Say what you will about Dear Abby or Dr. Ruth, about Dr. Laura or Dr. Phil. Nobody answers the kind of sex questions Dr. Tatiana does:

Dear Dr. Tatiana,

I'm a queen bee, and I'm worried. All my lovers leave their genitals inside me and then drop dead. Is this normal?

Dear Dr. Tatiana,

My boyfriend is the handsomest golden potto I ever saw. He's got beautiful golden fur on his back, creamy white fur on his belly, he smells delicious, and he has ever such dainty hands and feet. There's just one thing. Please, Dr. Tatiana, why is his penis covered with enormous spines?

Dear Dr. Tatiana,

I'd prefer to keep my identity secret, since I am writing to you not about me or my species but about my noisy neighbors - a group of chimpanzees. When those girls come into heat, it's enough to make a harlot blush. Yesterday, I saw a girl (have sex with) eight different fellows in 15 minutes. Another time I saw one swing between seven fellows, going at it 84 times in eight days. Why are they such (tramps)?

Cross-dressing sponge lice. Flatworms using their penises as swords. Male manatees that make out with, well, other male manatees.

Such is the startling and earthly natural universe well-known to Dr. Tatiana, the nom de plume of real-life author Olivia Judson, a 33-year-old Oxford-trained Ph.D. in zoology whose 2002 book, Dr. Tatiana's Sex Advice to All Creation, has quickly evolved into a national best seller.

On Wednesday night the British-born Judson will be here to discuss, as she did in a recent telephone interview, how her persona as a sex advice columnist (what the Brits call an "agony aunt") lets her convey in an entertaining, informative and often flabbergasting way a very simple but vastly unappreciated concept:

Sex is ... amazing!

Big news, you say?

Well, when Judson speaks of how fabulous sex is, she's not talking in the prurient or puerile sense. Nor does she mean it in the love-soaked I-can't-wait-to-see-you human sense.

Judson is talking about evolution. She's talking about how other creatures - from microscopic bacteria to gargantuan elephants - have evolved an array of fantastic sexual appendages and behaviors that never cease to amaze.

"I think most of us, bound in cities," Judson said, "don't get out all that much. And when we do, we don't necessarily think all that much about just how incredibly diverse organisms' lifestyles are - their sexual behaviors in particular. ... What makes biology so exciting is that things are so different."

Judson said the whole point of her book was to find an entertaining way to reveal that vast diversity. And to get people to open their eyes and appreciate something quite fundamental:

"Besides the obvious reasons people would be interested in sex, a lot of what humans like about nature actually has a lot to do with sex. We like peacock tails. We like bird songs. We like flowers. All of these things wouldn't exist if there wasn't sex."

Plus, Judson added, "Because almost all organisms do have sex, and because almost all organisms that don't do it go extinct very quickly, there is something very important about it."

And, well, interesting.

Dear Dr. Tatiana,

There's been a frightful accident. I was happily sitting in my usual spot at the bottom of the sea when I felt an itch on my nose. Being a green spoon worm, I don't have arms and I couldn't scratch. So I sniffed. And I inhaled my husband. I've tried sneezing, but he hasn't reappeared. Is there anything I can do to get him back?

In response, Dr. Tatiana tells her fictitious correspondent, "There is no use crying over snuffled husband. He wanted to be snuffled, and he's not coming back. By now he'll have assumed his position in your androecium - literally, 'small man room' ... where he can sit and fertilize passing eggs."

The female spoon worm, she explains, is 200,000 times larger than the male spoon worm. In human terms, it's like an average-size woman being made love to by a man no bigger than a pencil eraser.

In other chapters, Dr. Tatiana explores rape among other species, homosexuality, necrophilia, juvenile sex, promiscuity, incest and, of course, monogamy which, while not unheard of, is actually extremely rare in nature.

All of which, implicitly, raises questions about sex among humans, about what's "natural," and whether similar behaviors in humans may have a genetic basis.

Judson's response:

"Anything I say will be wildly speculative. But it seems to me to be quite likely that for many behaviors there is some genetic component. ... I think with monogamy, it may be quite likely that it is genuinely more difficult for some to be monogamous than it is
for others - meaning there is an underlying predisposition to wandering."

But, she notes strongly, whatever our genetic predispositions may be, "humans also do have self-control ... a lot of these impulses can be overcome."

"The way our society is organized," Judson continued, "we think that monogamy is a good, stable thing. So it is not obvious to me that just because you feel like being unfaithful that it is necessarily OK.

"The ramifications and the hurt that are caused by infidelity are big, and that matters. So I don't think we all should be embarking on a sexual free-for-all just because chimpanzees do. You know, I think that's sort of irrelevant."