@article {324696,
	title = {Na{\"\i}ve orangutans (Pongo abelii and~Pongo pygmaeus) individually acquire nut-cracking using hammer tools},
	journal = {American Journal of Primatology},
	volume = {n/a},
	year = {2021},
	note = {<p>https://doi.org/10.1002/ajp.23304</p>
},
	month = {2021/08/11},
	pages = {e23304},
	abstract = {<p>Abstract Nut-cracking with hammer tools (henceforth: nut-cracking) has been argued to be one of the most complex tool-use behaviors observed in nonhuman animals. So far, only chimpanzees, capuchins, and macaques have been observed using tools to crack nuts in the wild (Boesch and Boesch,\&nbsp;1990; Gumert et al.,\&nbsp;2009; Mannu and Ottoni,\&nbsp;2009). However, the learning mechanisms behind this behavior, and the extent of nut-cracking in other primate species are still unknown. The aim of this study was two-fold. First, we investigated whether another great ape species would develop nut-cracking when provided with all the tools and appropriate conditions to do so. Second, we examined the mechanisms behind the emergence of nut-cracking by testing a na{\"\i}ve sample. Orangutans (Pongo abelii and Pongo pygmaeus) have the second most extensive tool-use repertoire among the great apes (after chimpanzees) and show flexible problem-solving capacities. Orangutans have not been observed cracking nuts in the wild, however, perhaps because their arboreal habits provide limited opportunities for nut-cracking. Therefore, orangutans are a valid candidate species for the investigation of the development of this behavior. Four nut-cracking-na{\"\i}ve orangutans at Leipzig zoo (P. abelii; Mage?=?16; age range?=?10?19; 4F; at the time of testing) were provided with nuts and hammers but were not demonstrated the nut-cracking behavioral form. Additionally, we report data from a previously unpublished study by one of the authors (Martina Funk) with eight orangutans housed at Z{\"u}rich zoo (six P. abelii and two P. pygmaeus; Mage?=?14; age range?=?2?30; 5F; at the time of testing) that followed a similar testing paradigm. Out of the twelve orangutans tested, at least four individuals, one from Leipzig (P. abelii) and three from Z{\"u}rich (P. abelii\&nbsp;and P. pygmaeus), spontaneously expressed nut-cracking using wooden hammers. These results demonstrate that nut-cracking can emerge in orangutans through individual learning and certain types of non-copying social learning.</p>
},
	keywords = {individual learning, nut-cracking, Orangutan, Social learning, tool-use},
	isbn = {0275-2565},
	doi = {https://doi.org/10.1002/ajp.23304},
	url = {https://onlinelibrary.wiley.com/doi/10.1002/ajp.23304},
	author = {Bandini, Elisa and Grossmann, Johannes and Funk, Martina and Albiach-Serrano, Anna and Tennie, Claudio}
}
