Human ancestor Lucy celebrates 40th anniversary

Donald Johanson recalls pivotal discovery of A. afarensis fossil in 1974

  • by Tom Siegfried

"Donald Johanson is always looking at the ground. “I find more quarters by parking meters than anybody I know,” he says. As he was looking at the ground four decades ago, in a region called Hadar, named for a dry riverbed in Ethiopia, he saw something a lot more exciting than a quarter. It was a fossil bone.

“I found a little piece of elbow,” he said last week in Columbus, Ohio, while addressing a conference of science writers. “And I knew from studies of osteology and comparative anatomy that this had to be from a human ancestor.” By two weeks later, Johanson and his colleagues had collected enough bones to reconstruct about 40 percent of a skeleton. Those bones belonged to a primitive human forerunner now known as Lucy.

Next month paleoanthropologists will celebrate the 40th anniversary of Johanson’s discovery of the elbow bone on November 24, 1974. In the intervening four decades, many more fossils along with other clues have been discovered, rewriting the story of the human race. The evolution of earlier humanlike species and eventually modern humans has grown from the outline of a play with a small cast to an elaborate production with more characters than an Agatha Christie mystery, many remaining enigmatic with relationships still unclear.

“These fossils tell us a great deal about who we are, where we come from and how we fit into the natural world,” said Johanson, of the Institute of Human Origins at Arizona State University. He summarized the fossil story in delivering the annual Patrusky Lecture, honoring Ben Patrusky, emeritus director of the Council for the Advancement of Science Writing.*

The prelude to the modern story goes back to 1856 — three years before Charles Darwin published his treatise on evolution by natural selection — with the discovery of a fossil in Germany’s Neander Valley in Germany. That fossil was the first specimen from Neandertal man. A dozen years later, fossils of Cro-Magnon man turned up in France.

But Neandertal and Cro-Magnon turned out to be relative youngsters in human history. Darwin and his champion, Thomas Henry Huxley, knew that the whole story would get much more complicated” (read more if you have nothing better to do).

(Source: Science News)

Researchers evolve a molecule that flips the orientation of life

Even the simplest forms of life, like bacteria, have a handedness, one that’s built into the chemicals they’re composed of. The complex, three-dimensional molecules that are essential to life can have the same exact set of atoms, yet be physically distinct—one the mirror image of the other. All the amino acids that life uses have a single orientation; same with all the sugars.

While life is very good at operating with this handedness, called chirality, nature isn’t. Most chemical reactions produce a mixture of left and right forms of molecules. This seemingly creates a problem for the origin of life—if both chiral forms were available, how did life pick just one? The problem is even more severe than that. If both forms are present, then the reactions that duplicate DNA and RNA molecules don’t work. And without those reactions, life won’t work.

Now, researchers have found this doesn’t pose much of a barrier at all. Through a little test-tube based evolution, they were able to make an RNA molecule that could copy other RNA molecules with the opposite chirality. In other words, they made a right hand that could only copy the left. But the duplicate, the left-handed form, could then readily copy the right-handed version. And as an added bonus, the new RNA molecule may be one of the most useful copying enzymes yet evolved.

The work was done by just two people, Jonathan Sczepanski and Gerald Joyce of the Scripps Institute. They were interested in the issue of chirality and set out to create an enzyme that could work with molecules that were the opposite chirality. Rather than try to figure out what structure might work, they chose an evolutionary approach, starting with a population of 10^15 random RNA molecules and then putting them through several rounds of selection and mutation.

The molecule they wound up with is only 83 bases long. It’s made of right-handed RNA, and it only links together left-handed RNA molecules. When the researchers made a left-handed version of the RNA enzyme, the converse was true: it could only link together right-handed RNA. But the key thing is that it can perform these reactions even when there’s a random mixture of left- and right-handed molecules present. The apparent roadblock to life had been overcome in just 16 rounds of selection.

As a catalyst, it was also pretty good, accelerating the reactions it promotes by a factor of about 10^6. And it was indifferent to the length of the molecules it was copying, allowing it to link up molecules its own size or even longer.

But it also had one significant advantage over existing RNA-based copying enzymes. All of those were right-handed and copied right-handed RNAs. As such, a key part of their activity was base-pairing with the molecule they were copying. But left- and right-handed RNAs can’t base pair, so the new enzyme had to evolve a completely different way of sticking to RNAs. This means the enzyme is probably the most general one developed yet—it can operate on just about any RNA sequence.

Sczepanski and Joyce also point out that the enzyme is relatively young, only 16 generations away from a completely random sequence. With further evolution under different selective conditions, it could be possible to make this an extremely efficient and effective RNA copying enzyme.

The biggest impact of these results may be to cause a rethink about how we consider the origin of life. Many researchers have spent time trying to find ways that a mixture of chemicals could spontaneously segregate in ways that would allow chemistry to occur in a population of molecules dominated by a single chirality. It turns out that the exercise might not have been needed. “If early life did entail the cross-chiral polymerization of RNA,” the authors conclude, “then there would have been an era when both sides of the mirror were indispensable.”

Nature, 2014. DOI: 10.1038/nature13900  (About DOIs).


Offmic with PTX, part 6: Evolution of Beyonce

Location: ABC World News staffroom/newsroom.
Bring A Band To Work Day should be a thing, if only to cut through the tedium of cubicle living and tinny muzak over the PA system.

There’s been much debate about why animals took so long to evolve and thrive on Earth.

Now scientists say it was due to incredibly low levels of oxygen on Earth more than a billion years ago. A team determined the chemical composition of ancient rocks to find there was about 0.1% of the oxygen levels present compared with today.

The researchers present their work in Science journal

Creationism conference at large U.S. research university stirs unease

A creationist conference set for a major research campus—Michigan State University (MSU) in East Lansing—is creating unease among some of the school’s students and faculty, which includes several prominent evolutionary biologists.

The 1 November event, called the Origin Summit, is sponsored by Creation Summit, an Oklahoma-based nonprofit Christian group that believes in a literal interpretation of the Bible and was founded to “challenge evolution and all such theories predicated on chance.” The 1-day conference will include eight workshops, according the event’s website, including discussion of how evolutionary theory influenced Adolf Hitler’s worldview, why “the big bang is fake,” and why “natural selection is NOT evolution.” Another talk targets the work of MSU biologist Richard Lenski, who has conducted an influential, decades-long study of evolution in bacterial populations.

News of the event caught MSU’s scientific community largely by surprise. Creation Summit secured a room at the university’s business school through a student religious group, but the student group did not learn about the details of the program—or the sometimes provocative talk titles—until later, says MSU zoologist Fred Dyer. The talk titles led Dyer to suspect that the student group was not involved in planning the conference, he says, prompting him to look into its origins.

Creation Summit sought to hold the event at MSU because “four of our Board members live there in Michigan,” wrote Mike Smith, the group’s executive director, in an e-mail to ScienceInsider. “We hope to have conferences on campuses throughout the country, but ya gotta start somewhere.”

Full article

First planted in 1996, Bt corn quickly became hugely popular among U.S. farmers. Within a few years, populations of rootworms and corn borers, another common corn pest, had plummeted across the midwest. Yields rose, and farmers reduced their use of conventional insecticides that cause more ecological damage than the Bt toxin.

By the turn of the millennium, however, scientists who study the evolution of insecticide resistance were warning of imminent problems. Any rootworm that could survive Bt exposures would have a wide-open field in which to reproduce; unless the crop was carefully managed, resistance would quickly emerge.

Key to effective management, said the scientists, were refuges set aside and planted with non-Bt corn. Within these fields, rootworms would remain susceptible to the Bt toxin. By mating with any Bt-resistant worms that chanced to evolve in neighboring fields, they’d prevent resistance from building up in the gene pool.

But the scientists’ own recommendations — an advisory panel convened in 2002 by the EPA suggested that a full 50 percent of each corn farmer’s fields be devoted to these non-Bt refuges — were resisted by seed companies and eventually the EPA itself, which set voluntary refuge guidelines at between 5 and 20 percent. Many farmers didn’t even follow those recommendations.

Read more

See this is the problem: agribusiness creates a halfway decent product (Bt corn), but then expert science and caution go out the window when the profit margin is large enough.

This is also the problem with 50% of the world’s seed stock being owned by three multinationals [X]. The strength of their lobby undermines objective science, fairness, and neutrality.

The dangers of monocultures, be they GM or conventional, are many, but one such danger is that you create breeding grounds for fast-evolving organisms to perfect their mode of predation and pass on any acquired resistance.

This is the flawed logic with control-based technologies, in an evolutionary arms race. We need to work with principles of ecology, not against them.

#GMOs #insects #pest control #evolution

                                                          s o m e t  i m e s
                                                          I     push   people
                                                          a      w      a      y
                                                          to remind myself
                                                          that       I      don’t
                                                          d   e   s  e  r  v  e
                                                          t      h      e      m
                                                          ( and  I  probably
n e v e r  w i l l )

During its first billion years, the universe continued to expand and cool as matter gravitated into the massive concentrations we call galaxies. Within just the volume of the cosmos that we can see, a hundred billion of these galaxies formed, each containing hundreds of billions of stars that undergo thermonuclear fusion in their cores.
—  Neil deGrasse Tyson, Origins: Fourteen Billion Years of Cosmic Evolution