Wednesday, 15 August 2012

Culture – now available in bottled shape

Fauna is a rather odd association when it comes to culture, but a bunch of network analysts might put that in the past tense.

Scientists of The University of Georgetown explored whether the tool use of some bottlenose dolphins in Shark Bay may be considered a cultural thing, when it comes to the forming of groups. The basis fo the research was that this behaviour is  both a cognitive action, and a grouping criteria. The research included 36 spongers (animals that use marinal sponges for hunting) and 96 traditionally hunting dolphins. It became instantly obvious, that homofilia (the tendency to associate with similar others) based on tool use is legit, while other factors include: maternal kinship, location and gender. This supports the theory, that tool use is a cultural phenomenon. Female spongers for example prefer spongers to non-spongers, the same way people prefer other people within the same subculture.

Bottlenose dolphins live in open communities, characterized by high fission-fusion dynamics where members maintain long-term preferential bonds, but associations are temporally and spatially variable across minutes, days and years. This tool use is unique among cetaceans, and was only observed among 55 dolphins in Shark Bay. The hunting tactic gets passed on vertically, since the hunting itself is done alone, while newborns learn the tricks and techniques when they accompany their mother.
The 22 year (!) research distinguished male, female, sponger and non-sponger dolphins and revolved around the social behaviour of the animals.

The first network in the picture shows the four big hubs formed by 105 dolphins, with the bigger points marking the spongers. The thickness of the links marks their strength, and draw out the network of spongers. The second network shows the whole 500 population, the nonspongers are coloured purple and light blue.

The whole article is available on the Nature homepage, feel free to check it out!

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