Six degrees of social networking

The "six degrees of separation" theory – that any two strangers can be linked by an average of just six friendships – is to be put to the test online. Yahoo and Facebook have joined forces to conduct an online version of the "small world" social experiment devised in 1967 by the Harvard Professor Stanley Milgram.

Facebook volunteers will be assigned a random target from among the social network's approximately 750 million members and asked to message their details to one friend.

The message will be forwarded from friend to friend until it reaches the intended individual.