Susan McCarthy

He cited an experiment in which manipulating one gene in a mouse extended the mouse life span by 30 percent. “Without manipulation, it seems that the maximum human life span is about 100 years. It is possible that could be extended if we understand the pathways of aging better,” he said. He added that there are many ethical questions “that would have to be addressed before applying this on a broad scale.” (I know people who already wish to sign up for the narrow scale.)

The elderly mice in question are Italian, and were engineered to be deficient in p66shc, a protein that tells a cell to self-destruct when it has sustained too much damage from free radicals (molecules produced throughout the body in the process of oxygen metabolism). This is thought to be a defense against the possibility that the damaged cells will become cancerous. But without p66shc, the mice live 30 percent longer. (Being mice, whose lives are brief, this means a few extra months of mousy joys.)

Dr. Huber Warner, director of the biology of aging program at the National Institute on Aging (NIA) is also optimistic about the Human Genome Project and the outlook for living longer. “The fruit-fly genome has just been sequenced. Now, if you look at genes known to be involved in diseases, two-thirds of those genes are found in the fruit fly, including some very important genes that are tumor-suppressor genes.”

NIA is investing millions in research to find genes in animals like fruit flies or mice “which when mutated or expressed differently will alter the life span of those species,” says Warner. “Now if you can identify those genes in model organisms, then the sequence of the human genome will give you the information you need to begin to extrapolate. We will figure out ways to manipulate the genes in the model organism and it’ll suggest how those genes can be manipulated in humans.”

Organizations like the NIA and the American Federation for Aging Research emphasize that they are not interested in increasing life span so much as increasing “health span,” the years people can live with vitality, dignity and comfort.

Another avenue age scientists are racing down is telomere research. Telomeres are tasteful strands of nonsense DNA that decorate ends of chromosomes. Each time a cell divides, a bit of the telomere is clipped off. Eventually, when the telomere is a mere buzz-cut stubble, the cell stops dividing. There’s a way around telomere loss: an enzyme called telomerase, which adds on extra telomere each time it’s snipped shorter, so that it stays the same length, and the cell is not signaled to stop dividing. Scientific American has said telomerase “may well be the elixir of youth.”

Some human tissues that divide indefinitely, such as reproductive cells producing sperm and eggs, contain telomerase. So do cells in embryos, but the telomerase gene is inactivated in most cells after birth.

Reactivating telomerase could replenish lost cells. Warner mentions the possibility of restoring epithelial cells in the retinas to restore lost eyesight. Telomerase genes have been successfully reactivated in retinal epithelial cells grown in tissue culture, in work done at the University of Texas Southwestern Medical Center and the Geron Corporation. Geron has filed for patents on hTRT, the telomerase reverse transcriptase protein. Warner notes, “The problem with turning telomerase back on is that’s one of the things that happens in cancer.” Cancer cells are all about telomerase and unrestricted cell division.

Steven Austad is a zoologist who studies aging. In his lucid, engaging book “Why We Age,” he describes his study of opossums on a Georgia barrier island — Methuselah opossums who had smaller families, often bred two years in a row instead of one, and aged more slowly, living a whopping three years instead of two.

Austad notes that when we discover and examine genes in the human genome that can increase longevity, they may prove to come with trade-offs. “Of all these genes in these small animals [that extend longevity], none of them are ever found in nature. And they all have downsides. People have not been eager to investigate the nature of their downsides.”

Cancer obviously could be a downside, as could altered fertility.

Austad says he’s been snorted at by other scientists when he argues that we should study the cells of long-lived animals like whales and elephants instead of short-lived ones like mice and fruit flies if we want to understand how we might live longer. “Elephants contain about 40 times the numbers of cells we do, and whales as many as 600 times as many cells. Yet elephants and whales live, to a reasonable approximation, just as long as we do. Therefore, their cells must be 40 to 600 times more resistant to turning cancerous than our own. Could we perhaps learn something about cancer resistance from studying these cells?” he has written.

So far, Austad himself isn’t working with elephants. Instead he’s looking at parakeets. “They live up to 20-plus years,” he says admiringly. “That’s seven times as long as a mouse, and they’re the same size. They have unbelievable resistance to oxidative damage … if we could somehow mimic that in humans …”

So, downside or no, Austad also thinks findings from the Human Genome project will help us increase human longevity. “We already know that there are some genes that are associated with longer life in animals. I think we’ll find the [corresponding] genes in humans that have a small but measurable effect on how long we live. And it won’t be too many years before we have gene therapy for all kinds of things. It hasn’t worked too well yet, but that’s just a technical problem.”

Is there any theoretical limit that would keep increased longevity from becoming immortality? Warner says “There’s no theoretical limit. There’s a balance between constant damage and repair. It’s like a car. Theoretically you should be able to keep a car going forever — not yours, maybe, and not mine — but if you keep replacing the parts the car could last forever. Maybe the individual could live forever.”

“The only limit is that there is no such thing such as immortality because accidents still happen,” says Austad. “The theoretical limit is human behavior, not human physiology. If teenagers didn’t drive cars like crazy people, that would probably have more effect on life expectancy than curing cancer.”

Dr. Leonard Hayflick takes a darker view of longevity research than many scientists do. Hayflick’s view of significantly increased longevity is, basically, that it won’t happen, it can’t happen, and if it did happen it would be a bad thing.

Hayflick, a professor of anatomy at the University of California at San Francisco’s school of medicine, is the author of “How and Why We Age,” and has been thinking about longevity for 30 years, ever since he discovered what’s now called the Hayflick Limit. Until his research, it was thought that animal cells growing in tissue culture were immortal and could divide forever. In a series of meticulous experiments, Hayflick showed that normal cells in culture have life spans: They flourish and divide for a while, but after a certain number of generations, divide no longer and eventually die. The cell lines that do go on forever are cancer cells.

People fail to distinguish between curing disease and ending aging, Hayflick says. If all the diseases currently written on death certificates in developed countries were resolved, you could add perhaps at the most 15 years to human life expectancy. “And that’s it. Period.”

Aging itself will not be affected. “Aging is an inexorable process that begins at about the age of 30 in humans and continues indefinitely. If you resolve disease you then expose or reveal the underlying real cause of that vulnerability, and hence death.”

Hayflick doesn’t believe that we will be able to go beyond resolving disease to slowing or stopping the process of aging. You can replace parts all you want he says, but what will you do when you have to replace your brain?

It’s true that people object to aging as well as to death. Long life, while much admired, isn’t sought after so much as long healthy life, or perhaps long youth. We want to be 100 years old and dewy fresh.

Dr. Pier Paolo Pandolfo, one of the scientists who studied the mice that live 30 percent longer, told the New York Times that a drug to block the self-destruct protein p66shc (the one the mice were engineered not to have) could be applied in the form of a cream to reverse wrinkling and blemishes on aging skin.

Can we have both long life and long youth? “I would say that there’s no question about that,” says Austad. “Most people would say that if you can’t have better function there’s no sense in keeping people alive.”

It’s increasingly easy to imagine replacing our parts, renewing our tissues, and rewriting our DNA. We would also need to fix our memories. They can hold a great deal, but never needed to hold an infinite amount of experience. Yet there are various ways we might deal with that, such as adding memory chips to our brains. Or perhaps we’ll even figure out how to get rid of unneeded, unpleasant old memories and provide room for delightful new memories. It’ll be doable, eventually.

Is this really possible? I believe it is, though I’m not fool enough to suggest a timetable. To those who say it’ll never happen, I say: Don’t confuse “a hell of a long time” with never. I think rather highly of human ingenuity and biological science. I see no reason why we won’t eventually learn how to live forever and to live forever young.

I think less highly of collective human common sense. (As Kay tells Jay in that brilliant philosophical work, “Men in Black,” “A person is smart. People are dumb …) And so there’s no reason to suppose we will handle this knowledge wisely.

Why aren’t we immortal already? If it’s so easy to turn on a gene here and turn off a gene there, why do we wear out and die? It’s all about reproduction, of course. Once we’ve produced the next generation and gotten them on their feet, what happens to us is of no relevance to the future. People who have two children and live to be 100 are less successful from an evolutionary standpoint than people who have three children and keel over in their 50s.

So the impressive genes that allow people to reach 100 on a diet of bacon and beer are not favored by natural selection. (Although if the centenarians spend all their time calling up their great-grandchildren and asking when they’re going to have babies and the great-grandchildren cave in and produce more children than they otherwise would have, that might favor those genes a bit.)

Still, it seems a little odd that there are no immortal species around. Quahogs live to be 200, but they probably feel that’s not nearly long enough. Perhaps species of immortal animals would always be outcompeted by species of mortal animals, since mortal species evolve and acquire exciting new bells and whistles to repel insect pests, protect against disease and fool dinosaurs into thinking you wouldn’t dream of eating their eggs.

If we stop dying will our species stop evolving? Not if we keep reproducing. Not everyone thinks we need to keep evolving. Many of us feel that we are already the pinnacle of perfection and that all our species needs to do is stay as sweet as we are. Others disagree.

My friend Cynthia Heimel says she does not feel we are nearly finished evolving, and she is eagerly looking forward to an era when we have progressed to having just four toes on each foot. She says it is because little toes are no use and catch on the bed corner, but I believe she just wants to wear pointier shoes.

In the choice between living long and having kids, natural selection has always favored having kids. Now that choice will be up to us. Obviously if we choose to do both, the world will fill up with people to such an extent that we’ll have to look for new planets.

We will ourselves become natural selection — unnatural selection if you prefer. Instead of allowing the ceaseless cherry-picking of the generations to get rid of our back problems, our impetuous driving habits and that pesky fifth toe, we will do it all at once with gene therapy.

Will everyone get to live forever, or will we make decisions about how long people get to live and when they have to stop?

This is one of the reasons Hayflick thinks increasing longevity is a dreadful idea. “I defy anyone to describe a scenario in which it would be a good thing,” he says.

Hayflick told the Savannah Morning News, “If indeed we had a way of extending human longevity the probability is very high that therapy would be available to the rich and powerful. I don’t know how you feel about the rich and powerful, but I can think of lots of them that I would not like to see live forever.” For example, he notes, “I don’t think that having Adolf Hitler around for the next 500 years makes much sense.”

You know Fidel Castro isn’t ready to die. And while I am under the impression that I have accepted my own mortality, I must admit that I don’t accept the mortality of my loved ones. It’s not that I want them to be immortal, it’s just that I don’t want them ever to die.

The fact that we spend such a huge proportion of our health budget in the last few months of our lives is testimony to this. (As my father remarks, “You can’t tell what truly expensive way of living a little longer will be discovered.”)

Spending money on gene therapy will undoubtedly be more popular than the feeble unappealing ways we have now of extending life span a little. You know, boring stuff like eating right, keeping fit, signalling your lane changes.

There are some things people won’t do to live longer, after all. Yes, we’ll slam down melatonin, DHEA and random antioxidants by the fistful just in case they slow aging. But almost nobody has leapt on the caloric restriction bandwagon (which holds that since rats on meager diets live longer, maybe we would too, so let’s not eat anything at all every other day), because it’s so unpleasant.

I have also heard men complain about how unfair it is that women live longer on the average. (Some of them will glare at a lady as if she’d been sprinkling free radicals on their salads.) Yet although it has long been known that castration can extend a man’s life span by an average of 14 years, guys consistently pass on the chance to even the score.

Is it any more unnatural to use gene therapy to become more or less immortal, than it is to use prolong life in other ways? After all, during most of human history most children died as infants, women couldn’t effectively limit how many children they gave birth to (and were far more apt to die in childbirth), and very few of them reached old age — yet hardly anybody objects to medical care to fight these causes of death.

But what all these changes amount to for our species is simply a movement along the spectrum from the kinds of species that have brief risky lives in which they produce as many progeny as possible — like mice — to the kinds of species that have longer lives during which they have fewer progeny, in whom they invest more parental care — like elephants. These life strategies are called r selection and K selection, and there’s nothing so unusual about a species becoming more or less K-selected.

But among all the variously r- and K-selected creatures in the world, one thing seems constant: Everybody dies eventually. Immortality is something different.

Then there’s the matter of addressing ethical conflicts before we proceed. The track record on this is not so great. Conferences are held and panels meet and people go right ahead and do what they want. And people really really want to live. “If it becomes possible, people will do it,” says Steven Austad.

There are people worrying now about the way better health care is producing an unprecedentedly large population of older people, and the effects this has on medical spending, education spending, Social Security and the GNP. Oh, and the ballot box.

Well, they haven’t seen anything yet. The world will fill up a lot faster if nobody dies.

Maybe we’ll make people choose between living forever and having kids. If you’re going to bring more people into the world, you’ll have to be willing to leave it yourself on a reasonable schedule. Conversely, if you refuse to leave the party, you can’t bring crashers. Of course, this would create an interesting two-tiered world full of crabby child-haters who think they know so much because they’ve seen it all and breeders speaking smugly about how they’re being not only natural but also more evolved.

What about natural selection? It got us this far, didn’t it? If immortality is a bad idea, won’t nature take care of it? It might do just that, but not in way we’ll enjoy. Since natural selection is mindless and purposeless, it has no objection to dead ends and short-term successes. Eventually some species could come along which has all our excellences, plus the advantages of mortality, and it will eliminate us. Not if we can stop them first, of course, but eventually (and this is a very long run indeed) we will be out-competed. Will the new Lords of the Earth then turn to making themselves immortal? Very likely, but it won’t be our problem. Mother Nature doesn’t care, ahistorical, short-sighted fool that she is.

Perhaps in the far reaches of time, as one mortal species after another crushes species that have succumbed to the temptation of eternal life, a species will arise that will remain mortal, and will allow itself to change. Perhaps they will never be overthrown by another species. Perhaps they’ll have a zoo, and we’ll be in it, and will learn the full reality of a life sentence.

But PR Daily called it a successful stunt: “This story will be dead by Sunday, and GoDaddy will have won tons of coverage.” And Parsons derided critics as uncomprehending or hypocritical. He refused to take down the video, and promised to post one next year, when he plans to shoot another elephant.

However, in the last few days, the initial, more sensational video has been quietly replaced with an edited version. In this one, a trampled sorghum field in Zimbabwe is shown. Destitute villagers, the video claims, need help protecting their crop. A nighttime scene follows as “the team” stakes out the field awaiting a nocturnal elephant raid. Shots ring out. A daylight scene shows Zimbabweans in GoDaddy caps crowding around a dead elephant to divide the meat.

(Taken out of the first video: Captions to the nighttime scene that read “Bob Parsons fires first” and “Bob Parsons fires again,” images of Bob Parsons posing with the dead elephant. Also cut: AC/DC’s “Hell’s Bells” playing over the scene of people cutting up the elephant.)

Cue Parsons, playing savior. “These people have literally nothing and when an elephant is killed it’s a big event for them, they are going to be able to eat some protein. This is no different than you or I eating beef,” Parsons told myFoxPhoenix. “All these people that are complaining that this shouldn’t happen, that these people who are starving to death otherwise shouldn’t eat these elephants, you probably see them driving through at McDonald’s or cutting a steak.”

But eating elephant really is different from eating beef. For one thing, it’s unsustainable on a basic ecological level. Elephants take too long to grow up and reproduce too slowly to work as a human food source. Animals that are successfully raised for food grow fast and reproduce early. (That’s why chicken is cheaper than beef and there is no giant-tortoise ranching industry.)

So, about that hypocrisy? Parsons claims he shoots elephants to save people. “If you had the choice to take a few elephants or to let people starve,” Parsons propounded to Mashable, “what choice would you make?” Asserting that we must choose between humans and elephants is, of course, a false argument. There’s a more stripped-down form that goes, “If it comes to a choice between a wild animal and my child, I know which I’m picking,” and excuses the extermination of all wolves, mountain lions, rattlesnakes, etc. By viewing our relationship to animals as a series of false choices — elephants or starving villagers? wolf or toddler? eagle or fuzzy bunny? — this philosophy justifies wholesale destruction.

They ask him to shoot the elephants, Parsons says. Sure, farmers everywhere hate crop-eaters, whether they are elephants, deer or blackbirds. Fishermen hate seals, cattle ranchers hate wolves, and quail farmers hate hawks. There’s a genuine land-use problem. More and more land is being occupied by farming villages. Elephants are losing land to people, and people are losing crops to voracious elephants. In Parsons’ formulation the answer is to shoot a few elephants and the rest magically run “into the forest” and don’t come back. There are other answers, but they’re less simple, and they don’t yield a Great White Hunter photograph of yourself with your boot on a dead elephant.

CNN’s Piers Morgan asked billionaire Parsons why he didn’t, instead, give money to the poverty-stricken Zimbabweans if all he wanted to do was help. “I don’t know that one has to do anything with the other,” replied Parsons.

A lot of people are mad at Parsons because they love elephants. Elephants are charming to watch. The more you learn about them, the deeper the charm goes. They are intelligent, life-long learners. They have long memories to go with their long lives. They have complex emotions and social relationships.

That’s true even of male elephants — though Parsons asserts that they’re all relatively interchangeable. Parsons says that his killing of a bull “has no effect on the elephant social structure (as it is matriarchal) as well as the herd size. The reason is another bull quickly steps up and breeds in place of the bull taken.”

Ah, the worthless male, sperm donor, all-you-need-is-one, theory. That’s not what elephant experts say. Scientists and researchers working in Africa argue (as in a February 2005 essay in Nature) that older male elephants are critical to the social development of younger males, specifically in keeping young bulls from becoming hyper-aggressive and attacking elephants and other species, such as rhinoceroses. In groups of violent young males (orphaned in elephant culling operations) who were killing rhinos and other elephants, the re-introduction of older males stopped the killing sprees.

So, back to the hypocrisy, the other reason people are mad at Parsons. It’s as if Parsons doesn’t know much about elephants. (Some who saw the original video have even cast doubts about whether he knows the real sex of the elephant.) Or as if he prefers to hold an outlook that lets him shoot “huge” trophy elephants — and do it to help the poor. Maybe someone will buy that. Others are apt to believe that Parsons shoots elephants for fun and to look tough. And on top of that, he wants gratitude from African villagers and admiration from the hometown crowd.

Idiotic mistake or brilliant P.R. stunt? Even if Parsons’ video posting turns out to be a canny publicity move, and doesn’t maim GoDaddy’s bottom line, I’m going with idiotic mistake.

Tigers are among zoo visitors’ favorite animals. They’re also one reason many people hate zoos. Saddened by the picture of misery presented by the tiger who repetitively paces back and forth, back and forth, some people never go back.

“Tigers simply don’t belong in the zoo,” says Adam Roberts, senior vice president of the animal advocacy organization Born Free USA. “Tigers don’t belong on concrete, tigers don’t belong behind bars, and frankly, tigers don’t belong near people.”

Life in a zoo isn’t necessarily oppressive for all animals. Most animals didn’t evolve to explore as much space as tigers. But tigers in most zoos are like people spending their lives locked in an empty living room. They are confined to tiny spaces, with nothing to do. Life is intensely boring, year after year. Some animal observers say zoo life may also be stressful. Tigers, who like to lurk, skulk and hide, are on display, with groups of strangers staring at them. Freedom is absent, and so are choice and control.

The San Francisco Zoo is among the many older U.S. zoos saddled with the physical legacy of tiny, inhumane cells. Instead of replacing them all, zoos build a gorilla habitat here, a giraffe palace there, while other animals languish in the old cages. In the past decade, San Francisco Zoo has sought to shed its infamy. In 2002, it unveiled the Lemur Forest, a delight to behold, with five species of lemurs trooping over a large island and clambering through tall trees and climbing structures. In 2004, it opened the expansive African Savanna, where visitors walk along an pathway, observing giraffes, zebras and oryx rambling through open grounds. And it used the rescue of two young grizzly bears from Montana to help raise funds for a new bear exhibit bigger than all its previous bear grottoes combined.

Yet the grotto in which Tatiana and the zoo’s three other Siberian tigers lived was barely upgraded from 1940, when the zoo’s grottoes were built as part of the Works Project Administration. It was small, dull and, as we now know, not completely tiger-proof. In December 2006, Tatiana mauled and nearly tore off the arm of keeper Lori Komejan inside the feeding cages. As the San Francisco Chronicle reported, the state’s workplace safety agency, Cal/OSHA, blamed the zoo, citing defects that the zoo knew about but hadn’t fixed, and imposed an $18,000 penalty.

Whatever problems one zoo may have, conservationists argue that keeping tigers in zoos is a means to preserve a species in terrible danger. After all, wild tigers are losing ground fast. Assaulted by poaching and loss of habitat, populations are sinking. A hundred years ago there were probably 100,000 tigers. Now there are about 3,000.

Today, zoos are active in breeding programs to preserve tigers. Under the Species Survival Plan, only about 20 tiger breedings a year take place, planned to maximize genetic diversity. “The whole philosophy that I have lived by is that tigers in zoos are a genetic insurance policy,” says Ron Tilson, the director of conservation at the Minnesota Zoo and a respected tiger expert who directs the Species Survival Plan at accredited U.S. zoos. “There are the same number of Amur [Siberian] tigers in captivity as in the wild, and there’s greater genetic diversity in captive tigers.” If a virus like distemper or feline leukemia devastated the wild population, he adds, it could be rebuilt from the genes of captive tigers.

Even Peter Knights, executive director of the conservation organization WildAid, which strives to preserve threatened animals, including tigers, worldwide, acknowledges that zoos are valuable. “Zoos play a positive role in sensitizing people to conservation,” he says. “Tigers are in an ambassadorial role. The actual experience of seeing a physical animal is nothing like seeing it on a TV screen.”

Knights, however, is skeptical about ever reintroducing tigers, even if it could be done in a large protected area. Predation isn’t an easy trade to pick up, and wild cubs stay with their mothers for two years learning how it’s done, being supported while they learn. “We haven’t worked out how to reintroduce tigers into the wild yet,” he says. At the same time, various projects with other big cats suggest that while the first generation will starve if they’re not provisioned by humans, the second generation does fine. But it’s true: tigers can’t be reintroduced now. It’s not safe for them out there.

Roberts of Born Free USA has no patience with the defense of zoos, either for their genetic storage programs or their ambassador roles. “The tiger is a perfect example of the way that zoos are missing the point about conservation,” he says. Money spent on zoo tigers should be spent on protecting habitat for wild tigers. “There’s an expenditure of millions if not tens of millions of dollars on captive tigers. If we really want tigers and not just a shell of the beast we call the tiger, the real emphasis needs to be first and foremost in the field.”

Currently, despite the best efforts of groups like Born Free USA and WildAid, the outlook for tigers in the wild remains dim. The only place where wild tigers are doing well is eastern Siberia, which is also the only tiger habitat sparsely inhabited by people. “Everywhere else, everything is failing,” says Tilson. “It doesn’t matter how much money there is. It doesn’t matter how good the recovery team is. It comes down to: Is there a will from the government to put resources into it, to create laws, and to enforce those laws? For a real failure, go look at India.” There, prosecutions for poaching don’t stick; the Sariska Tiger Preserve has had every single tiger killed; and the Tribal Rights Bill now in Parliament would allow hundreds of thousands of people and their cattle to live in national parks.

The ideal situation for tigers would be the protection their wild habitat. Until that comes to pass, zoos will continue to serve a purpose for helping to preserve the species. But the new safety barriers the San Francisco Zoo has installed on its tiger enclosures shouldn’t be where we stop. We should also look seriously at how to make tigers happy. So why don’t we do some happiness research?

Setting aside the solipsistic notion that we can never know what’s in the heart of another, there are in fact multiple ways of getting at what tigers like. We could put on white coats and measure corticosteroids, stress hormones. We could find out if it’s true that active tigers live longer. We could then design zoo habitats better. After all, we should treat our captives well and intelligently. If they must be in prison, why can’t it be one of those country club prisons we keep hearing about?

There are encouraging signs in that direction. In recent years, zoos have constructed new tiger exhibits with big enclosures and greenery. There’s usually a pond, maybe even a waterfall. Zoos have also signed on to the concept of “enrichment.” They’re giving animals things to play with, things to destroy, things to take apart in search of snacks.

In the Bronx Zoo, keepers spray odd scents like cinnamon or musk around the enclosure to make things more interesting for the cats. At the Minnesota Zoo, tigers get a fake carcass. It’s a fake moose stuffed with meat, and the tigers have to wrestle with a long strip of rawhide to get to the meat. “The tigers really love this,” says Tilson.

In fact, Tilson assures me that zoo tigers are content. Of visitors saddened by the sight of zoo tigers, he says, “It may be a look of boredom they’re picking up on, but [the tigers] are not unhappy.” They live longer than wild tigers. They’re well-fed and safe from enemies. Tilson thinks all zoo tigers should have enrichment programs. He speaks well of the tigers-and-water shows at a few facilities, including an aquarium in Denver and an unaccredited wildlife theme park in Arizona. “As long as it’s done safely, it’s good for the animals,” he says.

Zookeepers also tell us that tigers are cats, happy just to eat and sleep. But zookeepers so badly want their tigers to be happy that they may not be the best judges.

Elizabeth Marshall Thomas, author of “The Tribe of Tiger,” argues that circus tigers are happier than zoo tigers because their lives are active and interesting. She cites an observation of Tilson’s from when the Minnesota Zoo was doing endocrine studies on tigers. The tigers were in small cages in a laboratory, and had blood samples taken several times a week — and they looked great. They were relaxed and bright-eyed, and their corticosteroid levels were far below those of the tigers on display. Apparently they liked being able to observe the activity in the lab, and they liked the regular, friendly interaction with the researchers.

If the horrible incident at the San Francisco Zoo makes people pay attention to conditions for tigers in zoos, maybe some good will come from it. It’s the least we can do for the tigers while our species continues to eat up their native homes.

In the chatty, opinionated guise of Dr. Tatiana, Olivia Judson brilliantly combines the ever-popular genre of the advice column with that of Sick Nature Facts. The combination is strikingly successful. As Dear Abby never has, Dr. Tatiana confronts the etiquette issues involved in depraved cannibal incest, for example, and uses them to illuminate biological insights into the nature of life on earth.

A typical section of Judson’s book, “Dr. Tatiana’s Sex Advice to All Creation,” will begin with a letter from a troubled or inquiring life-form and will go on to explore issues raised by that creature’s situation. She examines an instructive variety of dilemmas. I am particularly fond of a letter from “Hoodwinked in the Gulf of California,” one of life’s winners who nevertheless feels as if he’s slowly going mad: “I’m a sponge louse, and I recently won a battle for a sponge cavity that is home to a large harem of beautiful girls. But I’m starting to suspect that some of the girls are not what they seem: several look like men dressed as women. Am I being paranoid?”

Then there’s “Anxious in Amboseli,” an elephant with whom many will identify, who concludes his plaint: “I’m obsessed with sex. Night after night I have erotic dreams, and the sight of a beautiful cow sends me into a frenzy. Worst of all, my penis has turned green. Am I ill?”

Dr. Tatiana is able to reassure Anxious that his situation is perfectly normal, which is in fact her response to many worried beings. Her explanations of various bizarre evolutionary successes are clear and compact. My only complaint would be that I want to read even more letters from correspondents like “Neglected Househusband in Tamil Nadu” (a bronze-winged jacana) or “Group Sexists in Santa Catalina” (sea hares).

Dr. Tatiana often takes quite a folksy tone. (Surely this is fair to say when she addresses readers as “Folks”) Although I have read vast numbers of books on biology for popular audiences, I believe this is the first time I have encountered the term “rumpy-pumpy.” (In reference to the love life of Australian seaweed flies, as you might have guessed.)

Many are the shocking and tangled relationships revealed in Dr. Tatiana’s answers to her pen pals. No doubt you knew about and had adjusted to the hermaphroditism of banana slugs, but perhaps you were not aware that during sex the “gigantic and complex” penis of a slug may get stuck, whereupon one or the other of them has to gnaw it off. This ends that slug’s chances of playing the male role, but happily it remains in touch with its feminine side.

Then there are the button beetles (Coccotrypes dactyliperda), of whom you read so little in the Lifestyle section of the newspaper. Who has not heard the scuttlebutt to the effect that button beetles can and often do mate with their own brothers or sisters when they’ve only just hatched? Dr. Tatiana describes the even more scandalous behavior of a female button beetle who goes out in the world without taking this precaution. “On arriving at a new home, [she]… digs out a grotto and then lays a small clutch of unfertilized eggs. These develop into males. She mates with the first to hatch and then eats him and his brothers before laying a large brood of daughters — and perhaps one or two more sons for her girls to mate with.” Worse still, these amoral creatures are known to infest buttons on clothing.

Naturally, Dr. Tatiana does not shy away from counseling those in more conventional relationships. She is brisk in her reply to a young California mouse who has a crush on her neighbor’s husband, advising her that this species is so profoundly monogamous that once a male has a mate “he won’t even cheat on her even if he finds himself locked up with a virgin in heat.” Her assertions are carefully referenced, so you can look this up if you like. The footnotes answer questions such as: Who thinks up these experiments? Are these people scientists or screenwriters?

Or consider the Djungarian hamster, a species in which the male “is such an attentive father that he plays the midwife for the birth of his pups (the only male mammal so far known to do this as a matter of routine), helping them emerge from the birth canal, opening their airways so they can breathe, and licking them clean. For good measure, he eats the placenta.” Yes, but does he videotape the delivery? Perhaps not, as this vision of domestic felicity blurs when Dr. Tatiana casually mentions that Djungarian hamsters breed so busily that they can produce “eighteen litters of between one and nine pups” in a year. That’s up to 162 baby hamsters, each needing to be suckled, washed and kept in line. No wonder the male performs all the midwifely tasks — the female is far too exhausted. In fact, around the hundredth pup she is probably asking herself how bad it would be if they couldn’t breathe.

Like so many advice columnists, Dr. Tatiana is perfectly liable to respond to some heartfelt pleas for advice with information and commentary, perhaps even a warning, but with no actual advice. At least she spares us numbered lists of fire safety tips.

She does give advice to “Invisible in Sri Lanka,” a peacock with a substandard tail, telling him to join a gang, since peahens like to pick through groups of males for those that appeal to them most. But she has nothing to offer “Disgusted in the Galapagos,” a female marine iguana who complains of encountering groups of young males masturbating at her. Instead she rambles on about species with small testicles vs. species with big testicles: small help for Disgusted.

When it comes to scorpion flies, a species known to steal insects from spider webs, she is on surer ground, with advice for both sexes. “Tip: If you’re a boy scorpionfly, you’ll have a big bulbous penis. If you’re in a spider’s larder and the owner tries to stop you, whack her with your member and she’ll back off. Girls, if you ever find yourselves in the same predicament, your best bet is to head butt the poor spider.”

When all a correspondent wants is information, as when “Spooked in Gabon,” a golden potto, asks, “Please, Dr. Tatiana, why is his penis covered with enormous spines?” her answers are utterly satisfying, although some reader may be troubled by her reference to the relative dullness of the human penis, “notable only for its girth.” Comparing the anatomy of the male golden potto to that of the male damselfly, the male ghost spider crab, the male red-billed buffalo weaver, and so forth, she ends by suggesting that the spines may serve to stimulate the female golden potto, or to get rid of the sperm of other male golden pottos. True, she also notes that comparative studies indicate that such genital extras suggest that “female golden pottos sometimes sleep around” — if she were writing for a newspaper, I bet the editors would take that out.

Dr. Tatiana also issues the occasional “wake up and smell the coffee” letter. In her reply to “Bewildered Down Under,” a female splendid fairy wren who can’t understand why her mate keeps going to the doctor to have his sperm count checked when it checks in at 8 billion sperm at a time, she warns that “His ‘appointments’ are a thin disguise for philandering. Splendid fairy wrens are notorious for their extramarital adventures,” goes on to link this to his high sperm count, and concludes by casting aspersions on Bewildered’s own marital fidelity.

While Dr. Tatiana spares us numbered lists of what to keep in the glove compartment in case of emergency, in her section on crimes of passion she does provide a guide for female self-defense: “1. Don’t attract attention. Hide or be otherwise conspicuous. 2. Don’t leave home alone. Hire an escort or, failing that, stick with other females. 3. Do avoid groups of idle males. If they congregate at a place you must go to, try to time your visit to coincide with the arrival of other females. 4. Do carry weapons. Males tend to be servile if females are well armed.

I am certain I have read items 1-3 in Ann Landers, although not 4. She seems to have forgotten “Do carry your keys in your hand so you don’t have to fumble through your purse for them in a darkened parking lot” and “Don’t list your full name in the telephone book.” Tatiana’s tip No. 4 is one that is generally omitted in advice to our species, however.

There is a brief discussion of child care, which is appropriate, since, after all, the production of offspring is what has made the practice of sex such a winning strategy. Dr. Tatiana is fond of the hermaphroditic African leech, which carries its young in a pouch, like a kangaroo.

But I sorrow to note that Dr. Tatiana’s focus on reproduction has something regrettable in common with mainstream sex education in the United States today: She has nothing to say about birth control. Does she believe with many religious fundamentalists that birth control is “unnatural”? Surely it cannot be that what divides humanity from the rest of creation is not consciousness, nor laughter, nor tool use, nor tool manufacture, but our use of tools in family planning?

Undoubtedly blazing the trail for the inclusive future of sex advice, Judson closes with a transcript from “Under the Microscope: The Deviant Lifestyle Show!” with host Dr. Tatiana (glamorous in a scarlet suit) interviewing Miss Philodina roseola, the bdelloid rotifer, about whether it is true that bdelloid rotifers have reproduced only by cloning — no sex — for the last 85 million years. Irate audience members accuse the guest of lying, try to drown out the proceedings with political chanting, or give touching testimony and vivid demonstrations from their own lives as to the wonders of sexual reproduction. In a postscript Dr. Tatiana notes that the more she learns about the sexual practices and predilections of others, the more tolerant and, in some cases, the more envious she becomes. “I now think that many more things are normal,” she says, and wishes everyone “lots of great sex” unless they chance to be bdelloid rotifers.

At this point, because the Ninth Circuit decision is under appeal, schools are free to instruct kids to recite the God-enhanced version of the pledge. Recalling my own schooldays, when those words created a painful moment every day, I hope they don’t.

The ostensible cause of the pledge suit is a third-grader, the daughter of Michael Newdow and Sandra Banning. Newdow, an atheist who lives in Sacramento, Calif., filed suit arguing that his daughter should not be forced to watch and take part in a ritual including mention of God, and the majority of the court agreed.

This decision, as might be expected in these times, caused a huge flap, and afforded certain congressman the chance to summon cameras to view them reciting the pledge — including “under God” — and singing “God Bless America” on the Capitol steps. Had someone handed them flags, I am sure they would have wrapped themselves in them.

I’m an atheist, and I was particularly distressed by the part of the furor which involved public figures across the land proudly renouncing atheism and vowing to combat their oppression by atheists. But the last straw for me, the one that made me feel I’d kept my heathen mouth shut long enough, was an editorial cartoon showing Newdow’s daughter being crucified on an international “no” symbol by her callous atheistic father.

This display came on the heels of the child’s mother, Sandra Banning, announcing to the press that her daughter is not an atheist, that she does not want people to think that her daughter is an atheist, and that she doesn’t want her daughter to be a party to the suit. (The parents, unsurprisingly, have not been a couple for some time.)

Banning’s lawyer also says that Banning doesn’t want her child to be “branded for the rest of her life as the girl who was the atheist in the pledge case.”

It’s not clear that Newdow’s lawsuit hinges on his daughter’s being an atheist who does not wish to utter words of religious faith in the course of pledging allegiance to her country. Newdow has spoken of his right to guide his child’s religious education (although now that the mother says she has full custody, it’s unclear whether he indeed has that right), a statement which gives no hint of the child’s beliefs.

Perhaps it is true that, in this case, the father’s lawsuit misrepresents the convictions of the child. Perhaps the high point of her day is the chance to intone the words “under God” as part of the pledge. And I can certainly believe that being known as a party in her father’s lawsuit could create social agony for the girl. If I could, I would gladly put my younger self forward as a suitable plaintiff, because saying those words did indeed make me unhappy.

I’ve always been an atheist. I’m a third-generation atheist on one side of my family, second-generation on the other. When I was 6 or 7, a family friend gave me a book of Bible stories, which I liked (my favorite was the story of Moses and Aaron), but which didn’t make me a believer. When I asked my parents about God, they said that was a matter of personal conviction, and I could decide for myself when I got older. I was a serious, precocious child, and I didn’t wait to decide — but my beliefs haven’t been shaken with time.

Very early soon after my decision, I became aware that the matter of personal conviction was not a simple thing. One day after school, when we were both in the first grade, I casually remarked to my friend Amy that there was no Santa Claus and no God. Amy told her parents in distress, and they called my parents in outrage. Somehow my genius of a mother smoothed things over so that Amy was still allowed to play with me, but it was apparently a close call. My mother had a talk with me about respecting the beliefs of others, and it made a deep impression.

The next time we played together, Amy told me that while I had a point about Santa, I was mistaken about God. I don’t remember exactly what I said, but it was on the order of, “I’m sure you’re right. Let’s go play in the tree fort.”

At the Massachusetts school I went to, we didn’t say the pledge, but when we moved to California, it was a daily ritual. When we recited the pledge, I didn’t say “under God,” because I didn’t believe it. I was a conscientious child, and I didn’t want to lie. But I was afraid that people wouldn’t like it if I didn’t say it, or would tease me if they noticed that I didn’t say it, so I moved my lips during that phrase, but did not speak it. This was not my parents’ idea. I don’t think I told them about it, and in any case they were always urging me not to be so timid about things.

I have been told that my fear was not a rational one, and that other kids in other places either conspicuously did not say “under God,” or substituted all kinds of hilarious phrases, and that nothing bad happened to them. No one forced me to cower before a hypothetical threat.

But it so happens that between first and second grades I entered what it would be tactful to call an awkward phase, and I think I was correct that in my status as a spindly bespectacled dwarf who talked funny, any new deviation from the norm could have directed additional teasing my way. Moving from one school to another didn’t help. I was teased for the way I looked, the way I dressed, the way my parents looked, the fact that we ate dinner late, even — this was in a California suburb — for having dark hair. What I already underwent was bad enough without being exposed as a person whose morality was so questionable that other children might need to be sequestered from my company.

If my fears were indeed unreasonable at the time, perhaps they are becoming less so. Perhaps the danger of being exposed as a pledge heathen has been heightened. In the main part of their decision, the appeals court judges wrote that the insertion of the words “under God” sends the message that atheists are outsiders. And Sandra Banning’s desire that everyone know that her child is not an atheist after all would seem to confirm that.

I’d like to ask Banning: If it is so terrible for her daughter to be reputed to be an atheist, and if she must protect her child against that charge, what protection would she like to see for children who really are?

Atheist children aren’t the only ones who may confront this issue. When the pledge decision came down, the San Francisco Chronicle interviewed the Rev. Masao Kodani of the Sensai Buddhist Temple, who said that Buddhists don’t believe in God, and that he tells children in the temple’s dharma classes that they should say the pledge in school but be silent for the “under God” part. Brave children, if they do.

One of my children is a practicing Jew who nevertheless doesn’t believe that those words belong in the pledge. The other one, also an atheist, but not as fearful a child as I was, has never been bothered by the religious phrase in the pledge, but asks “What good is it?”

Indeed, what is the point? What do those two words accomplish? They certainly didn’t convert me, but they taught me an inimical lesson about pretending to go along.

When I heard about the court’s decision, I felt more worried than vindicated. I believe the decision is correct and I believe it will be overturned. I also think that because a majority of Americans believe those words should stay in the pledge, a rationale will be found. In the meantime, there will be a lot of hand-waving and posturing about God and country and about how you can’t have the latter without the former, and a lot of people will say things that indicate just how incomprehensible, alien, amoral and untrustworthy they think people like me are.

I fear that some reasoning will be found to reaffirm the edict that all children in our public schools must daily link God and country aloud — and a lot more people will be watching children’s lips.

The Bush administration has now taken the amusing position that the words “under God” are, of all things, a “secular” reference to the nation’s religious heritage. A history lesson, if you will.

That’s not what President Eisenhower said in 1954 when he signed the law inserting the words into the pledge, which had been fine without them for the previous 62 years. He said it would proclaim “the dedication of our nation and our people to the almighty.” A House committee report of the time said this would serve to “deny the atheistic and materialistic concepts of communism.”

It is probably true that, as Boston Globe columnist Jeff Jacoby wrote, the founders of the American Republic didn’t intend to create “a public square scrubbed free of God.” Me neither. I think if we talked about religion more, in fact, there might be a wider understanding that this is not a subject on which we can assume unanimity. But talking about faith in God is not the same as forcing people to parrot words of faith they may or may not feel.

Jacoby also wrote that the health of our political institutions depends “on our ethics and religions.” I’m with him on the ethics, but am alarmed by the notion that he may think we can’t have ethics without religion. Religion is where some people locate the wellsprings of their ethics, but others find a different way. Does Jacoby find atheists like me unhealthy and unethical? The more such pronouncements I read, the more I wonder whether my childhood fears of being exposed as an unbeliever were really so irrational. Atheists aren’t allowed to be Boy Scouts, for example, although admittedly I was already disqualified.

Surely no one believes that inserting the words “under God” in the pledge converts unbelievers or prevents backsliding. No, I think the real reason for the outrage at the thought of taking the words out is that most believers are furious that some people are offended by being instructed to utter the simplest, most basic tenet of their belief.

In a 1984 case, the Supreme Court ruled that the phrase “In God we trust” imprinted on our currency was not a problem because its significance has been lost through rote repetition. Not to me. I can read and I know what that means, and it means I’m not counted in the “we.” Whatever. It’s not like merchants force me to read my money aloud. If I were going to file a lawsuit, it wouldn’t be about that.

Judge Ferdinand Fernandez of the Ninth Circuit wrote in his dissent to the pledge ruling that he didn’t think the words “under God” were likely to bring about a theocracy. So? The Constitution doesn’t say we should have separation of church and state only when it looks threatened by a theocracy. It says we should have separation of church and state. Laws aren’t written to be ignored unless things get really bad.

Sandra Banning says that when she told her daughter (who, like a rape victim, goes unnamed in the media) that Newdow’s suit could drag on for some time, the child replied “that it was OK because she will still whisper “one nation under God” and no one will hear her and know she is breaking the law. Of course it is not true that she would be “breaking the law,” but it is a sad picture.

I’m sorry for the child because her parents are so antagonistic to each other, and I’m sorry for her because her unwanted status as a party in her father’s lawsuit has probably made her the target of unwanted attention at school; but I’m not sorry for her if she wants all children to have to say the words she would like to say.

I’m sorry for her because I too have been a quiet child who felt pressure to say what others wanted me to say and not say the things they didn’t like. I have been that child, and so I hope that none of the children in her class will be compelled to proclaim their religious views, or those of others, as part of the school day.

Among the subjects Zuk discusses in this spirit are homosexuality in animals, infidelity in apparently monogamous animals, the evolution of the female orgasm, why bonobos have replaced dolphins as the Cool Species We Can Learn From, the evolutionary significance of menstruation, sexual stereotyping, the “myth of the ecofeminist animal,” maternal instinct, the zany things animals do with sperm, the alleged Great Chain of Being, the dogmas of dominance hierarchies, and sex differences in math ability.

Zuk herself does much of her research with insects, in part because it is so much easier not to identify with their behavior and indulge in anthropomorphism than it is with chimpanzees, dolphins or other vertebrates.

In her discussion of homosexual behavior in animals, Zuk describes studying crickets and locating males in the grass by listening for their courtship songs. With any luck, she notes, she can find two crickets at a time by this method: the singing male and the object of his serenade, usually a female cricket. In the past, if she found a courting male with another male, she assumed that it was a case of mistaken identity. After reading Bruce Bagemihl’s work compiling reports of homosexual behavior in a wide variety of birds and animals, she says, she is not so sure. Perhaps it should be considered homosexuality — but what does that mean to a cricket? Can we really make the parallel? What about the times when she finds a courting cricket next to a leaf or twig? “Do we call that fetishism?”

An aside: In the spirit of full disclosure, I note that on this subject Zuk quotes a book review by this author, which appeared in this publication. In order to avoid the appearance of cronyism or logrolling I feel the need to insert a savage attack on Zuk at this point: The woman is unsound on the subject of earwigs. She admits to considering earwigs “cute and interesting” and to trying — unsuccessfully — to convert her students to this view. Had she ever planted tender lupine seedlings in her garden only to find them hideously chewed up in the morning, and had she gone out in the night to inspect her seedlings by flashlight in a frenzy of grief and concern, only to find earwigs stationed at the tip of each leaflet, remorselessly slashing at the delicate green flesh, I do not think the first word from her lips would have been “cute!” This is classic ivory-tower analysis, unmindful of ground truths the rest of us know from bitter experience. I concede that a mother earwig curled on her eggs is not without a certain charm — until you consider the sap-splattered career that brought her to this point and the similar destiny of destruction that, when they hatch out, awaits the teeny-tiny miniature earwiglets.

Then there’s the little matter of infidelity — rather, “extra-pair copulations” — in many species of birds hitherto thought to cleave only unto one another. Zuk writes that the fact that this happens pretty often upsets her students more than any other material covered in the class. Fuzzy animals eating their fuzzy babies, ghastly flesh-eating parasites, close-up photos of earwigs — apparently none of these is as upsetting as the news that Betty and Billy Bluebird might be indulging in quickies with Jimmy and Jessie Bluebird.

But as Zuk tries to convince her students, “It isn’t cheating if there are no rules to break.” It’s only in cartoons that Betty and Billy stand up before Judge Bluebird or Reverend Bluebird to say their vows. Zuk criticizes the fact that not only the popular press, but also some scientific articles, use terms like “illegitimate” or “wife-sharing.” In one example, researchers refer to “female promiscuity” in red-winged blackbirds despite the fact that the females could not have been tangoing alone.

“[T]hese are our categories, not theirs …” she points out, as her students vibrate in distress.

Zuk’s students apparently feel better about her lectures when she mentions bonobos and their sex-packed lifestyle than they do when she’s telling them about earwigs or imperfectly monogamous songbirds. In fact, they are riveted by the subject, and Zuk includes a selection of amusing student answers from a quiz given following a lecture in which a mere three minutes (out of 50) were devoted to the Bonobo Way. She notes that the student who wrote about bonobos “fornicating” didn’t get the word from her. The sex lives of bonobos, she says, explains why they have more or less replaced dolphins as icons of nature’s goodness, and argues that it was ironic that during the era of the Summer of Love advocates of sexual revolution were “championing creatures with invisible genitals.”

One of the key issues of sexual revolution, female orgasm, while subject to the analyses of evolutionary biology, is relatively free of animal models, because so little is known about it. We may assume that female bonobos or macaques have orgasms, judging by their behavior, but this is subject to what about that scene in “When Harry Met Sally”? criticisms, among others. So arguments on this subject focus on our own species.

Why do women have orgasms and, if they must have them, why aren’t they more — reliable? You know, like the ones men have?

Why would anyone wonder why women have orgasms? Isn’t it obvious that in both women and men, orgasms function as rewards for having sex, which, one should keep in mind, has a spooky tendency to lead to having babies, which leads to perpetuation of the species?

The reason people wonder — OK, the reason some male scientists wonder — is that the female orgasm is notoriously different from the male orgasm. More elusive. To some. From this dreadful observation, “… it is a small leap to the conclusion that if females differ from males in their sexual response, they have a problem,” writes Zuk.

The late Stephen Jay Gould, among others, argued that the only reason women even have orgasms is that men do, and we’re related. In other words, women have clitorises for the same reason men have nipples — the organ is adaptive in one sex, and the other sex gets a watered-down version as a developmental accident. On the way to crafting a penis, the genes create the clitoris but then, noticing that the embryo is female, abandon the project.

Many women have found this lucky slopover argument annoying. But evolution has given us lots of annoying stuff — you know, one-way knee joints, the vermiform appendix, no redundancy in the esophagus, thus enabling us to choke to death on the silliest stuff — so that doesn’t prove it isn’t so.

But Zuk cites primatologist Sarah Blaffer Hrdy’s observation that the clitorises of female primates of different species do not seem to mirror the penises of the same species, in size, shape or placement. In fact both are extremely variable, but not in similar ways. “This does not seem like a case of the clitoris demurely following where the penis has led, evolutionarily speaking,” writes Zuk. (See? Annoyed.)

Biologist John Alcock argues the view that the female orgasm is indeed an adaptation in its own right. The fact that it does not result from heterosexual intercourse as reliably as the male orgasm means that women will be inclined to seek better lovers, whose consideration will make them good partners in other ways. “Presumably along the lines of, ‘If he makes sure I enjoy sex and have an orgasm he’ll be more likely to take the kids to Little League’” writes Zuk, apparently not wholly convinced.

“Why is it less ‘efficient’ for women to have orgasms before, after and not always during intercourse? Why do they have to have one (or more) every single time a man does? And most of all, why is it such a problem for penis-in-vagina intercourse not to reliably result in orgasms for all women, all of the time?” queries Zuk. She quotes psychologist Carole Wade’s sports metaphor: “Sex is not a soccer game. The use of hands is permitted.”

“This situation does not appear to be a devastating defect for many women or their partners, but it has distressed numerous biologists,” Zuk notes. “It is as though they were concerned mainly with sex for amputees.”

Zuk discusses some of the other theories about female orgasm (the more elusive it is, the harder you hunt for it; the longer she lies there in a happy daze, the more likely it is that sperm can get to the egg) and notes how little information we have, not only about orgasm, but even about desire in females of other species. Pigs, for example. I know you’ve wondered about pigs. Researchers studying female sexual desire in animals usually look for two things, it seems: “cooperation” and “immobilization.” Zuk quotes Kim Wallen, author of “The Evolution of Female Sexual Desire,” on the pig issue: “Placing a boar’s saliva on the snout of an estrous sow produces an immobilization reaction so strong that a human can sit astride her without producing an escape response,” and adds austerely that “while this certainly seems as if it would be an endless source of amusement in research facilities, we are left not really knowing what females feel.”

There are real difficulties in such research, however, and Zuk writes that it seems meaningless to attempt to monitor sexual arousal in a spider, for example.

But she has one question she’d like answered. “Why do men have orgasms?” Given that men don’t have to be pregnant, give birth or breast-feed, to name a few advantages, it seems to Zuk that women are the ones who need a big motivator to have sex, not men.

She notes that assessments of relative sexual desire — where it is again often assumed that men want it more than women do — need to be taken in social context, and makes the comparison of the desire for food. The usefulness of hunger is pretty clear and there is no reason to suppose that avoiding starvation and getting adequate nutrition were unimportant to females in the course of evolution. “The fact that many Western women are dieting or have psychological problems about eating does not in the least suggest that males and females are selected to respond to hunger differently. Should we conclude that women have a less intense physical hunger drive than men?”

Zuk has fun with her chapter on the evolutionary significance of menstruation, mocking both the biologist who wrote that the phenomenon of menstruation has “worried man since early times” and writers who treat menstruation as a spiritual phenomenon putting women in touch with the earth/matriarchy/goddesses/dragons. With rationalist glee she cites the work of anthropologists debunking the image of the “menstrual hut” found among some preindustrial peoples as a place for women, free of their daily chores, to kick back, relax, and bond with one another, a sort of Club Red.

In fact, Beverly Strassmann’s studies of the Dogon farming people of Mali found that although women don’t have to cook for their husbands while staying in the hut, they’re still expected to work in the fields; that women say the huts are boring and confining and they don’t want to go there, but their husbands insist; that women’s use of the huts is determined by their husbands’ religious beliefs, not their own; and that perhaps a main function of the huts is to allow men to monitor the reproductive condition of women and know when they conceive.

Evolutionary biology’s analyses of female orgasm and menstruation are the exception, in that they are not heavily reliant on animal models. Most sociobiological analyses of human behavior make extensive use of comparisons to other species of animals, like the polygynous male meadow vole, with his great math skills and giant hippocampus and the monogamous prairie voles, with their unisex hippocampus. But when it comes to humans, “Men are far more like women than they are like voles, even male voles,” Zuk writes. “This statement seems to require much more vigorous assertion than one might think, perhaps because we are often so intent on scrutinizing the world for differences that support our biases.”

Beyond the wish to compare humans to other species, Zuk is bemused by people’s attitudes toward different species of animals. She describes an incident when, while working at a Southern California museum in the 1970s, someone brought in a dying loon. The loon died in the arms of the would-be rescuer, who identified himself as Wing Bamboo. Persuaded by Zuk to leave the loon’s body behind to become a museum specimen, Bamboo bade it farewell, saying, “Goodbye, Brother Loon.” She wondered, she says, why he claimed kinship with a bird he knew nothing about — she had to tell him its species — and “why ‘brother’ and not ‘sister’?”

Later in the book she grumbles about the unlikelihood that Wing Bamboo would have made the same effort for Brother Earwig. It seems that we must be careful when thinking about animals, even when we are not consciously making a comparison.

In short, there are serious limits to what we can learn about our own behavior from studying animal behavior. Zuk doesn’t see this as a problem, since she’s interested in animals (even earwigs) for their own sakes, and finds it restful to look at nature without an agenda. Not only that, “we should not be using animals to guide our ethics in the first place, regardless of which side of the social or political fence we prefer.”

Looking at an orgiastic writhing ball of mating snakes, and pondering the fact that female adders mate with many males, Zuk does not conclude that all males are beasts nor that we must reclaim the female as sexually empowered earth-goddess, but that animals are interesting to study and that not all stories have morals. “Sometimes … snake sex is only about sex in snakes.”