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“Such is the essential mystery”*…

 

For about a billion years, life on earth was a relatively simple proposition: it was composed entirely of single-celled organisms (prokaryotes) in either the bacteria or archaea families.  Then, about 2.1 billion years ago, one of those single-celled critters crawled inside another; the two merged, and a new kind of life– multi-cellular (eukaryotic) life– was born…

This inner cell—a bacterium—abandoned its free-living existence and eventually transformed into mitochondria. These internal power plants provided the host cell with a bonanza of energy, allowing it to evolve in new directions that other prokaryotes could never reach.

If this story is true, and there are still those who doubt it, then all eukaryotes—every flower and fungus, spider and sparrow, man and woman—descended from a sudden and breathtakingly improbable merger between two microbes. They were our great-great-great-great-…-great-grandparents, and by becoming one, they laid the groundwork for the life forms that seem to make our planet so special. The world as we see it (and the fact that we see it at all; eyes are a eukaryotic invention) was irrevocably changed by that fateful union—a union so unlikely that it very well might not have happened at all, leaving our world forever dominated by microbes, never to welcome sophisticated and amazing life like trees, mushrooms, caterpillars, and us.

Read the extraordinary story of how one freakish event may well account for all sophisticated life on earth in “The unique merger that made You (and Ewe, and Yew).”

* Lao Tzu

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As we fill out our family trees, we might send microscopic birthday greetings to Carl Woese; he was born on this date in 1928.  A microbiologist, Woese recognized and defined (in 1977) the existence of archaea as a third domain of life, distinct from the two previously-recognized domains, bacteria and “life other than bacteria” (eukaryotes).  The discovery revolutionized the understanding of the “family tree” of life.  And the technique he used to make it– phylogenetic taxonomy of 16S ribosomal RNA— revolutionized the practice of microbiology.

 source

 

Written by LW

July 15, 2014 at 1:01 am

Well that changes everything…

source: Imperial College, London

As all of one’s assumptions about the future (and thus the past) seem to be weakening, two dispatches from the world of science are genuinely foundation-shaking…

First, from New Scientist (and though NS doesn’t mention it, earlier from Freeman Dyson in NYRB):

Just suppose that Darwin’s ideas were only a part of the story of evolution. Suppose that a process he never wrote about, and never even imagined, has been controlling the evolution of life throughout most of the Earth’s history. It may sound preposterous, but this is exactly what microbiologist Carl Woese and physicist Nigel Goldenfeld, both at the University of Illinois at Urbana-Champaign, believe. Darwin’s explanation of evolution, they argue, even in its sophisticated modern form, applies only to a recent phase of life on Earth.

At the root of this idea is overwhelming recent evidence for horizontal gene transfer – in which organisms acquire genetic material “horizontally” from other organisms around them, rather than vertically from their parents or ancestors. The donor organisms may not even be the same species. This mechanism is already known to play a huge role in the evolution of microbial genomes, but its consequences have hardly been explored. According to Woese and Goldenfeld, they are profound, and horizontal gene transfer alters the evolutionary process itself. Since micro-organisms represented most of life on Earth for most of the time that life has existed – billions of years, in fact – the most ancient and prevalent form of evolution probably wasn’t Darwinian at all, Woese and Goldenfeld say…

Woese can’t put a date on when the transition to Darwinian evolution happened, but he suspects it occurred at different times in each of the three main branches of the tree of life, with bacteria likely to have changed first…

As we remember that what has changed can change again, we can read the whole story here.

Second, from ArXiv and ITWire, a suggestion that we might not have as long to figure this out as we have been thinking:  entropy in the universe is much higher than previously expected; thus the “heat death” of existence as we’ve known it, much closer. As Tapecutter observes in Slashdot,

In a paper soon to be published in the Astrophysical Journal [ArXiv link, above], Australian researchers have estimated the entropy of the universe is about 30 times higher than previous estimates. According to their research, super-massive black holes “are the largest contributor to the entropy of the observable universe, contributing at least an order of magnitude more entropy than previously estimated.” For those of us who like their science in the form of a car analogy, Dr. Lineweaver compared their results to a car’s gas tank. He states, ‘It’s a bit like looking at your gas gauge and saying “I thought I had half a gas tank, but I only have a quarter of a tank.”

Happily a quarter of a tank should be good for hundreds of thousands (if not millions) of years.

As we regain our bearings, we might note that this was a bad day for revolutionaries of another stripe:  it was on this date in 1606 that Guy Fawkes was executed for his role in the Catholic Restorationist “Gunpowder Plot.”

Guy Fawkes

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