Captive-bred Orangutans voluntarily choose to reward themselves with cabbage containing greater amounts of anthocyanin in a two-alternative decision task

Abstract

Anthocyanins are an important part of the human diet and the most commonly consumed plant secondary metabolites. They are potent antioxidants, and in several recent studies the ingestion of anthocyanins has been linked to positive health benefits for humans. Here, we not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/099432 doi: bioRxiv preprint first posted online Jan. 11, 2017; ! 3! show that when given a choice between two alternative samples of cabbage to ingest, captive born orangutans (n = 6) voluntarily chose the sample that contained greater amounts of anthocyanin. This occurred when they had to decide between samples of red cabbage (Brassica oleracea var. capitata f. rubra) from the same plant (p<0.05), and samples from green cabbage (Brassica oleracea var. capitata) (p<0.01). This indicates that anthocyanin holds a reward value for these hominids. There was no difference in L*a*b* colour between ingested and discarded samples in red cabbage, but when the choice was between two green samples, the animals chose samples that were more green and yellow. There was also no difference in the amount of lightness (L*) between chosen and discarded samples of either plant. It is therefore unclear if the animals use leaf colour in decision-making. In addition to other macro nutrients provided by plants, anthocyanin is also chosen by these endangered apes.