The advent of social networking sites like Facebook and
Twitter have made us all more connected, but long-distance social networks
existed long before the Internet.
An article published in the Proceedings of the
National Academy of Sciences sheds light on the transformation of social
networks in the late pre-Hispanic American Southwest and shows that people of
that period were able to maintain surprisingly long-distance relationships with
nothing more than their feet to connect them.
How the study was
Led by University of Arizona anthropologist Barbara Mills,
the study is based on analysis of more than 800,000 painted ceramic and more
than 4 800 obsidian artifacts dating from A.D. 1200-1450, uncovered from more
than 700 sites in the western Southwest, in what is now Arizona and western New
With funding from the National Science Foundation, Mills,
director of the UA School of Anthropology, worked with collaborators at Archaeology
Southwest in Tucson to compile a database of more than 4.3 million ceramic
artifacts and more than 4 800 obsidian artifacts, from which they drew for the
They then applied formal social network analysis to see what
material culture could teach them about how social networks shifted and evolved
during a period that saw large-scale demographic changes, including
long-distance migration and coalescence of populations into large villages.
Their findings illustrate dramatic changes in social
networks in the Southwest over the 250-year period between A.D. 1200 and 1450.
They found, for example, that while a large social network in the southern part
of the Southwest grew very large and then collapsed, networks in the northern
part of the Southwest became more fragmented but persisted over time.
"Network scientists often talk about how increasingly
connected networks become, or the 'small world' effect, but our study shows
that this isn't always the case," said Mills, who led the study with
co-principal investigator and UA alumnus Jeffery Clark, of Archaeology
"Our long-term study shows that there are cycles of
growth and collapse in social networks when we look at them over
centuries," Mills said. "Highly connected worlds can become highly
Not as restricted
Another important finding was that early social networks do
not appear to have been as restricted as expected by settlements' physical
distance from one another. Researchers found that similar types of painted
pottery were being created and used in villages as far as 250 kilometers apart,
suggesting people were maintaining relationships across relatively large
geographic expanses, despite the only mode of transportation being walking.
"They were making, using and discarding very similar
kinds of assemblages over these very large spaces, which means that a lot of
their daily practices were the same," Mills said. "That doesn't come
about by chance; it has to come about by interaction – the kind of interaction
where it's not just a simple exchange but where people are learning how to make
and how to use and ultimately discard different kinds of pottery."
"That really shocked us, this idea that you can have
such long distance connections. In the pre-Hispanic Southwest they had no real
vehicles, they had no beasts of burden, so they had to share information by
walking," she said.
The application of formal social network analysis – which
focuses on the relationships among nodes, such as individuals, household or
settlements – is relatively new in the field of archaeology, which has
traditionally focused more on specific attributes of those nodes, such as their
size or function.
Changes in structure
The UA study shows how social network analysis can be
applied to a database of material culture to illustrate changes in network
structures over time.
"We already knew about demographic changes – where
people were living and where migration was happening – but what we didn't know
was how that changed social networks," Mills said. "We're so used to
looking traditionally at distributions of pottery and other objects based on
their occurrence in space, but to see how social relationships are created out
of these distributions is what network analysis can help with."
One of Mills's collaborators on the project was Ronald
Breiger, renowned network analysis expert and a UA professor of sociology, with
affiliations in statistics and government and public policy, who says being
able to apply network analysis to archaeology has important implications for
"Barbara (Mills) and her group are pioneers in bringing
the social network perspective to archaeology and into ancient societies,"
said Breiger, who worked with Mills along with collaborators from the UA School
of Anthropology; Archaeology Southwest; the University of Wisconsin, Milwaukee;
Hendrix College; the University of Colorado, Boulder; the Santa Fe Institute;
and Archaeological XRF Laboratory in Albuquerque, N.M.
"What archaeology has to offer for a study of networks
is a focus on very long-term dynamics and applications to societies that aren't
necessarily Western, so that's broadening to the community of social network
researchers," Breiger said. "The coming together of social network
and spatial analysis and the use of material objects to talk about culture is
very much at the forefront of where I see the field of social network analysis
Going forward, Mills hopes to use the same types of analyses
to study even older social networks.
"We have a basis for building on, and we're hoping to
get even greater time depth. We'd like to extend it back in time 400 years
earlier," she said. "The implications are we can see things at a
spatial scale that we've never been able to look at before in a systematic way.
It changes our picture of the Southwest."