Some people have a way of stating the obvious.

"Gee," said Daphne Soares, "what are these little dots on the face?"

She was not being rude. It was not the pimply face of a little friend or the stubbled chin of an old grandfather. It wasn't even human at all. Soares was staring at an alligator.

Sitting atop the 8-foot-long creature in the back of a pickup truck roaring along a Louisiana backwater -- just graduate student and gator -- Soares finally asked the right question about a species that, after 200 million years of belly-scraping in the bayous, no one else had bothered to become quite so intimate with.

Looking down that long, gnarly snout, she simply couldn't help herself.

So what are those little dots on the face?

Well, nobody knew. Not even a clue.

Investigating the neuronal paths of bird brains, which has been Soares' specialty at the University of Maryland at College Park, was one thing. The side trip to the swampy backwaters of Louisiana in 1999 to study Crocodilia was only supposed to enhance what she knew about birds. Since, as everybody knows, alligators and crocodiles are the closest living relatives to birds ("The way their auditory brain stems are put together are almost identical," she says), Soares only wanted a little insight into how gators hear. She thought it might tell her more about how birds make sense of sound.

But those weird bumps ...

"So I thought, this is a good side project," she said. "I called and e-mailed everyone I could think of and asked, you know, 'What is this?' People thought they were maybe salt detectors, so if alligators were going out into the ocean they would think about coming back. Or taste buds. Or signal detectors. But no one had ever actually researched it."

Before you knew it, she had eight baby gators in her biology lab at College Park. Her work was about to take a startling turn.

The "little dots" that speckle an alligator's face are not cosmetic blemishes or taste buds or anything of the kind, as Soares found out. The tiny domed structures, which she discovered through fossil records had been evident since the Early Jurassic period 200 million years ago, actually were pressure sensors. Big, important stuff.

"The first time I dissected one, I was amazed at how big the nerves were," she said. "They are the biggest things around. I thought they were muscles at first."

Examining alligator skulls, Soares found thousands of nerves threading through holes in the facial bone, wrapping into a larger nerve that connected directly into the brain. Although an alligator has a fairly small brain, about the size of a peach pit, Soares discovered by injecting a chemical tracer into the receptors and dissecting the brain to see where the chemical ended up that a huge portion of the brain was devoted to responding to the "little dots" on alligators' faces.

What could be that important?

Easy does it

That a graduate student, at the cusp of her career, might make a significant finding that experts had overlooked would be unusual. So Soares proceeded carefully.

She had ideas developing into a major hypothesis. She kept a very low profile.

"You don't want to make a silly person out of yourself by saying, 'Hey, look what I found!' and then have someone turn around and say, 'Yeah, we've known that forever.' Oh, I really wanted to make sure I was right."

So she went slowly.

For the first year, she traveled around the country to look at old bones, tracking the natural history of pressure sensors on the faces of alligators and crocodiles and lizards. She searched the world's scientific literature, hoping to find out who else had ever noticed the little dots. She came across a few old German manuscripts from the 1800s and then a paper by a Harvard scientist in 1986. That was it. A few scientists had noticed the dots and even gave them an impressive name, "integumentary sensory organs," which Soares thought awfully dull. But behind the fancy name, there was little else to report.

Soares was on an adventure.

She was onto something big.

Could those little dots, she wondered, be one of the defining characteristics in the evolution of the species?

For two years, as she pursued a Ph.D. on the neurobiology of bird brains, she kept getting acquainted with the eight little alligators in her lab. She traveled to Louisiana and brought back alligator eggs. You should have seen her slipping through the X-ray machine at a Houston airport with her box of fragile eggs.

"The security guy was saying, 'What's this?' and I thought, 'Uh oh,' because the embryos looked pretty far along," she said. "So I got on the plane and put them in my lap and started reading a magazine. Next thing I knew I hear, 'eeek, eeek, eeek!' And the lady next to me is looking over, and my heart sank because that's the noise they make when they hatch.

"So every time they started to 'eeek, eeek!' I coughed. Hack, hack, hack! I spent an hour and a half coughing. I'm sure the lady didn't buy it, but she was polite enough not to call the stewardess."

Trial and error

By 2001, with fossil bones and newly hatched babies and a growing crowd of eight juveniles, Soares won a fellowship at the Marine Biological Laboratory in Woods Hole during the summer to begin a carefully planned series of experiments. She called her project, "In search of the modality of the sensory organs present in the face of alligators."

She conducted behavior experiments between 1:30 and 3:30 in the morning and studied physiology during the day. She would stick an electrode in the little dots of her alligators' faces and make a little hole in the skulls to attach another electrode and then try to stimulate the nerve with various devices.

"I tried electric fields to see if alligators responded like sharks. I ground up fish -- ugh! -- and tossed disgusting little fish bits into the water to see if the sensors responded to taste or smell. You know catfish have taste buds all over their bodies, so they can sense their environment by tasting it, which is kind of cool. But not alligators. No response to electric fields. Nothing for these disgusting fish bits. I tried light -- who knows, maybe they were eyes. They didn't look like eyes, but I had to cover all the bases. They weren't eyes. I tried stinky things. And then I tried poking them. And they liked to be poked."

It is a common misimpression that scientists have spectacular moments of breakthrough, when suddenly a solitary experiment sends a radio signal bouncing off a satellite or a tiny spark fires a piston or chromosomal change skews a whole family's hereditary traits. Such moments are few. Science is an incremental process. Usually, only the lucky ones have the pleasure of standing back and saying, "Aha!"

But one night in her quiet little lab at Woods Hole, it happened. Soares said "Aha!" (Actually, "Holy cow!")

She had anesthetized her alligator, stuffed his ears to shut off hearing and put him in a large tank of water. By raising and lowering the water level, she was able to make slight contact with individual pressure receptors along the gator's jaw. She hooked electrodes to individual nerves and then touched the surface water to make a wave.

"It was phase locked," she said. "In other words, whenever the ripple hit the nerve, it was 'blip-blip-blip' on the monitor. I could touch the water and hear the nerve responding."

If she covered the pressure receptor, there was nothing. If she exposed it, it sounded off -- blip-blip-blip.

Soares was ecstatic.

"I said, 'Holy cow! I found it!' I called everybody. My eyes filled with tears. It had been two years that I didn't know what this was. I knew it was something really important for the animal. You know, some kind of big innovation, but I didn't know what it was. I was just so curious. And that night it responded, we opened champagne and everything. We were in the fish room with all these rare fish swimming around, and I'm sure we woke them up and stressed them out. But this is what scientists live for. I was thrilled. Absolutely thrilled!"

Finding direction

It may seem like a little thing, these domed pressure sensors that cover alligators' snouts. But what Soares had discovered was something vital to alligators' evolution and survival. It began to explain how a creature built like an armored tank could be so sensitive that any stirring on the surface of a swamp or pond or lagoon could set it off. It explained why alligators respond so rapidly to any potential threat and seem so alert that they can snatch up any delectable creature moving along in their direction.

With thousands of ultra-sensitive receptors popped up along their jaws, she discovered, alligators have an extraordinary capability to detect changes in surface water. As they stretch out in a body of water and lie as still as logs with their heads perched right on the surface, the complex circuitry of nerves connecting to their peach-pit brains give alligators exceptional directional sensitivity for hunting and defending their territory. Soares suspects, but has not yet proven, that the sensors give alligators a very detailed, real-time map of their environment.

"I'm hesitant to say the only reason alligators have survived for 200 million years is because of the dome pressure receptors, because these are fantastic animals in a variety of ways," she said. "But that said, I think the receptors are very important to their survival. They are very successful predators. They're like armored tanks, but they're also very sensitive. It's such an elegant way to solve that problem. They have a way to take advantage of information in their environment that no other animal has. It's cool. They're cool!"

In April, Soares defended her dissertation on bird brains and earned her Ph.D. in biology. In May, her first big paper, "An Ancient Sensor Organ in Crocodilians," was published in the prestigious science journal Nature. She has officially changed the name of those little dots on alligators' snouts from "integumentary sensory organs" to "dome pressure sensors" and has a National Science Foundation fellowship to continue her research at the California Institute of Technology. The response to her work, from the media, from scientists, from people all over the world, has been, she says, overwhelming.

"Sometimes I go to open my e-mail, and there are hundreds of people writing to me about alligators, and I feel like crying," she said.

And it's been great.

How does she explain it? How could a lowly graduate student make such a big splash with such an obvious observation about something experts had managed to overlook, well, practically forever?

Curiosity. Type A personality. "I don't sleep very much." And one other thing, perhaps.

"I did an FMRI (functional magnetic resonance imaging) on my brain once, and my brain is crooked," Soares said, with a joker's smile. "My visual cortex has expanded and is taking over. Definitely, something's going on back there."