People are more likely to snack faster when someone else is around because humans are hardwired with a ‘forager mentality’
- Humans snack on small portions more frequently in the presence of food rivals
- Social animals adapt to signs of food competition – and humans are no different
- The behaviour could be an evolutionary trait to prevent our food getting nicked
The presence of someone else when we’re eating makes us switch to a ‘foraging tactic’ that makes us eat reach for small food portions more regularly, scientists say.
Japanese experiments found that even when there was no real competition for food, humans in pairs reached for smaller portions of crisps, but more frequently.
This compared to participants in the study that were on their own who, in comparison, grabbed bigger portions of potato chips less frequently.
The research team compared the results to groups of mammals and birds that automatically eat small portions quicker in the presence of a ‘food rival’.
Such a behavioural shift in nature may be a built-in tactic to reduce the risk of part of their portion stolen by nearby scroungers
The researchers provided human subjects with a plate of potato chips and compared their foraging behaviour solo and in pairs
Humans and other animals may have a built-in systems that automatically triggers the shift in the presence of others.
‘Our results showed that the behavioural shift was triggered by the mere presence of a co-eater, even without competition,’ the researchers write in Royal Society Open Science.
‘This suggests that the underlying mechanism for the shift may be a built-in system that activates automatically in response to relevant social cues.’
To test whether a shift in eating behaviour would be triggered in humans, study participants were asked to engage in a lab-based ‘taste test’ alone or in pairs.
They recorded the frequency at which the participants reached for potato chips, the weight of potato chips per reach and the total amount consumed.
An electronic balance that was invisible to subjects was place under the plates to record the timing and weight of crisps taken with each reach.
Paired subjects (left) sat at opposite corners of a table, each with their own plate of potato chips, while in the solo condition (right), a participant ate alone. Someone else on the other side of the table affected eating behaviour, even when it was clear they had their own portion to eat
The scales beneath the plate recorded how often participants took a portion – and how big their portion sizes were
Subjects were also instructed not to eat two hours before the experiments to ensure consistent hunger levels.
In the paired participants, even though the other subject had their own plate of crisps, subjects reached for smaller food amounts more frequently.
However, overall food intake did not increase in the ‘paired’ settings compared with the solo condition.
The research team conducted experiments separately for men and women, following results from a preliminary questionnaire that indicated women were more apprehensive about the quantity of meals than men.
Sure enough, reach frequency and overall food intake were both higher in men than in women, they found.
Previous research with crows has shown that smaller foods are less likely to be ‘scrounged’ than larger foods
Social foraging – the act of searching for food in groups – in the wild provides animals with various benefits, including a bigger chance of encountering food and a collective monitoring of potential predators as they eat.
However, it can also create competition among co-foragers because individuals can ‘free-ride’ on others’ successful search efforts and by stealing morsels.
The tactic of retrieving small morsels more frequently rather than large morsels less frequently reduces the risk of scrounging by other individuals.
A previous study found chicks approached and pecked at food more frequently when a co-forager was present, compared to when they were isolated.
Another study with crows found that smaller foods are less likely to be scrounged than larger foods.