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Needles and bone awls would have been a decisive technology for human survival during the coldest periods of prehistory.
The hypothesis is already old in archaeology, according to , but it was reinforced this month by new research, according to which these tools made it possible to manufacture more efficient clothing, helping Paleolithic human groups to conserve body heat, avoid hypothermia and occupy increasingly hostile regions during the Ice Age.
The work in PLOS One is led by researchers McKenna Litynski, Sean Field e Randall Haassought to demonstrate in a quantitative way the relationship between extreme cold and the use of these tools.
To this end, the team analyzed ethnographic records from 59 indigenous groups in North America and concluded that the lower the temperatures, the greater the probability of finding in the archaeological record the so-called “punchers”, technical category that includes needles and punches.
According to the data presented, in territories where the average minimum temperature of the coldest month fell to −35.5 °C, the probability of these tools appearing reached 52%. In much less rigorous areas, where values could reach positive 12.9 °C, this probability dropped to 37%. For the authors, the difference suggests that the need to produce clothing and other thermal protection artifacts was a determining factor in the development and dissemination of the technology.
Much more than clothing production
Although clothing manufacturing is the single activity most frequently associated with needles and punches, with 133 records, about 69% of documented uses relate to other practices. Among them are tattoos, basket weaving, ritual ceremonies, medical sutures and fishing.
The researchers argue, therefore, that these pieces emerged in response to a concrete climate need, but ended up gaining multiple social, technical and symbolic applications.
The team drew on ethnographies gathered in the eHRAF World Cultures database, which compiles documentation on more than 300 indigenous and ethnic groups from around the world. In the case of this study, all references to needles and punctures in 467 ethnographic documents relating to 59 North American groups were examined. In total, the researchers cataloged 1,191 individual observations, recording the type of tool, the material and the activity with which it was associated.
To measure the impact of climate, the average minimum temperature of the coldest month in each territory was used, based on the WorldClim climate database. The authors then turned to statistical models designed to correct for spatial autocorrelation, that is, the tendency for geographically close groups to share similar cultural characteristics.
The study also relates this innovation to the Recent Dryasan episode of abrupt cooling that lasted about 1,300 years, between approximately 12,900 and 11,600 years ago. According to the authors, this period significantly increased the importance of thermal regulation technologies, such as the production of fitted leather clothing, also favoring the manufacture of sewing needles.
The oldest known bone needles date back to at least 45 thousand years, while punches could have appeared about 75 thousand years. For the researchers, this chronology places the invention at the center of the global expansion of Homo sapiens, but they warn that the presence of these tools should not be automatically interpreted as direct proof of the use of shelter clothing. What the study consolidates is above all the idea that an innovation created to respond to the cold ended up becoming a striking example of the human capacity for adaptation and cultural evolution.
