About Me

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I am a former middle and high school science teacher pursuing a doctorate in Science Ed. at George Mason University, with a concentration in cognitive science and the evolution of cognition and learning. Postings on this blog represent my own views, not those of my employer or school. All writing displayed on this page is original work unless otherwise noted, and thus copyrighted.

31 October 2009

Happy Hallowe'en, don't eat the candy!

This would be hilarious if it were a joke... unfortunately someone actually believes this.

29 October 2009

Chirality and Life

Marcelo Gleiser is, if not more intelligent, certainly more educated than I am. Thus I'm a but surprised to find such fundamental errors of thinking in his latest SEED article, here. Gleiser states, quite correctly, that all the proteins that make up life could, chemically, be right-oriented or left-oriented. He also cites his and colleagues' research that the early Earth appears to have contained molecules of both chiralities, and then asks why life only has left oriented molecules present. Marcelo, how is this not at least semi-obvious?
Let's start with a fundamental assumption; Life began once and only once on our planet, created from (insert correct answer here, we don't have it yet) to form self-replicating strands of nucleic acids and the proteins for which they code, somewhat like viruses or prions. This isn't that poor of an assumption, given the low probablity of spontaneous generation of life in the first place. It had to happen somewhere, given the numbers of stars and planets, and obviously it happened here or we couldn't write and read blogs written by graduate students of no current academic importance, but proposing it occured multiple times is a bit of a mathematical stretch. If you'd like, we can concede that life was unlikely to start more than once at a time, allowing the possibility that early life began several times sequentially, and that will not affect this dicussion at all. So, given that life occured once, or once to start, then the proteins incorporated in that first organism were likely of one chirality, given the simplicity of early life-like molecules and the coding for proteins written into whichever nucleic acid (likely RNA, from current evidence) was employed. That life had to replicate, using the available amino acids, proteins, and other molecules, and would replicate using the same structure without fundamental changes in the RNA (mutations). Molecules of the wrong chirality couldn't even interact chemically with those of early life, it'd be life trying to use the mirror image of a key. (Gleiser uses the mirror analogy to describe chiral molecules first, and it's apt, so I'm stealing it. Thanks Marcelo, you'll never likely see this, but I'm giving credit anyway)
Briefly, then, what we're seeing in the exclusivity of "left-handed" proteins is a what Dawkins calls a frozen accident, the vestige of the structure of our most distant ancestors and the necessary structures for their replication and survival, all the way down to us. There's no reason to suppose that life on other planets would necessarily follow this blueprint, and actually finding samples would be a requirement for making any statements of that kind.

Gleiser states it thusly:
If one traces life’s origins from its earliest stages, it’s hard to see how life began without molecular building blocks that were “chirally pure,” consisting solely of left- or right-handed molecules. Indeed, many models show how chirally pure amino acids may link to form precursors of the first protein-like chains. But what could have selected left-handed over right-handed amino acids? My group’s research suggests that early Earth’s violent environmental upheavals caused many episodes of chiral flip-flopping. The observed left-handedness of terrestrial amino acids is probably a local fluke.

Obviously we're not far apart on most of this view, it's the "it's hard to see how" statement that vexes me... his local fluke may be much more local than he believes, as in local to the particular location on the planet where life began.

19 October 2009

Sham Charity...


An organisation called Orphan Outreach runs volunteer trips to the Dominican Republic, many of which are taken by public schools. This, at first glance, sounds like a wonderful idea. The issue I derive from this is that the founders of O.O. are not only religious (that's immaterial), but that they require the orphans to attend Pentecostal Church services nightly, according to their volunteer guide. Volunteers, of course, aren't mandated to attend, but then again they aren't the target here. On top of that, the volunteers are required to not only pay for the trip ($1600 for a week) and their own airfare, they're expected to bring a 50lb. suitcase of food to donate and give any flight coupons that might be received if they're bumped on a flight. Hmm... not that I have a problem with supporting the orphanage, but if I chose to go and volunteer, what would I have to pay $1600 for a week's worth of beans and rice and a place to sleep under a mosquito net in an open air building? What exactly does that money cover? Not to mention that fact that I would then get to pass through customs in a third world nation with 50lbs of food, and then identify myself as an American for a nice trip through an area where we're advised by the State Department not to travel alone or after dark. It sounds to me like, under the guise of a good cause, those who run this programme are financially exploiting the charitably minded and seeking to convert young children to their religion.

02 October 2009

Pat Condell's latest...

Patriotic Jackassery

Someone will disagree with this, but, hell, someone disagrees with everything else I write as well. At the outset of a school pep rally today, our athletic director threw out two male Hispanic students who refused to stand and recite the Pledge of Allegiance. They weren't disruptive or disrespectful, in fact they weren't even speaking, they simply didn't stand and say the pledge. I was told, by the athletic director, to take them to our version of in-school suspension for that "offence", which I refused to do. Rather, I let the students stand just outside the gym doors and watch until I could get the attention of an administrator who promptly took them back in to be seated. The AD is furious that I went over his head (and that I took the students' side on this).
As I explained to the AD, I also refuse to say the pledge, although not for the same reasons as the students. Unless our government sees fit to remove the blatant and unconstitutional endorsement of religion from that document, I will continue to refuse to say the pledge, and if that were to happen I would still have reservations in publicly swearing allegiance to a piece of cloth and the nation. I have no intention of betraying the nation in which I live, and there are a number of things about this country that I admire and support, not least the fact that I have the freedom/right to decide whether or not I wish to say something like the Pledge of Allegiance because of the way our government was constructed. The students actually refused because they aren't yet citizens of the U.S., although they are here legally. That two adolescents (17 and 18 respectively) chose not to swear allegiance to a nation, of which they are not citizens (and that, at times, treats those of their ethnicity rather unjustly, to say the least), does not offend me in the least as a citizen of that nation. The athletic director, on the other hand, was absolutely incensed both with their conduct and my failure to condemn it.
A little research turns up this gem: 1943 West Virginia State Board of Education v. Barnette, in which the Supreme Court ruled that it was unconstitutional for the government, schools included, to compel speech in the manner of the Pledge. This at the height of World War Two, no less. Attempts since then to challenge the constitutionality of the words "under God" in the pledge, as they expressly support monotheism as a religious belief, have not resulted in Supreme Court rulings ( Newdow v. California was dismissed because the plaintiff was deemed not to have parental standing in the case). There are a number of more recent rulings that uphold the opinion that coercion of speech is not constitutional.
Basically, Wake Co. schools should be thanking me for saving them a lawsuit. Somehow I doubt I'll ever hear that thanks.