Brazilian capuchin monkeys stone use may show similarities with earlier hominin activities
An international team investigate primates looking for clues about hominin technological development and to learn more about the use of pounding stones by Homo antecessor (dated ca. 1 Ma). These primates have been observed using stones to crack open nuts or dig holes looking for spiders or roots.
Fossils and stone tools are key findings unearthed at any archaeological site focused on human evolution studies, however, behavior does not fossilize, and it is not possible to observe hominins using their tools. Thus, primatology plays an important role, as the study of modern primates can help us to understand the behavior of the earliest human populations. In this context, an international research team is focused on the analysis of capuchin monkeys from Serra da Capivara, in Brazil. The main goal is to investigate the use-wear marks developed on the stone tools used by these monkeys and build a theoretical model that could help to understand the emergence of hominin behavior.
“There are around 30 individuals (capuchin monkeys) that live in the wild across the Oitenta area at Serra da Capivara”, explain Adrián Arroyo, a Juan de la Cierva fellow at IPHES (Institut Català de Paleoecologia Humana i Evolució Social) and specialised in functional studies of prehistoric tools through the analysis of the marks left on them. Dr Arroyo, who compared on his PhD pounding tools from African sites (Olduvai Gorge and West Turkana) and stones used by chimpanzees, is currently applying this methodological approach to the objects found at Gran Dolina (Atapuerca, Burgos), used by Homo antecessor, species that was discovered here for the first time and is dated to ca. 1 Ma.
“The study of capuchin monkeys can help us to understand those activities that our ancestors could do by comparing the stone tools used by these primates and the ones identified in archaeological places like Atapuerca, although this methodology can also be applied to the earliest stages of human evolution. In fact, this is one research field with a great potential, as it can be used to interpret the beginning of the technology, how did it emerge as well as investigate if before stone flaking, the use of stones was already assumed by hominins, and how they began knapping stone tools”, explain Adrián Arroyo.
Hominin activities are investigated through the use of microscopic and functional studies, a discipline that allows researchers to observe the traces developed on the stones tools after being used and compare them to the ones identified on other experimental reference collections. Thus, continuing the functional studies developed at IPHES, a group of stone used by capuchin monkeys from Serra da Capivara will be studied, allowing the researchers to understand their tools and will help to understand potential activities carried out within the earliest stages of Atapuerca.
This study is part of an international project funded by the Leakey Foundation and led by Dr Tomos Proffitt, British Academy Fellow at the Institute of Archaeology (University College London). Team members are Dr Adrián Arroyo (IPHES), Dr Lydia Luncz (Oxford University) and Dr Tiago Falótico (Sao Paulo University). As well as collaborators, Prof Ignacio de la Torre (UCL), Prof Sonia Harmand and Dr Nicholas Taylor (Stoney Book University).
“At Serra da Capivara we re-visit those places where the monkeys have done their activities. They use stones to crack nuts, dig holes to search for spiders or roots, they also hit others stones to pulverize the surface and lick the dust produced, in fact, this activity is still investigated to determine why they do it”.
During the field season, the team map the stones that have been used by the monkeys and document their position as it is done in an archaeological site. The main difference is that in this case, the tool users are present. “It is quite a new research line within human evolution studies, especially because till now there were no systematic studies of the stones used by primates from an archaeological perspective. There were quite a number of behavioral studies, but very few about their lithic technology”, detail Adrián Arroyo.
The systematic research of capuchin monkeys from an archaeological perspective began in 2012 in Oxford. Before then, archaeologist did not have access to the archaeological signature made by capuchin monkeys in order to identify similarities and differences with the hominin record. Thus, thanks to the collaboration with this international team, functional studies of hominin stones tools developed at IPHES are increased now with stones used by primates.