from watching the same video together. An eye-tracking camera was used to monitor what the apes were looking at as the videos played, with red dots showing their shifting focus (as seen in the video above).

When the videos ended, the researchers opened the door separating the chimps’ rooms. The apes spent about seven more seconds in the same room with each other after watching the videos together than when they watched the videos separately. They also only groomed each other when they had watched the video together, the team reports today in the Proceedings of the Royal Society B.

In a separate experiment, the researchers paired apes with a human instead. They found that the apes were more motivated to approach the human, who sat on the other side of the cage, after watching the video with them—approaching them 12 seconds faster, on average—than when the two species watched the video separately.

The scientists say apes don’t seek out shared experiences just to connect with others, like humans do. But they claim their study is the first to suggest apes have some of the psychology required to do so. More studies need to be done to see whether such short-term interactions, like sharing a video, strengthen great ape relationships in the long run, the team notes.

https://www.sciencemag.org/news/2019/07/chimpanzees-grow-closer-when-they-watch-movie-together

By Lucy Huang

Ants infected with fungal pathogens steer clear of other cliques within the colony—avoiding wider infection, and allowing for a sort of immunity. Lucy Huang reports.

It’s peak cold and flu season, which means taking a lot of preventive measures. Frequent hand-washing is a must. As is avoiding co-workers or friends who are sick. But we humans are not the only animals that change behavior to keep diseases at bay. So do ants.

“So there are the foragers and the nurses– it’s two different groups of work.”

Nathalie Stroeymeyt of the University of Lausanne. She and colleagues observed ants to see their reaction to the presence of a pathogen.

“With the nurses staying inside the nurse taking care of the brood and being made of young workers. And the foragers are all the workers at outside of the nest to collect food and defend the territory.”

Forager ants are at greater risk of getting exposed to diseases because they leave the safety of the nest. So the researchers sprayed a common fungus on a small group of forager ants and then followed their movements to see the way other ants reacted.

“We marked all ants in the colony was individual labels, which carries these two-dimensional bar code marks like QR code which is automatically detected and recorded using a tracking system.”

After the infection, the nurse and forager ants stayed within their cliques and interacted less outside of their work group. The researchers also saw that forager ants spent more time outside of the nest.

“They increase that amount by 15 percent so by quite a long large amount.”

The researchers also measured the amount of fungus on each ant and saw that it was almost completely contained within the foragers group. Some nurse ants and even the Queen did have trace amounts of the fungus’ spores on them but the amount was small enough that they could easily groom them off of their bodies. The study is in the journal Science. [Nathalie Stroeymeyt et al., Social network plasticity decreases disease transmission in a eusocial insect]

Not only does the cliquish behavior stop the spread of the fungus, “but it allows you to develop immunization. Something that’s quite interesting in these ants that’s been shown by other study is that when you receive very small amount of these spores, you don’t have an increase in mortality risk because it’s low enough that you can heal, it’s sort of boost your immune defenses and protect you against later exposure to the same pathogen.

Seems that in their ability to avoid infecting other members of the community, ants may be more advanced than we are.

https://www.scientificamerican.com/podcast/episode/ants-stick-to-cliques-to-dodge-disease/


Patterns of gene expression unite the prairie vole Microtus ochrogaster with other monogamous species, including certain frogs, fish, and birds. YVA MOMATIUK AND JOHN EASTCOTT/MINDEN PICTURES

By Kelly Servick

In the animal world, monogamy has some clear perks. Living in pairs can give animals some stability and certainty in the constant struggle to reproduce and protect their young—which may be why it has evolved independently in various species. Now, an analysis of gene activity within the brains of frogs, rodents, fish, and birds suggests there may be a pattern common to monogamous creatures. Despite very different brain structures and evolutionary histories, these animals all seem to have developed monogamy by turning on and off some of the same sets of genes.

“It is quite surprising,” says Harvard University evolutionary biologist Hopi Hoekstra, who was not involved in the new work. “It suggests that there’s a sort of genomic strategy to becoming monogamous that evolution has repeatedly tapped into.”

Evolutionary biologists have proposed various benefits to so-called social monogamy, where mates pair up for at least a breeding season to care for their young and defend their territory. When potential mates are scarce or widely dispersed, for example, forming a single-pair bond can ensure they get to keep reproducing.

Neuroscientist Hans Hofmann and evolutionary biologist Rebecca Young at the University of Texas in Austin wanted to explore how the regulation of genes in the brain might have changed when a nonmonogamous species evolved to become monogamous. For example, the complex set of genes that underlie the ability to tolerate the presence of another member of one’s species presumably exists in nonmonogamous animals, but might be activated in different patterns to allow prolonged partnerships in monogamous ones.

“We wanted to be bold—and maybe a little bit crazy” in the new experiment, Hofmann says. Instead of doing a relatively straightforward genetic comparison between closely related species on either side of the monogamy divide, he and colleagues wanted to hunt down a gene activity signature associated with monogamy in males across a wide variety of species—frogs, mice, voles, birds, and fish. So in each of these groups, they selected two species, one monogamous and one nonmonogamous.

Rounding up the brains of those animals took an international team and years of effort. Hostile regional authorities and a complicated permitting system confronted the team in Romania as they tried to capture two types of a native songbird. Hofmann donned scuba gear and plunged into Africa’s Lake Tanganyika to chase finger-length cichlid fish into nets. Delicately debraining them while aboard a rocking boat, he says, was a struggle.

Back the lab, the researchers then grouped roughly comparable genes across all 10 species based on similarities in their sequences. For each of these cross-species gene groups, they measured activity based on how much the cells in the brain transcribed the DNA’s proteinmaking instructions into strands of RNA.

Among the monogamous animals, a pattern emerged. The researchers found certain sets of genes were more likely to be “turned up” or “turned down” in those creatures than in the nonmonogamous species. And they ruled out other reasons why these monogamous animals might have similar gene expression patterns, including similar environments or close evolutionary relationships.

Among the genes with increased activity in monogamous species were those involved in neural development, signaling between cells, learning, and memory, the researchers report online today in the Proceedings of the National Academy of Sciences. They speculate that genes that make the brain more adaptable—and better able to remember—might also help animals recognize their mates and find their presence rewarding.

It makes sense that genes involved in brain development and function would underlie a complex behavior like monogamy, says behavioral neuroscientist Claudio Mello of Oregon Health & Science University in Portland. But because the researchers didn’t dissect out specific brain regions and analyze their RNA production independently, they can’t describe the finely tuned patterns of gene expression in areas that are key to reproductive behavior. “It seems to me unlikely that by themselves these genes will be able to ‘explain’ this behavior,” he says.

“The fact that they got any common genes at all is interesting,” adds Lisa Stubbs, a developmental geneticist at the University of Illinois in Urbana. “It is a superb data set and an expert analysis,” she says, “[but] the authors have not actually uncovered many important biological insights into monogamy.”

The study did turn up a curious outlier. Some of the genes with decreased expression in most of the monogamous species showed increased expression in one of them—the poison dart frog Ranitomeya imitator. Young notes that in this species’s evolutionary history, fathers cared for the young before cooperative parenting evolved. As a result, these frogs may have had a different evolutionary starting point than other animals in the study, later tapping into different genes to become monogamous.

Hoekstra, who has studied the genetics of monogamy in mice, sees “a lot of exciting next steps.” There are likely mutations in other regions of DNA that regulate the expression of the genes this study identified. But it will take more work to show a causal relationship between any particular genetic sequence and monogamous behavior.

People also often opt for monogamy, albeit for a complicated set of social and cultural reasons. So, do we share the gene activity signature common to monogamous birds, fish, and frogs? “We don’t know that,” says Hofmann, but “we certainly would speculate that the kind of gene expression patterns … might [show up] in humans as well.”

http://www.sciencemag.org/news/2019/01/monogamy-may-have-telltale-signature-gene-activity

Activating something called the behavioral immune system puts a damper on dating, new research shows.

About a decade ago, evolutionary psychologists suggested that humans have evolved a first line of defense against disease: this behavioral immune system or BIS.

The theory is that perceiving, rightly or wrongly, the threat of disease unconsciously activates this system. Although we cannot see microorganisms with the naked eye, we are nevertheless able to identify cues—such as coughs, unpleasant smells, or skin lesions—that hint at the possible presence of pathogens, whether or not these are actually present or represent real health threats.

Scientists have suggested that the activation of the BIS leads to prejudiced and avoidant attitudes and behavior towards those who display superficial cues connoting disease.

But how does this affect our dating lives, where two competing needs are pitted against one another—i.e., the potential benefits of connecting and finding a mate versus the need to protect oneself from disease? McGill University scientists set out to find out, by looking at the activation of the BIS in young, single, heterosexual Montrealers in both real speed-dating events and in experimental online dating.

The results were convincing. And not very happy.

“We found that when the behavioral immune system was activated it seemed to put the brakes on our drive to connect with our peers socially,” says first author of the study Natsumi Sawada, who holds a PhD in psychology from McGill University.

“We hadn’t expected this to be the case in real life situations like dating where people are generally so motivated to connect. The results suggest that beyond how we consciously or unconsciously think and feel about each other there are additional factors that we may not be consciously aware of, such as a fear of disease that may influence how we connect with others.”

This video explains how the experiments worked:

The findings appear in the Personality and Social Psychology Bulletin. The Social Sciences and Humanities Research Council (SSHRC) and the Fonds de Recherche sur la Société et la Culture (FRQSC) supported the work.

https://www.futurity.org/behavioral-immune-system-dating-1745362-2/

BY RACHEL EHRENBERG

Getting your groove on solo with headphones on might be your jam, but it can’t compare with a live concert. Just ask your brain. When people watch live music together, their brains waves synchronize, and this brain bonding is linked with having a better time.

The new findings, reported March 27 at a Cognitive Neuroscience Society meeting, are a reminder that humans are social creatures. In western cultures, performing music is generally reserved for the tunefully talented, but this hasn’t been true through much of human history. “Music is typically linked with ritual and in most cultures is associated with dance,” said neuroscientist Jessica Grahn of Western University in London, Canada. “It’s a way to have social participation.”

Study participants were split into groups of 20 and experienced music in one of three ways. Some watched a live concert with a large audience, some watched a recording of the concert with a large audience, and some watched the recording with only a few other people. Each person wore EEG caps, headwear covered with electrodes that measure the collective behavior of the brain’s nerve cells. The musicians played an original song they wrote for the study.

The delta brain waves of audience members who watched the music live were more synchronized than those of people in the other two groups. Delta brain waves fall in a frequency range that roughly corresponds to the beat of the music, suggesting that beat drives the synchronicity, neuroscientist Molly Henry, a member of Grahn’s lab, reported. The more synchronized a particular audience member was with others, the more he or she reported feeling connected to the performers and enjoying the show.

https://www.sciencenews.org/article/brain-waves-concertgoers-sync-shows

Any ad executive will tell you that sex sells. But why? Do sexy images stimulate our biological urges, somehow motivating us to buy products? Or do marketers merely exploit and perpetuate our cultural obsession with sexual imagery? Do people want the beauty, wealth and power celebrities have, and use the products they endorse in the hope of achieving these same qualities?

These explanations are plausible, but my colleagues and I have a new one, based on decades of work comparing the behavior and neurobiology of decision-making in monkeys and people: Our brains have been fine-tuned by evolution to prioritize social information, and this laser focus on others profoundly shapes our decisions.

As early as the 1870s, companies like Pearl Tobacco and later, W. Duke & Sons, employed social advertising, showcasing nude or partially exposed women on posters and trading cards. Although the images had no direct link to the products, sales increased. A century and a half later, it seems impossible to escape sexual imagery in advertising. The same is true for celebrities in marketing campaigns—actors, musicians, athletes, even politicians and business leaders. These celebrities often don’t even use the products they advertise, yet the method still seems to work.

Our brains have circuits specialized for identifying, remembering and inferring the mental states of others so we can predict their behavior and make good decisions. In other words, we’re built to deal with people. But we’re not alone in this connection. Many species of monkeys and apes—our closest living relatives—also live in large, complex, dynamic societies. Behavioral studies show that, like us, these primates identify others, track prior encounters, empathize with friends and relatives, and make inferences about individuals’ mental states.

For people and monkeys alike, it’s important to find a good mate, make powerful allies and avoid potential threats. Paying close attention to social cues can improve these choices. In fact, both men and male monkeys are exquisitely sensitive to indications of female fertility. Men rate ovulating women as more attractive, and tip more for lap dances by fertile women. Similarly, male rhesus macaques prefer images of females with artificially reddened faces and hindquarters, coloration that predicts ovulation and sexual receptivity.

Women and female monkeys are also sensitive to clues about male quality, although what we know about that is based on fewer studies. A woman’s preference shifts toward more masculine faces—broader jaw, wider-set but smaller eyes—during ovulation. Female macaques, when ovulating, tend to mate with higher-ranking males and prefer those with reddened faces caused by a testosterone surge. Other studies found that both people and monkeys pay more attention to high-status individuals and are more likely to follow their gaze.

According to economics, we can quantify how much someone values something—coffee, a magazine—by how much he or she will pay for it. In our latest work, we developed an assessment, dubbed the “pay-per-view” test, to measure subconscious value of visual images. In the experiment, monkeys had the option to forego juice or food for a glimpse at a picture of another monkey. People could choose whether to accept a smaller cash reward to peek at a picture of another individual.

Our findings were striking. Male college students paid slightly more money to view an attractive woman than an unattractive one, losing several dollars during the experiment. Female students were much less motivated to see attractive men. Monkeys of both genders valued sex and status, accepting less food or juice to see images of monkey genitalia and faces of high-status males. In contrast, they required extra food or juice to look at faces of low-status males.

Based on these findings, it’s clear that monkeys and humans value information about sex and status so much that it can replace rewards like food, juice and money. Strong parallels between the two suggest shared brain mechanisms at work.

To test this idea, we used fMRI to scan the brains of male students in two circumstances: one, while they viewed female faces of varying attractiveness, the other while money was either deposited or withdrawn from their study stipend. The sight of attractive faces strongly activated a network of brain areas previously implicated in processing rewards—including the orbitofrontal cortex, ventromedial prefrontal cortex, and medial and ventral striatum—and neural activity increased with increasing attractiveness. The same happened with monetary rewards and losses. We believe this network computes economic “utility,” a person’s internal desire for or satisfaction with a good or service, thought to underlie decisions.

To determine the physiological basis of these signals, we measured individual brain cell activity in monkeys. Some fired strongly when male monkeys chose to see female genitalia, a high-status male face, or a large juice reward, but fired less when they chose low-status faces or small juice rewards. Specific brain cells reacted to images of faces and genitals but not juice, indicating the brain’s reward system possesses dedicated hardware for identifying and prioritizing key social information.

Can these discoveries help explain the power of sex and status in advertising? In theory, ads that associate sex or status with specific brands or products activate the brain mechanisms that prioritize social information, and turning on this switch may bias us toward the product.

To test this idea, we exposed male rhesus macaques to logos of household brands like Nike and Pizza Hut paired with a social image (e.g., female genitalia, high-status male face) or the same image with pixels rearranged to make it unrecognizable but retain the same brightness, contrast, and color, salient cues that could draw attention to a stimulus. Monkeys received a sweet treat for touching the screen after the ad, then had the choice between brands paired with a social image or its scrambled version.

Our advertising campaign was remarkably effective. Monkeys developed preferences for brands linked with sex and status. Both males and females preferred logos paired with sexual cues and the faces of high-status monkeys. And the more often male monkeys saw sexual advertisements, the more they preferred the brands. Sound familiar? Even monkeys, it seems, can be persuaded to choose a brand through social advertising.

Given the nearly identical specializations of brain reward circuits to prioritize social information in monkeys and people, is it any wonder that sex and status sell?

https://blogs.scientificamerican.com/observations/what-monkeys-can-teach-us-about-advertising/