Friday, September 17, 2010

The Origin of Life

I always thought metal and science are alike. Both require technical mastery and precision, and metal, like science, usually looks down on religion with the disdain and ridicule it deserves (unless it's Christian metal, but Christian metal is an oxymoron like 'honest politician' or 'abstinent teenager', because if you're smart enough to play metal, you shouldn't be dumb enough to fall for religion).
So the time has come for another science posting... on the origin of life!
If there is a God, then instead of being a beardy weirdo in the sky, it's probably some sort of giant bacteria God, because in the grand scheme of things, bacteria win. There are more bacteria in a handful of soil than there are humans on Earth, and bacteria sat around on their own on the Earth for 2 billion years before any other life came along. That means almost half of the history of life was dominated by bacteria only, and humans... well, humans make up less than 1% of life's history.
It was Space Week on National Geographic channel last week, and aside from the annoying lady who kept comparing the Earth to a tennis ball and the sun to a basketball and wandering around city blocks incessantly yammering on about how far tennis ball Earth is from basketball sun in city-block distance, there were some interesting things going on.
Have you heard of the Murchison meteorite?

Well, it's just a rock from outer space that smashed into the Earth in the 60s, but scientists found amino acids on the Murchison meteorite. Amino acids are the chemical building blocks of DNA, so they're pretty exciting, but if your brain's skepticism center is working properly, you're probably saying "So what? Obviously the meteorite was contaminated by dogs weeing on it and plants growing around it and birds shitting on it, so these amino acids just came from the Earth, and there's nothing to get your knickers in a twist about."
Good point, but there are only about 22 amino acids that occur regularly on Earth, and this meteorite has over 100 on it. Not only that, but molecules have something called chirality, which means they can always take two different mirror image forms, a right-handed form and a left-handed form. All the molecules that make up life on Earth like amino acids are left-handed, but on the Murchison meteorite, there were left-handed amino acids and right-handed ones.
So a rock can come from space with chemicals that don't exist on Earth, the precursors of extraterrestrial DNA, and crash into our humble planet - and this was much more common when our planet had just formed, around the time life began, because there were bits of debris smashing around everywhere in the solar system. No God, no Allah, no Adam & Eve, no Puff the Magic Dragon, just a rock from space and a few chemicals.
In fact, you don't even need a rock from space. There was a scientist called Stanley Miller in the '50s who built a contraption with some tubes and filled them up with water vapour, Nitrogen, ammonia, and some other chemicals that were around when all the planets formed, and he zapped this concoction with electric currents to simulate lightning bolts (lightning happens on other planets too), and out of the tube dripped all the ingredients of life, a primordial soup made of half-formed bits of DNA (nucleotides) and amino acids (which make up DNA and the proteins that form living things), as well as sugars.

So life was made by chemical reactions, some lightning bolts and some meteorites, not by a beardy weirdo on the sky, just as thrash is made with hours of practice, beer and headbanging. Next postings will review Ozzy Osbourne and Dave Mustaine's autobiographies, a cross-cultural study in the differences between European (Brummy, no less) debauchery and American excess!
I will get around to it if I ever finish my Biology lab readings for uni.

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