Natural History, December 31, 2002

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In the past decade, as molecular biologists have learned to read DNA sequences rapidly, the chimpanzee has clearly emerged as humanity’s closest living relative. Our DNA is astonishingly similar. You can see for yourself by visiting the “Silver Project” Web site of Japan’s National Institute of Genetics (sayer.lab.nig.ac.jp/~silver/), which is home to a growing database of chimpanzee DNA. With a couple of clicks you can compare the sequence of DNA nucleotides for a particular chimpanzee gene — molecular fragments whose identity is given by one of the four “letters” in the DNA “alphabet” — with the sequence in the corresponding human gene.

Continue reading “Searching For Your Inner Chimp” →

Natural History, September 30, 2002

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What does it mean to be a man? Part of the answer depends on where you ask the question. In some places, being a man may include spending Sundays watching football. In others, it may include completion of a rite of passage, such as getting buried up to your chin in an ant nest on your thirteenth birthday. Of course, there’s some biology involved, too, and crucial to that biology is a peculiar chromosome called the Y. Men and women normally carry twenty-three pairs of chromosomes. Each pair consists of two matching chromosomes, with one exception: men normally have one chromosome called X paired with a dramatically smaller one called Y. Women, on the other hand, have two X’s.

Continue reading “The Once and Future Male” →

Natural History, June 30, 2002

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Smell, above all other senses, is our link with history. It takes just a sniff of certain odors-the ozone tang of rain falling on blacktop or the crisp sting of frying onions-to instantly hurl us back decades. And our sense of smell has a history of its own, reaching back more than 500 million years. Until recently, however, scientists have had relatively little evidence on which to base a reconstruction of its evolution. They’ve only been able to compare the olfactory senses of living vertebrates or turn up the occasional fossil nose.

Continue reading “The Rise And Fall Of The Nasal Empire” →

Natural History, April 30, 2002

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“The eye to this day gives me a cold shudder,” Charles Darwin once wrote to a friend. If his theory of evolution was everything he thought it was, a complex organ such as the eye could not lie beyond its reach. And no one appreciated the beautiful construction of the eye more than Darwin-from the way the lens was perfectly positioned to focus light onto the retina to the way the iris adjusted the amount of light that could enter the eye. In the Origin of Species, he wrote that the idea of natural selection producing the eye “seems, I freely confess, absurd in the highest possible degree.”

Continue reading “Crystal Balls” →