Sep 01 2009
How many partners before settling down?
By David Finnigan
Clio Cresswell’s (packed out) ‘Mathematics and Sex’ talk at the Ultimo Library was a brief introduction to that fringe territory where Mathematics is being applied to the social sciences.
Is Clio Cresswell a hormonally crazy mathematician? According to Clio Cresswell: No. Image: abc.net.au
It’s an intriguing area and my interest was piqued as soon as Cresswell cited a paper entitled The Mathematics of Marital Conflict. So how does Maths connect with marital conflict?
The missing link, says Cresswell, is the discipline of Psychology. Psychologists carry out controlled experiments and interviews with people about their attitude toward and behaviour within relationships. The data they accumulate becomes the raw material for mathematicians like Cresswell to analyse and unpick for patterns.
Clio provided a brief sketch of some areas within the social sciences to which Maths has provided insights, then went into some detail with one particular question: How many partners should we have before settling down?
Really, how many?
Once you’ve answered the question, you may read on.
How many partners did Fred Astaire have before Ginger Rogers came along? Image: Wikipedia
Assuming you’re seeking the ideal partner, the answer depends on several different questions:
1. How many potential partners are there? 2. What would the ideal partner be? According to Cresswell, these questions factor consciously or subconsciously into our search for a mate.
The current understanding of the brain is that it uses simple strategies called heuristics, or rules of thumb, to make decisions.
Cresswell demonstrated one effective strategy to finding a good mate with a simple experiment. One female and ten male volunteers were drawn from the crowd. Each of the men was given a folded sheet of paper with a number on it representing their yearly income, which they kept a secret until their turn came. The girl’s aim was to end up with the man with the highest income. (How closely this scenario translates to the real world is another discussion altogether.) Starting with the first man in line, she could choose to stay with him or move on to the next man. Once she moved on from a gentleman, she could not go back to him later.
The first man in line revealed an income of $100,000; a respectable sum. But with nine other possibilities out there, Cresswell’s volunteer decided to keep searching. After Gentlemen #2, #3 and #4 proved to have per capita incomes of between $4,560 and $1.20, her first suitor began to look more attractive. As soon as Gentleman #5 revealed his earnings of $120,000, the volunteer decided that the search was over.
Cresswell described the strategy at work here: test a small sample, and then settle for the next best. If there are ten potential partners out there, you might be well advised to try four, see what the range of qualities is like, then stick with the next person who scores well by those criteria.
So in a world of six billion strangers and so little time, how many people should you roadtest before you give up the game?*
TWELVE.
But don’t give up before you meet Ginger Rogers. Or her living equivalent.
* CAVEAT: in this context, ’should’ is used to mean ’statistically effective’. 10 Days of Science is not telling you how to find a perfect mate, nor are we advocating you ditch your spouse if you were lucky enough to find true love with your high school sweetheart.
