Saturday, October 5, 2013

Life and Death in This Saturday in Science

Well, this being the month of Halloween, perhaps its appropriate that This Saturday in Science take a look at some of the science surrounding the two thing all living creatures have in common, existence and, its end.

Today we bring you some information about how science illuminates all the different and macabre ways that things die and, the perhaps even stranger story of how they got here in the first place.

Let's start off with a carnivorous plant.

No, not the Venus fly trap but the lesser known, but no less deadly, pitcher plant.

This one, perhaps the largest on Earth, was recently discovered in the Philippines and is named after Sir Richard Attenborough, the steady but excited voice (and guiding hand) behind so many of the nature films one sees on Nova and similar programs.

This one, has consumed a shrew:

Definitely not how any of the staff at Digital Notebook Tower want to go....

As for how we came, well much of that, as any evolutionary biologist worth his salt will tell you, was determined in the Cambrian explosion 520 million years ago.

But what caused this sudden explosion of vital diversity.

Some scientists have identified one cause, other scientists another.

Around 520 million years ago, many major groups of animals
appear in the fossil record for the first time.
Trilobites belonged to the same lineage
as today's crustaceans and insects
But Paul Smith, the director of the Oxford Museum of Natural History and his colleague David Harper of the University of Durham have a different view.

When asked which of those changes, geological, biological, astronomical, is responsible, their answer is: "yes."

As The New York Times reported Sept. 19, "Dr. Smith and Dr. Harper argue in a commentary in this week’s Science, but it’s a mistake to search for a single cause. They propose that a tangled web of factors and feedbacks were responsible for evolution’s big bang."

Here is the really interesting passage that is at the heart of their theory:
It took a global flood to tap that capacity, Dr. Smith and Dr. Harper propose. They base their proposal on a study published last year by Shanan Peters of the University of Wisconsin and Robert Gaines of Pomona College. They offered evidence that the Cambrian Explosion was preceded by a rise in sea level that submerged vast swaths of land, eroding the drowned rocks.
Claws AND shells did you say?
“There’s a big kick that correlates with the sea level rise,” Dr. Smith said of the fossil record. He and Dr. Harper propose that this kick happened thanks to the new habitats created by the sea level rise. These shallow coastal habitats were bathed in sunlight and nourished with eroding nutrients like phosphates. Animals colonized these new fertile habitats, Dr. Smith and Dr. Harper argue, and evolved to take up new ecological niches.
But these great floods also poisoned the ocean. The erosion of the coastlines released calcium, which can be toxic to cells. In order to survive, animals had to evolve ways to rid themselves of the poison. One solution may have been to pack the calcium into crystals, which eventually evolved into shells, bones, and other hard tissues. Dr. Smith doesn’t think it’s a coincidence that several different lineages of bilaterians evolved hard tissues during the Cambrian explosion, and not sooner.
These shells and other hard tissues sped up animal evolution even more. Predators could grow hard claws and jaws for killing prey, and their prey could evolve hard shells and spines to defend themselves. Animals became locked in an evolutionary arms race.

Of course life evolved all kinds of interesting ways to kill prey, not just bone-crushing claws and piercing spikes.

Another effective agent is poison and perhaps no other animal symbolizes that particular mode of mortality than the black widow spider.

In this interesting first-person account, published Sept. 16 in The New York Times, writer Jackson Landers talks about his experience after being stung (bitten?) by one.

Because The New York Times is too clever (or I'm too technically inept) to let me steal their videos for shameless self-promotion here, I can offer you only this link to his recounting.

Here's an FYI: The black widow is unfairly named. Female spiders rarely kill the male after mating, and possibly only in captivity. The male looks very different from the mature female; he is smaller and brownish. (The hourglass marking is quite variable in both sexes.) Both sexes carry the same venom, but the females have more of it and their fangs can inject it deeper.

On the subject of evolution, allow me to point out that our children may not learn what it is. Like so many things in this country, the blame can be laid on Texas.

"As Texas gears up to select biology textbooks for use by high school students over the next decade, the panel responsible for reviewing submissions from publishers has stirred controversy because a number of its members do not accept evolution and climate change as scientific truth," The Times reported on Sept. 28.

"One is a nutritionist who believes “creation science” based on biblical principles should be taught in the classroom. Another is a chemical engineer who is listed as a “Darwin Skeptic” on the Web site of the Creation Science Hall of Fame. A third is a trained biologist who also happens to be a fellow of the Discovery Institute, the Seattle-based center of the intelligent-design movement and a vice president at an evangelical ministry in Plano, Tex."

So why should we care right? We don't live in Texas.

Yes, but some of our textbooks do.

You see, Texas buys its textbooks on a state-wide level, a huge sales incentive for textbook publishers to tailor their texts to something that will please the people in Texas who decide what books get bought.

Ahhh, now, you're seeing the problem.

"Historically, given the state’s size, Texas’ textbook selections have had an outsize impact on what ended up in classrooms throughout the country," the Times reported.
Four years ago, a conservative bloc on the state school board pushed through amendments to science standards that call for students to “analyze and evaluate” some of the basic principles of evolution. Science educators and advocates worry that this language can be used as a back door for teaching creationism.
“It is like lipstick on a Trojan horse,” said Kathy Miller, president of the Texas Freedom Network.
Well, evolution will go on whether we're studying it or not.

But one has to wonder how the scientists of tomorrow, taught to doubt what is now accepted scientific fact, will deal withe challenges of the future.

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