From Quanta Magazine:
Life emerged so long ago that even the rock formations covering the planet at that time have been destroyed — and with them, most chemical and geological clues to early evolution. “There’s a huge chasm between the origins of life and the last common ancestor,” said Eric Gaucher, a biologist at the Georgia Institute of Technology in Atlanta.
The stretch of time between the origins of life and the last universal common ancestor saw a series of remarkable innovations — the origins of cells, metabolism and the genetic code. But scientists know little about when they happened or the order in which they occurred.
Scientists do know that at some point in that time span, living creatures began using a genetic code, a blueprint for making complex proteins. It is those proteins that carry out the vital functions of the cell. (The structure of DNA and RNA also enables genetic information to be replicated and passed on from generation to generation, but that’s a separate process from the creation of proteins.) The components of the code and the molecular machinery that assembles them “are some of the oldest and most universal aspects of cells, and biologists are very interested in understanding the mechanisms by which they evolved,” said Paul Higgs, a biophysicist at McMaster University in Hamilton, Ontario.
According to the theory discussed in th article, the amino acid tryptophan came last.
A Quanta reader wrote to them to point out that the author uses much too colourful language, language that implies that evolution has intelligence or a goal. For example: “It then grew in complexity over time, as these proteins learned to make more sophisticated molecules.” Proteins learn? Are these newer structures “more sophisticated” (implying intelligence) or merely more complex?
Humph. Playing our song and not crediting us.
Also, Paul Schimmel, quoted in the article: “It speaks to the refinement and subtlety that nature was using to perfect these proteins and the diversity it needed to form this vast tree of life.”
Nature isn’t suppose to be a person, but in any event, it is not clear any more that there even is a tree of life
If author Emily Singer gets it on the ear from naturalists, it’s too bad. Especially when one considers that they have got hardly anywhere at all with the origin of life problem, except for all the fascinating ideas.
Which are fun, to be sure—but not quite the same thing as scientific progress.
See also: With Enceladus the toast of the solar system, here’s a wrap-up of the origin-of-life problem
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