The Tangled Tree: A Radical New History of Life
The worldwide influenza epidemic of 1918-19 was accompanied by a strain of bacterial pneumonia that killed millions of people. In searching for a treatment, a British researcher named Fred Griffith discovered that some forms of the bacterium were relatively mild, but others were virulent. He further discovered that combining the live mild form with the dead virulent form created a live virulent form.
It was the quintessential horror story of transformation from the mild-mannered into the Beast, played out in a Petri dish.
Griffith’s report documents the first known observation of a phenomenon now known as horizontal gene transfer, or HGT. The unfolding understanding and implications of several related, relatively recent lines of scientific inquiry, including HGT, form the subject David Quammen’s latest book.
Quammen is the master of deconstructing complex, obscure scientific concepts and reconstituting them into coherent, understandable, and illuminating narratives. In The Tangled Tree: A Radical New History of Life, he does this primarily by focusing on the people behind the science who, in a very short period of time — whether working with or against each other — have changed much of what we thought we knew about evolution, heredity, and, yes, the origin (and definition) of species.
The title refers to the common metaphor of the “tree of life” that has been drawn and redrawn, since before Darwin, in our attempts to show the hierarchical and evolving relationships of life forms. In the last 40 years or so of scientific endeavor, that tree has instead revealed itself to be a web.
Serving as the central figure in this narrative is Carl R. Woese, a scientist whose work at the University of Illinois Urbana starting in the 1960s eventually made him the father of a branch of science now known as molecular phylogenetics. Woese’s interest was in discovering the oldest origins of the genetic code and figuring out how it evolved. He was attempting to go all the way back to the beginning....MUCH MORE
In the years before complete genomes of various species were mapped, before computer-based sequencing was possible, this work involved a mind-numbingly manual and dangerous process of RNA sequencing that helped to reveal degrees of ancient relatedness, something never before possible.
It was Woese who demonstrated that, beyond prokaryotes and eukaryotes — the two scientifically accepted kingdoms of life at the time — there was a third: the archaea. He called the resulting new diagram of evolutionary relationships “the Big Tree.”...
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