This is testable isn't it?
You'd need a fridge, some ketchup plus some miscellaneous condiments, and a clip board and white coat of course (since otherwise people would think you were a nutter). Set up in a public space and ask men and women to "find the ketchup". Observe their movements and note the point at which they start "hunting" behaviour. Bit of analysis for men versus women, maybe add in control trials where there is no sauce in the fridge, and hey presto - you PhD is assured.
If you want to get really posh, link a sensor to the fridge door to start the time trial and get the subject to stand on a Dance! Dance! revolution mat so you can see how their weight shifts.