1. Berlzebub says

    That was really interesting. Just goes to show you don’t have to be pretty to be functional (fortunately for me).


  2. Anton Mates says

    As an interesting contrast, dolphins and other toothed whales also have lots of air sacs and bone ridges which they use to bounce sound around during echolocation…but they’re all inside their head, probably due to the need for underwater streamlining, so they get to stay cute.

  3. redstripe says

    In the spirit of self-deprecation, when I first read the post, I thought the insult was “yo mama e(ats)chocolates.” I am an idiot.

  4. Mike Fox says

    I like the part about how the Noseleave designs are going to be used for radio antenea. Proof that the natural selection operating on bats is better than Man’s intellegent design of radio antenea!!
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  5. thwaite says

    Well, some people have tried unintelligent design of antennae too, and it works pretty well. From the en.wikipedia on ‘evolvable hardware’,
    “NASA used a genetic algorithm to design a novel antenna (see PDF paper for details)”

  6. Anton Mates says

    Anton, in dolphins, the lower jawbone is one of the bones involved in echolocation. It transmits the vibrations to the inner ear.

    Yup. Whereas the outgoing clicks originate in the dorsal bursae (“monkey lips”) of the nasal passage, are focused mostly by bouncing off the skull and air sacs, then finely-focused, filtered and acoustically coupled to the surrounding water as they exit through the melon. Kind of ironic given their complex behaviors and learning ability; it’s probably that non-brain-containing melon which is most responsible for making them look simultaneously brainy and babyish to human eyes.

    There’s some nice diagrams and CAT scans of dolphin cranial tomography at James Aroyan’s website, I have just discovered.

  7. thwaite says

    Pictures of the evolved antennae are at available through the NASA web site, which is fortunate since the PDF file seems to be unavailable now. It looks a bit bizarre but so do many designed units – good looks aren’t an antenna parameter very often.

    Which brings up a point about the bats – their noseleaves clearly can’t be ugly to themselves (and bats indeed aren’t very visually oriented). The origin of beauty is via sexual selection for what’s pleasing: the peacock’s tail (even though it’s a handicap in natural selection); the attractive symmetry of most bilateral critters, which is correlated with healthy well-fed development. So we can infer that bats aren’t displeased by ugly mugs on their mates.

    Sexual selection still is somewhat controversial, as from Darwin’s original exposition in his DESCENT OF MAN book. A major current proponent: Geoffrey Miller in THE MATING MIND. A prominent detractor: Joan (formerly Jonathan) Roughgarden, lately notorious for her claim to reconcile evolutionary concepts with Christianity.

  8. Anton Mates says

    when I first read the post, I thought the insult was “yo mama e(ats)chocolates.”

    Which she has to find by echolocation! Because she can’t see very well! Because she’s fat! AM I RIGHT FOLKS!

    “Her middle name is Mudbone, and on top of all that…”

  9. Anton Mates says

    Sexual selection still is somewhat controversial, as from Darwin’s original exposition in his DESCENT OF MAN book.

    I wouldn’t say it’s controversial within evolutionary biology. It may be up in the air whether lots of individual traits are produced by it or some other mechanism, but there’s no real question that it happens. Roughgarden’s criticism seems to be based on a misunderstanding of what sexual selection is supposed to explain. (For instance, she argues that homosexuality and other non-reproductive sexual behaviors somehow conflict with it, when they don’t really have anything to do with each other.)

    A quick literature search turns up quite a bit of sexual selection research in microchiropteran bats, mostly focused around courtship flights, mate-attraction calls and penis morphology. As you say, they probably can’t even see one another’s faces clearly enough to have a preference based on that…though maybe flying foxes might well have them.

  10. thwaite says

    Not so controversial now, but sexual selection has been ignored historically, even more than natural selection was at its nadir in the 1920’s-1950’s, after the initial contest between Darwin and Wallace. Wallace thought that since sexual selection was so often for traits which reflected good health or vigor, that it ultimately reduced to natural selection; Darwin looked at peacocks’ tails and saw only beautiful liabilities. Of course, the somewhat modern view of Zahavi reconciles these with his logic of selection for handicaps … but this seems to de-emphasize the conspicuous beauty.

    The history of sexual selection from then to about 2000 is articulately presented by Helena Cronin’s book THE ANT AND THE PEACOCK, which makes for good reading as both biology and history – and some philosophy, since that was her initial training.

    Sexual selection for penis morphology, heh. As Miller puts it, “natural selection equips you to get through the day, sexual selection through the night”.

    And yes, Roughgarden’s understanding of what sexual selection is explaining seems vague.