I guess this is a Valentine’s Day story

It’s about snails looking for love.

But I just have to intrude rudely and mention that handedness in snail shell coiling has been studied for a long time, and we mostly know the answer: the direction is specified by a maternal effect gene, so what matters is the genotype of Jeremy’s mother, not Jeremy’s phenotype. Jeremy and Lefty are almost certainly heterozygous, the product of a homozygous left-coiling mother and a mate who was almost certainly (because this is a rare trait) homozygous for the right-coiling allele, and because they carry the right-coiling allele, all of their little baby snails will be right-coiling. He’s going to have to look in their grandchildren to find more left-coiling snails.

Technical details of the genetics aside, it must be frustrating to have to take chirality into consideration when trying to mate. Imagine a world where being left-handed makes sex with right-handers require all kinds of twisty gymnastics to line the bits up just right.


  1. says

    Imagine a world where being left-handed makes sex with right-handers require all kinds of twisty gymnastics to line the bits up just right.

    There’s also a huge potential for fun in that!!

  2. blf says

    Ducks? At least some have corkscrew-shaped female and male parts, albeit I vaguely recall they tend to twist in a compatible manner.

  3. Richard Smith says

    I seem to recall that pigs’ genitals are also helical, with farmers having to take chirality into consideration when breeding them.

    If our genitals had similar chirality, would that have an effect on a certain other “handedness”? There have been “stranger” questions…

  4. voyager says

    Personally I have always found left handed men more desirable. Not really sure why, except perhaps they seem more exotic. Well, that and possibly Paul McCartney, I wonder if a left coiling snail is like a rock and roll god to the righty snails?

  5. cartomancer says

    I’m left-handed, and I’ve always found sex to be awkward, frustrating, depressing and virtually impossible to get. So maybe there’s more to this than we realise…

  6. vucodlak says

    I’m reminded of a novella* I read a few years ago, in which every person has genitals shaped like a key or a lock. For each lock, there was only one key, and vice versa. Of course, people didn’t HAVE to match their genitals up to find love (non-straight people are at least mentioned, if I recall), but they did have to match if they wanted children. There is even a government agency where people can go to get a plaster cast made of their genitals, and be matched with their key/lock (provided that the other person is also in the system).

    The protagonist of the novella goes to the agency at the urging of his family. He discovers that his match was, in fact, a tick person, which is something that has never happened before. Oh, did I mention that all these people are living on the back of a giant dog, and that some minority of these people are in fact giant ticks that had evolved to look vaguely like people? ‘Cause that’s kind of important.

    Anyway, I won’t spoil the tale. It would be a good story to read on Valentine’s Day. Especially if you hate Valentine’s Day. Just don’t read it while eating yogurt.

    *”The Tick People” by Carlton Mellick III

  7. Tethys says

    Huh, I’ve never considered the effects chirality on ones love life. I have several late Cambrian to early Ordovician mollusk fossils. Most coil to the right, but left coiling is the norm for several species. Genitals aren’t mentioned in the fossil guide, but I imagine some adjustments were necessary in order to adapt to terrestrial life. Snails have complex mating, seeing as how first they decide which will be making eggs and which will be fertilizing them. Love darts are a real thing.

    Some of my Ordovician echinoderms and brachiopods also display a degree of rightward chirality in their body plan, but it is only a quarter twist and they have distinctly different right and left sides. The sessile echinoderms are especially strange. I have no idea what to call a 5/3 body plan that lacks a mid-line and mirroring. Bilateral asymmetry maybe?