Can't stand staying at home for a few days? See how animals practice social isolation

Wash hands frequently, wear masks, avoid crowds... The COVID-19 pandemic has caused many changes in people's behavior habits, but did you know that this is not unique to humans? In order to prevent the spread of diseases, many social animals will adopt "social isolation", and some are more "conscious" than humans.

Source | www.treehugger.com

Compiled by | Dahe

Proofreading | Gao Peiwen

Even when it is a matter of life and death, social isolation is not an easy thing for social animals like humans, otherwise there wouldn't be so many people complaining that they can't stay at home anymore after just a few days.

Keeping a distance from one's own kind for the sake of survival may seem awkward or even unbearable, but in fact, isolation is common in the animal kingdom. This does not only happen to animals that are used to living alone. For many social animals, social isolation is also rooted in their genes.

From the bees and ants we are familiar with to mice, monkeys, and frogs... whenever viruses, bacteria or parasites attack unexpectedly, they will naturally stay away from danger in order to reduce collective infection.

Ants: Act quickly and mobilize everyone

Ant colonies, known as "superorganisms," are often composed of countless ants, and they work in an orderly manner, just like neurons in the brain. As highly social creatures, ants are of course good at "social isolation," but their methods and effectiveness in detecting germs and preventing their spread are still amazing.
Take the black garden ant, which is widely distributed around the world. Once a member of an ant colony is infected with a fungus, its behavior will change rapidly. Usually, an ant colony consists of at least two types of ants: caretakers and collectors. The former are responsible for taking care of the ants at home, while the latter are responsible for foraging for food. Collectors are more likely to be infected with pathogens. Once they are accidentally infected during their travels, both caretakers and collectors will quickly take measures to prevent the spread of pathogens.

A study in the journal Science shows that this reaction begins even before the forage ants become ill, and they will actively "self-isolate." The researchers exposed some forage ants to a fungal spore, and in less than a day, these forage ants began to extend their "out-of-town" time and reduce contact with other ants. Uninfected forage ants also began to stay away from infected "teammates" as much as possible, and caregivers would quickly move the young ants deeper into the ant nest.

It's unclear how the ants knew they were infected, but the fact that they acted so quickly was undoubtedly effective in curbing the outbreak - an opportunity that human communities have missed in many epidemics.

Honey bees: Two pheromones are key signals

Like all ants, hundreds of bee species are also social insects, with a sophisticated division of labor system, often with several generations living together. For such a large family, the only way to avoid "mass deaths and injuries" caused by the virus is to "detect and deal with it early."

For example, there is a bacterial disease called foul brood. Once infected, bee eggs emit two special pheromones. When adult bees sense the mixed smell of these two pheromones, they will act quickly and react much more actively than if they sense only one pheromone. Once they find the source, they will not hesitate to move all the infected eggs out of the hive. The study was published in the journal Scientific Reports.

Tadpoles: It’s safer to swim farther away

In the past, it was not clear whether animals other than humans have the ability to recognize sick peers and reduce the risk of infection to other members. Until the late 1990s, researchers found that the tadpoles of the American bullfrog are very good at avoiding a dangerous bacterial infection that can cause digestive diseases. Once the tadpoles find that their companions are infected, they will swim away from them about a foot away.

Professor Skelly, a Yale University scientist who led the study, believes that when prey encounter natural enemies, their behavior and even their bodies will undergo huge changes. From the perspective of animals, similar responses to disease risks are likely based on the same principle, that is, to protect themselves and stay away from danger. Healthy bullfrog tadpoles can smell the chemicals released by sick tadpoles in the water, but the specific mechanism of discovery is still unclear.

Western lowland gorilla: If something looks wrong, leave immediately

Like humans, gorillas have highly developed vision, so even though they can't sniff out danger like bees or tadpoles, they can still detect disease with their eyes and move away.

Western lowland gorillas are social animals, and female gorillas in them will choose to live between different groups. A 2019 study found that whether a group has yaws is a key factor in whether a female gorilla chooses to join that group. Yaws is a tropical skin disease that can cause severe swelling of the skin. After tracking nearly 600 gorillas for 10 years, researchers found that female gorillas will avoid groups with yaws at all costs.

Chimpanzees have similar vigilance. As early as the 1960s, primate expert Goodell first reported that chimpanzees would reject individuals with polio, and healthy chimpanzees would even attack individuals with the infectious disease, although Goodell also found that some sick chimpanzees would eventually recover and return to the "big family".

Mouse: I don’t mind being sick

When rats cross the street, everyone shouts and beats them. In most people's eyes, rats are synonymous with dirtiness and filthiness. However, compared with the previous animals that choose to stay away from, abandon, or even expel sick companions, the rats in the experimental observation behaved in the opposite way in terms of social isolation. They would not easily overturn the "friendship boat", which makes people feel that they are quite chivalrous!

In 2016, scientists conducted a study on wild mice in a barn in Switzerland to see how an outbreak of an infectious disease would affect their behavior. To simulate disease, the researchers injected some of the mice with lipopolysaccharide, a substance that makes up the cell walls of bacteria, which can cause an immune response in mice and lead to systemic disease. All mice in the colony were equipped with radio tracking devices to observe the different behaviors of sick mice and healthy mice.

The results were unexpected. Unlike insects and gorillas, healthy mice seemed to ignore the sick mice and continued to live with them as usual. The sick mice themselves reduced their contact with other mice. Ropes, a biologist at the University of Zurich, believes that this may have biological evolutionary significance: sick mice may just feel listless rather than intentionally staying away from their relatives, but this does reduce the risk of infection for other mice.

Baboons: Less grooming to stay safe

Although some of our primates have very drastic ways of avoiding diseases: some drive "sick friends" out of the group, and some sick people "voluntarily leave the group", these practices depend largely on the type of animal and the disease. For example, for highly social baboons, they will not take "forced isolation" for members infected with parasites at all, but simply reduce the time of grooming their hair until the "patient" is well.

Researchers have studied 25 baboons in Gabon for more than two years. They found that baboons infected with more parasites were less likely to be groomed by other baboons, but everything else was normal. They were not expelled or abandoned by the group like gorillas. The researchers collected the feces of the baboons and found a special chemical in the feces of sick baboons. Healthy baboons also avoided these feces, indicating that they know there are more parasites in these feces and can judge when to cut back on grooming the owner of the feces.
Once the researchers treated the sick baboons and removed the parasites, other baboons resumed grooming them as normal.

Vampire bats: More attached to close family members

Vampire bats live in groups, with the number of bats in each group ranging from a few hundred to several thousand. Social behavior is extremely important for their survival. "Mutual aid behaviors" such as touching each other and sharing food are indispensable to every bat. Vampire bats need to eat about a tablespoon of blood every night, and they will die if they do not drink blood for three days. Those bats that find blood often feed the precious fruits of their labor to their less fortunate companions through rumination.

In a recent study, scientists from the Smithsonian Tropical Research Institute in Panama studied a small group of captive vampire bats. They injected some of the bats with bacteria that stimulated their immune systems and made them sick. Observations showed that all bats still interacted and shared food as usual, but sick bats reduced their social interactions with other members. Interestingly, much like humans, they tended to cut off "weak ties", providing and receiving less mutual grooming to general members, but interacted more normally with close family members.

Researchers believe that understanding how bats' social behavior changes in the face of disease is key to predicting how pathogens spread through a population and how quickly they spread. Observing the behavior of vampire bats can help us understand how social animals interact with each other and how this interaction may change or remain unchanged, which is important.

All in all, the sacrifices humans make to fight the epidemic are not as "unnatural" as we think. As a member of the animal kingdom, "social isolation" is really a normal thing.

References:

https://www.treehugger.com/social-distancing-wildlife-species-avoid-disease-4865293

https://news.yale.edu/1999/09/21/yale-scientists-find-evidence-healthy-animals-detect-and-avoid-sick-animals

http://www.cnrs.fr/en/female-gorillas-detect-and-avoid-sick-groups

The article is produced by the "Central Kitchen" of the China Association for Science and Technology, and you are welcome to forward it.