Body-based units of measure are surprisingly diverse and fit for purpose

A group of researchers from the University of Helsinki have carried out the first globally comprehensive analysis of the use and distribution of body-based units of measure. By analysing digital ethnographic archives, the group found evidence of the extensive use of body-based units in 186 cultures around the world.

The study reveals that body-based units of measure were not limited to simple measuring tools. Instead, they have been used elaborately and with purpose.

For example, body-based units were an integral part of ergonomic design in traditional technologies and in the design of tools. In addition, the use of body-based measurements continued long after the introduction of standardised units of measure, indicating their usefulness and practicality.

Many Finns are familiar with their traditional units of measurement, such as vaaksa (hand span), syli (fathom) and kyynärä (cubit). Traditionally, the units fathom and hand span have been used to measure both skis and tar-burning pits. Similar units based on body measurements have probably been used for millennia. For example, many of the earliest standardised units of measure, such as the ancient Egyptian royal cubit, most likely derived from body-based measurement.

While measurement systems have played a key role in technological and cultural development, little is known about how and what kind of body-based units of measure have been used. The historical use of units of measurement is important to understand and investigate, as it helps to understand the origins of early quantitative thinking. The units can also shed light on how different cultures have designed, for example, their daily tools used to solve everyday problems.

Carefully considered ergonomic design

“Previously, it was thought that body-based units of measure were relatively simple measuring tools that had no more specific purpose. In the history of measurement, such units have often been considered as merely a preliminary step towards supposedly more advanced units of measure, such as the metric system,” says Postdoctoral Researcher Roope Kaaronen from the Faculty of Biological and Environmental Sciences, University of Helsinki.

However, the new review conducted at the University of Helsinki demonstrates that the use of body-based units of measure continued, depending on the region, even for centuries or millennia after the introduction of the first standardised units. The continued use of body-based units of measure is explained by their usefulness.

“The use of such units was often carefully considered. For instance, customising traditional technologies, such as bows, kayaks, skis or clothing, to their users has been important. This is why these tools have often been designed using your own body parts as units of measure,” Kaaronen says.

For example, the Khanty, Karelian and Sámi peoples have designed and measured their skis using their own height or fathom, that is, the distance between the fingertips of outstretched arms, as measuring units. The study demonstrates that ergonomic design has been much more prevalent in the history of human cultures than previously thought. Body-based units of measure have also been used because they are readily available and convenient to use. For example, the length of a rope, cloth or fishing net is easy to measure using the fathom.

“Slack objects such as rope are difficult to measure with a ruler or a measuring tape, but you can easily stretch the rope straight between your outstretched arms. By repeating the movement, you can handily measure even long items,” Kaaronen explains.

Body-based units of measure are still used in the Western world too. For example, the inseam is typically used to determine the right bicycle frame size, while the length of cross-country skis is matched with the size of the user.

Kaaronen says that he carves kayak paddles using his fathom and cubit as measurements.

“The Greenlandic traditional paddle is an ergonomically designed tool with which I have paddled from Helsinki to Mariehamn.”

The study has received funding from the Research Council of Finland, the Kone Foundation and the EU’s Horizon 2020 programme.

Original article

Roope O. Kaaronen et al., Body-based units of measure in cultural evolution. Science 380, 948-954(2023). DOI: 10.1126/science.adf1936