Giraffes can do basic stats to pick out their favourite treat

Media release

Giraffes can predict the odds of choosing their favourite treat

Giraffes can calculate which option is more likely to produce their preferred food based on basic statistical calculations, reports a paper published in Scientific Reports. The findings, based on the small study of four giraffes at the Barcelona Zoo, suggest that giraffes may have more sophisticated statistical abilities than previously thought. 

The ability to make statistical inferences is considered a highly developed cognitive function and has only been tested in large-brained animals such as primates and keas (Nestor notabilis). However, the statistical abilities of animals with proportionally smaller brains, such as giraffes (Giraffa camelopardalis), have not been tested.

Federica Amici and colleagues presented two male and two female giraffes with a choice between two vegetable sticks held in a closed fist that had been drawn from transparent containers holding different proportions of preferred carrot sticks and less-preferred courgette (zucchini) sticks. While the giraffe could see the amounts of the different vegetables in each container, they could not see which vegetable the authors selected and offered.

The different conditions included a container holding 20 carrots plus 100 courgette pieces versus one holding 100 carrots plus 20 courgette pieces, 20 carrots plus 100 courgette pieces versus 20 carrots plus four courgette pieces, and finally 57 carrots plus 63 courgette pieces versus 3 carrots and 63 courgette pieces. The latter two conditions tested whether giraffes could assess the relative frequencies of the vegetables, rather than just the absolute numbers of each. In at least 17 out of 20 trials, the giraffes were reliably able to select the container that was more likely to produce their favoured carrot sticks. The authors used control conditions to rule out whether the giraffe were using any other information, such as their sense of smell (instead of seeing the containers) or clues from the experimenters, when making their choice. The authors report that these results demonstrate statistical reasoning akin to that observed in primates and keas.

Given the relatively small brain sizes of giraffes, the authors suggest that a large brain may not be a prerequisite for complex statistical skills, and that the ability to make statistical inferences may be more widespread in the animal kingdom than previously thought.