Smithsonian.com

The closest living relatives of Tyrannosaurus rex are birds such as chickens and ostriches, according to research published today in Science (and promptly reported in the New York Times). Paleontologists used material discovered in a chance find in 2003 to pin down the link.

The dinosaur-ness of birds has been suspected for many years based on anatomical similarities, but the new research is the first molecular evidence. For decades, dinosaurs were thought to be reptiles: big ones, to be sure, but basically cold-blooded, slow-moving, and dim-witted. The movie Jurassic Park popularized the idea of dinosaurs as quick, smart and birdlike. (The movie’s ideas had been proposed in the 1970s–a book by paleontologist Robert Bakker, called The Dinosaur Heresies, nicely conveys this change in thinking and the controversy that accompanied it.)

To get molecular evidence about dinosaurs, you need some actual molecules–a tall order for a group of animals that died out 65 million years ago. But in 2003, scientists Jack Horner and Mary Schweitzer discovered some unfossilized material inside a T. rex bone by a combination of luck, desperation, and sharp eyes (see Smithsonian, May 2006). Faced with flying a giant femur out of a remote Montana field site, they broke the bone in half so it would fit inside their helicopter. If they’d had a larger helicopter, we might never have known.

Unlike in Jurassic Park, the real-life researchers couldn’t recover any DNA from the ancient remains. But they did retrieve molecules of collagen, a structural protein that appears in slightly different forms in many animals. They compared the dinosaur version with 21 living animals, including humans, chimps, mice, chickens, ostriches, alligators and salmon. T. rex‘s collagen proved to be most similar to chickens and ostriches; its next closest match was to alligators.

Chickens and ostriches are only distantly related to each other, so the research says little about what kind of birds might be the closest relatives of the famous carnivore. The scientists noted that answering that question would require data from more molecules than just collagen. Whether they are currently cracking into any more giant fossils in search of material was not divulged.

(Images courtesy Science)

Here at The Gist we were going to try to make it through the week without saying anything about any former New York governers – because, you know, ew. But as you may have noticed, that hasn’t stopped everyone else in the world. And then ace Gist-er Virginia Hughes pointed out on her own blog an interesting evolutionary-psychology angle printed in the L.A. Times. Unfortunately, author David Barash boiled down his evolutionary primer to a single, creepy shoulder shrug:

You want monogamy? Elect a swan. Or better yet, a [worm called] Diplozoon paradoxum.

Surely there had to be a way to write that article without implying that unfaithful men make better politicians. Thankfully, science writer Jennie Dusheck promptly set Barash straight in the same newspaper, just six days later. She gets in some good ones, including:

Barash makes the threadbare argument that men just can’t help themselves, titillating his readers with the tattered news that male animals copulate with more than one mate…

Even Natalie Angier, in the New York Times, couldn’t resist wading into the fray on Tuesday. But both these writers seemed mostly content to point out that female animals are just as capable of faking monogamy as males. Cheating is entirely unoriginal, Angier says, no matter how much time a pair spends

reaffirming their partnership by snuggling together like prairie voles or singing hooty, doo-wop love songs like gibbons, or dancing goofily like blue-footed boobies.

The ubiquity of what academics delicately call extra-pair copulation is worth pointing out. But as an argument against male randiness, it’s a little like saying Clyde wasn’t so bad because Bonnie was also a mean person.

The really interesting lessons come from a bit deeper in the evolutionary textbooks. The great variety of romantic norms in the animal world stem from a few basic principles, such as how much care the kids require in order to survive. Does it take two parents working for months on end just to raise one fat, happy kid? Choose monogamy – just ask an emperor penguin. Or can a mother raise a kid or two on her own? Then she’s likely to look for no more than a hasty donation of genes from a strong male of her choosing. Think elk, bighorn sheep, elephant seal. Many fish don’t even bother to get acquainted, simply spewing gametes into the water and trusting to the wisdom of the currents. Kids never know either parent.

Take a still closer look, and the soap opera of the sexes gets positively bizarre. Some people may take heart in the stories of phalaropes – shorebirds whose females wear bright colors and dominate males, leaving incubation to them. Then there’s the across-species relationship between relative testes size and degree of monogamy (you don’t want to know where humans fall on that graph). And that’s just the beginning of the field of sperm competition. It’s a world nicely described (with appropriate nudges and winks) in Dr. Tatiana’s Sex Advice to All Creation (now a TV show!).

If it’s any consolation, all this does suggest that philandering politicians are just about as advanced as your typical weevil or prairie dog. Now about the rest of us….
(Wikipedia: Bonnie and Clyde)

In case we need more convincing that the Anthropocene is upon us, take a look at how we’ve reshaped the world with agriculture (see EcoCenter: The Land).

As Diana Parsell writes, about 35 percent of the world’s ice-free land is now under cultivation, up from a minuscule 7 percent in the year 1700. And humans are continually improving the very crops we grow, she writes: in the last 40 years, farmers have doubled their yield while planting just 12 percent more land.

Perhaps the most controversial way we improve crop yields – genetic modification – just absorbed a dose of bad news yesterday in Nature Biotechnology. Scientists from the University of Arizona reported the first case of an insect pest evolving resistance to “transgenic” cotton plants that make a pesticide called Bt. Say what you want about whether evolution is real – this change took about seven years.

Genetic engineering is a touchstone issue: it’s anathema to many, while to others it’s our crowded world’s only practical hope. Though GM crops are banned in the European Union, Bt-producing cotton and corn have flourished on more than 400 million acres since they were first planted in 1996, the study reports. The immense planted area created what biologists call a strong selective pressure, favoring the survival of any pests with resistance to Bt and speeding evolution of the trait.

To be fair, Bt is a model pesticide that’s been used widely since the 1950s. Far different from the likes of DDT, the chemical is produced organically, by a bacterium called Bacillus thuringiensis, and it is very specific, affecting only certain groups of insects. Most other animals can ingest it without so much as a hiccup. By genetically engineering plants to produce Bt instead of scattering it from the wings of a cropduster, farmers can avoid the collateral damage that comes from spraying plants other than their crop. And, the authors point out, resistance has so far appeared in only one of many pest species, and only in about a dozen small localities.

Still, this week’s news resurrects an old hobgoblin of pesticide use. Barely a decade after the first delighted reports of DDT’s effectiveness – and the awarding of the Nobel prize to its developer – the first reports of resistance trickled in. Ever since we’ve seen an escalating arms race between ingenious people and adaptable insects. Already the new article’s authors are pointing to a new generation of Bt-engineered crops – these now produce two varieties of Bt to boost their effectiveness. But the writing is on the wall: resistance is inevitable.

Interestingly, a separate article in the journal reports new efforts to begin to evaluate the effect of pesticide-producing crops on “nontargetâ€? insects – the innocent bystanders and the good guys. A laudable effort, but perhaps regrettable that it’s happening 10 years after the first mass plantings. The question with genetic engineering remains: Can our knowledge of what we’re doing keep up with how fast we’re doing it?
(Image: the pest in question, Helicoverpa zea, the bollworm moth; USDA-Agricultural Research Service)

German scientists recently unearthed the fossilized claw of an 390 million-year-old sea scorpion. The finding was, literally, huge: the claw was 18.1 inches long, making the beast that used it longer than 8 feet!

The scientist who actually found the claw, Markus Poschmann of the Mainz Museum in Germany, describes what happened when he was excavating a quarry in Prüm, Germany:

I was loosening pieces of rock with a hammer and chisel when I suddenly realised there was a dark patch of organic matter on a freshly removed slab. After some cleaning I could identify this as a small part of a large claw. Although I did not know if it was more complete or not, I decided to try and get it out.

The fossil analysis, published last week in the journal Biology Letters, identified the claw as sea scorpion Jaekelopterus rhenaniae, an extinct species that gave rise to modern scorpions and possibly all arachnids.

I’ll leave you with an intriguing question about the scorpion posed by a reader on Carl Zimmer’s blog, The Loom: “Would it taste like lobster?”

(Above, an Egyptian deathstalker scorpion, Leiurus quinquestriatus, under blacklight. Flickr, by furryscaly)

With hairy legs, scraggly facial hair and eight eyes, the wolf spider is one scary beast. The spry hunters don’t use a web to catch prey, but run it down instead. And creepiest of all: sometimes they eat their own eggs.In the natural selection game, where the ultimate goal is to produce as many fit offspring as possible, killing your babies generally doesn’t make sense. Yet “filial cannibalism” occurs in species across the animal kingdom, from damselfish to house finches to bank voles. So, since the behavior persists, ecologists have tried to pin down the environmental and social conditions in which it might be evolutionarily advantageous.

In the past, scientists had hypothesized that eating eggs may be the only way for parents to survive in times of food scarcity. (If the parents die, after all, the eggs wouldn’t have a chance, anyway.) But this theory was questioned when researchers observed some fish species that continued to snack on their eggs even when food was abundant.

Turns out other factors make filial cannibalism pay off in the long run, according to computer models made by zoologist Hope Klug, of the University of Florida and Oxford ecologist Michael Bonsall. The pair published their results in the December issue of The American Naturalist.

First off, if parents eat only the eggs that take the longest to hatch, then the egg-hatch rate will increase over many generations. In other words, cannibalism might be a way to weed out the young that will need the most care. And if parents spend less time on each kid, then they can use the extra energy to produce more.

More perplexing, the researchers also found that when adults eat some of their young, they become more attractive to potential mates, thus further increasing their reproductive rates. Sexy, huh?

(Flickr: JLplusAL)