A study of two hunter-gatherer societies located half a world apart has found similarities in the shape of their social networks. These structures have great survival value during hard times, and commonalities with societies where the interconnecting web is worldwide, rather than a food web. Having lived for so much of our history in environments like this, such structures may have laid the foundations for our networks in a digital age.
We have plenty of reasons to connect with other people, but our original needs were for sustenance and safety. "No other apes share food to the extent that humans do," said Dr Andrea Migliano of University College London in a statement.
Migliano conducted a study, reported in Current Biology, of the Agta people in the Philippines and the Mbendjele people in the Republic of Congo. Neither conducts their own agriculture, although each trade foods they catch or collect with neighbors who do cultivate crops.
Agta children gathering seafood. Rodolph Schlaepfer
Migliano mapped the food sharing networks. In each case, individuals were part of a household usually made up of five to six people. Three to four households would come together in a “cluster” to share food frequently, while also being part of a wider camp, which could be relied on for support if hardship struck an individual household. “In larger camps, there are more clusters rather than larger clusters,” the paper reports.
"Despite being from different continents and living in very different ecologies, both groups of hunter-gatherers had a strikingly similar social organization," said first author Mark Dyble. "Cooperation and especially food sharing are essential for survival in a hunting-and-gathering economy,"
Humans need this level of sharing, the authors argue, because we have such long childhoods when we cannot fend for ourselves, and relatively short periods between births, ensuring parents are often supporting substantial numbers of children. Moreover, the paper notes, “We have moved to a dietary niche that often involves the exploitation of difficult to acquire foods with highly variable return rates.”
The only way to get through periods where it is difficult to secure food is to cooperate, the authors suggest, and despite major differences in culture and the foods being collected, similar structures have proven to provide the best support.
Nevertheless, the systems were adaptable for the circumstances. Among the Agta, who live primarily on fish and foods collected in the intertidal zone, camps averaged 63 individuals. The Mbendjele, whose food is more dispersed, average just 41 people to a camp.
The authors tracked every meal consumed over a period of more than three months, observing that 61 percent of the calories consumed by the Mbendjele were produced within the household, while among the Agta 74 percent of food was produced in-house. Although most of the rest came from closely related households, the wider camp provided a buffer that could be drawn upon in times of need.
Despite decades of anthropological studies of traditional societies, Dyble said this is the first to quantify how social networks shape food gathering and distribution
Dyble concluded: "The proverb that 'it takes a village to raise a child' is certainly true for hunter-gatherers, who, without food sharing to mitigate the day-to-day shortfalls in foraging, could simply not survive."
A Mbendjele household sharing food. Gul Deniz Salali