Why did David Petraeus risk a dazzling career and even a possible future presidential candidacy for sex with his biographer?
Petraeus's already considerable power expanded when he took over CIA. And power is drug with psycho-active properties, one of the strongest of which is as an increase in sexual appetite. As Henry Kissinger famously observed, "power is an aphrodisiac".
President JF Kennedy reputedly had sex with a new woman almost every day of his presidency, and even Franklin D Roosevelt had numerous affairs. Quite how the most powerful nation on earth is going to nurture and keep its most brilliant leaders if it dispenses an aphrodisac and then condemns them when it works, is a mystery that this country must solve very quickly.
The usually iron-willed general had an affair with a young, female biographer who had to have very frequent contact with him in order to write her adulatory text and the affair ended some months ago. These facts suggest that simple availability played its part in the kindling of this temporary affair and that the pharmacology of power temporarily trumped the self-control.
Both men and women who have a high need for power have sexual intercourse more often than those who have lower power needs and dominance and sex are biologically linked in every mammalian species, including humans. Roughly one in twelve Asian men, for instance, possess a Y chromosome which can be traced back to a single sexually-prolific individual who lived in Central Asia around 1200 AD - almost certainly Genghis Khan.
Sex and power are linked as they both cause a surge in the hormone testosterone in both sexes. Testosterone in turn ramps up activity of the chemical messenger dopamine in the brain's 'reward network'. Everything we experience as pleasure or reward - from being paid a compliment through drinking a cocktail to having sex - has its effects via this dopamine-rich brain system. And power is another incredibly strong activator of the reward network.
This is why power is an aphrodisiac - by ramping up the reward system it also increases appetite for other reward-rich activities such as sex. The high testosterone levels which high political office triggers can therefore further increase sexual appetites in a politico-erotic vicious circle which can bring the most able of people to do things that their self-controlled selves would not countenance.
However, these appetites do not just stimulate a hunger for more power and more sex - they also have profound effects on the way the brain functions more generally and this can help explain the bewildering lapses of judgment that we see in the fallen great.
The power - and sex - increased dopamine levels also change the way the prefrontal cortex of the brain, which is key to forethought, planning, inhibition and attention, functions.
Dopamine however, like some other chemical messengers in the brain, has a 'goldilocks zone', an optimal level where the brain functions at its best. Moderate increases, therefore, can make people smarter, more focussed and strategically better in their thinking via their effects on the way the prefrontal cortex of the brain functions. Too high-doses, on the other hand, can take people out of their goldilock's zone, to the extent that their forethought and inhibition may be temporarily diminished.
This may explain some of the lapses of judgment shown by powerful leaders such as Petraeus: the very parts of their brain which are crucial for their self-control are the ones which may be disrupted by the aphrodisiac dispensed to them by their government.
Leaders must enjoy power without becoming corrupted by it and they must benefit from its neurologically-wondrous emboldening and smartening effects if we are going to nurture good leaders. Inevitably their sexual drives will increase and ultimately many may lapse when they encounter the blandishments of young, beautiful suitors: remember, power can be a stronger aphrodisiac for the acquaintance than for the leader.
If David Petraeus had crashed his car because a doctor had prescribed too strong a sedative drug, no-one would demand his resignation. Why should a side effect of the drug power have brought him down?
Ian H Robertson is Visiting Professor of Neurology at Columbia University, New York and Professor of Psychology at Trinity College Dublin, Ireland. His book The Winner Effect: The Neuroscience of Success and Failure, is published by St Martin's Press, New York.
Follow Professor Ian Robertson on Twitter: www.twitter.com/@ihrobertson