I'll be home for dinner (but don't wait up)!

Can snails find their way 'home'?  The possibility of a snail homing instinct has long been suspected by, for example, people who want to get rid of snails without killing them so just toss them over the hedge, but a listener to the BBC's Material World program, Ruth Brooks, wanted to actually test the hypothesis. She was chosen by the program last spring as one of four 'amateur scientists' to work with a mentor to try to answer the question.

To do so, she marked a handful of snails from her garden with nail polish and counted how many came back after she had carried them varying distances away from where she'd originally found them.  While her experiments are still ongoing, to her science advisor's surprise, her preliminary data (snails are sluggish) suggests that snails placed less than 10 meters away easily return home, though anecdotal evidence she's receiving due to all the media coverage she's getting (on many sites, including on the BBC website) suggests that they can return to a garden from up to a quarter of a mile away.

Ms Brooks and her mentor are now asking anyone in Britain with a garden and a willing neighbor to add data to their database by marking snails from their own garden and swapping them with differently marked snails from their neighbor's garden.  (You can follow the experiment on their Facebook page or check it out on the Material World website.)

But why was the advisor surprised?  As he says, it's because conventional thinking has it that snails are far too simple to do something complicated like find their way home.  But this is odd since we all know that 'simple' insects like bees and ants and butterflies very ably find their way home.

It seems to us that this experiment is testing more than the snail homing instinct.  It's also testing the testers' preconceived assumptions about the what makes organisms simple and what makes them complex.

Indeed, it's largely our assumptions about what 'simple' organisms can do that makes the exhausting treks of many birds, fish, whales, and insects (like Monarch butterflies) seem so remarkable and truly worth featuring on programs like Discover and Nova.  How it works is still largely unknown but magnetic particles in neurons, celestial navigation, and olfaction, seem variably to be part of it.  It also seems easy to evolve, since it's happened in parallel, using largely if not entirely different mechanisms and through different media and distances, in so many species.

Probably it's hard for us to imagine because it's so different from our own experience.   But a remarkable fact is that we, too, have evolved an uncannily accurate homing mechanism, and we've done it very, very rapidly.  It's called a GPS navigator.

Bawling like a baby....but which baby?

A study published last week in Current Biology reports that newborns already speak their mother's language (Current Biology 19, 1–4, December 15, 2009, Newborns’ Cry Melody Is Shaped by Their Native Language, Birgit Mampe et al.). Or rather, the tonality of their cry tends to mimic the intonation of their native language (you can listen to the differences here). The researchers analyzed the cries of 30 French and 30 German newborns and found that the cries of the French babies tended to rise, while those of the German babies fell, both in line with the intonation patterns of the language spoken by the infants' mothers. This was a repeatable observation, according to the authors, who attributed it to what they heard around them in their last trimester of gestation (amazing! They didn't say there was a gene for the trait!).

This isn't really a surprise, as the same sorts of results were found by psychologist Gilbert Gottlieb when, in the 1960's and 70's, he experimented with embryonic ducks to determine whether responding to their mother's vocalizations was learned or innate. He devocalized embryos so they couldn't make their own sounds in the egg, which they do naturally, and raised the eggs in isolation so they weren't hearing their own or their mother's vocalizations.  He found that they didn't respond readily to their mother at hatching, unlike chicks that develop normally.

In fact, Gottlieb was a central figure in the growth of developmental systems theory, the idea that genetics is generally considered to be far more integral to development than it actually is, and that evolutionary theory should be less centered around genes.  Evidence for the effects of the environment on gestational development in general, and on language learning specifically, is nothing new, and the fact that the current story has made such a splash suggests another case of ignoring what's already known (a state of affairs that we discussed here). 

We tend these days to attribute everything to genes and hard-wiring, because that fits our current culture's deterministic predisposition. There is a tension between human exceptionalizing--making us different from other species--and the juicy, almost prurient need many geneticists seem to feel to pry into our genomes and discover what really makes us what we are.  In a way, that's different from giving us free will, which many in our society would like to do.

Of course, we know very well that the uterine environment can affect us in many ways. Even late-onset disease risks reflect pre-natal effects. But we have tended to attribute behavioral traits to either post-natal learning--or to genes. The baby crying study reminds us of something we already know--gestational learning can make behaviors look like instinct.