Hunger encourages risk-taking

October 05, 2020

The lives of animals in the wild are full of risky situations with uncertain outcomes. Whether they are exploring new habitats in unfamiliar terrain or searching for new food sources, they run the risk of being caught and killed by a predator. In many instances, their very survival depends on a single decision. Whether an animal decides to take a risk or prefers to avoid danger varies greatly from one individual to another.

"Just as there are humans who are more cautious and others who take more risks, among animals of a particular species there are also individuals that are more or less risk-averse," says population ecologist Prof. Holger Schielzeth of the University of Jena. These differences are to some degree innate, but to a considerable extent they also depend on an individual's development. As Prof. Schielzeth, his Bielefeld colleague Prof. Klaus Reinhold and their research teams have now shown in an extensive meta-analysis, an animal's risk appetite is decisively influenced by the nutritional conditions it experiences while growing up. The researchers report on their findings in the latest issue of the specialist journal Biological Reviews.

Study results involving over 100 animal species compared

The researchers, working with lead author Nicholas Moran, analysed more than 120 experimental studies involving over 100 animal species and the results. Species studied included spiders, insects, crustaceans, fish, amphibians and birds. Common to all the studies was the fact that the animals had experienced phases of good and bad nutrition, and that their risk appetite was measured later in life. There were two opposing hypotheses: "On the one hand, one could assume that animals that have always enjoyed good circumstances and are therefore in a better condition would have more to lose and would therefore be more risk-averse," says evolutionary biologist Reinhold. On the other hand, he adds, a better nutritional status could mean that an animal would escape more easily from a risky situation, and would therefore be more likely to take a risk.

The analysis of the results of all the studies has now made things clear. 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.

"We were surprised that this result was so clear and unambiguous," says Schielzeth. The correlation applied to virtually all the behavioural contexts studied, such as exploration behaviour, migration and risky searches for food. There were of course variations in the strength of the effect. Nevertheless, Schielzeth assumes that this correlation could also exist in humans, at least to some extent, as we are, after all, also an "animal species".

This meta-analysis was carried out within the framework of the Collaborative Research Centre Transregio 212, "A Novel Synthesis of Individualisation across Behaviour, Ecology and Evolution: Niche Choice, Niche Conformance, Niche Construction" (NC3), which is based at the universities of Bielefeld and Münster, and in which the University of Jena is also involved. Dr Nicholas Moran is currently an MSCA Research Fellow at the National Institute of Aquatic Resources, Technical University of Denmark.
Original publication:

Moran NP et al. Poor nutritional condition promotes high-risk behaviours: a systematic review and meta-analysis, Biol. Rev. (2020), DOI: 10.1111/brv.12655,


Prof. Klaus Reinhold
Department of Evolutionary Biology
Konsequenz 45, 33615 Bielefeld, Germany
Tel.: +49 (0)251 / 1062721

Prof. Holger Schielzeth
Institute of Ecology and Evolution of Friedrich Schiller University Jena
Dornburger Straße 159, 07743 Jena, Germany
Tel.: +49 (0)3641 / 949410

Friedrich-Schiller-Universitaet Jena

Related Behaviour Articles from Brightsurf:

Infection by parasites disturbs flight behaviour in shoals of fish
Shoal behaviour in fish is an important strategy for them to safeguard their survival.

The influence of social norms and behaviour on energy use
People tend to conform to what others do and what others regard as right.

Brainstem neurons control both behaviour and misbehaviour
A recent study at the University of Helsinki reveals how gene control mechanisms define the identity of developing neurons in the brainstem.

Couples can show linked behaviour in terms of risk factors to prevent type 2 diabetes
New research being presented at this year's Annual Meeting of the European Association for the Study of Diabetes (EASD), held online this year, shows that when one half of a couple shows high levels of certain behaviours that prevent type 2 diabetes, such as good diet or exercise, that behaviour also tends to be high in the other half of the couple.

Addicted to the sun? Research shows it's in your genes
Sun-seeking behaviour is linked to genes involved in addiction, behavioural and personality traits and brain function, according to a study of more than 260,000 people led by King's College London researchers.

Less flocking behavior among microorganisms reduces the risk of being eaten
When algae and bacteria with different swimming gaits gather in large groups, their flocking behaviour diminishes, something that may reduce the risk of falling victim to aquatic predators.

Vibes before it bites: 10 types of defensive behaviour for the false coral snake
The False Coral Snake (Oxyrhopus rhombifer) may be capable of recognising various threat levels and demonstrates ten different defensive behaviours, seven of which are registered for the first time for the species.

Unwanted behaviour in dogs is common, with great variance between breeds
All dog breeds have unwanted behaviour, such as noise sensitivity, aggressiveness and separation anxiety, but differences in frequency between breeds are great.

The Lancet Psychiatry: Life-course-persistent antisocial behaviour may be associated with differences in brain structure
Individuals who exhibit life-course-persistent antisocial behaviour - for example, stealing, aggression and violence, bullying, lying, or repeated failure to take care of work or school responsibilities - may have thinner cortex and smaller surface area in regions of the brain previously implicated in studies of antisocial behaviour more broadly, compared to individuals without antisocial behaviour, according to an observational study of 672 participants published in The Lancet Psychiatry journal.

World-first studies reveal occurrence of 'chew and spit' eating behaviour
A landmark study into the prevalence of the disordered eating behaviour known as 'chew and spit' has revealed concerning levels of such episodes among teenagers.

Read More: Behaviour News and Behaviour Current Events 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