In 2007, shortly after the release of my first book The Evolutionary Bases of Consumption, I was invited by my good friend Peter M. Todd to speak at the Cognitive Sciences Colloquium at Indiana University. As part of the same trip, I was fortunate enough to also speak at the School of Informatics of Indiana University-Purdue University at Indianapolis (on the kind invitation of Karl MacDorman). You can watch my lecture here. During my visit, I had a chance to meet many lovely colleagues, all of whom were conducting fascinating works. At one point, I visited the lab of Eliot Smith, a social psychologist whose team had collected data on Facebook users. I asked casually whether they had collected information on individuals’ average number of Facebook friends across their sample, to which he answered in the affirmative. I ventured that I would be willing to bet that the number was around 150 (which proved to be correct). I was able to offer this guess because I was familiar with Dunbar’s number, which stipulates that the human brain’s computational capacity to manage social relationships is set around that number (see the recent Businessweek article on Dunbar's number here). In my 2011 trade book The Consuming Instinct: What Juicy Burgers, Ferraris, Pornography, and Gift Giving Reveal About Human Nature, I cite two studies that have confirmed that the average number of Facebook friends is indeed around 150 (see p. 317, footnote 26 for the references).
Can you think of other social gatherings wherein one might put Dunbar’s number to the test? In my trade book, I propose weddings as an intriguing possibility. Specifically, I predicted a priori that the average number of wedding guests should conform to Dunbar’s number. True to form, it turns out that the average number of guests at a wedding is indeed around 150 (in my book, I cite an estimate of 164 but I’ve just uncovered other references that set it at 148 and 138 respectively). The explanatory power of evolutionary psychology is limitless!
Since we are on the topic of weddings, some readers might be interested in my earlier Psychology Today article wherein I discuss one of my current research projects (headed by Sigal Tifferet) in which we examined gift giving practices at Israeli weddings (specifically the fact that the maternal sides of the bride and groom offer larger sums than the paternal ones, and the correlation between the genetic relatedness of gift givers and recipients, and the size of their monetary gifts).
But perhaps the most important takeaway from today’s article is to make sure that these two guys do not end up counting as part of your wedding guests!
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