Following the recent paper in the Journal of Zoo and Aquarium Research describing food-washing behaviour in babirusa (Ito et al., 2017), it seemed to be a good time to look at the phylogenetic aspect of this behaviour.
The food-washing behaviours of primates (Maca spp., Pongo abelii, Gorilla gorilla and Pan spp.) are well known and observed both in the wild and in captivity.
However, more research is needed into the food-washing behaviour of the babirusa pig (Babyrousa celebensis) and the raccoon (Procyon lotor).
Allritz, M., Tennie, C. and Call, J., 2013. Food washing and placer mining in captive great apes. Primates, 54(4), pp.361-370.
ITO, Masaaki et al. Food preparation behaviour of babirusa (Babyrousa celebensis). Journal of Zoo and Aquarium Research, [S.l.], v. 5, n. 2, p. 97-103, apr. 2017. ISSN 2214-7594. Available at: http://www.jzar.org/jzar/article/view/274.
Galef, B.G., 1990. Tradition in animals: Field observations and laboratory analyses. Interpretation and explanation in the study of animal behavior, 1, pp.74-95.
Nakamichi, M., Kato, E., Kojima, Y. and Itoigawa, N., 1998. Carrying and washing of grass roots by free-ranging Japanese macaques at Katsuyama. Folia Primatologica, 69(1), pp.35-40.