October 24, 2008
Men are under natural selection to become richer, according to a report in the November issue of American Naturalist. That’s right: the same way natural selection once encouraged longer necks in giraffes and duck bills on ducks (and platypuses), men are now feeling that Darwinian pull toward the corner office.
The Newcastle University researchers found the effect only in men, and explained it by saying that
men strive for cultural goals such as wealth and status in order to convert these achievements into reproductive success.
Women showed the opposite effect: lower incomes were associated with more children (the researchers interpreted this as women giving up earning potential in order to have kids). All sorts of other interesting societal lessons cropped up in the study. The effect held across typical Western societies (the U.K., Sweden), in African hunter-gatherer societies, and in family records of Europeans spanning the last 500 years.
This research is kind of a brutal reminder that civilization doesn’t trump evolution, it just shifts the focus. Quasi-philosophical discussions about whether we’ve stopped evolving are fun, but there’s really only one right answer: Of course we’re still evolving.
Evolution is just the slow genetic shifting of the norms in a population. It happens to the best of species – even ones that have invented flu shots, indoor plumbing, and airbags. Case in point: I have terrible eyesight, but thanks to contact lenses I’ve avoided being eaten by wolves or walking off cliffs. So you might argue that our superb mammalian eyeballs have stopped evolving.
But I’m still childless. If I keel over tomorrow then, evolutionarily, I’ll have vanished.**** My genes will sink into the dirt along with the rest of the contents of my cells. Which of my genetic traits will be to blame? My enormous Anglo-Saxon cranium? The tendency to recite Monty Python on first dates? Too busy blogging to meet real people? Or my paltry earning power?
The point is that natural selection is at work, blindly weeding out genes, even if in less blood-curdling fashion than we often think of it. Of course, selection is only one of evolution’s three ingredients. To actually evolve, a population needs to be variable, different individuals must have differential reproductive success (that’s selection), and they must be able to pass those differences on to their offspring (that’s heritability). But all those are met, the researchers argue: just ask the Kennedys.
Presumably we’re not evolving some kind of Susan B. Anthony-producing sweat gland, of course. But more subtle abilities (or predispositions) to accumulate wealth are being rewarded with more children. And although evolution takes a long time, the results from this study suggest this selective pressure is as old as the barter system. I wonder what exaggerated features it has already produced, giraffe- or peacock-like, in our bodies and our psyches?
(Image: courtesy Matt Schwartz. disclaimer: enormous cranium notwithstanding, that’s not me in the picture)
***Except for whatever I have in common with my nephews and nieces.
August 20, 2008
Behavioral ecology, the study of what animals do and how it affects their lives, can be delightfully arcane. One research team designed a robot stickleback in order to learn how many fish it takes to persuade a school to change direction. (Early results suggest the answer is two.)
Another team found that African honeybee workers surreptitiously raise their own eggs rather than those of their queen overlords, in effect staging a bloodless coup.
Mitchell Baker, of Queens College, New York, had some amazing insights into pesticide resistance studying the formidable Colorado potato beetle. “If you leave them alone,” he said, “they will eat a field down to brown sticks.”
A pesticide, like an antibiotic, is supposed to kill any pest that’s not resistant to it. But when survivors get together to breed, one thing they all have to bequeath to their young is pesticide resistance. “Potato beetles can evolve resistance to anything you can throw at them, usually within three generations,” Baker said.
Resistance can have a downside for the beetle, though. It comes with a grab bag of handicaps. Through novel experiments at agricultural fields, Baker discovered that pesticide-resistant beetles hatch later, move more slowly, have compromised immune systems, mate less successfully, raise fewer young, die off during the winter at greater rates, and get cannibalized by their nestmates more often than non-resistant beetles.
Apparently, the genes that make a beetle resistant have such debilitating side-effects that it takes the application of deadly pesticides just for them to survive the competition. Baker’s research could point to ways to postpone widespread resistance by taking advantage of those weaknesses.
It’s tempting to view the world as a collection of species perfectly adapted to living together. But what I find fascinating about evolution are the compromises that constantly play out on any species’ scrap heap of talents. For potato beetles, pesticides are pulling resistance to the top of the pile. But change what’s killing them-a different pesticide, perhaps, or maybe hotter summers-and resistance will fall to the wayside in favor of something equally vital for the moment.
July 22, 2008
You’ve still got a couple days this month to step outside, look up, and enjoy a tremendous yellow moon. One of my favorite features is that little belly-button of a crater at the bottom, called Tycho. When the moon is full, this crater and the long rays emanating from it always make me wonder if perhaps the whole orb is just a delicate paper lantern.
But if appreciating a real Moon involves too much squinting, or if the mosquitoes where you live simply won’t permit prolonged viewing, give thanks that you live in an era of unprecedented space exploration. Since last year, a Japanese probe called SELENE has been taking thousands of high-resolution images of Tycho. Now the scientists have pieced the images together into an animated video flyover of the crater in fantastic detail.
In these days of Google Earth and computer-rendered fighting pandas, it can be difficult to appreciate reality as anything more than a poor approximation of a movie. But the cliffs, plains, and pinnacles sweeping past in the video really are up there, rotating in space and baking under the glare of the Sun.
That pinprick in Tycho’s center, for example, is a mile-high mountain range complete with jagged peaks, old remains of landslides, and what looks like a totally manageable hike up one side. SELENE takes you on a 360-degree, eye-level tour and then, just as a flourish, spins out to the crater rim and zooms along the side like a NASCAR driver going into a turn.
Incidentally, the Japan Aerospace Exploration Agency’s SELENE homepage offers a refreshing and inimitably Japanese take on what a space agency’s website can look like.
(Images: Joe Huber/Wikipedia; JAXA/SELENE. Hat tip to Bad Astronomy, who is currently on something of a lunar bender owing to Apollo 11′s 40th anniversary and an actual time-lapse, color video of the moon crossing in front of the Earth).
July 11, 2008
It’s been a good week for people who look through microscopes at fossils. First off, Scientific American told us about some German scientists who discovered evidence of 400-million-year-old life trapped in seawater trapped inside volcanic rock.
Far more buzz circled around the second report: that we may be able to figure out what color dinosaurs and ancient birds were. This means that one day, paleontologist-artists may have to stop dreaming up rosy purples and outlandish greens to clothe their dinosaurs in (remember Mark Witton’s lovely pterosaurs a few posts ago?).
Is there any ephemeral detail that scientists can’t discover about long-dead creatures through clever chemistry? They’ve figured out the diet of an extinct seabird, learned about Aztec travels from records in exhumed teeth, and now they’ve put back together the stripes on a 100-million-year-old bird.
The evidence sat in front of them for years in the form of a powdery residue on some fossils. It was long thought to be the meaningless remains of carrion-eating bacteria, but Yale graduate student Jakob Vinther‘s electron microscope revealed the powder looked exactly like the pigment-bearing sacs that occur on modern-day feathers. Nowadays, those sacs are full of melanin which give birds colors ranging from black to russet brown.
Though the work was done on fossil birds, the scientists report that similar residues from dinosaur scales and the hair of ancient mammals may reveal their colors as well. The researchers were also careful to point out that the residues didn’t contain any intact melanin (unlike the T. rex discovered in 2005 with actual protein still preserved inside a massive thigh). A hundred million years is a long time, after all.
(Image: J. Vinther/Yale)
May 21, 2008
Here at The Gist we deeply admire everything that Monty Python has done for science (including but not limited to their work with silly walks, confused cats, migrating swallows, etc.).***
But who could have known that their famous dead parrot sketch – involving a shady pet shop and a parrot rumored to be Norwegian – could have had any basis in reality? Yet the current issue of Palaeontology carries the news that two ancient parrot species have been discovered from a Danish fossil bed. Some 55 million years ago, according to the report, these birds squawked and fluttered over ferny lagoons that stretched from Copenhagen to Oslo.
The British press has gone bonkers over the news, though they seem more interested in the Python angle than in any revelations about psittaciform evolution per se. The article’s author, David Waterhouse of Norfolk Museums and Archaeology Service, a Python fan himself, has helped out by peppering his interviews with snippets from the sketch.
And the last laugh: the bone that clinched the specimen as a parrot? It came from the upper arm. Or humerus.
(Image: David Waterhouse; hat tip: the KSJ Tracker)