The New York Times, November 7, 2013

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In 1799 the great naturalist Alexander von Humboldt and his companions set out from Caracas, Venezuela, to climb the Andes. They struggled up a mountainside enveloped in mist so thick they had to clamber over rocks by hand. When the fog cleared, von Humboldt was left astonished by the view. Vast grasslands stretched all around him, home to an astonishing number of different trees, shrubs and flowers.

“Nowhere, perhaps, can be found collected together, in so small a space, productions so beautiful and so remarkable in regard to the geography of plants,” he later wrote.

Continue reading “Fast-Paced Evolution in the Andes”

It’s not exactly true to say that each of us has our own genome. We have genomes. Some of us, known as chimeras, have genomes from more than one person. The cells of children linger behind in their mothers; in the womb, cells from twins can intermingle. The rest of us non-chimeras can trace our genomes to one origin–the fertilized egg from which we developed. But as the cells in our bodies divided, they sometimes mutated, creating a panoply of genetic variation known as mosaicism.

Continue reading “Our Speckled Brains”