Hummingbirds chirp with their tails

Online at Proc. R. Soc. B: high-speed video and experimental results suggest that male Anna’s Hummingbirds use their tail feathers to produce a chirping sound during courtship displays. This sort of thing is known from other bird species (notably two genera of Manakins), but there was some dispute about how Anna’s Hummingbird chirps. The high-speed video is on You Tube, though it basically only shows a male hummingbird flaring its tail at the bottom of a display dive. The experimental evidence apparently consists of air jet and wind tunnel tests on feathers collected (ouch) from wild birds.

Reference:
Clark, C.J., and T.J. Feo. 2008. The Anna’s hummingbird chirps with its tail: a new mechanism of sonation in birds. Proceedings of the Royal Society Series B.

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Christian schools: win Ben Stein’s money

In the wake of the victory for common sense that was the Dover Trial and Michael Lynch’s trouncing of their only paper to be published in a peer-reviewed journal, the Intelligent Design movement has refocused its efforts on propaganda. Specifically, the documentary Expelled, in which none other than Ben Stein will apparently argue that evil atheist scientists have “expelled” ID “theory” from its rightful place in the science curriculum. I first heard about Expelled when the New York Times reported that Richard Dawkins and NCSE’s Eugenie Scott were interviewed for the film under false pretenses.

Now, ERV (SA Smith) points out a scheme to bribe Christian schools to take their students to Expelled. How pathetic is that? The producers aren’t even sure that their assumed core demographic (Christian teens) will show up to this movie if they don’t institute “mandatory field trips.” It’s also maddening to me: I went to a Mennonite high school, where I actually got a pretty good grounding in biology, and where I took the class that inspired me to pursue graduate study of evolution and ecology (Thanks, Mr. Good!). Which is to say that, even though many do, there’s no reason that Christian schools have to teach pseudoscience. This Expelled initiative tries to provide exactly such a reason.

An aside: Who exactly is making Expelled, anyway? According to the Times article, the production company that arranged the interviews with Dawkins and Scott called itself Rampant Films – but it turned into Premise Media when the real nature of the project was revealed. Premise Media has a website [mind the creaky flash intro on your way in], the contents of which are concerned only with Expelled. Anyone want to bet it’s a front for the Discovery Insitute?

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Moralizing unhelpful? What a silly idea!

This week’s NY Times Magazine cover story is a thoughtful exploration of the emerging scientific understanding of human morality. It covers a lot of the same ground as one of my favorite RadioLab episodes (including an interview about trolley car ethics with Joshua Greene), but goes beyond the simple biology to ask whether there is a universal human grammar of morality, and consider what insights that hypothesis could lend to modern hot-button ethical issues like global warming. The concluding suggestion is that moralizing an issue might actually be counterproductive:

In many discussions, the cause of climate change is overindulgence (too many S.U.V.’s) and defilement (sullying the atmosphere), and the solution is temperance (conservation) and expiation (buying carbon offset coupons). Yet the experts agree that these numbers don’t add up: even if every last American became conscientious about his or her carbon emissions, the effects on climate change would be trifling . . . [effective measures against climate change] will have to be morally boring, like a carbon tax and new energy technologies, or even taboo, like nuclear power and deliberate manipulation of the ocean and atmosphere.

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Trees ditch mutualist ants when herbivory stops

In this week’s issue of Science: African Acacia trees reduce support for a mutualistic species of ant when they aren’t experiencing herbivory [abstract only without subscription]. Normally, the whistling thorn tree (Acacia drepanolobium) enlists the help of an ant, Crematogaster mimosae, to fight off large herbivores and harmful insects. It works like this: The tree attracts ants by providing sugary nectar from glands at the base of its leaves and balloonlike growths called domatia (see photo), which the ants use for shelter. The ants attack anything that tries to eat the tree, for the very reasonable (and selfish) reason that it’s also their nest. It seems like a mutually beneficial arangement, but no one has tested the hypothesis that, if the trees no longer need defense, they’ll stop “paying” their ants to stick around.

Palmer et al. do exactly that by comparing ant provisioning on trees in plots that are fenced in (preventing access by big herbivores) with trees in control plots that aren’t. After ten years inside the fence, they found that Acacia trees had reduced their nectar output and the rate at which they developed new domatia. The mutualistic ants, dependent on these rewards, were displaced by another species, C. sjostedti, which doesn’t need nectar or domatia, but also doesn’t defend the tree as much.

None of the changes in trees’ provisioning for ants are the result of immediate natural selection – the time over which this happened is considerably less than one generation for Acacia. This is individual trees “judging” that they no longer need ant protection because they’re not under attack, a response that is expected to evolve over long periods of balancing the need for protection against the cost of provisioning ants. Another ant species that uses Acacia nectar and domatia, C. nigriceps, didn’t suffer from the lack of large herbivores, probably because it prunes the trees it occupies, which the authors think may be enough to make the tree “think” it’s still being eaten.

Reference:
Palmer T.M., M.L. Stanton, T.P. Young, J.R. Goheen, R.M. Pringle, and R. Karban. 2008. Breakdown of an Ant-Plant Mutualism Follows the Loss of Large Herbivores from an African Savanna. Science 319:192-5.

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The science ticket

Via the essential beatfinger: Wired Science summarizes Science’s assessment of how the Republican and Democratic presidential candidates stand on science issues. These include support for science funding in general, support for embryonic stem cell research, acceptance of evolution, plans for improving science education, and willingness to address global warming. Barack Obama comes out on top of the Democrats, but the differences between him and Hillary Clinton or John Edwards seem mainly related to emphasis. Among the Republicans, the list-makers seem to have had difficulty coming up with anything nice to say: Rudy Giuliani gets credit just for being pro-choice!

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Electronic matchmaking for voters

Glassbooth lets you take positions on a variety of political issues, then compares them with the positions taken by every Democratic and Republican presidential candidate. I think it was Time magazine that set up something like this in 2004. My results: I’m best-matched to Dennis Kucinich (91% similarity), followed by Mike Gravel (85%) and John Edwards (75%). Barack Obama, who is actually my (current) preferred candidate, only scores 69%.

Via Wired.

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Will Huckabee kill the Christian Left?

The results from yesterday’s Iowa caucus: Barack Obama and Mike Huckabee are the winners in their respective parties, by solid margins. It’s an interesting pairing, because the Democratic victor represents a response to a kind of conservative politics that the Republican victor has abandoned.

Obama is a good representative of the Christian Left – explicit about his religion, but understanding the Gospel to be about economic and social justice, not condemning abortion and homosexuals (neither of which is discussed by Jesus himself). The most public exponents of this position are Jim Wallis and his organization Sojourners.

The political strategy of the Christian Left has been to combat the Christian Right by attacking its wholehearted embrace of mainstream conservative stances on economics and the role of government as un-Christlike. Wallis’s favorite image is of a Bible with every reference to the poor cut from it: basically, a pile of shredded paper. This critique is valid and important, but it also allows the Christian Left to leave more divisive doctrinal positions of liberal Christianity, like acceptance of homosexuals and acknowledgment of the fact of evolution, in the background. Focusing on economics lets Sojourners be bipartisan, because while the Republicans have actively made life worse for poor Americans, the Democrats haven’t exactly made it better.

Huckabee poses a problem for this strategy – he rejects the post-Reagan ties between conservative Christianity and big business interests in favor of a distinctly liberal-flavored populism. But theologically, and on social issues, he’s very conservative: anti-abortion, anti-gay, and anti-science. And there’s the problem – on the issues the Christian Left has emphasized, Huckabee looks to have conceded the point. For Jim Wallis and Co. to oppose him without getting nit-picky about specific policy (though Huck’s “fair tax” looks ripe for nit-picking), they either have to start talking about more than economics, or they have to endorse (or at least not oppose) Huckabee.

So what will the Christian Left do? As of now, Sojourners’ “God’s Politics” blog has two responses to the Iowa result: one, by Diana Butler Bass, that identifies the Obama/Huckabee contrast; and one, by Wallis, that cheers the bipartisan victory of economic populism. Neither takes a position for one candidate over the other – which they don’t really need to this early in the campaign, admittedly. The question is, how long can they wait to choose?

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