I wrote about the links between smell and memory for the April issue of the APS Observer, the magazine of the Association for Psychology Science. Now, before you go read it, let me warn you: the formatting of the page is kind of weird, so when it refers you to a sidebar in the second paragraph, it’s actually talking about the two slightly offset paragraphs at the bottom of the text, about Proust and the madeleine. If you don’t know about Proust and the madeleine, I recommend reading that before you read the rest of the story, “Fragrant Flashbacks.”

Fun fact: Multiple sources mentioned Proust. When you’re talking about smell and memory, that’s pretty much the go-to cultural reference. Although I also really like the scene in Ratatouille when the cranky old food critic eats a bite of Remy’s ratatouille and is transported to his childhood, coming in sad from the outdoors and sitting down with his mom’s ratatouille. That scene makes me kind of teary.

Yeah, call me a philistine, but I’d take Pixar over Proust anytime. (Well, I say that, but really all the Proust I’ve ever read is this one passage. He’s probably pretty good.) (You like how I just described one of the most important French novelists ever as “probably pretty good”?)

Anyway, any time you have poop, you have a record of what an animal ate, and the scientists used this one to look at bugs and pesticides over several decades of the 20th century.

One of my editor’s complaints about the story was how much I used the word “chimney.” I see what he’s talking about. The first paragraph of this blog post uses the word six times, four of them in one sentence. The problem is, there aren’t any good synonyms. He tried “smokestack,” but I think you can really only use that for a chimney on a factory, right?

Photo: Bruce Di Labio

You can’t really test this with primates in real life–you’d need thousands of years. But this week for ScienceNOW I wrote about an alternative: a computer simulation of brain evolution. Science writers generally stay away from modeling papers, but I thought this one was worth writing about.

Yesterday for ScienceNOW I wrote about a study on a different famine: the one that resulted from the Great Leap Forward in China. Tens of millions of people died when Mao’s campaign for quick industrialization went very, very wrong.

The paper I wrote about was looking at particular evolutionary theory that predicts the sex ratio of offspring should change in different conditions. So, if a mother is in good condition, she ought to have more male babies, and if she’s in poor condition, she ought to have more female babies. This has been shown many times for animals that aren’t humans, and scientists have looked for this before in the Dutch data but haven’t come up with conclusive results. Here’s my story.

The researchers found evidence that this boldness in honeybee scouts–the willingness to go out and look for new sources of food even though there’s a perfectly good flower right there–involves some of the same genes as novelty-seeking in humans and other vertebrates, which has been pretty well studied.

Fun fact: The graduate student on this study, who has been stung many times and really seems to be quite a determined young person, is allergic to bee stings. She got allergy shots to desensitize her to the allergen. They worked.

photo: Alex Wild, alexanderwild.com

The interview is with Northern Arizona University undergraduate and climbing enthusiast Anne Berlioux. I had fun putting this together and I’d love to do some more video sometime.

The day after I interviewed the scientist at Yale for my blue feathers story, I sat in on a lab for the ornithology class he teaches. It was the day they were doing feathers, so there were tons of bird skins out on the benches and feathers to look at under the microscope and so on. This didn’t make it into the story at all, but wow, it was cool to look at all the different feathers. Birds are amazing.

Here’s how you fit a flamingo into a museum drawer.

Those birds all get their yellows, reds, and oranges from carotenoid pigments. You may have heard of carotenoids–they’re one of those things you’re supposed to eat. In the body, they’re converted into retinol, a form of vitamin A.

This bowerbird has a very splashy bit of hot pink at the back of his neck.

There are about 20 species of bowerbirds. They’re native to Australia and New Zealand, and they have this crazy mating thing: Males build a little stage, or bower, to show off their awesomeness to females. Look, I can’t do this justice. Go watch this David Attenborough video about bowerbirds. You won’t be sorry.

These birds use a combination of pigments and structural colors. Remember, green is yellow (pigment) plus blue (structural).

This bird may not look like much in the visible spectrum, but in UV–which birds can see–it is a super exciting bright color.

So there you go. More birds. If you missed the story I was reporting, read about blue feathers.

So here’s the full list of things you ought to check out in the March issue:

Visualize This by Sarah Zielinski
Sweat and Tears by Sarah Everts
Why So Blue? by me
Truth and Beauty by Andrew Curry
a truly delightful penguin photograph by Chris Linder
And, of course, much behind-the-scenes work by editor Laura Helmuth.

So it’s the best issue of Smithsonian ever, if the metric you care about is how many of my friends are in it.

As often happens in my line of work, I collected a bazillion times more material than I could ever possibly use in the story. This was even more true than usual because the final story is about half the length it was originally assigned at. (Nothing to do with me–there have been big changes at Smithsonian recently.)

Here’s what’s going on with bird colors. They get yellow and red and orange from their food. You can buy color supplements to feed to pet canaries, and zoos have to make sure flamingos get the right food to keep their cheerful color.

But that doesn’t work for blue, because birds (and mammals) digest the pigments that make blue in plants. It turns out blue is a structural color. It doesn’t come from a pigment; the birds actually build it into their feathers. The proteins in their feathers are arranged so, when light bounces off of them, the red wavelengths cancel each other out and the blue gets amplified, so your eye sees blue.This works for all different shades of blue and even ultraviolet. Green, as you might guess, is yellow plus blue–a yellow pigment and a blue structural color.

Rick Prum, the scientist, spent a lot of time with me, explaining his research and then walking around the storage area at the natural history museum, pulling out drawers of skins and talking about different birds.

This paradise tanager from South America uses a whole patchwork of strategies to color itself.

You’ve got the splash of red, a pigment from something the bird ate. The black comes from the protein melanin, which the bird makes itself. The blue is a structural color and the green is the structural color plus a pigment from food.

Just look at this cuteness!

These are two species of manakin, a kind of bird that lives in the American tropics. Look at their exciting blue caps. Their slightly different shades of blue come from the way the proteins came together as the feathers grew.

Final note: I wrote several other blog posts along the way which I can now tell you were related to this story. I saw two museums while I was in New Haven, the Yale University Gallery and the Beinecke Rare Book and Manuscript Library. And I came across this charming explanation of a synchrotron while I was trying to make sure I knew how they work.

The study found that snow leopards eat mostly ungulates, which was no surprise. But the researchers also found the remains of one solitary chukar partridge. If you would like to live like that adventurous bird-eating snow leopard, here’s a University of California extension document on raising chukar partridges. Like snow leopards, chukar partridges are native to Eurasia, but unlike snow leopards, they have been introduced to the western U.S.

Illustration: ”The Cat: An introduction to the study of backboned animals” by St. George Mivart, 1881