Does Disease Cause Religion?

University of New Mexico biologists Corey Fincher and Randy Thornhill are proposing the idea that religions proliferate as a way to prevent the spread of infectious diseases. As the Telegraph reports:

Religions thrived to protect our ancestors against the ravages of disease, according to a radical new evolutionary theory of the genesis of faith….

[The researchers] come to this conclusion after studying why religions are far more numerous in the tropics compared with the temperate areas.

"Why does Cote d'Ivoire have 76 religions while Norway has 13, and why does Brazil have 159 religions while Canada has 15 even though in both comparisons the countries are similar in size?" they ask.

The reason is that religion helps to divide people and reduce the spread of diseases, which are more common the hotter the country, the research suggests.

Any society that increased its coherence by adopting a religion, and dealt less with local groups with other beliefs as a result of cultural isolation, gained an advantage in being less likely to pick up diseases from its neighbours, and in the longer term to have a slightly different genetic makeup that may offer protective effects, for instance by making them less susceptible to a virus.

Equally, societies where infectious diseases are more common are less likely to migrate and disperse, not because of the effects of disease itself but as a behaviour that has evolved over time.

" If this argument is correct then, across the globe, religion diversity should correlate positively with infectious disease diversity," they say.

So can we conclude that as we control more infectious diseases, secularization will spread? Or does correlation necessarily mean cause in this case?

Whole Telegraph article here.