Tag Archives: isolation

Social isolation can lead to overeating and under-sleeping — if you’re a fruit fly

New research on fruit flies provides the first reliable animal model for studying our bodies’ reactions to loneliness.

Image credits Mohamed Nuzrath.

Social isolation; we’re all probably more intimately familiar with the term, given these past two years, than we’d like to be. But we’re not the only ones who suffer when we’re separated from our group. New research on fruit flies shows that they as well sleep too little and eat too much when deprived of social interactions. The paper also reports on changes in gene expression, neural activity, and behavior seen in the flies.

The findings are of interest to all of us today, as they point to novel ways of understanding the effects loneliness has on our bodies. They’re also relevant to scientists directly studying fruit flies, or those whose work involves fruit flies, as accounting for these effects would go a long way to improving the reliability of our conclusions.

Flyin’ solo

“Flies are wired to have a specific response to social isolation,” says corresponding author Michael W. Young, the Richard and Jeanne Fisher Professor and head of the Laboratory of Genetics at Rockefeller. “We found that loneliness has pathological consequences, connected to changes in a small group of neurons, and we’ve begun to understand what those neurons are doing.”

It’s not a stretch to say that most of us have had trouble maintaining our pre-lockdown sleep schedule. Many of us are also overeating, or eating at odd hours, and have gained weight. The team behind this study suspected that the social isolation brought about by the lockdown is, in itself, to blame for this. It seems like their hypothesis panned out, as the results describe how chronic separation from the group can have measurable effects on the body (at least in fruit flies). These effects include changes in gene expression, neural activity, and behavior.

Fruit flies (Drosophila melanogaster) are a very social species. They forage and eat in groups, have complex mating rituals, and even engage in some tiny fights from time to time. However, they spend most of their time (up to 16 hours each day) sleeping — also in groups. They have long been a model organism for researchers in various fields of biology. So, when the team turned to them to test their hypothesis.

“Over and over again, Drosophila have put us on the right track,” says Young. “Evolution packed a great deal of complexity into these insects long ago and, when we dig into their systems, we often find the rudiments of something that is also manifest in mammals and humans.”

“When we have no roadmap, the fruit fly becomes our roadmap,” adds lead author Wanhe Li.

The team first compared how fruit flies behave under various lockdown conditions. Flies were kept together in groups of various sizes, ranging from several individuals to a single fly, for a week. For the most part, the insects didn’t have any problems; even flies who were kept with a single other fly didn’t show any distress. However, those that were entirely isolated from their peers started sleeping less and eating more as the trial progressed.

The team further reports finding changes in the expression patterns of a constellation of genes linked to starvation in the brains of these lonely flies. This, they argue, is the genetic link between social isolation and the observed biological changes. One group of cells known as P2 neurons were involved in changing the flies’ feeding and resting behavior. When the P2 neurons were disabled in chronically-isolated flies, they reverted to more normal feeding and sleeping patterns. Amplifying their activity in flies that were only isolated for one day caused them to exhibit the sleeping and overfeeding behavioral patterns of flies who had been isolated for a full week.

“We managed to trick the fly into thinking that it had been chronically isolated,” says Wanhe Li. “The P2 neurons seem to be linked to the perception of the duration of social isolation, or the intensiveness of loneliness, like a timer counting down how long the fly has been alone.”

While these findings haven’t been replicated in humans, the team is confident that more or less the same biological mechanisms seen in these flies operate in isolated humans as well. It’s not the same as confirming that people who ate more and slept less during the lockdown did so because of their P2 neurons — but it’s a starting point, at least.

“Clinically-oriented studies suggest that a large number of adults in the United States experienced significant weight gains and loss of sleep throughout the past year of isolation precautions due to COVID-19,” Young says. “It may well be that our little flies are mimicking the behaviors of humans living under pandemic conditions for shared biological reasons.”

The paper “Chronic social isolation signals starvation and reduces sleep in Drosophila” has been published in the journal Nature.

Close-in of an ant carrying something.

Ants handle social isolation about as well as humans do — poorly

If you’re having a hard time coping with the isolation this pandemic has imposed on us, find solace in the fact that ants, too, would be just as stressed as you in this situation.

Close-in of an ant carrying something, probably a crumb of bread.
Image via Pixabay.

A new paper reports that ants react to social isolation in a similar way to humans and other social species. The most notable changes identified in ants isolated from their groups involve shifts in their social and hygiene behaviors, the team explains. Gene expression for alleles governing the immune and stress response in the brains of these ants were also downregulated, they add.

The burden of loneliness

“[These observed changes] make the immune system less efficient, a phenomenon that is also apparent in socially isolating humans — notably at present during the COVID-19 crisis,” said Professor Susanne Foitzik from Johannes Gutenberg University Mainz (JGU), lead author of the study. The study on a species of ant native to Germany has recently been published in Molecular Ecology.

I don’t think I need to remind you all of this, but humans find social isolation to be a very stressful experience. It can go as far as having a significant and negative impact on our physical health and general well-being. Loneliness, depression, and anxiety can set in quite easily in isolated individuals, they also develop addictions more easily, and their immune system (along with their overall health) takes a hit.

Still, we know much less about how social insects respond to isolation than we do about social animals, including humans. Ants are extremely social insects, living their whole lives in a dense colony and depend on their mates to survive (just like everyone else there). Their lives are so deeply steeped in the social fabric of their colony that worker ants don’t even reproduce, instead caring for the nest and queen, who does all the baby-making. This would be an unthinkable proposition for most other species on Earth.

The team worked with Temnothorax nylanderi, a species endemic to Western Europe. This species lives in cavities formed in fallen plant matter such as acorns or sticks, with colonies usually containing a few dozen workers. The researchers collected young worker ants who were involved in caring for the young from 14 colonies, keeping them in isolation for varying amounts of time. The shortest was one hour, and the longest, 28 days.

After the isolation period, these ants were released back to their colonies. The team explains that these individuals seemed to show lower interest in their adult colony mates, spent less time grooming themselves, but spent more with the brood.

“This reduction in hygienic behavior may make the ants more susceptible to parasites, but it is also a feature typical of social deprivation in other social organisms,” explained Professor Susanne Foitzik.

Gene activity was also impacted. The authors report that a constellation of genes involved in governing the immune system and stress response of these ants was “downregulated”, i.e. less active. This finding is consistent with previous literature showing a weakened immune system after isolation in other social species.

“Our study shows that ants are as affected by isolation as social mammals are and suggests a general link between social well-being, stress tolerance, and immunocompetence in social animals,” concludes Foitzik.

The paper “Social isolation causes downregulation of immune and stress response genes and behavioral changes in a social insect” has been published in the journal Molecular Ecology.

Self-isolation can lead to accents

It’s not like the coronavirus pandemic will make us all talk funny. But according to recent research, even short isolation periods can cause some shifts in the way we shape sounds.

Isolation can change the way you speak — but only slightly. Image credits: Olivier Guillard.

The fact that isolation brings forth new accents is not new. There are numerous examples of isolated populations that started with one accent and ended with another or a different dialect altogether. But even shorter periods of isolation can create micro-accents.

“You can’t hear the differences very well because they are so small,” says Jonathan Harrington, a linguist at the University of Munich and lead author of the study, published in the Journal of the Acoustical Society of America. “But you can measure them.”

The catalyst for change in these very earliest stages of accent formation is thought to be communication density — who talks to whom and how often. Obviously, our communication patterns have changed significantly since the start of the lockdown, but is this sufficient to generate accents?

In order to test how this process happens, Harrington and colleagues recorded the speech of several individuals before and after they spent a few months isolated in the Antarctic as part of the British Antarctic Survey.

“We sought to predict these changes in Antarctica using an agent-based computational model applied to the same individuals’ speech data recorded before they had left for Antarctica. The situation in which Antarctic ‘winterers’ are together for several months is the closest present-day microcosm of former colonial settlement: there is no access to or from Antarctica in winter and the winterers are in regular (spoken) contact with each other,” the study reads.

The study found two types of phonetic changes among volunteers’ vocabulary. The first was a novel one: a phonetically more fronted /ou/, compared to their pre-Antarctica pronunciation. The second was a slight convergence between participants when it came to vowel pronunciation. Researchers predict that the more people spend time together, the more they start talking alike, but the cause of the former change is less clear.

Researchers note that there may also be other factors at play when it comes to explaining these phonetic differences and more research is required to understand how new accents form in isolation. For instance, one of the volunteers’ native language was German, and this may have had a slight effect on the other participants. If you are stuck inside the house for a longer period of time, there is a chance that other peoples’ accent might rub off on you, or that you’ll start to develop new accents altogether — but these changes will almost certainly be imperceptible.

It’s not clear if the changes are temporary.

The study has been published in the Journal of the Acoustical Society of America.