Perfect Planet, Clever Species: How Unique Are We?

by William C. Burger

For many years the federal government funded the Search for Extraterrestrial Intelligence (SETI), later popularized by Carl Sagan's novel Contact and the movie starring Jodie Foster. Though in actuality SETI never did make contact with signals from an alien civilization, the search continues to this day through privately funded endeavors. How likely is it that intelligent life exists elsewhere in the universe? This is the intriguing question that has prompted William Burger's illuminating and absorbing exploration of the unusual circumstances surrounding life on earth.
Examining the critical episodes in our planet's early history and the peculiar trajectory of life on our world, Burger shows that the long odyssey of planet Earth may be utterly unique in our galaxy. For example, he describes features of the sun that are far from average. By some estimates, 95 percent of the other stars in the Milky Way galaxy are smaller, and it is unlikely that any of them could supply the energy requirements for a life-sustaining planet such as our own. Earth, as the third planet from the sun, sits within the "Goldilocks" it is in the perfect position to receive not too much heat (like Mercury and Venus) and not too little (like more distant planets of the solar system) but just the right amount to foster the development of life.
Turning to the evolution of life itself, Burger points out a host of amazing accidents (for example, the extinction of dinosaurs and the proliferation of flowering plants) that make the steps along the way to Homo sapiens seem like very rare events indeed. He also calls attention to the curious fact that the early hominid brain tripled in size over the relatively short time period leading to the appearance of modern human beings. Finally, he notes aspects of humanity's cultural evolution that seem unlikely to have been duplicated anywhere else.
Burger's enlightening evaluation of evolutionary and cosmic history, full of fascinating details, shows that the human achievement may be unique in our galaxy.

345 pages, Hardcover

First published September 1, 2002

Reviews

[Dennis Littrell · Rating 5 out of 5]

Really outstanding book with one major flaw

This is an outstanding recapitulation of who we are and how we got that way written by a wise and learned man. William Burger, who is Curator Emeritus at the Field Museum of Natural History in Chicago, begins with our sun and its place in the universe and ends with reflections on human beings and how rare we might be. Along the way he demonstrates that he is well-grounded in a variety of disciplines, including most especially evolutionary biology. I found his insights into the discoveries of science most interesting and edifying. I especially liked his clear prose and forthright statements shorn of humbug and euphemism.

Strange to say, however, I am not in agreement with the spirit of his central thesis. While it is true that we human beings are unique in the most technical sense of the term, just as every fingerprint is unique, it is questionable whether the essence of who and what we are as intelligent beings is unique in this unimaginably vast universe. Indeed, I am amazed that Burger, who is so objective about our savage tenancies as well as our incredible ability to manipulate our environment to our perceived advantage, can be so, shall we say, myopic in his inability to see the possibilities in the wider scheme of things.

Near the end of the book he recalls the famous Drake Equation, and as others have done, examines each of the factors and comes to the conclusion that it may very well be that we are the only intelligence species extant in the galaxy.

I have pointed out the fallacies inherent in such an endeavor elsewhere, but let me note here that at least 90% of the matter in the universe is still a complete mystery to us. While it is technically feasible to say that intelligent life as we know it; that is, carbon-based life dependent upon liquid water, etc, may very well be rare in our galaxy, it is a mistake to suppose that any convincing argument against the existence of intelligence life itself has been made.

There is also a peculiar fallacy in the argument (sustained throughout the book) that there is something marvelous or probabilistically rare in the unique series of events that have characterized the odyssey (as Burger calls it) of our planet's "perfect" history, leading to our rise. This argument can be seen as a sidebar to the "anthropic cosmological principle," which I like to call the "anthropic cosmological fallacy," in the sense that we are here only because of a miraculous series of events, when in fact we are here precisely because of those events. The fallacy can be seen in being dealt the following hand at poker: the nine of hearts, the five of clubs, the king spades, the eight of spades, and the trey of diamonds. This is quite an amazing hand. The odds against it being dealt are 2,598,959 to 1! (same as the odds against being dealt a royal flush in, say, diamonds). It is only our perspective that makes the one hand seem commonplace and the other miraculous.

Burger writes, "However unlikely our odyssey, the incontrovertible fact is that our planet, our solar system, and our star are ideally configured for the development of intelligent life..." (p. 290)

This is not only ex-post facto reasoning, it is misleading since beings living near (or even on, for all we know) a brown dwarf may make a similar observation, citing the congenial warmth of their star and the lack of "visible" radiation as part of the unique factors that make their life possible. They might even point to how "lucky" they are at being particularly good at sensing the surfaces of things, a talent that would not have developed in a "sighted" world, a talent that has allowed an intelligence of a particularly high order to evolve.

Earlier in the book, Burger argues convincingly that it was the stresses and demands of inter-group war (a biological arms race within our species) that promoted the rapid grown of our brains. This is a fine insight. However on page 280 Burger writes that without our stabilizing moon, "a badly wobbling planet...[would] put huge stresses on terrestrial vegetation and the animals it supports." His conclusion is that without the "accident" of our precisely perfect moon, intelligent life is unlikely to have evolved. But, to recall his own reasoning, is it not possible that the "stresses" of a "wobbling planet" could lead to compensations by life forms, perhaps even serving as a factor in the growth of intelligence?

Burger concedes that bacterial life may be common in the universe and that there may even be life under the surface of frozen worlds, as on Jupiter's moon, Europa. However he writes that "Such an environment...won't give rise to complex life-forms that are hungry for energy." He adds, as though in explanation, that "there's not a lot of energy available." (p. 277) But, it is hard to see how such an explanation explains anything. When there is a scarcity, perhaps it is the other way around: creatures then become even cleverer at finding what they need.

I wish I had more space to talk about the rest of this excellent book and to point to the many fine observations made by Burger and to celebrate the 99% of his book which is wonderful and a delight to read. I have cited his idea that war is what has swelled our brains (see p. 211). That argument alone is worth the price of the book, but there are many others, including a devastating critique of the possibility of interstellar travel to colonize the galaxy beginning on page 272. I also liked the many sharp and candid statements that sparkle the text. Here's one to think about:

"Killing members of our own group is murder, but killing members of other groups is the fastest way for a male to gain social prestige." (p. 215)


--Dennis Littrell, author of “The World Is Not as We Think It Is”