Digging Through the World’s Oldest Graveyard
Following the fossil hunters in Ethiopia who are searching for the origins of humanity.
If the World Began Again, Would Life as We Know It Exist?
Scientists are conducting experiments to learn what might happen if we went back in time and life started over again:
Rather than attempt to reconstruct history with fossils, Richard Lenski, an evolutionary biologist at Michigan State University, decided to watch convergence and contingency unfold in real time, in the controlled environment of his laboratory. In 1988, he separated a single population of Escherichia coli bacteria into 12 separate flasks containing liquid nutrients, and let them each evolve separately. Every few months for the past 26 years, he or one of his students has frozen a sample of the bacteria. This archive of frozen microbes gives Lenski the ability to replay E. coli’s tape of life from any point he wishes, simply by thawing out the samples. Along the way, he can examine how the bacteria change both genetically and in ways that are visible under a microscope. Lenski says, “The whole experiment was set up to test how reproducible evolution was.”
The Disappearing Physicist and His Elusive Particle
On March 25, 1938, 31-year-old physicist Ettore Majorana boarded a ship and seas never seen again. His work made him a pioneer in neutrino physics and the quantum mechanics of spin:
No one around Majorana even remotely understood what he was up to: the other Boys, for all their gifts, were much more down-at-heel. Like most physicists at the time, they regarded Majorana’s constructions as pure mathematics, without any relevance to physics. Applying group theory to physical problems, as Majorana had done, was just embellishment, or as the English like to say, “over-egging the pudding.”
Majorana didn’t care. Part of his strength was a sense of self-deprecation with which he smeared everything he did; indeed he was even more negative about his own ideas than about the others.’ He could try out unusual avenues because he didn’t take himself seriously, and so wasn’t constrained by a fear of failure. In a letter to a friend regarding his early efforts on symmetry and its toolbox, he said, “As for myself I do nothing sensible. That is, I study group theory with the firm intention of learning it, similar in this to that Dostoyevsky character who started one day to set aside his small change, fully persuaded that soon he’d be rich like Rothschild.”
The Unique Merger That Made You (and Ewe, and Yew)
In more than 3 billion years of existence on Earth, this merger happened once—and resulted in the complex life we have today:
There are many possible explanations, but one of these has recently gained a lot of ground. It tells of a prokaryote that somehow found its way inside another, and formed a lasting partnership with its host. This inner cell—a bacterium—abandoned its free-living existence and eventually transformed into the 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.
The Madness of the Planets
On the evolution of our solar system and the truth about its instability:
“Things are not as simple as they were supposed to be, with the planets staying quiet forever,” says Alessandro Morbidelli, a planetary dynamics expert at the Nice Observatory in France. “When the planets form they don’t know they have to form on good orbits to be stable for billions of years! So they are stable temporarily, but are not stable for the lifetime of the star.”
Translation: Earth was forged in chaos, lives in chaos, and may well end in chaos.