Stephen Jay Gould's death in 2002 opened up the position of our most celebrated scientist-seer, a post currently filled in Britain by Richard Dawkins. The job requirements seem to include starting out as a specialist in one of the life sciences and then developing a taste for generalizing about humanity. Among the contenders: Gould's old rival, Edward O. Wilson (author of Sociobiology and Consilience) and the younger Steven Pinker (How the Mind Works and The Blank Slate).

In 2005, UCLA geographer and physiologist Jared Diamond has made his bid, becoming omnipresent in the media with

• An environmentalist bestseller, Collapse: How Societies Choose to Fail or Succeed.

• An exhibit at the LA Natural History Museum based on Collapse.

• A three part documentary currently showing on PBS based on his 1997 Pulitzer Prize winner Guns, Germs, and Steel: The Fates of Human Societies, which stars Diamond and his Captain Ahab beard.

(Note that Diamond is not shy about giving his books ambitious subtitles!)

Before Diamond began writing for a popular audience, around his 50th birthday in 1987, he was a professor at UCLA's medical school and a leading birdwatcher in New Guinea. His early magazine articles in Discover and Natural History were collected in his initial and, to my mind, best book, The Third Chimpanzee: The Evolution and Future of the Human Animal. His subsequent big books, Guns, Germs, and Steel and Collapse, were both sketched out in tour de force chapters in The Third Chimpanzee.

The power-to-weight ratio of Diamond's writing didn't improve when he expanded them into doorstop books. As a prose stylist, Diamond, while perfectly adequate, isn't quite in the same class as Gould, Dawkins, Wilson, or Pinker, and his long books can be a tough slog.

Third Chimpanzee was also distinguished by a fair degree of courage. Diamond tackled politically incorrect questions like: Why did most of the big mammals that lived in North America at the time the Indians arrived—such as wooly mammoths, camels, and horses—go extinct so quickly after the first Indians arrived across the Bering Strait?

Diamond's answer: the Indians ate them.

In fact, back in 1986 Diamond published a study in Nature that is so unfit for polite society that it would probably get him lynched by his current admirers if they ever heard of it: "Ethnic Differences: Variations in Human Testis Size." Personally, I don't have a lot of first-hand experience, so I couldn't give you my opinion on the validity of Diamond's findings on racial differences in testicle size. But Diamond seemed pretty fascinated by the subject.

Unfortunately, the market for the uncomfortable truths is a lot smaller than the market for what people want to hear. So after his initial book, Diamond remained a cult figure.

But Diamond has certainly solved that problem. He turned to the topic of race, offering impressive-sounding rationalizations for what intellectuals wanted to believe anyway.

Diamond helped launch the Race Does Not Exist fad with his November, 1994 Discover article "Race Without Color." In this, he suggested that we could define races on any physical characteristic we chose. Norwegians and Nigerian Fulanis could belong to the Lactose Tolerant race and Japanese and Nigerian Ibos belong to the Lactose Intolerant race.

The reason that defining Fulanis and Ibo as belonging to separate races is obviously ridiculous is because the most useful definition of race is not built on any particular trait. Instead, it's built on ancestry. We all intuitively know that Fulanis and Ibos are more racially similar to each other because they have more recent ancestors in common with each other than they do with Norwegians or Japanese. Race starts with boy meets girl, followed by baby.

That line of thought suggests that the most useful definition of a racial group is "a partly inbred extended family," as I pointed out a few years later in response to Diamond.

But, when it comes to race, obfuscation pays a lot better than illumination.

Diamond turned himself into Jared Diamond, Superstar! with his 1997 bestseller Guns, Germs, and Steel. This book purported to Disprove Racism, which he defined tendentiously as merely believing that genetic differences in human capabilities along racial lines exist.

This book certainly made him a fixture as a speaker at the tonier sort of conference. (For instance, I saw Diamond at legendary financier Michael Milken's annual confab.)

Diamond's goal in his book was to explain why Eurasians conquered Africans, Australians, and Americans instead of the other way around. Conventional social scientists shy away from such a fundamental question out of fear of what they might find. And Diamond duly proclaimed genetic explanations "racist" and "loathsome." He set out to reaffirm the equality of humanity by showing the radical inequality of the continents. To him, the three most important engines of history were location, location, and location.

Diamond asked:

"Why didn't rhino-mounted Bantu warriors swarm north to decimate horse-mounted Romans and create an empire that spanned Africa and Europe?"

His answer: rhinos and other African animals are impossible to domesticate, unlike Eurasian beasts such as horses and cattle.

Guns, Germs, and Steel contained a lot of useful information and reasonable speculation. But a little thought raises serious questions:

• Not all sub-Saharan Africans lack domestic animals. For instance, the Fulanis are mostly lactose tolerant precisely because they evolved an ability to drink cow's milk as adults because they herd cattle on a massive scale.

• It's true that Africans never domesticated the ostrich, but a Mr. Hardy pulled off the trick in the 19th Century. In the late nineteenth century, South African farmers raised almost a million of these 300-pound birds to supply the fancy hat industry with feathers.

• Most strikingly, Diamond failed to recall that elephant-mounted African warriors did swarm north to decimate horse-mounted Romans and almost create an empire that spanned Africa and Europe in perhaps the most famous feat of ancient warfare: Hannibal crossing the Alps. (Although a biopic with Denzel Washington as Hannibal has long been under development in Hollywood, the North African Carthaginians were actually the Semitic descendents of the Levantine Phoenicians.)

But those are quibbles compared to the central contradiction in Guns, Germs, and Steel: Diamond makes environmental differences between the continents seem so compelling that it's hard to believe that humans would not become somewhat genetically adapted to their homelands through natural selection.

Most of his readers must have assumed that natural selection can't work fast enough to diversify humans. But Diamond knows that's not true, as his lactose tolerance illustration demonstrated.

This mutation didn't begin to spread until people started milking animals sometime in the last 13,000 years. However, by now 98 percent of Swedes are lactose tolerant as adults versus two percent of Thais.

This example of human biodiversity is hardly trivial: evolving the ability to digest milk has had a sizable economic and cultural impact on, say, the Swiss.

Self-defeatingly, Diamond began Guns, Germs, and Steel by making a eugenic argument that New Guineans are smarter than whites because "natural selection promoting genes for intelligence has probably been far more ruthless in New Guinea than in more densely populated, politically complex societies…"

Of course, the reality is actually that while New Guineans are, on average, no doubt better at Stone Age life than you or I would be, people whose ancestors have survived for many generations in "densely populated, politically complex societies" tend to be better at functioning in the modern world.

As far as I can tell, Diamond only lectures, never debates. I've never heard of him ever allowing himself to be dragged into a public discussion with a well-informed opponent.

I talked to Diamond once after he gave a speech. We were chatting nicely until I asked him a tough question along the lines outlined above: Wouldn't different agricultural environments select for different hereditary traits in different locales?

I mentioned how James Q. Wilson's The Marriage Problem has a couple of chapters on how tropical agriculture in West Africa affects family structures. Since women can raise enough food to feed their kids, men don't invest as much in their individual children. So wouldn't the kind of man with the most surviving children be different in a tropical agricultural environment, where he doesn't need to work too much to support them, than in a temperate agricultural environment, where he does?

Now, Diamond has spent a lot of time birdwatching in New Guinea, which is similar to Africa. So he knows all about what tropical agriculture selects for. But he had no intention of touching that tar-baby with a ten-foot pole. To get away from me and my question, he grabbed his papers and literally dog-trotted at about 5 mph out of the auditorium!

Diamond can run, but he won't be able to hide from the facts forever. I hear there are now several scientific papers in the publication pipeline about racial differences in genes that affect cognition and personality, each comparable in importance to the recent blockbuster paper on the genetic roots of Ashkenazi Jewish IQ,

Diamond's latest bestseller, Collapse, is about "ecocide" or unintentional ecological suicide, due to environmental disasters such as deforestation. Ecological concerns are pooh-poohed by many free-market ideologues, but environmental problems, which economists call "externalities," are indeed inherent in any economic system. And Diamond supplies a lot of useful, if overstated, information.

But "ecocide," while significant, is less important than Diamond implies. That's why he spends so much time on trivial edge-of-the-world doomed cultures, like the Vikings in Greenland and the Polynesians on Easter Island, rather than on more important collapses such as the decline and fall of the Roman Empire.

Generally, homicide, not suicide, is the main cause of collapse. Societies get invaded and overwhelmed.

Diamond cites the disappearance of the Maya—but what about the Aztecs and the Incas, still going strong when the Spanish arrived? He points to the Anasazi Indians—but there were also the Cherokee, the Sioux, and countless others. He notes the Easter Islanders—but I counter with the Maoris, the Tasmanians, the Australian Aborigines, the Chatham Islanders (exterminated by the Maori), and so forth. He cites the Vikings in Greenland—but how about the Saxons in Britain and the Arabs in Sicily, both conquered by descendents of the Vikings?

Still, Collapse can be valuable, especially if you look for the parts where Diamond shows more courage than is normal for him these days.

A close reading demonstrates that Diamond is quite unenthusiastic about mass immigration. For instance, in his chapter about the ecological fragility of Australia, he relays this optimistic hope for better policy in the future: "Contrary to their government and business leaders, 70 percent of Australians say they want less rather than more immigration."

Diamond also points out that the quality of immigrants matters. In an interesting chapter comparing the two countries that share the island of Hispaniola, the mediocre but livable Dominican Republic and dreadful Haiti, he notes that one reason the Dominican Republic is now both more prosperous and less deforested and eroded than tragic Haiti is the difference in their people:

"… the Dominican Republic, with its Spanish-speaking population of predominantly European ancestry, was both more receptive and more attractive to European immigrants and investors than was Haiti with its Creole-speaking population composed overwhelmingly of black former slaves."

Ironically, when I left the "Collapse" exhibit, with its warnings about overpopulation, at Los Angeles's Natural History museum, I turned out of the parking lot onto Martin Luther King Boulevard, where the billboards were in Spanish. In LA, the African Americans have been pushed off even MLK Blvd. by Latin American immigrants.

Diamond writes:

"I have seen how Southern California has changed over the last 39 years, mostly in ways that make it less appealing… The complaints voiced by virtually everybody in Los Angeles are those directly related to our growing and already high population… While there are optimists who explain in the abstract why increased population will be good and how the world can accommodate it, I have never met an Angeleno … who personally expressed a desire for increased population in the area where he or she personally lived... California's population growth is accelerating, due almost entirely to immigration and to the large average family sizes of the immigrants after their arrival."

Unfortunately, Diamond's bravery then breaks down again. Rather than call for doing something about immigration, such as enforcement of the laws against illegal immigration, he merely laments, "The border between California and Mexico is long and impossible to patrol effectively …"

No, it's not. Israel, with two percent of America's population, is successfully fencing off its West Bank border, which is ten percent as long.

In another important section, Diamond illustrates how ethnic diversity makes environmental cooperation more difficult. He praises the Dutch as the most cooperative nation on earth and attributes their awareness of and willingness to tackle problems to their shared memory of the 1953 flood that drowned 2,000 Netherlanders living below sea level. (Unfortunately, he doesn't mention whether Holland's rapidly growing immigrant Muslim population remembers when the dikes failed 52 years ago.)

Diamond notes that there are three possible solutions to what Garrett Hardin called "the tragedy of the commons," or the tendency for individuals to over-consume resources and under-invest in responsibilities held in common, leading to ecological collapse.

• Government diktat.

• Privatization and property rights — but that's impractical with some resources, such as fish.

• "The remaining solution to the tragedy of the commons is for the consumers to recognize their common interests and to design, obey, and enforce prudent harvesting quotas themselves. That is likely to happen only if a whole series of conditions is met: the consumers form a homogenous group; they have learned to trust and communicate with each other; they expect to share a common future and to pass on the resource to their heirs; they are capable of and permitted to organize and police themselves; and the boundaries of the resource and of its pool of consumers are well defined." (My emphasis)

Wow!

(A classic supporting case that that Diamond doesn't bring up: American shrimp fishermen in Texas were universally denounced as racists in the late 1970s when they resisted the government's efforts to encourage Vietnamese refugees to become shrimpers in their waters. French director Louis Malle made a movie, Alamo Bay, denouncing ugly Americans fighting hardworking immigrants.

(What got lost in all the tsk-tsking is that fishing communities always resist newcomers, especially hardworking ones, because of the sizable chance that the outsiders who don't know the local rules or don't care about them will ruin the ecological balance and wipe out the stocks of fish—all things for which Vietnamese fishermen are now notorious).

The evidence Diamond assembles indicates, although of course he never dares to state it bluntly, that the fundamental requirement for dealing effectively with environmental danger is: start with a population that's limited in number, cohesive, educated, and affluent.

Needless to say, mass immigration from the Third World works against all those characteristics.

My conclusion: keep in mind while reading Diamond's bestsellers that, after a promising start, he mostly sold out to political correctness. Then you can salvage something from his books.

It's not edifying behavior from a tenured professor—but in the current climate, we have to take what we can get.

[Steve Sailer [email him] is founder of the Human Biodiversity Institute and movie critic for The American Conservative. His website www.iSteve.blogspot.com features his daily blog.]