% pubman genre = article
@article{item_3337857,
title = {{Na{\"\i}ve orangutans (Pongo abeliiand Pongo pygmaeus) individually acquire nut{-}cracking using hammer tools}},
author = {Bandini, Elisa and Gro{\ss}mann, Johannes and Funk, Martina and Albiach{-}Serrano, Anna and Tennie, Claudio},
language = {eng},
issn = {0275-2565; 1098-2345},
doi = {10.1002/ajp.23304},
publisher = {Wiley},
year = {2021},
date = {2021-08-11},
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, 1990; Gumert et al., 2009; Mannu and Ottoni, 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 {\textequals} 16; age range {\textequals} 10{\textendash}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 Additionally, we report data from a previously unpublished study by one of the authors (Martina Funk) with eight orangutans housed at Z{\"u}rich zoo (six P. abelii and two P. pygmaeus; Mage {\textequals} 14; age range {\textequals} 2{\textendash}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 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.}},
journal = {{American Journal of Primatology}},
volume = {83},
number = {9},
eid = {e23304},
}