GUESSWORK DOESN'T ALWAYS YIELD CORRECT ANSWERS

by Whit Gibbons


August 6, 2006


Being wrong can be viewed as a reminder to us that the world is full of surprises. Also, it is salutary for would-be experts to be proved wrong from time to time. If you think I am remembering, and justifying, a time when I was wrong, you are correct.

I had been asked this question. "Could the small, white eggs the size of mothballs in the wooded area in my backyard be the eggs of a venomous snake?"

I asked for more information. Were they laid in an old stump, under a log, underground? And how many were there?

"Four, lying in leaves on the ground."

I explained that they were not eggs of a rattlesnake, cottonmouth, or copperhead, as all North American pit vipers are live-bearers; they do not lay eggs. Also, they were not the eggs of a coral snake as the caller was outside the geographic range of the species. So, whatever they were, they would not hatch into anything venomous. I proclaimed that they were probably lizard eggs based on the description. The true answer was revealed a few days later.

Meanwhile, the answer to another question about venomous snakes required less guesswork.

Q. I will be giving a speech on poisonous snakes to my Toastmasters group. I have found no answer to this question: How do lists get created that rank snakes in order according to their deadliness? Do a bunch of snake experts sit around and reach a consensus based on personal experiences and readings?

A. Personal opinions of people who deal with snakes certainly come into play, as well as medical records from hospitals. But such rankings are also based on scientific research. The U.S. Navy published a book called "Poisonous Snakes of the World" in which the venom yield and lethality of 40 venomous species were compared. Mice were the victims in a series of tests to determine the amount of venom required for a lethal dose to a mouse. Because of the variability of response to venom, the determination was based on how much venom needed to be injected into an individual mouse before half the mice in the sample were killed. In other words, what was the lethal dose for 50 percent (known as the LD50) of the mice? Drop-for-drop the Australian tiger snake in the cobra family was 47 times more deadly than an eastern diamondback rattlesnake. One of the sea snakes was 4 times deadlier than the tiger snake. After a point, it probably doesn't much matter, as many other factors can influence the seriousness of a snakebite. Health of the victim, site of the bite, and how much venom, if any, is injected can be particularly important.

The answer about how venom potency is ranked was relatively straightforward compared to the question about the small, white eggs. Two days later we got the answer to that one. My wife answered the phone, chuckled, and said to me. "Turns out they found out what the white eggs were."

"And that would be?" I asked, feeling like I was being set up.

"Well, what kind of lizard did you think it was?"

"Probably one of the blue-tailed skinks. Don't tell me they were coral snakes. That would be a geographic range extension."

"They were mushrooms! They pushed on up through the leaves." The caller and my wife had clearly had a good laugh over that one, so I had to respond. "I asked her where the eggs were. She didn't say they were sitting out in the open."

"I remember you said she said they were in the leaves. Of course, mushrooms grow up through leaves. I guess that's the way they hatch." More laughter at my expense.

I knew it would be a long reach for a recovery if I merely noted that at least I had been right about their not being snake eggs. Instead, I said that I hoped she had told the caller not to eat the mushrooms until she knew for sure what kind they were. True, they would not hatch into venomous animals, but they just might be poisonous.



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