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Monday, November 18, 2013

Darwin's Fly

Fred Reed has some questions about evolution.

One of them:
The Bot fly is a squat, ugly, hairy fly that catches a mosquito, lays its eggs on said mosquito after positioning it correctly, and attaches them with a kind of glue. It releases the mosquito. When the little feathery syringe lands on, say, a human, the eggs drop off, hatch, and burrow into the host. These make nasty raised lumps with something wiggling inside them. Later they exit, fall to the ground, and pupate.

How did this evolve? Did a grab-a-mosquito gene occur as a random mutation (assuming that a single mutation could cause such complex behavior)? It would have to be a grab-a-mosquito-but-don´t-cripple-it gene. That is an awful lot of precise behavior for one mutation. At this point the bot fly would have a mosquito but no idea what to do with it. It would need simultaneously to have a stick-eggs-on-mosquito mutation. This would seem to require another rather ambitious gene.

Catching the mosquito without laying the eggs, or squashing the mosquito in the process, or laying eggs in mid air without having caught the mosquito, would seem a losing proposition. Yet further, the glue mechanism for making the eggs drop off onto the host instead of before or not at all, would also have to be present, caused by yet another complex simultaneous mutation. None of these awfully-lucky mutations would be of use without the others. How do you evolve this elaborate dance by gradual steps?

My preferred example along these lines is Darwin's orchid, a flower with a spur that measures 10 to 15 inches in depth. It generates a pungent perfume, but only at night, and exudes a nectar which fills the bottom quarter of the spur. Well, Mr. Charles Darwin surmised, the orchid must be pollinated by a moth with a proboscosis around 12 inches long, and so it is. How would this happen? Why would this happen? Like Fred says, it's beyond dispute that evolution occurs, but Something Else is definitely going on. Nobody knows what else, and that's where the handwaving starts.

I've come across these same questions from agnostic and atheist individuals (like Fred) who've contemplated Fermi's paradox. Why is sentient life such a rare phenomenon in the observed universe? Interstellar travel must be extremely problematic, or the parameters for the spontaneous generation (and maintenance) of sentient life have to be very, very narrow, but that just begs more questions. Interstellar travel is that problematic even for evolving civilizations? The universe is that hostile to sentient life? WTF--we're all alone on this speck of iron ore? The storyline for a thousand potential Hollywood screenplays and sci-fi novels now untenable. How? Why?

5 comments:

lannes said...

"WTF"??? Are you trying to be a hipster?

The Anti-Gnostic said...

I'm trying to be polite.

Anonymous said...

Physicist with an interest in astrobiology here. Just thought I'd point out that, while Fermi's Paradox is still a big deal, it's not because we haven't detected any signals. We shouldn't be able to, unless aliens decide to build an enormous radio array (miles across) and point it directly at us.

Interstellar space isn't empty and, except for a few frequencies that aren't good for much else, radio doesn't penetrate it that well over interstellar distances. That doesn't even get into the fact that due to "angels or apes" the aliens probably either:

a) haven't invented the radio (or fire, for that matter)

b) are using something much better than radio, or maybe even just directional rather than broadcast communications (note how Earth's radio signature is decreasing with advanced technology as we do more with fiber optics)

The reason Fermi's Paradox is still important is that, assuming you can build a starship and assuming you want to colonize other star systems then even at very low rates of diffusion one technological civilization or another should have colonized the galaxy by now.

Of course those are big ifs.

The Anti-Gnostic said...

Thanks for commenting! I am over my head in hard science so please stick around.

Sentient life occupies an extremely narrow band which provides sufficient explanation for the paradox. And we end up right back at the question of why most of the universe is inimical to sentient life, and how things in such a hostile environment aligned to generate and maintain it at such a stunning level of complexity.

It really is beyond strange.

Resident Scientist said...

Decided to get myself a name since I'm going to be doing more than drive-by posting here.

You're right that it's all quite mystifying, but the statement "sentient life occupies an extremely narrow band..." might be begging the question.

In spatial and temporal terms, life and especially sentience are certainly very rare in the universe. However, it seems very possible that "life" is not dependent on the specific physicality of its instantiations and may well be a state reachable from many different and environmentally diverse origins. There is some reason to believe that the phenomenon we refer to as life may occur wherever the environment is sufficiently complex and dynamic; conditions that to the best of our knowledge should be pretty common in the Universe. I'd also point out that an incredibly, cosmically unlikely event can become commonplace if you give it hundreds of trillions of opportunities to occur, as is the case with the scale of the physical cosmos.

Sentience is rather different matter, rather less well understood (understatement of the century?). However, to avoid wall-o-texting you to death I will leave you with the results of a fascinating computer simulation. Researchers programmed agents in a simulated environment whose only goal was to maximize entropy. The agents proceeded to go around the environment opening boxes and removing the contents, getting into hard-to-reach spots, and otherwise acting rather like curious, intelligent beings.

Not necessarily entirely relevant, but food for thought.