Friday, September 28, 2007

Fruit-cutting ants

A nice piece of natural history from the latest Ecological Entomology.

The workers of leaf-cutting ants (Atta) fall into two categories — minors, which do the forgaing, and majors, which are more involved in colony defence. But Sophie Evison and Francis Ratnieks at Sheffield have spotted that Brazilian leaf-cutters will also chop fruit (in this case mango) into bits and cart it back to the nest.

But the fruit-cutting is done by the majors - presumably because their jaws are big enough to handle three-diimensional stuff like mango, whereas small jaws are only good for leaves. So we can add a new job to the majors' task list.

The question that occurred to me was - what happens to this fruit in the nest? Leaf-cutters can't digest leaves, so they feed it to fungus in the nest, then eat the fungus. But most of us can digest mango, so does fruit bypass the fungus farm and get eaten raw?

Monday, September 24, 2007

I frass, you frass, he frasses, they frass

A couple of weeks ago, Sara and I were talking, as you do, about the word 'frass', which is the technical term for insect poo.

She said it sounded more like a verb than a noun. It hadn't occurred to me that different types of word sounded different, and I wondered whether they did.

Well, they do. I was chatting with some researchers on Friday, and they mentioned work by Morten Christiansen at Cornell and his colleagues on just this topic. Last year, they published a paper showing that nouns and verbs do cluster together in phonological space.

But the categories aren't rigid. There are 'nouny nouns', which are found in the middle of noun space, but also 'verby nouns' which are closer to verbs. Likewise, there are verby verbs and nouny verbs.

The team did experiments showing that people process nouny nouns more quickly than verby nouns. For example, they are quicker to grasp the meaning of:
The curious young boy saved the marble that he found on the playground.

The curious young boy saved the insect that he found in his backyard.

because 'marble' is a nouny noun, whereas 'insect' is more verby.
The same difference was shown between sentences containing verby verbs, such as 'amuse' and nouny verbs, such as 'ignore'.

Last year's paper cites earlier studies showing that 'adults are more likely to use a nonsense word as a noun when it is multisyllabic'. So I would guess that 'frass' would fall amid the verby nouns.

Christiansen et al argue that these cateogries exist in other languages besides english, and suggest that learning these categories is one of the steps in acquiring language.

From idle speculation to scientific resolution - just how I like it.

Thursday, September 20, 2007

Batty like a FoxP2

Back in 2001, FoxP2 was the first gene to be linked to human language. The gene was hunted down by studying a British family with extreme difficulties in forming speech. I wrote about (paywall) this work at the time.

Since then, there's been a bunch of studies on the gene - revealing, for example, relatively large differences between the human sequences and that of other primates. But it was thought that, humans aside, there was relatively little variation in vertebrates.

Well, just goes to show how taxonomically restricted our genetic knowledge is, because a Sino-Anglo team has just discovered that the gene varies lots in bats, which don't talk, but do echolocate. There's a news report about their PLoS One paper here.

To see how the variation between closely related bat species really does dwarf that seen between much more distantly related beasts, check out this figure.

Nice. But FoxP2 is not giving up all its secrets just yet. The pattern of evolution - what's been selected for what - is not clear from the sequences, there's just a lot of difference. And comparing bat sequences with other species doesn't help much

Evidence from birds, which likes bats and people show vocal learning, is shows 'no evidence of specific mutations associated with vocal learning abilities...if variation in FoxP2 has a role in vocal learning then it is not straightforward'. Nor are there clear similarities with whales, which also vocal learn and echolocate.

So what is FoxP2 uP2? If it's a 'language gene' it looks as if it's role isn't in what we think of as the clever stuff of language - grammar and syntax - but in the mechanics: the motor control needed to produce tightly controlled sounds, say. But, as far as I can tell, there's no hard and fast links between the gene sequence and this ability. It's just involved somewhere down the line.

One clue is that FoxP2 is a transcription factor - it's product controls the activity of other genes. Maybe this is why comparing species gives few clues as to how its sequence relates to its function: because it's an information processing gene and not making something like haemoglobin, the structure of which is jolly important, maybe its free to vary more, and to mean different things to different animals.

I don't know how much we know about the genes it regulates - I couldn't see anything in the paper, so I'm guessing not much.

Thursday, September 13, 2007

Underground networking

Todays's Nature contains a News Feature by me (behind a paywall, I'm afraid), looking at the possibility that mycorrhizal fungi transfer nutrients between plants, and in the process undercut the above-ground competition between plants by robbing the rich to feed the poor - subsidizing plants less able to photosynthesize.

How, why and whether they do this is still uncertain and occasionally controversial. But everyone seems to accept that mycorrhizal networks do exist - namely, that a single fungus can link many plants, potentially of different species, creating a arena for a rich range of ecological interactions. It's just we're not sure what they are. But a bunch of people are doing their damnedest to find out. Mycorrhizal ecology looks like a funky (and fungi) field right now.

For a more technical (than my piece), but freely accessible introduction to this field check out this TREE paper.

Wednesday, September 12, 2007

Why you will never get everyone to agree with you

Here’s what the recent Nature Neuroscience paper ‘Neurocognitive correlates of liberalism and conservatism’ (See here for one of the many news reports) made me think.

This looks like the (one of the) neural manifestation of a personality axis, such as bold/timid, extrovert/introvert. People and animals spread out all over these — reflected in animals in how quick they are to explore new environments, how far they disperse, and so on. You could probably redefine liberalism/conservatism in terms of these (people probably already have).

So the big question, I think, is: what maintains this diversity in a population? It could be frequency-dependent selection — it becomes more advantageous to be liberal if you’re surrounded by conservatives, and vice versa. Seems unlikely.

More plausible is that it’s balancing selection: there are some environments and tasks that favour a liberal approach, and some that favour conservatism. In great tits, for example, bold, far-dispersing males do better after mild winters, when territories are at a premium, and food is plentiful, whereas stay-at-homes do better after harsh winters. For females, the reverse is true.

So no one strategy can take over. And personality in these birds has a strong heritable component. So, in a variable environment, where genes don't know which sex of bird they're going to be on (unless they're on the females-only W chromosome in birds, or the male-only Y in mammals), a braod range of personality types can persist.

It seems plausible that something roughly similar might be at work in people — the benefits of reaching out, trying new stuff, versus the benefits of staying put and consolidating will depend on the environment. Question here is, why can’t each of us (or each great tit, for that matter) work that out, and adapt to any environment? What is it about our brains, and the genes (and environments) that make them constrains us to occupy our place on the personality axis?

It seems, anyway, that if our politics come from inside us, as well as being a consequence of what the world does to us, we can’t expect political extinction for either liberals or conservatives, just as there are bold and timid great tits.

Of course, when it comes to voting, there’s lots of other stuff at work. It struck me that this is a US study, where, because the different parties don’t offer anything different in the way of economics, peoples’ voting decisions may be more swayed by all that ‘values’ stuff that tickles these particular ‘am I up for this?’ bits of the brain. Also I’m guessing that those studied were students, and occupied a narrow socioeconomic band. It’s perfectly possible to be a left-wing conservative, but more likely if you’re working class, I’d guess.

Friday, September 07, 2007

South Bank Wayang

In non-science-related news, there's a piece by me in today's Guardian about the all-night Javanese shadow puppet play (wayang), including the South Bank Gamelan Players, at the festival hall tomorrow. I doubt it's sold out.

In other news, the Independent newspaper recently put ITBOAH on its list of 10 best nature books. Which is nice. No sign of this online, but Oliver Morton has reproduced the list (which includes his own Eating the Sun) on his photosynthesis-related blog.

Tuesday, September 04, 2007

Fibonacci watch

One of my partner Sara's bugbears is that all efforts to group art and maths together lazily invoke the Fibonacci sequence (Something, I admit, I've been guilty of myself.)

But my crimes pale next to this absolute humdinger, from the August issue of The Wire. This is Philip Sherburne writing about techno musician and DJ Ricardo Villalobos.
When it comes to rhythm, Villalobos is certainly one of the canniest producers in contemporary electronic dance music. His youthful training in Afro-Latin percussion explains some of his sense of timekeeping, but it doesn't necessarily address the uncanny quality of so many of his beats, which take shape with the same kind of natural/unnatural ease with which a sunflower sprouts seeds according to the Fibonacci sequence.

Let's enjoy that again.
the same kind of natural/unnatural ease with which a sunflower sprouts seeds according to the Fibonacci sequence.


Other egregious Fibonaccisms welcome.