Category Archives: biology


Above: A throbbing, wheeling mob of several thousand restless starlings, near a strip mall in Clayton, North Carolina, 27 October 2007. Below: Snow geese on maneuvers near Ashburn, Missouri, 12 November 2004. In the 1930s, Edmund Selous argued that flocking … Continue reading

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The family tree

When is a tree (large, woody plant) not a tree (connected acyclic graph)? This has something or other to do with the topic of the previous post. (The tree (?) is a crepe myrtle near the campus of North Carolina … Continue reading

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How many of your ancestors are you related to?

David Aldous asked me that question over lunch one day. I didn’t have an answer, so he explained: In the simplest model of human genetics, you get half your genes from each parent, a fourth from each grandparent, and so … Continue reading

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The green fuse

The spirals and whorls seen in sunflowers, pine cones and various other plant structures have long held a special fascination for mathematicians and for biologists with a mathematical bent. After all, you can find Fibonacci numbers in those natural patterns—who … Continue reading

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