Tag / intelligent design

by Roslyn

Furious about eyespots

I think I flubbed an interview this week. My supervisor Bob and I just published a paper that is getting some press, because it addresses a recent controversy about the peacock’s train1. Eager for the interview with Nature News, I wasn’t exactly prepared with good lines for the reporter to go on – and I wonder if that’s why he had to pump up our story as a “furious debate”2.

In truth, most of the “debate” played out in a flurry of news articles back in 2008. That was when Mariko Takahashi and her colleagues in Tokyo and Kanagawa published the fruits of their exhaustive 7-year study of the peafowl at the Izu Cactus Park in Shizuoka, Japan3. I’ve never met Takahashi, although I did meet her supervisor and one other player in this story at a conference back then, and all were quite friendly. But the title of Takahashi’s 2008 paper, “Peahens do not prefer peacocks with more elaborate trains” was a direct jab at an earlier one, “Peahens prefer peacocks with more elaborate trains”, by Marion Petrie in the UK4. Takahashi and her coauthors had the difficult task of proving a negative – and they did it pretty convincingly, with the aid of a much more extensive data set than anyone had gathered before with this species. The upshot? For a peacock in Japan, having a bigger train ornament doesn’t necessarily win you any favours with the ladies.

Bigger in terms of the number of eyespots visible in the ornament during courtship, that is; males have about 150 on average, each on the end of a single feather. The results of the Japanese study were in direct contradiction to Marion Petrie’s earlier work as well as some recent studies of peafowl in France suggesting that eyespot number is often correlated with male mating success4,5. What’s more, in the 1990s Petrie had confirmed the causal effect of eyespots by showing that you could alter a male’s fate just by removing about 20 of them6.

Peacock in flight

Taken at the Los Angeles Arboretum in 2009. Photo by Roslyn Dakin.

The Japanese team proposed a rather bold new hypothesis. Perhaps the cumbersome, ridiculous train ornament is obsolete – a relic of sexual selection past, no longer used by females in quite the same way as it was when it first evolved3.

This was taken up with gusto by the news media. Check out the headlines: “Peacock feathers: That’s so last year”, “Have peacock tails lost their sexual allure?”, “Peacock feathers fail to impress the ladies”. Amusingly, this last article was also published with the title, “Female peacocks not impressed by male feathers” by Discovery News7-10. Males could probably be forgiven for striking out with those elusive female peacocks, since they don’t actually exist.

Headlines aside, Takahashi’s interpretation is somewhat of a concern. Here’s why: creationists picked up on this story too11.

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by Roslyn

The ancient mariner

I drove a tractor for the first time a few weeks ago, when we were furiously collecting the last of the sap run for maple syrup. A small triumph for me since it seemed so terrifying at first. Trying to hide my confusion, I waited until the last moment to ask, “Which pedal is the brake, again?” Both of them? Right. No chance for a screw up, so I charged ahead. It only took until my second trip – with shouts of “Slow down!” from the trailer behind – for me to figure out why those two brakes weren’t working so well. Turns out that the hand throttle was the missing part of my pedal equation.

Locomotion does not come naturally to me. It does, however, for a huge variety of other living things. Powered flight evolved several times in the history of life: at least once in the ancestors of birds, and separately in insects, pterosaurs and bats. Human inventors have had a much harder time with it: unlike animals, we haven’t progressed much beyond our earliest working designs. Orgel’s second rule applies:

“Evolution is cleverer than you are.”

Thinking about this made me realize that the situation today, where most of us are more familiar with human-engineered forms of locomotion than we are with the natural examples, is kind of strange. For most of our history, the inspiration to look for new ways to get around probably came from seeing it done in nature.

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by Roslyn

A royal waste?

Giant pandas are in the news again, this time for their annual date night at the Smithsonian National Zoo in Washington DC. But hardly a day goes by without a report somewhere on the latest captive panda birth, strategic breeding attempt or panda relocation.

A blogger at the London Review of Books compared the bears to members of the British royal family: both are suffering from shrinking ecological niches and in serious danger of extinction, hanging on by virtue of their marketing potential. The similarities don’t end there. Giant pandas, like royals, are expensive to house, with a fee of over $1 million per year for a zoo to lease a pair from China. Naturally, the breeding activities of giant pandas are as intensely scrutinized as those of Prince William.

This entails some surprising efforts when it comes to the pandas. The history of captive breeding for Ailuropoda melanoleuca is no sordid royal affair. It’s long, and for the most part, pretty unfortunate; zoos have been failing to produce heirs to the panda legacy for decades.

For starters, it’s nearly impossible to get the bears to mate in captivity, and it’s not just their deficiency in the looks department, as comedian Mike Birbiglia suggests. Captive pandas can’t seem to figure out a working sexual position1. Females often start things off all wrong by lying down, but the males are just as clueless. This led to panda porn: zoos started making videos of pandas achieving copulatory success, as training tools for the more hapless bears2. Other attempts to use Viagra on pandas were less encouraging, but the porn worked – for females as well as males – leading to a boom in captive births in recent years3.

Giant panda cub

Visitors can pay to see the cubs at the Chengdu giant panda breeding centre. File photo modified from newssc.org.

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by Roslyn

Deep archives: Irreducible beauty

Peacocks and audience at the Toronto Zoo

Were peacocks designed with this kind of audience in mind?

A while back I was searching for images of peacock feathers on Google, and I stumbled upon this article. It’s a piece by Stuart Burgess, an engineer who is head of the Department of Mechanical Engineering at Bristol University, and apparently also quite an opinionated creationist.

Burgess’ idea is that the peacock’s train feathers “contain an extremely high level of optimum design”, so much so that they provide evidence against Darwinian evolution. He thinks that the aesthetic features of the peacock are so complex, so contingent upon each other, that no step-by-step process of evolutionary change could have produced them. He’s right that these ornaments are highly complex, and that selection for this kind of extreme aesthetic feature presents a bit of a puzzle for evolutionary biology. To claim that the extraordinary complexity must be “irreducible”, however, is a big assumption.

The article provides a lot of amusing examples of twisted logic along the way. For example, one of the features that Burgess finds irreducibly beautiful is the fact that the peacock’s train forms a fan-like shape. This is because “the axis of every feather can be projected back to an approximately common geometrical center” – indeed, the body of the bird that grew them!

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