I’ve the privilege of giving the commencement talk for the University of New Mexico Biology Department’s graduation ceremony tomorrow, and I’m nervous as hell. It’s such an honor to be asked, and feels like such a hopeless task – hard to match words to the measure of the importance of the day. (“A commencement speaker is like the corpse at a funeral,” a friend told me in what is certainly a very old joke. “It’s important that it be there, but you don’t want to linger over it too long.”)

I’m going to talk a bit about curiosity. It’s on my mind partly because I’ve just read the fun new book A Curious Mind, which my friend Charles Fishman wrote with Brian Grazer. But mostly it’s on my mind because of an old story tied to the UNM biology department that I love to tell.

It was ten years ago in early spring, and I was out in the Albuquerque bosque, the riverside woods along the Rio Grande, with a never-quite-retired ecologist named Cliff Crawford. Much of what we know about the strained and troubled ecosystem that is our bosque is a result of the work of Cliff, some smart colleagues, and a long tradition of inquisitive students. I was writing a feature about some work Mary Harner, one of the Cliff’s students, was doing, and she invited him along for the field trip.

We were visiting at that precious spring moment when the first clumps of leaves begin to appear on the cottonwoods, the moment when its color palette begins turning from the browns of winter to the great green of summer. Some trees had a few leaves, most did not.

It wasn’t pertinent to the story, just my own curiosity, when I pointed at one of the clumps of leaves and asked Cliff, “What makes the tree decide when to do that?”

I expected an answer about day length, or changing temperature, or the rise in groundwater levels adjacent to to the river as spring runoff swells the Rio Grande. Instead from Cliff I got this: “We don’t know!” With a look of delight on his face.

Here was a man, late in a long and distinguished career, who had spent much of it working in this very field area, who remained delighted by the things we do not yet know.