[jewayne]

I'm pretty sure there's already a popular hypothesis that relates to evolutionary biology, but I don't know the name of it.

Essentially, as hunter-gatherers every group of humans needed one or more experts on the local megafauna, so virtually all of us have some degree of fascination with big animals baked in, but some have more than others. I've also heard the same hypothesis used to express young boys' obsessions with trucks and trains.

[euroderf]

My young lad went thru a brief phase where we went thru picture books of common vehicles and for page after page, he pointed at every wheel of every vehicle and had me name it. "Wheel." "Wheel." "Wheel." ...

Probably a developmental phase somehow connected to quadrupeds. Large object of interest. Four supporting thingies.