title: Tools to tipple: ethanol ingestion by wild chimpanzees using leaf-sponges.
abstract: African apes and humans share a genetic mutation that enables them to effectively metabolize ethanol. However, voluntary ethanol consumption in this evolutionary radiation is documented only in modern humans. Here, we report evidence of the long-term and recurrent ingestion of ethanol from the raffia palm (Raphia hookeri, Arecaceae) by wild chimpanzees (Pan troglodytes verus) at Bossou in Guinea, West Africa, from 1995 to 2012. Chimpanzees at Bossou ingest this alcoholic beverage, often in large quantities, despite an average presence of ethanol of 3.1% alcohol by volume (ABV) and up to 6.9% ABV. Local people tap raffia palms and the sap collects in plastic containers, and chimpanzees use elementary technology-a leafy tool-to obtain this fermenting sap. These data show that ethanol does not act as a deterrent to feeding in this community of wild apes, supporting the idea that the last common ancestor of living African apes and modern humans was not averse to ingesting foods containing ethanol.
authors.affiliation: Centre for Research in Anthropology (CRIA-FCSH/UNL) , Lisbon 1069-061, Portugal ; Anthropology Centre for Conservation, Environment and Development , Oxford Brookes University , Oxford OX3 0BP, UK.
authors.forename: Kimberley J
authors.initials: KJ
authors.lastname: Hockings
authors.affiliation: School of Anthropology and Conservation , University of Kent , Canterbury CT2 7NR, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Bryson-Morrison
authors.affiliation: Center for the Advanced Study of Hominid Paleobiology , George Washington University , Washington DC, 20052, USA ; Interdisciplinary Center for Archaeology and Evolution of Human Behavior , Universidade do Algarve , Faro 8005-139, Portugal.
authors.forename: Susana
authors.initials: S
authors.lastname: Carvalho
authors.affiliation: Primate Research Institute , Kyoto University , Inuyama 484-8506, Japan ; Center for Southeast Asian Studies , Kyoto University , Kyoto 606-8501, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Fujisawa
authors.affiliation: School of Anthropology and Conservation , University of Kent , Canterbury CT2 7NR, UK.
authors.forename: Tatyana
authors.initials: T
authors.lastname: Humle
authors.affiliation: Department of Archaeology and Anthropology , University of Cambridge , Cambridge CB2 1QH, UK.
authors.forename: William C
authors.initials: WC
authors.lastname: McGrew
authors.affiliation: Wildlife Research Center , Kyoto University , Kyoto 606-8203, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Nakamura
authors.affiliation: Wildlife Research Center , Kyoto University , Kyoto 606-8203, Japan ; Japan Monkey Centre , Inuyama 484-0081, Japan ; Chubu University , Kasugai 487-8501, Japan.
authors.forename: Gaku
authors.initials: G
authors.lastname: Ohashi
authors.affiliation: Wildlife Research Center , Kyoto University , Kyoto 606-8203, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Yamanashi
authors.affiliation: Center for African Area Studies , Kyoto University , Kyoto 606-8501, Japan.
authors.forename: Gen
authors.initials: G
authors.lastname: Yamakoshi
authors.affiliation: Primate Research Institute , Kyoto University , Inuyama 484-8506, Japan ; Japan Monkey Centre , Inuyama 484-0081, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Matsuzawa
keywords: elementary tool-use; ethanol ingestion; great apes; raffia palm