In a brilliant essay John Quiggin asks:

Supposing a Keynesian utopia [of a short working week] is feasible, will we want it? Or will we prefer to keep chasing after money to buy more and better things?

A new paper by economists at the University of Western Australia suggest that the answer to this question lies in sex. They describe a model in which men undertake conspicuous consumption in order to attract women, and to fund this consumption they work long hours or set up businesses:

The male signalling behaviour necessary to attract potential mates underpins modern levels of economic growth. As females prefer males who conspicuously consume, an increasing proportion of males engage in innovation, labour and other productive activities in order to engage in conspicuous consumption. These activities contribute to technological progress and economic growth.

This echoes a paper (pdf) by Jill Sundie and colleagues which demonstrates experimentally that men looking for casual sex really do spend more on conspicuous consumption, and that women looking for a fling are more attracted (ceteris paribus) to men who buy Porsche Boxsters than Honda Civics. They say:

Just as peacocks have evolved to flaunt their wasteful tails before potential mates, men might similarly woo with wasteful expenditures to charm potential mates.

Perhaps, therefore, men work longer than necessary in part simply because they want to shag around.

This suggests that economic growth will be n-shaped with respect to sex. Where there are strong taboos against non-marital sex, the motive for conspicuous consumption will be weak - because it'll not get you sex anyway - and so labour supply and innovation and growth will be weak. But where women give it up for anyone, there'll be no need for men to spend to impress, so growth will also be weak. It's middling degrees of sexual promiscuity that are best for growth.

History is consistent with this. Max Weber relates how, in traditionalist societies, it was very hard to get men to work more than the bare minimum - though he had very different ideas as to how this habit was overcome! And economic growth in such societies tends to be negligible.

By contrast, growth in the west was fastest in the 1950s and 60s when traditional sexual morality weakened, and - as Mad Men shows us - economically successful men could shag around.

Whether the slowdown in growth since then is related to an increased availablity of sex for men and hence a decline in the need for conspicuous consumption is a matter of which I have no knowledge.