Nicholas Christakis nsIn human chemistry, Nicholas Christakis (1962-) is an American medical sociologist noted for Granovetter-inspired 2007 to 2010 carbon atom bonding social models.

In 2007, Christakis gained fame with his article “The Spread of Obesity in a Large Social Network Over 32 Years”, co-authored with American sociologist James Fowler, in which they presented the results of a study, which showed that obesity can spread from a person to person, through social networks, much like a virus during an epidemic. [2]

In 2009, Christaksi and Fowler, in their Connected: the Amazing Power of Social Networks and How They Shape Our Lives, builded on some of American sociologist Mark Granovetter’s 1969 hydrogen bonding based weak ties and strong ties sociology model, to argue that thinks such as obesity and happiness are dependent on one’s social network. [3]

In 2010, Christakis, in his “The Chemistry of Social Networks” interview, uses a type of human atom model to explain the properties of social networks on the model of how the properties of graphite verses diamond differ not due to the carbon atoms but to bonds or ties between each atom. To quote an excerpt: [1]

“Like atoms in a molecule, we’re all linked together. Studying the complex matrix that results can illuminate everything from bucket brigades to Bernie Madoff.”

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Carbon (graphite vs diamond)
Christakis' 2010 carbon ties model of social networks.

Carbon | Social network model
The following is the outline of Christakis’ properties of social network model based on carbon bonding:

“One of the key ideas about human social networks is that in the addition of ties between people and specific patterns of ties that obey particular mathematical rules the whole becomes greater than the sum of its parts. The collection of human beings have properties that do not reside within the individuals, and this collection of human beings is now able to do things that they previously were not able to do. And one of the illustrations or examples that I most like to give about this is something that most people are familiar with from high school or college chemistry and that is the example of carbon.

So you can take carbon atoms and you can assemble the carbon atoms into graphite and here we put particular hexagonal pattern of ties and you get sheets of graphite and this graphite is soft and dark. Or we can take the same carbon atoms and assemble them differently into a kind of a perimetral structure with the ties between them, the bonds between the carbon atoms and we get diamond, which is hard and clear and these properties of softness and darkness or hardness and clearness first of all differ dramatically, not because the carbon is different. The carbon is the same in both, but rather because of the ties between the carbon atoms. And second these properties are not properties of the carbon atoms. They’re properties of the group, properties of the collection of carbon atoms. Therefore, when we take constituent elements and assemble them to a larger whole, this larger whole can have properties that we could not have foreseen merely by studying the individual elements and properties which do not reside within the individual elements.”

Christakis goes on to argue that the same thing happens with humans in networks, and the differing properties that develop based on how people are tied together.

Christakis completed his BS in biology at Yale University in 1984, his MPH in 1988 and MD in 1989 at Harvard Medical School, and his PhD in medical sociology in 1995 at University of Pennsylvania. He then became professor of sociology and medicine at the University of Chicago. Since 2001, he has been a professor of sociology at Harvard and medicine at Harvard Medical School.

1. Allen, Austin. (2001). “The Chemistry of Social Networks: Interview with Nicholas Christakis”, May 06.
2. Christakis, Nicholas A. and Fowler, James. (2007). “The Spread of Obesity in a Large Social Network Over 32 Years” (abs), New England Journal of Medicine, 357(4): 370-79.
3. Christakis, Nicholas A. and Fowler, James. (2009). Connected: the Amazing Power of Social Networks and How They Shape Our Lives. HarperCollins.

External links
Nicholas A. Christakis – Wikipedia.
Nicholas Christakis (faculty) – Department of Sociology, Harvard University.

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