Winter 2009: Of Note

Exploring Evolution

Earth’s wild abundance, mutating enzymes, and sexy species were hot topics at packed symposium

By Mary J. Loftus

 

Origins: The first experiment

Recreating the conditions present at the moment that life began on Earth about 4.5 billion years ago might be considered a near-impossible task.

And yet, that’s what Candler Professor David Lynn, chair of Emory’s Department of Chemistry, and his colleagues at Emory and Georgia Tech have been charged with in the Origins Project, an ambitious initiative sponsored by the National Science Foundation.

Several competing theories about life’s molecular origins exist, and the researchers have divvied up a few of the most compelling to simulate.

Lynn is studying prions—proteins that can reproduce themselves—as a model of a self-replicating system. “Molecules, like organisms, compete for the niche that they live in,” he says.

Nicholas Hud, associate professor of chemistry and biochemistry at Georgia Tech, is studying the “RNA world” hypothesis, which proposes that RNA is the basis on which all living systems evolved. “It’s not magic, it’s chemistry,” he says matter-of-factly.

And Associate Professor of Biochemistry Ichiro Matsumura, director of the Emory/Georgia Tech Center for Fundamental and Applied Molecular Evolution (FAME), is investigating enzymes that are capable of mutating, making their own food, and distinguishing between light and dark. “All of us,” he says, “are products of lucky accidents in the past.”

Seduction: Required for reproduction

Evolutionary biologist and New York Times columnist Olivia Judson, author of Dr. Tatiana’s Sex Advice to All Creation (described as “Charles Darwin meets Dr. Ruth”), spoke provocatively at the evolution conference about the various ways creatures attract mates. “There are many ways to seduce,” she said. Common techniques from humans to butterflies include: wining and dining, displaying one’s wealth, making a nuisance of oneself, or strutting about while showing off one’s looks.

Judson, a research fellow in biology at Imperial College in London, has discovered that in any species where the males are much larger than the females, “there is a lot of fighting going on,” and that it appears, in many species, as if females are as promiscuous as males. Asexuality does make appearances on the evolutionary tree, she says, but “those are the twiggy parts of the branches,” and such creatures usually become extinct.

“Sex is half of evolution,” she says. “Evolution is all about reproduction and survival.”

Humans: Big-brained primates

What makes the human brain unique?

Todd Preuss, associate professor of neuroscience, says human brains are “enormous—just unexpectedly large . . . three times that of a chimp, and six to seven times what we’d expect for our body size.”

Humans are one of more than two hundred primate species, Preuss said, and one of fourteen species of hominid primates. Chimps and humans are thought to have separated from a shared evolutionary ancestor about six to eight million years ago, which makes them more closely related than any other species in the world.

We know very little about the origin and evolution of the human brain, however, as “brains don’t leave fossil records,” says Preuss.

Researchers needed a method to directly compare humans and other animals that was noninvasive, and a few good technologies have emerged in recent years to do just that: neuroimaging and genomics.

Despite conventional wisdom that chimps and humans are 99 percent alike genetically, Preuss feels the similarity is closer to 94 percent: “Humans have some genes that chimps don’t, and vice versa.”

Altruism: The apes have it

Darwin didn’t go far enough, says Charles Howard Candler Professor of Primate Behavior Frans de Waal, author of Our Inner Ape: “We aren’t descended from apes, we are apes.”

And apes are us—or at least, they act like us at times. De Waal’s studies at Emory’s Yerkes National Primate Research Center have shown that apes have a sense of fairness and the ability to act altruistically. “We might even say that animals have empathy, if we define empathy as the ability to share feelings instead of the ability to understand what other animals are feeling.”

He showed a video of a chimp sympathetically yawning after seeing another chimp yawn—the behavior clearly as infectious as it would be between humans. Chimps, part of the great ape family that includes humans, gorillas, and orangutans, are more pro-social when dealing with kin, less so with strangers. Apes also share food, groom each other, and return favors. “If one chimpanzee grooms another in the morning,” de Waal says, “the groomed chimp is more likely to share food with that chimp later in the day.”

Each Yerkes chimp knows its own name and the others’ names, he says: “You can ask them to go fetch someone.” Deception is rather common in the ape world, although “individuals who do it too often are mistrusted and ostracized.”

Healing Earth: The life you save may be your own

In his new book, Creation: An Appeal to Save Life on Earth, biologist E. O. Wilson writes, “The only way to save the diversity of life and come to peace with nature is through a widely shared knowledge of biology and what the findings of science imply for the human condition.”

The Pulitzer Prize–winning author sees a historic partnership between scientists and religious leaders as the only way to preserve the planet’s “wild abundance.” To the crowd that filled Glenn Memorial Auditorium, Wilson paid tribute to Darwin’s The Voyage of the Beagle (1845), On the Origin of Species (1859), Descent of Man (1871), and The Expression of the Emotions in Man and Animals (1872). Darwin, he said, was at the Galapagos Islands for only six weeks, and he was homesick. “It took the viceroy to point out to him that the turtles differed from one island to the next.” Nevertheless, here would start the “one true law unique to biological systems that has taken on the solidity of a mathematical theory . . . natural selection.”

Theory: A scientific explanation

Sixty-two high school science teachers from the Atlanta area gathered at Emory’s Center for Ethics for a daylong workshop on teaching evolution. Some said they’ve had students cry, shout, and mount organized protests if they dared to mention the word “evolution” in class. Others said the chapter in the textbook dealing with evolution was omitted from the list of required reading. Part of the problem, said the teachers, is that some students—as well as parents and pastors—don’t understand that scientific theories such as evolution must be supported by factual evidence and are not just “educated guesses.”

The workshop offered hands-on ideas for teaching evolution in action. Teachers handled replicas of skulls from Homo ergaster (“working man”) to Homo habilis (“Twiggy”). They were encouraged to use jelly beans to represent a gene’s alleles, and identified PowerPoint slides of endangered species including scrub mint, a Hawaiian hoary bat, and a California condor. Graham Balch, a Grady High biology teacher, invited several of his students to attend. Freshman Caitlin Wade said she finds room for both religion and science in her beliefs: “I don’t have to choose.”