Animal personalities more human-like than thought

Scientists have found for the first time that, just like humans, unpredictability is also a consistent behavioural trait in the animal world.
Animals are known to show consistent individual differences in behaviour, which is often referred to as them displaying 'personality'.
In contrast to previous research into these predictable aspects of behaviour, the latest study has shown that some individual animals, just like humans, are consistently more unpredictable than others over time.
Unpredictability is a known and accepted aspect of human behaviour much like we have always viewed predictable aspects of personality. However, until now it has never been studied in animals.

"Until now, unpredictability has only been studied extensively in humans, where it has been linked to learning, ageing, and to certain diseases that produce erratic behaviour due to fluctuations in brain chemicals," said Associate Professor Peter Biro, a behavioural ecologist with Deakin University's School of Life and Environmental Sciences and lead researcher on the study.
"The results of this new study shed light on another important aspect of animal personality that has previously not been considered," Biro added.

Working with Dr Bart Adriaenssens at the University of New South Wales, Biro observed the behaviour of adult male mosquitofish over 132 days.

They found that the behaviour of some individuals was consistently more predictable in a given context than others. Mosquitofish were used for the study because they are widespread and easily sampled from ponds in and around cities.
"We observed that individuals differed in their average levels of activity, but also differed in variability about their average activity," Biro explained.
"Some individuals chose to be active, others chose to be sedentary, some were consistent in their chosen level of activity, others not. But, we found no association between activity levels and predictability.
"What this tells us is that the fish differed in how unpredictable they were, and that this unpredictability is a consistent attribute over time.

"We believe that unpredictability might represent a form of behavioural flexibility that facilitates learning, or makes animals unpredictable to predators or competitors. Some have even referred to this phenomenon as representing 'free will' in animals.
"Our study, having confirmed that unpredictability is a trait, now sets the stage for further studies to test for this phenomenon in other species, and to tease out the causes and consequences of this behavioural variation," Biro said.
The study is published in The American Naturalist.