"She said, 'I don't like spiders and snakes,

And that ain't what it takes to love me,

You fool, you fool' ... "

Stacy Innerst, Post-Gazette Click illustration for larger image. Related coverage Creature holds can be broken Spider e-mail is web of lies What creatures are you most scared of? Vote in our online poll. Hear Jim Stafford's "Spiders and Snakes" Listen In: Hear excerpts from infant researcher David Rakison's conversation with the PG's Mark Roth about fear of things creepy and crawly: Why women are much more likely than men to have phobias about spiders Babies do not seem to be born with automatic fear of snakes and spiders Most phobias appear to be related to evolutionary cautions

When country-western artist Jim Stafford wrote those lyrics in 1973, he was playing off the old story of an immature boy trying to interest a girl by showing her creepy-crawlies.

But he was also tapping into an ancient human dread -- the fear of snakes and spiders -- which lives on today in such films as "Snakes on a Plane" and "Arachnophobia" and explains why snakes and spiders are the top two creature phobias in the psychological landscape.

But is this horror of cobras and tarantulas something we have learned, or something we're born with?

The answer seems to be both.

Infant research being done at Carnegie Mellon University suggests that babies are born with a tendency to pay more attention to the shapes of snakes and spiders than to other kinds of creatures, but that they don't fear them until an adult teaches them to.

Carnegie Mellon's Infant Cognition Laboratory is headed by David Rakison, a British-born psychologist who uses innovative techniques to figure out how and when babies learn about the world around them.

For his work on snakes and spiders, Dr. Rakison has done two experiments so far.

With 11-month-olds, he has shown that they tend to group spiders and snakes together, suggesting that babies put them in the same mental category.

And with 5-month-olds, he has shown they pay more attention to simple drawings of spiders on a video screen than they do to scrambled versions of the same picture, implying they have an inborn orientation toward the creatures. He's about to extend that experiment to shapes of snakes.

Since neither group of babies can talk, Dr. Rakison gauges their perceptions by having student assistants track how long they look at images on a video screen.

Even though the babies pay special attention to spiders and snakes, they do not innately fear them, Dr. Rakison said.

Darrell Sapp, Post-Gazette Five-month-old Brady Schier of White Oak gazes intently at photos of spiders during an experimental session at the Infant Cognition Laboratory at Carnegie Mellon University. Click photo for larger image.

"If you put a baby in a tank with a snake," he said, "they would show no fear whatsoever."

Instead, babies seem to have a "perceptual template" for the creatures that primes them to be scared of them once they see an adult showing such fear.

All of this could be rooted in our evolutionary history, Dr. Rakison said, and could even explain why we might fear spiders and snakes more than lions and cheetahs, for instance.

"It's thought our ancestors spent a great deal of time on the savannas in Africa, so you could see lions coming from a distance," he said.

"Spiders and snakes tend to be hidden from view, though, and you tend to see them close up. Our ancestors, particularly the women, spent a lot of time gathering food, on their knees with their infant close by, so you can imagine you're picking plants out of the ground and all of a sudden there's a snake or a spider right there."

Dr. Rakison's baby studies build on earlier work with monkeys done by Susan Mineka at Northwestern University.

She showed that monkeys reared in a laboratory did not exhibit any fear of snakes until they were shown a picture of a wild monkey reacting fearfully to the reptiles. She also demonstrated that when the lab monkeys watched videos of the scared monkeys in conjunction with pictures of flowers and rabbits, they didn't acquire the same kind of fear of those objects, suggesting that primates' brains are wired to react more strongly to snakes.

Not by instinct

Not everyone buys this theory. Isabelle Blanchette, a researcher at the University of Manchester in the United Kingdom, has shown that adults react just as strongly to images of such modern-day threats as guns and syringes as they do to snake and spider pictures.

And a baby researcher at the same university, Sylvain Sirois, is also skeptical of the evolutionary explanation for spider and snake reactions. "I'm extremely reluctant to go down that road because usually people have a hard time backing up these evolutionary arguments," he said.

Babies may gaze longer at anything that's novel, Dr. Sirois said, and their interest isn't necessarily being driven by an ancient genetic code.

Still, he and other infant researchers agree that there are several instinctive behaviors that probably have evolutionary roots.

The sucking instinct (to get food) and the startle reflex (to shy away from sudden surprises) both would have survival advantages, he said.

Infants also are primed to recognize faces, Drs. Rakison and Sirois said, as well as to imitate smiles, both of which help them interact with their parents or other caregivers.

When babies first begin smiling at about six weeks of age, Dr. Sirois said, it's an instinctive reaction rather than an expression of happiness. "The baby starts to smile just when you're suffering from a lack of sleep and you're starting to wonder about this parenting thing, and it bootstraps the social interaction."

At 7 months, Dr. Rakison said, babies develop a fear of heights and of men's faces, both of which could be evolutionary adaptations.

That raises the question of why spiders and snakes don't create an automatic fearful reaction themselves.

Martin Antony, a phobia expert at Ryerson University in Toronto, said fear may only increase the odds of survival if there is neither too little of it nor too much of it.

If evolution "set the threshold of fear in the brain too high," Dr. Antony said, "nobody would feel fear, which wouldn't be good, but if it was set too low, everyone would be walking around terrified all the time, and that wouldn't be advantageous either."

When it comes to phobias, he said, the social ones -- fear of public speaking and meeting new people, or performance anxiety -- are the most prevalent, affecting about 12 percent of the population.

In fact, some surveys show the fear of speaking in public is greater than the fear of dying, which reminded him of a Jerry Seinfeld monologue where "he said that means if you're at a funeral, you'd rather be in the casket than delivering the eulogy."

Mixed symbols

Phobias of creatures afflict 5 percent to 7 percent of the population, Dr. Antony said, and Dr. Rakison said that three to four times as many women as men have a spider phobia.

But snakes are the No. 1 phobia creature, Dr. Rakison said, and Dr. Antony surmised that may have as much to do with their slithering movement as with their appearance.

Many ancient cultures worshipped snakes, which evoked both fear and reverence, said Laurie Cozad, a religion professor at the University of Mississippi.

In India, she said, snake worship is mentioned in religious texts as early as 1,500 B.C., and snake veneration is still a part of Hinduism and Buddhism.

The Garden of Eden story in the Bible, in which the snake is cursed for tempting Adam and Eve to eat the forbidden fruit from the tree of knowledge, might suggest that snakes are only equated with evil in the Judeo-Christian tradition.

But Jack Sasson, chairman of Judaic and Biblical Studies at Vanderbilt University, said the snake's image in the Bible is actually more ambivalent.

While many people are familiar with the Garden of Eden saga, Dr. Sasson said, fewer know about the Old Testament story in which Moses made a bronze serpent, and those who looked at it were cured of snakebites.

"The two images of the snake are so blurred," he said. "Think about it: we use it as a symbol of medicine and fertility, and on the other hand, we have the imagery of Satan as a serpent."

For most people in American society, though, fear probably wins out over reverence at the sight of a snake in the open.

Even if they don't run for the nearest doorway, they may find ourselves joining Indiana Jones in saying: "Snakes -- I hate snakes."

For more information on the Carnegie Mellon University Infant Cognition Laboratory, see www.psy.cmu.edu or call 412- 268-6122.