Texas...Again!

This is a follow-up post to another one on March 21.  Hot on the heels of the Texas State Board of Education striking language in the state science standards that would require teachers to “evaluate” scientific theories as they teach them, comes another bill that is an attempt to allow teachers to do exactly that. The Texas Observer has this to say:

Representative Valoree Swanson, R-Spring [natch!], is making a case for why her bill protecting the “academic freedom” of public school teachers wouldn’t amount to an unconstitutional teaching of religion in classrooms.

House Bill 1485 would “free our teachers to where they don’t live in fear of frivolous accusations” and give teachers the ability to criticize scientific theories, she told members of the House Public Education Committee Tuesday evening. Among the theories that teachers would be able to question in elementary, middle school and high school classrooms? Climate change.

Of course she doesn't stop at climate change:

But under Swanson’s bill, public schools are encouraged to create an environment where students can consider “differences of opinion about scientific subjects” and “assist” teachers in teaching subjects that may cause controversy. The bill lists climate change, biological evolution, the chemical origins of life and human cloning as examples of such controversial subjects.

The bill also prohibits school administrators and the State Board of Education from blocking teachers who are helping students “understand, analyze, critique and review” the “scientific strengths and weaknesses” of science subjects.

How is that climate change, biological evolution, the chemical origins of life and human cloning are always the “examples?”  How do you create this kind of environment with “differences of opinion about scientific subjects” without evaluating them?   My experience is that most high school teachers are not equipped to evaluate these subjects because they do not work in these fields.  That is why the language to do so was stripped from the original wording.  The study of the biochemical origins of life is extremely technical, with a  considerable amount of mathematics and, as with all of these subjects, requires considerable time and education to master. 

Nothing good can come from this.  

Early Evolutionary Step Replicated

This from Science Daily: a story where an early evolutionary step in which single-celled organisms began to band together to form mats and communities is replicated. The author writes:

It all started about two years ago with a casual comment over coffee that bridging the famous multi-cellularity gap would be "just about the coolest thing we could do," recall postdoctoral researcher Will Ratcliff and associate professor Michael Travisano, both from the Department of Ecology, Evolution and Behavior.

So they decided to give it a try. Then came the big surprise. It wasn't actually that difficult. Using yeast cells, culture media and a centrifuge, it only took them one experiment conducted over about 60 days, says Travisano, who is senior author on the PNAS paper.

"I don't think anyone had ever tried it before," says lead author Ratcliff. "There aren't many scientists doing experimental evolution, and they're trying to answer questions about evolution, not recreate it."

Although this doesn't answer all of the questions about how early life evolved, it answers some important ones.

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A Meteorite With an Organic Signature?

ScienceDaily has an excellent story on the Tagish Lake Meteorite, known as a carbonaceous chondrite. It seems that the great rock from the sky has chemicals that are similar to the proposed prebiotic organic material on earth, lending more credence to the idea that early life may have had an extraterrestrial impetus. The story notes:

If--as many have speculated--the organic material in meteorites had a role to play in the origin of life on Earth, the attraction of the common-source hypothesis is that the same organic material would have been delivered to all bodies in the Solar System. If the common source was the interstellar medium, then similar material would also be delivered to any forming planetary system.

The research team -- led by Christopher Herd of the University of Alberta, Canada, and including Carnegie's Conel Alexander, Larry Nittler, Frank Gyngard, George Cody, Marilyn Fogel, and Yoko Kebukawa -- studied four meteorite specimens from the shower of stones, produced by the breakup of a meteoroid as it entered the atmosphere, that fell on Tagish Lake in northern Canada in January 2000. The samples are considered very pristine, because they fell on a frozen lake, were collected without hand contact within a few days of landing and have remained frozen ever since.

According to the story, If these meteorites were part of a larger group of meteors or one larger body, it may be that they were part of the original body that formed the solar system. Sort of takes the “how could life on earth happen by pure chance” argument and turns it on its ear.

Looking in the Wrong Place?

Research out of the University of Copenhagen suggests that we have been looking in the wrong place for a source of oxygen that had to have been present for life to evolve on earth at the end of the Proterozoic eon. The story, in ThaiIndian states:

By analysing the isotopes of chromium in iron-rich sediments formed in the ancient oceans, a scientific team, led by Professor Robert Frei at the University of Copenhagen in Denmark, has found that a rise in atmospheric oxygen levels 580 million years ago was closely followed by the evolution of animal life.

The data offers new insight into how animal life - and ultimately humans - first came to roam the planet.

“Because animals evolved in the sea, most previous research has focussed on oceanic oxygen levels,” explained Newcastle University’s Dr Simon Poulton, one of the authors of the research paper.

“Our research confirms for the first time that a rise in atmospheric oxygen was the driving force for oxygenation of the oceans 580 million years ago, and that this was the catalyst for the evolution of large complex animals,” he added.

Distinctive chromium isotope signals occur when continental rocks are altered and weathered as a result of oxygen levels rising in the atmosphere.

According to the research, oxygen levels began to rise around 2.8 Gya but dropped again and did not experience its second rise until around 580 Mya. This would put it after the the most recent (Kaigas) of the "snowball earth" periods (assuming that is a viable theory).

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Early Life and the "Snowball Earth"

Evidence is building that between 850 and 500 million years, the earth was subjected to a series of mega-ice ages that resulted in a condition called "snowball earth." Now it is being suggested that this "snowball earth" may have been enough to give life its needed boost. An article in the NewScientist, by Douglas Fox and Michael La Page recounts the recent discoveries leading to this:

Some of the biggest finds have come from an ancient seabed in China, called the Doushantuo Formation, where unusual conditions preserved some extraordinary fossils. Layers between 550 and 580 million years old, during the last part of the Ediacaran, contain tiny spheres consisting of anything from one to dozens of different cells - just like the early embryos of animals. Some have suggested they are the remains of giant bacteria, but a series of studies over the past decade have left little doubt that they really are animal embryos.

In 2007, for instance, Leiming Yin of the Nanjing Institute of Geology and Paleontology in China reported finding embryos encased inside hard, spiky shells - unlike anything produced by bacteria. What is more, shells that are identical apart from the lack of preserved embryos on the inside can be found in rocks as old as 632 million years - the dawn of the Ediacaran - suggesting that the animal embryos themselves go back this far.

How did the ice ages play a role?

"This glaciation reset the chemistry of the oceans," he says. Ice caps covering the continents halted delivery of sulphur to the oceans and cut off production of hydrogen sulphide. "You have changes in ocean chemistry like an increased availability of molybdenum and zinc," says Ariel Anbar, a biogeochemist at Arizona State University in Tempe, "all of which play into making the world more hospitable for eukaryotes and ultimately, metazoans."

Sponges or something like them would have been the first animals on the scene. They lack a nervous system and have no need for circulatory systems. Animals like jellyfish might also have evolved early.

More pieces of the puzzle.

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