Month / April 2011

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 Perhaps the cumbersome, ridiculous train ornament is obsolete – a relic of sexual selection past, no longer used by females in quite the same way as it was when it first evolved3.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

Cultured tastes

Dinner in Shippagan, New Brunswick. Photo by Charlie Croskery.

We drove halfway across the country for the party, but the main course alone was worth the trip. When the pig was finally hauled out by a crew of strapping male relatives, the guests at Anne-Claire and Martin’s wedding converged at the carving table. Small children, I’m told even a Jewish person or two – nobody could resist a taste of warm skin ripped straight off with a knife. Not after seeing (and smelling) the thing turn that entire August afternoon.

I doubt we would have made the cross-country trip if charlem was on the menu. That’s what Vladimir Mironov, an expert in stem cell and tissue science, calls his latest culinary invention. Mironov’s product is grown right in his lab at the Medical University of South Carolina in Charleston – hence the name, short for Charleston engineered meat.

In a handful of labs around the world, scientists like Mironov are working on a curious agricultural problem: how to generate edible meat products without the farm – or the animals1,2. Their solution is to grow meat from animal stem cells. Some use cells taken from embryos, while others, like Mark Post at Eindhoven University in the Netherlands, are looking into the feasibility of growing muscle satellite cells taken from adults1. These can be extracted from domestic pigs or fowl with a quick and painless biopsy, and used to seed in vitro cell cultures.

In the future, this could be an easier way to serve a crowd. Like human cancer cell lines immortalized in a Petri dish, satellite cells can potentially go on multiplying forever in the lab, so long as you give them enough growth medium. Vladimir Mironov sees industry ultimately growing “charlem” – his cultured turkey – in bioreactors the size of football fields that he likes to call “carneries”. He imagines a world where fresh charlem is also grown at your local grocery store, in miniature appliance-size versions of the bioreactor machines3.

His work is, in part, funded by PETA, in an effort to stem the unmeasurable output of animal suffering caused by industrial agriculture. In 2008, the animal rights group also announced their in vitro chicken prize for the first person to develop a commercially viable product and sell it in at least 10 US states. To be eligible, the chicken also has to pass a panel of tasters when breaded and fried. The $1 million dollar reward is still up for grabs3,4.

No doubt this is a noble goal*. Large-scale meat production is an environmental scourge. The North American “meat guzzler”, as Mark Bittman calls it, is not sustainable6. Influential food writers like Bittman and Michael Pollan, and others including star chef David Chang, have been urging us to rethink our eating habits for years7. Environmentally, there’s a lot to be said for the alternatives: we could save a lot of resources by switching to the Asian practice of using small amounts of meat to complement dishes where vegetables and grains are the main event.

According to Nicholas Genovese from Vladimir Mironov’s lab, “Animals require between 3 and 8 pounds of nutrient to make 1 pound of meat. It’s fairly inefficient. Animals consume food and produce waste. Cultured meat doesn’t have a digestive system.”3

He’s right, of course. But his last point also happens to be the very reason charlem will never make it: meat from an animal is more than the sum of its in vitro parts. Want nutrients? We’ll have to add those in at the factory. Vitamin B12 and iron – two of the main nutritional reasons for eating animal protein in the first place – come from gut bacteria and blood1. You can’t get them from muscle tissue in isolation. Want taste? Let me see if we have an additive for that too…

Scientists may figure out how to culture meat efficiently in the lab, but it won’t be a viable solution to our agricultural problems, at least not anytime soon. The trouble with fake meat is that it’s up against evolution on two fronts, and, ironically, morality on a third.

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by Roslyn

Dating the rainbow

Buttermere Lake, with Part of Cromackwater, Cumberland, a Shower

The truth is beautiful in Buttermilk Creek. That was the Texas site of a recent major archaeological find. In the village of Salado, just a couple hundred metres downstream from an important cache of artifacts of the early American Clovis people, anthropologists uncovered something just a few centimetres deeper1. In geological terms, that usually means older – and the assortment of stone tools found by Mike Waters and his team might be the definitive evidence needed to overturn the longstanding “Clovis first” theory.

“Clovis first” is the idea that North America was initially populated by a group of big game hunters known for their interchangeable fluted spear tips – a portable tool that fit well with the nomadic lifestyle. I won’t get into the details (see elsewhere), but many researchers now believe that other migrant groups arrived from the north well before Clovis domination. For example, fishing tools found in California’s Channel Islands provide evidence that a seafaring clan made its way south by hopping along the coastline2.

I also won’t cover the Buttermilk Creek find (again, see elsewhere for this). But there is a poetic element to this discovery worth sharing. The proof that the Buttermilk Creek people arrived ahead of Clovis hunters comes, not from the usual radiocarbon dating methods, but from dating the rainbow.

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