Friday, May 29, 2009

My journalistic heroes...

...are the guys who couldn't be arsed to follow up on Watergate. That's what I call work/life balance.

Why is it easier to get away with keeping a live leopard than wearing a dead one?

I can see why people take drugs, despite their illegality. Drugs get you high. But I find it a lot harder to understand the massive illegal trade in live animals. I guess a pet leopard or monitor lizard is a status symbol, but not one that's easy to flaunt, and what kind of a dick wants one in the first place?

That's what I thought when I read the excellent New Yorker piece ($) from April about the havoc being wreaked by escaped exotic pets in Florida.

The answer must be partly because the chances of getting caught are minimal and the punishments footling. That's unlikely to change (and besides, drugs policy shows how ineffective prohibition is). What we need instead is an effort to change norms. The animal rights movement has had some success in demonizing the wearing of fur (this train of thought was prompted when I saw the piece in today's Guardian about PETA's shock tactics, which I haven't read, because life's a bit on the short side), likewise the campaign against conflict diamonds. The conservation movement - so polite, reasonable and ineffectual compared with those who campaign for the welfare of captive animals - needs to do the same for exotic pets.

Of course, you wear a fur coat in public. Which brings me back to pondering the point of a status symbol you need to hide, and makes me wonder and despair at what in human nature (including mine) delights in ownership for its own sake.

Thursday, May 28, 2009

More research is needed

Apparently, you need to kiss a lot of frogs before you find a prince.

Turns out you also need to examine a lot of piles of elephant dung before you find a frog. 48.33, to be precise.

Now, if someone could be a bit more quantitative about the frog/prince ratio, we could work out princes per pile of elephant dung.

Wednesday, May 27, 2009

Nascence man

Having been away from my computer, this is now a week old. But I've written a feature for Nature about Mike Russell's work on the origin of life, especially his efforts to recreate the key moment in the lab.

No animals, no trees

A couple of recent papers show how seed dispersal is harmed when forest vertebrates disappear - it's not just bees and microbes that provide ecosystem services, we need the big stuff too.

In Biotropica, Stephen Blake of the WCS and colleagues look at seeds in the dung of forest elephants in the Congo. There are a lot:

Analysis of 855 elephant dung piles suggested that forest elephants disperse more intact seeds than any other species or genus of large vertebrate in African forests, while GPS telemetry data showed that forest elephants regularly disperse seeds over unprecedented distances compared to other dispersers. ... Our results suggest that the loss of forest elephants (and other large-bodied dispersers) may lead to a wave of recruitment failure among animal-dispersed tree species, and favor regeneration of the species-poor abiotically dispersed guild of trees.

And in Ecological Applications a US/Thai team look at the impact of bushmeat hunting on the dispersal of the hog plum, Choerospondias axillaris which, as the name suggests needs mammals (although not just pigs) to move it about. The clue is in the paper's title 'Bushmeat poaching reduces the seed dispersal and population growth rate of a mammal-dispersed tree.' "Extinction of C. axillaris is a real possibility, but may take many decades," they add. "Recent and ongoing extirpations of vertebrates in many tropical forests could be creating an extinction debt for zoochorous trees whose vulnerability is belied by their current abundance."

In Guanacaste, Costa Rica, they (especially Dan Janzen) got round this problem by introducing cattle, replacing the large herbivores that had gone extinct in prehistory. The trees thrived as a result. But Guanacaste is a dry forest. To paraphrase the music hall song about the horse and the lighthouse, I imagine it'd be harder to keep a cow in a jungle.

Thursday, May 14, 2009

Cruel to be kind

Why are people such *****? I've got a feature in this week's New Scientist looking into it.

Wednesday, May 13, 2009

Blood feuding and antagonistic pleiotropy

This week, I wrote a story for Nature’s online news about a PNAS paper on the link between violence and reproductive success in the Waorani, an Amazonian tribe. The basic message is that men who went on more blood-feud-motivated raids had fewer children surviving to adulthood. This is the opposite result to that found by Napoleon Chagnon’s studies of the Yanomano, where men who had killed in raids had more wives and children.

Chagnon’s work and methods have been controversial, and the debate around all that, and what this study says about the possible link between aggression, reproduction and natural selection is too complicated to go into here.

Instead I want to offer up some quarter-baked speculation on a slightly different topic. The paper suggests that one reason that Waorani violence seems counterproductive is that, unlike the Yanomano (and apparently other societies where blood feuding goes on), there’s no gap between rounds of violence. The Yanomano, says the paper, wait a generation between taking up the cudgels, during which time the attacks are sorcery-based. The Waorani were always at it.

This long delay reminded me of what’s called antagonistic pleiotropy. This is the idea that organisms age because natural selection can favour a gene that has a selective benefit in one’s youth but is detrimental later on — i.e., the bad stuff kicks in after you’ve bred and evolution has stopped caring about you. Could something similar, I wondered, allow delayed blood-feuding to persist, or even confer a benefit to such behaviour in some circumstances?

I can imagine how the initial aggressor might benefit. You prove your toughness in a handicap-principle kind of way, and/or reduce the competition, and then get to enjoy the benefits for a couple of decades. But what does he who waits get out of it? Maybe it reduces the cost that continual feuding imposes on everyone — apparently the Waorani were on their way to wiping themselves out. Or maybe the delay has kin-selection benefits — if the feud passes down the generations, maybe the next cohort gets to prove its toughness, reap the benefits etc.

I thought the analogy was interesting, but I don’t know if there’s any validity to this comparison, and I’m not saying blood feuding is, like, cool. And besides, these days we have libel lawyers to settle this sort of thing. Who, I suppose, are the sorcerers de nos jours.

Friday, May 01, 2009

Networks, finance and ecology

A couple of days ago, the FT reported on a speech by Andy Haldane, the Bank of England's head of financial stability:

Financial risk management and regulation should cast aside many elements of traditional finance theory and learn lessons from ecology, the spread of diseases, biology and engineering, according to a senior Bank of England official...

[Haldane] likened financial mathematical models which "pointed to the stabilising effects of financial network completeness" to the now-discredited 1970s-style ecological orthodoxy that asserted the complex networks of enemies and parasites in rainforests would always guarantee their survival.

What I think Haldane's talking about is the belief that more complex food webs were more stable, because diversity is, like, good. This was challenged by Bob May's famous 1973 finding that if you add links to a food web at random it actually becomes less stable the more complex it gets. SInce then, to quote a 2007 paper "the complexity–stability debate has been a central issue in ecology: does network complexity increase or decrease food-web persistence?"

And yet, to quote me, nature is full of large groups of species interacting in complex ways, and field and lab studies suggest that more complex, diverse ecosystems, in fact, show smaller fluctuations in their population sizes. So how's that work?

What ecology has shown us is that complexity per se isn't a disaster, so long as it's the right sort of complexity. Real food webs aren't random, and highly interconnected webs are in fact more robust to the removal of species - i.e. if one species/company goes extinct/bust, there isn't a cascade of other extinctions/bankruptcies. (This is Jennifer Dunne's work.)

The piece also says Haldane said that "the biggest and most interconnected banks should be subject to tougher regulations than smaller firms because they were most likely to be a super-spreader of financial risk. He likened them to heroin users or promiscuous homosexuals who were most likely to spread the HIV virus."

This is an allusion to the finding that small-world networks, such as the Internet, are robust to the removal of a random link, but very sensitive to the targeted removal of the best-connected links. This might be a bad thing in terms of cybercrime, but if you're trying to, say, stop disease spread, it can be turned to your advantage, because by targetting the best connected/most promiscuous individuals you can have a big impact on spread.

AIG, Citigroup etc., in other words, aren't too big to fail - they're too interconnected to fail.

Food webs are a bit different. In a study of the food webs of fish and plankton species living in lakes in the Adirondacks, Dunne and colleagues found that the species most vulnerable to extinction are the ones that result in the fewest secondary extinctions. This suggests, at least in the absence of human manipulation, that the structure of ecosystems maximizes biodiversity persistence. Researchers are now trying to deduce what shapes ecological networks into these robust configurations-forces such as natural selection or thermodynamic constraints on energy flows within the food web might each be at work.

So complexity per se isn't a bad thing. It's what you do with it that counts. Financially, what we need is to understand what makes a robust network, and then try and build that into the system - although that might not be compatible with everyone getting as rich as possible as quickly as possible. Then, although we won't see the shocks coming, we will be able to reduce their impact.

That's not to say the science is all neatly worked out. Haldane said that financial theory was a generation behind ecology. Which made me want to put my money under the mattress, because, although ecologists are getting some ideas about the general properties of ecological networks, food-web theory is still full of contradictory and disputed ideas. Still, maybe this will see a wave of ecologists following George Sugihara into finance, echoing the wave of maths and physics PhDs who became quants a decade or two ago. Remember how well that turned out?

Haldane's compete speech is here. (This post is based largely on the SFI Bulletin piece linked to above, 'Risk in Financial Markets - Learning from Nature' what I wrote (sound of own trumpet) 18 months ago.)