Darwin's
18-Wheeler
Written By Mark Cherrington
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Monkey Business
So, personally, I'm coming around to the idea that nature is the dominant factor. Boys like trucks because they're wired to like them. I'm backed here by a relatively new and, to some, controversial field called evolutionary psychology. Its practitioners explore human behavior via biochemistry, genetics, and other physiological elements. For example, they've found that girls born with high levels of male hormones (due to an adrenal-gland disorder) have a notably increased preference for "boy" toys and activities, and are much less drawn to "girl" toys and activities.
A striking 2002 paper on gender and toy choice in the journal Evolution and Human Behavior bolsters the evidence of biological underpinnings. Gerianne Alexander of Texas A&M and Melissa Hines of City University in London reasoned that if plaything preference is a product of biology, then it ought to show up in our close biological relatives. That is, monkeys. So they doled out toys to 44 male and 44 female vervet monkeys, all presumably safe from the pernicious influence of indoctrinating parents and clever Tonka pitchmen. The methodology for the monkeys was the same as for the kids: Give them stereotypical boy toys (a ball, a perky police car), girl toys (a pink-faced soft doll, a cooking pot), and sex-neutral toys (a picture book, a stuffed dog) and see which ones intrigue whom.
The results do not bode well for nurture advocates. The females clearly preferred the doll and pot, the males the ball and vehicle. Some females even held the doll just as they would a monkey baby, and some males were seen rolling the police car on the ground. (The study didn't say if, like Nathaniel, they tossed in dramatic siren sound effects.) This kind of cross-species analysis also colors the work of David Geary, a cognitive developmental psychologist at the University of Missouri. In his book Male, Female, Geary uses findings on brain chemistry and maturation periods to trace sexual differences in behavior in such creatures as elephant seals, bower birds, and Homo sapiens. I asked him about boys and trucks. "Boys' interest in construction toys may be related to the evolution of tool use," says Geary. "Tool making and construction of inanimate things (fishing equipment, weapons, arrows) is almost exclusively a male activity in traditional societies." Trucks and building toys also reflect "basic differences in spatial orientation, and how to manipulate objects in different ways." So Geary thinks boys' object-oriented play with trucks, blocks, and the like preps them for problem-solving tool use.
He cites a 2005 study by David Bjorklund, of Florida Atlantic University, in which 3-year-olds were shown an out-of-reach Furby or Cookie Monster and a group of tools, only one of which would help them grab the toy. If the child got stuck, an adult offered hints about the correct tool. Once the kids fetched the Furby, they tried for the Cookie Monster with a fresh set of tools, so researchers could see if they'd absorbed the underlying principle and could reapply it.
After they found the right tool, girls were just as good as boys at using it to fetch the Furby, and as good as boys at transferring the principle. But the boys chose the right tool more often without hints — 77 percent to the girls' 31 percent. The implication? Girls are equal to boys at using tools and understanding their use. But boys are more inclined to recognize a tool as the solution to a problem.
The next time I was at Nathaniel's house, he was in the middle of showing me his favorite website, implosionworld.com, where buildings are demolished with high explosives, when he sprang up and raced to the front door. The garbage truck was here and he was jumping up and down in delight. I'd seen this reaction before and had always assumed the allure was connected with the power of the engine or the scale and noise of the vehicle.
But now, with Geary's tools 'n' trucks theory in my head, I saw something else. Nathaniel was studying the truck, making mental notes about its principles of operation. It was all those moving parts: the hydraulic lifts, dumpers, compactors, and rolling bins. It was a symphony of physics, a cornucopia of contraptions. Tool heaven. That's when I decided Geary is probably right. This is what connects Fred Flintstone and Leonardo da Vinci, the Dukes of Hazzard and Steve Jobs — me and Nathaniel.
