Science Magazine, August 20, 2009

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We are, fundamentally, a fusion. As I wrote in my essay for Science on the origin of eukaryotes, there’s now a wealth of evidence that our cells evolved from the combination of two different microbes. The mitochondria that generate fuel for our cells started out as free-living bacteria. Today, they still retain traces of their origin in the bacterial DNA they carry, as well as their bacterial structure, including the membrane within a membrane that envelops them.

Scientists I spoke with as I worked on the essay agreed that this merging was a profound event in the history of life. No living eukaryote, whether animal, plant, fungus, or protozoan, has completely lost its mitochondria since that symbiotic milestone some 2 billion years ago. It wasn’t the only time that two species merged, however. Plants, for example, descend from algae that engulfed a species of photosynthesizing bacteria. Many protozoans have swallowed up photosynthetic partners as well.

Continue reading “Microbes within microbes within microbes” →

Discover, August 19, 2009

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Some of the common words we use are frozen mistakes. The term influenza comes from the Italian word meaning “influence”—an allusion to the influence the stars were once believed to have on our health. European explorers searching for an alternate route to India ended up in the New World and uncomprehendingly dubbed its inhabitants indios, or Indians. Neuroscientists have a frozen mistake of their own, and it is a spectacular blunder. In the mid-1800s researchers discovered cells in the brain that are not like neurons (the presumed active players of the brain) and called them glia, the Greek word for “glue.”

Continue reading “The Dark Matter of the Human Brain” →

Science, August 7, 2009

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You may not feel as though you have much in common with a toadstool, but its cells and ours are strikingly similar. Animals and fungi both keep their DNA coiled up in a nucleus. Their genes are interspersed with chunks of DNA that cells have to edit out to make proteins. Those proteins are shuttled through a maze of membranes before they can float out into the cell. A cell in a toadstool, like your own cells, manufactures fuel in compartments called mitochondria. Both species’ cells contain the same molecular skeleton, which they can break down and reassemble in order to crawl.

Continue reading “On the Origin of Eukaryotes” →

Yale Environment 360, August 3, 2009

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In 1997, Arthur Weis found himself with an extra bucket of seeds. Weis, who was teaching at the University of California at Irvine at the time, had dispatched a student, Sheina Sim, to gather some field mustard seeds for a study. When Sim was done with her research, Weis was left with a lot of leftover seeds. For no particular reason, he decided not to throw the bucket out. “We just tossed it in a cold, dry incubator,” said Weis.

Weis is glad they did. When a severe drought struck southern California, Weis realized that he could use the extra bucket of seeds for an experiment. In 2004 he and his colleagues collected more field mustard seeds from the same sites that Sim had visited seven years earlier.

Continue reading “First Comes Global Warming, Then an Evolutionary Explosion” →

The New York Times, July 27, 2009

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