The Unbroken Thread

So now there is a fourth "symphony of science" by John Boswell, this time with David Attenborough and Jane Goodall, with the poshumously peripatetic Carl Sagan. Here are some of the best lines:

"Those are some of the things that molecules do, given 4 billion years of evolution." [Sagan]
"Its a very wuzzy line and it's getting wuzzier all the time." [Goodall]
"Our planet is, as far as we know, unique in the universe; it contains life" [Attenborough]
"Its continued survival now rests in our hands." [Attenborough]

"There's an unbroken thread from those first cells to us." This is Sagan's line and it is taken as the theme of this symphony. That's what we've learned about the genetic code: that while it is ever changing, it is also eternal. It's as if a notebook was opened at the creation, and it has been gathering notes continuously ever since. The number of copies has expanded, seemingly without limit, though in practice there are of course limits, especially on each genomic variation. But overall, the notebook proliferates and each new note adds to the storehouse of information about what works and what does not work for life on this planet. And each individual has their own copy and makes contributions that are realized in new copies of the genome. Darwin may not have known about the molecular machinery, but he certainly grasped the essence of the situation when he wrote:

"There is grandeur in this view of life..as the Earth has gone on cycling... from so simple a beginning, endless forms most wonderful and beautiful have been, and are being evolved." -- Charles Darwin, 1872