Rats give more generously in response to the smell of hunger

March 24, 2020

How do animals that help their brethren manage to prioritize those most in need? A study publishing March 24 in the open-access journal PLOS Biology by Karin Schneeberger and colleagues of the Universities of Bern in Switzerland and Potsdam in Germany, shows that rats can use odor cues alone to determine how urgently to provide food assistance to other rats in need.

Reciprocal cooperation among unrelated individuals is widespread in the animal kingdom. For example, Norway rats (Rattus norvegicus) exchange food reciprocally and take into account both the cost of helping and the potential benefit to the receiver. Rats show their need for food through solicitation, which increases the chances they will receive help. But communication through calls and gestures may not honestly reflect the actual need of the recipient, and might instead be used to trick a potential donor into helping. In the new study, Schneeberger and colleagues used Norway rats to investigate odor as a potentially "honest cue" by which prospective donors can assess others' need for food.

The researchers provided rats with odor cues from hungry or well-fed rats located in a different room. They found that the rats were quicker to provide help (by pulling a food tray within reaching distance of another rat) when they received odor cues from a hungry rat than from a well-fed one.

The authors then analyzed the air from around the rats, revealing seven different volatile organic chemicals that differed significantly in their abundance between hungry and satiated rats. According to the authors, the olfactory cues may result directly from recently ingested food sources, from metabolic processes involved in digestion, or from a putative pheromone that indicates hunger. This "smell of hunger" can serve as a reliable cue of need in reciprocal cooperation, supporting the hypothesis of honest signaling.

The authors add: "Rats donate food preferably to social partners in urgent need."
-end-
In your coverage please use this URL to provide access to the freely available article in PLOS Biology: https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000628

Citation: Schneeberger K, Röder G, Taborsky M (2020) The smell of hunger: Norway rats provision social partners based on odour cues of need. PLoS Biol 18(3): e3000628. https://doi.org/10.1371/journal.pbio.3000628

Funding: This project was funded by the Swiss National Science Foundation (SNF), grant numbers 31003A_156152 and 31003A_176174 to M.T. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.

PLOS

Related Hunger Articles from Brightsurf:

Plant genetic engineering to fight 'hidden hunger'
More than two billion people worldwide suffer from micronutrient malnutrition due to deficiencies in minerals and vitamins.

Hunger encourages risk-taking
An insufficient food supply causes animals to engage in higher-risk behaviour: the willingness to take risks rises by an average of 26 per cent in animals that have experienced hunger earlier in their lives.

Free trade can prevent hunger caused by climate change
An international team of researchers investigated the effects of trade on hunger in the world as a result of climate change.

One in four UK adults at risk of hunger and potential malnutrition following lockdown
One in four adults in the UK are experiencing food insecurity, which is likely to have left them susceptible to hunger and potential malnutrition, during the COVID-19 pandemic.

Rats give more generously in response to the smell of hunger
How do animals that help their brethren manage to prioritize those most in need?

How hunger makes food tastier: a neural circuit in the hypothalamus
Using optogenetic and chemogenetic techniques, researchers at the National Institute for Physiological Sciences in Okazaki, Japan, identified brain circuits underlying hunger-induced changes in the preferences for sweet and aversive tastes in mice.

To address hunger, many countries may have to increase carbon footprint
Achieving an adequate, healthy diet in most low- and middle-income countries will require a substantial increase in greenhouse gas emissions and water use due to food production, according to new research from the Johns Hopkins Center for a Livable Future based at the Johns Hopkins Bloomberg School of Public Health.

Scientists link 'hunger hormone' to memory in Alzheimer's study
Scientists at The University of Texas at Dallas have found evidence suggesting that resistance to the 'hunger hormone' ghrelin in the brain is linked to the cognitive impairments and memory loss associated with Alzheimer's disease (AD).

'Hunger hormone' enhances memory
A team of neuroscience researchers at the University of Southern California have identified a surprising new role for the 'hunger hormone' ghrelin.

Researchers identify new hunger pathway in the brain
A newly identified hunger pathway in the brain can quickly modify food intake in the presence of food, according to a study of mice published in JNeurosci.

Read More: Hunger News and Hunger Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.