Boom, they all died

An analysis of sedimentary deposits laid down in the times bracketing the Permian extinction reveals something a bit unsettling: the Earth’s biota was thriving and doing just fine right up to the sudden end, and then almost all species abruptly kicked the bucket in a geological flash.

The end-Permian mass extinction, which took place 251.9 million years ago, killed off more than 96 percent of the planet’s marine species and 70 percent of its terrestrial life—a global annihilation that marked the end of the Permian Period.

The new study, published today in the GSA Bulletin, reports that in the approximately 30,000 years leading up to the end-Permian extinction, there is no geologic evidence of species starting to die out. The researchers also found no signs of any big swings in ocean temperature or dramatic fluxes of carbon dioxide in the atmosphere. When ocean and land species did die out, they did so en masse, over a period that was geologically instantaneous.

So what could have caused the sudden, global wipeout? The leading hypothesis is that the end-Permian extinction was caused by massive volcanic eruptions that spewed more than 4 million cubic kilometers of lava over what is now known as the Siberian Traps, in Siberia, Russia. Such immense and sustained eruptions likely released huge amounts of sulfur dioxide and carbon dioxide into the air, heating the atmosphere and acidifying the oceans.

Complicating matters, though, is that these eruptions proceeded for a long time before, during, and after the mass extinction, so it seems that life persevered until it reached an abrupt breaking point, and then ecosystems collapsed.

“We can say there was extensive volcanic activity before and after the extinction, which could have caused some environmental stress and ecologic instability. But the global ecologic collapse came with a sudden blow, and we cannot see its smoking gun in the sediments that record extinction,” Ramezani says. “The key in this paper is the abruptness of the extinction. Any hypothesis that says the extinction was caused by gradual environmental change during the late Permian—all those slow processes, we can rule out. It looks like a sudden punch comes in, and we’re still trying to figure out what it meant and what exactly caused it.”

“This study adds very much to the growing evidence that Earth’s major extinction events occur on very short timescales, geologically speaking,” says Jonathan Payne, professor of geological sciences and biology at Stanford University, who was not involved in the research. “It is even possible that the main pulse of Permian extinction occurred in just a few centuries. If it turns out to reflect an environmental tipping point within a longer interval of ongoing environmental change, that should make us particularly concerned about potential parallels to global change happening in the world around us right now.”

This is why we need a big-picture perspective of our planetary environment. It’s like a game of Jenga — we keep knocking out little bits and pieces (or species or biomes) and congratulating ourselves that the tower is still standing, but eventually we’ll reach the point where one last insult causes everything to topple. Then, I’m sure, there will be people lying in the rubble, wondering why they’re starving or dying of disease or watching the natural catastrophe rolling in their direction, and they’ll be totally surprised by it all.

If it’s Monday, it must be spider feeding day

Mondays are usually awful, but now at least I have one thing to look forward to: it’s feeding day down on the spider ranch. The adults get a nice chewy cricket each, while I go through the spiderlings’ chambers and toss them a fruit fly each. Since Vera was so avidly hungry today, I recorded her trapping her prey and then picking at it for an extended period of time.

This one is only for spider obsessives who can enjoy staring at close-ups of arachnids doing strange things with their jaws for 15 minutes or more. Are you one? Let me know, and we can start a club.

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Biochemistry, it turns out, is not a creationist’s friend

Oh, look. Biochemists have found a recipe that spontaneously produces all four nucleotides used in RNA.

Carell’s story starts with only six molecular building blocks—oxygen, nitrogen, methane, ammonia, water, and hydrogen cyanide, all of which would have been present on early Earth. Other research groups had shown that these molecules could react to form somewhat more complex compounds than the ones Carell used.

To make the pyrimidines, Carell started with compounds called cyanoacetylene and hydroxylamine, which react to form compounds called amino-isoxazoles. These, in turn, react with another simple molecule, urea, to form compounds that then react with a sugar called ribose to make one last set of intermediate compounds.

Finally, in the presence of sulfur-containing compounds called thiols and trace amounts of iron or nickel salts, these intermediates transform into the pyrimidines cytosine and uracil. As a bonus, this last reaction is triggered when the metals in the salts harbor extra positive charges, which is precisely what occurs in the final step in a similar molecular cascade that produces the purines, adenine and guanine. Even better, the step that leads to all four nucleotides works in one pot, Carell says, offering for the first time a plausible explanation of how all of RNA’s building blocks could have arisen side by side.

Spider update (no spider photos)

I’m getting a little anxious — my spider family is in a quiet phase right now. I have 6 breeding pairs of adults (well, Gwyneth ate her consort after mating, so 5½, and maybe bred pairs is the better term). I’m down to one egg sac — again, from Gwyneth, who is a sick Goth freak because she knitted an ugly, sloppy sac with the dead corpses of her prey imbedded in it, but it does have developing embryos inside it. She also littered the floor with decapitated fly heads. Gwyneth scares me sometimes.

But otherwise, I’m just waiting for them to produce more. My goal is to have a steady reliable output of eggs, and these little hiatuses are nerve wracking, but also understandable, since the colony is so small yet.

I do have a lot of tiny little juveniles coming up, at least. They’re getting a little overwhelming — these are my spider-children, in these little vials I picked up at JoAnn Fabrics (they’re intended for storing and sorting beads, but I have perverted them to my own wicked ends.) Thirty vials, thirty hungry little babies.

I have to go in every couple of days and tend to them. Put one or two flies in each vial (I made a little fly-shaker out of an Eppendorf tube — it’s like a salt shaker, only when you shake it flies come out), give ’em a spritz of water from an atomizer, and agonize over their health and predatory instincts. As they get big enough, I move them to an adult-sized tube, and when I’m confident of their sexual maturity, I’ll pair them up.

But right now it’s a waiting game with placid little beasties (except for Gwyneth) quietly tending to their webs, nibbling on flies and crickets, making me fret over when they’re going to spawn again.

By the way, over half the vials I’m cultivating contain Gwyneth’s progeny — she’s a fecund little monster. I’ll be interested to see if her distinctive behaviors carry on into the next generation. I’m planning on doing some inbreeding of her offspring to see if I can get a brood of savage spider mothers.

Don’t ever play the racist game

A simple question: did Elizabeth Warren have an Indian ancestor? Yes. Definitely. As Carl Zimmer explains, the science is good and robust on this one. Anyone who is arguing that this is fake science ought to be immediately fired from any job that involves setting science policy. Bye, Donald!

More complex question: does Elizabeth Warren have any legitimate claim to any kind of Indian affiliation? Nope, not that she claimed she did. And she played right into Trump’s racist hand.

Warren ended up providing one of the clearest examples yet of how Trumpian rhetoric shifts the political conversation. The woman who is hoping to become the most progressive Democratic nominee in generations is not merely letting herself get jerked around by a Trumpian taunt. She is also reinforcing one of the most insidious ways in which Americans talk about race: as though it were a measurable biological category, one that, in some cases, can be determined by a single drop of blood. Genetic-test evidence is circular: if everyone who claims to be X has a particular genetic marker, then everyone with the marker is likely to be X. This would be flawed reasoning in any area, but what makes it bad science is that it reinforces the belief in the existence of X—in this case, race as a biological category. Warren’s video will hardly convince a Trump voter, who will see only a woman who feels that she has to prove something. Trump himself has already walked back his promise of a million-dollar charity donation. Warren, meanwhile, has allowed herself to be dragged into a conversation based on an outdated, harmful concept of racial blood—one that promotes the pernicious idea of biological differences among people—and she has pulled her supporters right along with her.

See? You can understand that it is good science while also recognizing that she’s promoting odious ideological implications that are contrary to her political position.