When innovation pays off: Food quality changes the link between innovation and survival in mice

Being good at solving new problems does not automatically improve an animal’s chances of survival. A study published in Biology Letters shows that food quality affects how readily house mice innovate and, more strikingly, whether solving a problem quickly or slowly is associated with longer survival. The direction of that relationship changed with the environment.
 

To the Point:

• Food quality affected innovation. Mice raised on a high-quality diet were more likely to innovate early in life than mice raised on standard-quality food.
• Innovation was not linked to better body condition. Neither the likelihood of innovating nor innovation speed predicted changes in body mass over time.
• The link between innovation and survival depended on the environment. Faster innovators survived longer under high-quality food conditions, whereas slower innovators survived longer under standard-quality food conditions.
• There was no simple survival advantage to being innovative. The consequences depended on how an animal innovated and on the conditions in which it lived.

Innovation allows animals to respond to unfamiliar situations, for example by finding new ways to access food. But trying something new can also cost time and energy or expose an animal to risk. Whether innovation ultimately improves an individual’s fitness is therefore less obvious than it may seem.

Fragkiskos Darmis from the Max Planck Institute for Evolutionary Biology and Anja Guenther from the University of Hildesheim tested this in wild-derived house mice. The animals came from populations maintained for several generations on either standard-quality or higher-quality food. As young adults, they were presented with three standardised problem-solving tasks: opening a LEGO house, lifting the lid of a Petri dish and removing a paper ball from a tube to reach a food reward.

The researchers recorded two aspects of innovation: whether a mouse solved at least one task and how long successful animals took to do so. The mice were then released into semi-natural enclosures with the same food quality they had experienced during development. Their body mass and survival were monitored for six months.

The first difference appeared before the mice entered the semi-natural enclosures. Seventy-seven per cent of animals in the high-quality treatment solved at least one task, compared with around half of those in the standard-quality treatment. This difference was driven mainly by females. The average time needed to solve a task, however, did not differ between the two food treatments.

That result runs counter to one common prediction: animals facing poorer conditions might be expected to innovate more because they have greater need to find alternative ways of obtaining resources. In this experiment, the opposite pattern emerged early in life. Mice with access to the higher-quality diet were more likely to innovate.

Innovation also did not translate into higher body mass. Neither the likelihood of solving a task nor the speed of solving it predicted how body mass changed over time. Being more innovative, in other words, was not simply associated with better physical condition.

The advantage depends on the environment

The clearest result concerned survival. There was no convincing evidence that innovators as a group consistently outlived non-innovators in either food environment. Among the mice that did innovate, however, speed mattered.

Faster problem-solvers survived longer in the high-quality environment. Under standard-quality food conditions, the pattern was reversed: slower innovators survived longer. The same behavioural measure was therefore associated with different survival outcomes depending on food quality.

The study does not establish why. Darmis and Guenther suggest that under more constrained conditions, slower problem-solving could reflect a more cautious approach, with animals spending more time gathering information before acting. That might reduce energy expenditure or exposure to risk. Where high-quality food is available, rapid problem-solving may instead allow animals to exploit opportunities more efficiently. These explanations remain hypotheses and will need to be tested directly.

The results also help clarify why links between innovation and fitness have been difficult to pin down across species and studies. Treating innovation as a generally advantageous trait may be too simple. Its consequences can depend on the environment, and even different components of innovation, such as the tendency to solve a problem and the speed of doing so, need not have the same relationship with fitness.

By measuring behaviour under controlled conditions and then following the same animals for six months in semi-natural populations, the study connects individual differences in problem-solving with longer-term outcomes under more realistic ecological conditions.