WIRED, December 20, 2007

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About 470 million years ago, back when our ancestors were jawless fishes and the land was ruled by insects, Earth was pounded by a series of enormous meteorites. The traces of that hammering still survive today in ancient rocks in southern Sweden and central China, where scientists have found exotic mineral grains found only in meteorites.

By measuring the amount of the grains in the rocks, the scientists calculated the rate of meteorite impacts jumped by a factor of 100 around 470 million years ago. A number of the impacts were big enough to leave 20-mile craters. The energy unleashed was 10 million times greater than the energy in the nuclear bomb dropped on Hiroshima.

Continue reading “Meteorites May Have Fostered Life on Earth”

When I first met Hans Thewissen, he spending an afternoon standing on a table, pointing a camera at a fossil between his feet. He asked me to hold a clip light to get rid of some shadows. I felt like I was at a paleontological fashion shoot.

Thewissen was taking pictures of bones from a whale that walked. As I later wrote in my book At the Water’s Edge, Thewissen has discovered some crucial clues to the transitions that the ancestors of whales made from land to sea. In Pakistan, he discovered a 47-million-year-old fossil called Ambulocetus natans, that had an otter-like body. It was the first whale fossil ever found with functional legs.

Continue reading “Whales: From So Humble A Beginning”

Is it wrong to find pictures of destruction beautiful? This is a frame from a supercomputer simulation of the Tunguska meteorite. It exploded over Siberia in 1908 and flattened miles of trees. The simulation suggests that the devastation could have been caused by a far smaller explosion than previously thought–3 to 5 megatons, instead of 10 to 20. And since there are many more asteroids in that smaller size range, the risks of a devastating impact may be greater than previously thought. Maybe not enough to cause mass extinctions, but to knock out a fair piece of real estate. Go here to read more and to watch a series of simulation movies.

Continue reading “Little Asteroid, Big Fireball”

This is the sort of thing that made me decide to write a whole book about these bugs…

LS9 Inc., a company in San Carlos, Calif., is already using E. coli bacteria that have been reprogrammed with synthetic DNA to produce a fuel alternative from a diet of corn syrup and sugar cane. So efficient are the bugs’ synthetic metabolisms that LS9 predicts it will be able to sell the fuel for just $1.25 a gallon.

Synthetic DNA on the Brink of Yielding New Life Forms – washingtonpost.com 

Originally published December 17, 2007. Copyright 2007 Carl Zimmer.

I’ve got a new conversation up at bloggingheads.tv. This time around I talk to University of Washington paleontologist Peter Ward about the mass extinctions that wiped out millions of species in the past, and how disturbingly difficult it is to rule out the possibility that we’re sending ourselves into another great die-off. 

Originally published December 16, 2007. Copyright 2007 Carl Zimmer.