It turns out that man who supposedly caused AIDS, was innocent. But he still illustrates one of the most important drivers of change in business.

Gaetan Dugas was a was a good-looking Canadian flight attendant. His job entailed travelling large distances. He was also extremely sexually active within the gay community, claiming to have had over 2500 sexual partners. Unfortunately, he also contracted AIDS. Before dying of kidney failure in 1984, Dugas is thought to have spread AIDS to many hundreds of people.

So far, there is no controversy. The above is true.

But Dugas also became known as “patient zero.” Popular mythology says that he caused AIDS.

Now he has been cleared –it turns out that the nickname ‘patient zero’ comes from a typo – in health records. In fact, his records described him has patient with the letter ‘O’, not 0, meaning zero. The letter meant he came from California, or so suggests new research just published.

Richard McKay, historian and co-author of the study from the University of Cambridge said: “The current study provides further evidence that patient 57, the individual identified both by the letter O and the number 0, was not patient zero of the North American epidemic. In many ways, the historical evidence has been pointing to the fallacy of this particular notion of patient zero for decades. This individual was simply one of thousands infected before HIV/Aids was recognised.”

Well, as it happens this is not new.

But it misses the point.

Network theory has a concept known as a small world network. To explain: a network, be it a shoal of fish, neurons in the brain, computers that make up the internet, people on Facebook, or the people who contracted AIDS, is made up of nodes – that is the individual in each network. The nodes are connected to each other. Some nodes have an unusually high number of connections; they are called hubs. Some hubs have an even more massive number of connections – they are called super-hubs. Network theory shows that the distribution of ordinary nodes, hubs and super-hubs follows a power rule. This means that the vast-majority of nodes have a modest number of connections. A small number are hubs with a much larger number of connections, and a very small minority are super-hubs. We all know someone on Facebook with thousands of friends, this person is either a hub, or if the number of people in their network is in the tens of thousands, they are a super-hub.

It is these hubs that enable a network to function. You may have heard of the idea of six degrees of separation, suggesting that we are all connected to every other person on this planet. Actually, six degrees of separation is a myth, it is more like 11 – according to more recent analysis of the original study that yielded the six degrees of separation claim.

But the point is that it is hubs and super-hubs that give the network its structure, and means that all nodes in a network are only separated by a small number of degrees.

Marketing managers are familiar with hubs – only they call them opinion formers.

Hubs are the means by which change occurs.

Dugas may not have been patient zero, but he was a central hub in the early spread of the disease in North America. Had Dugas not contracted the illness its spread might have been far slower, giving scientists more time to study it and giving the message of safe sex more time to become widespread. On the other hand, it was inevitable that a hub such as Dugas would be among the first to catch the disease. It is likely that there were not many degrees of separation between the hubs in the network of AIDS sufferers and more peripheral figures that may have contracted the disease earlier.