Observing, skeptically

The first time I ever visited a "wild" cave was decades ago, in the karst-rich country of the southern Appalachians. Caves in their natural state bear little resemblance to commercial caverns: no freight elevators or tastefully lighted stalactites, no care and gift shop at the main entrance. The entrance to my first cave was a pit, 160 feet deep; to enter, my guides and I tied a rope to a tree, dropped the other end to the bottom, and rappelled down. The adventure got even better. We scrunched into a crack in the floor of the pit, belly-crawling a few dozen feet through a tight little passage. But then we emerged, rewarded for our efforts, into an immense room at the base of a deafening waterfall, cascading from a darkness too high for our headlamps to penetrate.

Charles Darwin, as far as I know, never crawled around in caves; his weakness as an explorer was isolated volcanic islands. But there's no question he would have been fascinated by Luis and Monika Espinasa's story on page 44, "Why Do Cave Fish Lose Their Eyes?" Darwin posed the same question, and was not able to answer it to his own satisfaction. Subtle observations of the bones in the fishes' eye sockets, and the genes in the fishes' cells, may finally resolve the conundrum.

Lynn Margulis is another close observer of nature, but she is also a scholarly explorer and a fiercely independent thinker. Remarkably, nearly four years after the anthrax attacks of 2001, the life history of the anthrax disease agent remains an open scientific question. Where, Margulis pointedly asks, is the anthrax bacterium in nature?

The usual response is, it's the spore of a soil bacterium, lying in wait to infect an animal. But the bacterium doesn't grow, or develop, or infect anything in the soil; describing it as a "soil bacterium," as Margulis deadpans in her article "Jointed Threads" (page 28), is not very "useful." In fact, the label is more likely just a placeholder covering for scientific ignorance.

Margulis and her coworkers have now added a surprising piece to the anthrax puzzle: Bacillus, the genus to which anthrax belongs, has a stage in its life history as a threadlike collection of cells, growing benignly on the intestinal walls of many animals.

What light will this work shed on the anthrax bacillus? It's impossible to say. But you would think, given the threat of anthrax spores as a biological weapon, that a basic understanding of their life cycle in nature would not be a place to skimp in the nation's budget.

If you're a graduate this month, or know one, you're liable to be reminded, portentously, that life is an adventure in learning. I don't disagree. But my word to the graduates this commencement season is, Look to Darwin, or the Espinasas, or Margulis for examples of lives to emulate. Be skeptical. Challenge dogma. Ask: "How do you know?" See--and think--for yourself. And if you're exploring a cave, make sure you're observing closely enough to keep track of where you came from.

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