April 24, 2006

So, mangoes prove a hostile designer exists?

Some of you may be aware that Kirk Cameron grew up to be a fundamentalist wacko. In this ID video, he and his trusty sidekick disprove atheism. Using a banana. And quotes taken out of context from famous scientists. It's half an hour, but be sure to watch from 3:30 to 4:36 if nothing else.

What's especially funny is that the banana is actually a fantastic illustration of natural selection in action. Before their domestication, bananas were tiny, bitter and virtually inedible (if you ever ate a really green banana or a raw plantation, then you know how bad they tasted). But the environment changed in a way that favoured those plants that produced larger, sweeter, and softer fruits when ripe -- in particular, humans came along -- and those plants flourished. Then, there was a freak mutation, which resulted in a strain of bananas that were still more successful than their cousins -- given the environment (humans cultivating the kind of bananas they preferred), those without seeds were able to reproduce much more prolifically than those with seeds.

Arguably, this new strain of bananas was a speciation event -- the new kind of bananas reproduce in a completely different way from the old kind, and hence are a related, but distinct, species. This is important, because creationists like to claim that we've never observed 'macroevolution', where one species transitions into a new one. But they're wrong: bananas have undergone macroevolution! Even if you don't buy this, the history of bananas still debunks the myth that 'all mutations are harmful' -- while the seedless strain of bananas would have failed miserably in other environments, it flourished in the one in which it happened to arise, and hence was a beneficial mutation. And it was really just one little mutation -- at the genetic level, nothing all that dramatic or unusual.

A creationist might still object, claiming that cultivation isn't natural selection. But 'selection pressures' just means the way an organism with (or without) a given trait is more or less successful at reproducing in a given environment. It doesn't matter what links that trait with success, whether it's a change in the local climate or humans cultivating strains with traits they find desirable.

Finally, it's also important to keep in mind that banana farmers weren't, for the most part, breeding bananas to encourage particular traits (like sweetness and seedlessness): as banana plants with more desirable traits cropped up at random, they were cultivated more, and bananas with less desirable traits were cultivated less. Farmers certainly couldn't have foreseen that a seedless strain would develop!

The history of the banana, then, is a human-scale illustration of natural selection. Random and genetically minor but compounded mutations were disproportionately favoured by the environment, with the result that a new species formed and was better able to reproduce than the old. And all within a few thousand years (meaning this supports Gould's theory of Punctuated Equilibrium, too).

Via Jesus' General


MosBen said...

Dan, I can think of few things more awesome than if you got interviewed by these guys.

MosBen said...

It's also increadibly annoying, if predictable, that they find an "atheist" that's stupid enough to go along with their rediculous car analogy.

MosBen said...

One other thing, I wonder what the existence of Nightshade proves about God. Is God objecitvely pro-murder?

Noumena said...

I can think of few things more awesome than if you got interviewed by these guys.

Senior year, I was walking home one afternoon when a Jehovah's Witness (I think) stopped me. I was a bit of an ass then (even more so than now), and heard later from a friend who lived on that block that he was almost crying after the conversation with me.

Is God objectively pro-murder?

Well, who came up with death as the punishment for eating the wrong kind of fruit in the first place? (Yes, I know, it's actually a punishment for disobedience and sin, but it's still disproportionate.)