Berkeley Bumpers: Self Loathing Motorists?

Over the past couple days I've seen variations of this image on two Hondas: an evolutionary progression of ape into man riding a bicycle. I'm hard pressed to argue the merits of what I take to be the underlying message, that in our contemporary society man has evolved the potential to be contemplative of his impact on the world, and so rides a bike. I do find it curious that this message should appear on the rears of cars, and one of them an SUV no less. Is this a self-flagellating gesture? An eco-conscious hankie code alerting those in the know that these motorists are at heart bicyclists, constrained by circumstance to ruin the environment against their will at a faster rate than they would otherwise desire? Is this the new way of saying "My other car is a bike"?

The owners of the vehicles weren't around for me to ask about their bumper stickers so we'll just have to speculate on who or what is making these poor people drive their cars instead of their bikes.