Wills and Bada point out that researchers use two avenues to explore the origins of life, which they characterize as the bottom-up and top-down approaches. They describe these two approaches as “working toward the golden spike” of the creation of life, just as the western and eastern teams of the Union and Central Pacific Railroads did as they raced toward each other, finally meeting on Promontory Summit near Ogden, Utah, on May 10, 1869. It’s a curious analogy, drawn from the American frontier, and as becomes apparent later in their book, the search for life’s origins is intimately tied to the endeavors of the last American frontiersmen, the astronauts of NASA.
The Spark of Life is largely devoted to a discussion of the bottom-up approach, which progresses through experiments such as Miller’s, and through trying to determine from paleontological, astronomical, and chemical studies what the world might have been like at the time that life arose. The top-down approach is conducted via analysis of the chemistry of life, particularly the genetic material contained in all living things. It aims to find the common genetic features shared by all life in order to deter-mine what the original genetic configuration might have been like. Because genetic mutation occurs at a fairly regular rate (giving rise to the so-called molecular clock), the top-downers also hope that by calculating how many mutations have occurred they will be able to pinpoint just when life arose.
At about 11:00 AM on September 28, 1969, the bottom-up school received a gift from the heavens, a sort of Rosetta Stone which fell to earth near the town of Murchison, Victoria, in southern Australia. The Murchison meteorite, as it is now known, is a fragment of a “planetesimal” or small, solid fragment that condensed out of the solar nebula as the solar system formed. Most planetesimals aggregated to form planets, but the Murchison meteorite somehow escaped incorporation. It wandered the void of space for over four billion years until that September day in 1969, when it belatedly became incorporated into planet Earth.
The meteorite comprises 2.5 percent organic matter that is very similar to the organic goo generated by Miller in his experiments. The bottom-up school believe that this demonstrates that “somewhere in the far reaches of space, about 4.5 billion years ago… nature had carried out an experiment almost identical to Miller’s,” though just how this might have occurred remains unclear.
The Murchison meteorite is referred to repeatedly throughout Wills and Bada’s book. Analysis of its chemistry has formed the basis for new experiments, as well as reviving old ideas about how life might have been formed. The fact that when the organic matter from the meteorite is dissolved in water it forms bubbles, for example, has given new life to the idea, first postulated then discarded decades ago, that life might have begun in greasy bubbles which concentrated organic molecules and acted as primitive cell membranes.
So prestigious is the search for life’s origin that The Spark of Life is littered with the names of Nobel laureates, whose contributions are carefully documented, as is their institutional affiliation. Its final chapters concern the search for life beyond Earth. NASA looks set to champion this venture, for Daniel Goldin, its chief administrator, has become an enthusiastic supporter of the search for extraterrestrial life.
NASA is, like the transcontinental railway, a creature of the frontier, and if it is to survive in the current age it must identify green pastures somewhere beyond the known. Increased interest in the search for extraterrestrial life must have seemed like a godsend for the organization.
Many searchers for life beyond Earth seem to be possessed of an almost Panglossian optimism, and since their speculations include the entire universe, their optimism might seem justified; yet Wills and Bada document many earlier hopes that resulted in nothing but disappointment. In the early nineteenth century the moon was widely believed to be inhabited by four-foot-tall humanoids with wings. So convincing were the reports that the women of Boston began planning to contact the moon-dwellers in an attempt to convert them to Christianity. By the early twentieth century the focus had shifted to Mars and its apparently regularly laid out canals. For many Martian life seemed to be a certainty, though curiously, one of the stoutest skeptics of the idea of life on Mars was Alfred Russel Wallace, co-publisher with Darwin of the theory of evolution by natural selection. In 1907 Wallace (who lived a long life) wrote that because of a lack of water, “Mars is not only uninhabited by intelligent beings…but is absolutely UNINHABITABLE.” Only with the Mars landing, and its finding that Martian soil contains a highly reactive element that is apparently inimical to life, have most scientists been won over to Wallace’s view. And yet a few die-hards from NASA hold out, claiming to have found traces of life in a Martian meteorite, a finding now widely disbelieved.
In our own time Venus has been the field of speculation, Carl Sagan suggesting in 1967 that the planet might be inhabited by floating, balloonlike beings; yet closer inspection has made the existence of any life on Venus appear unlikely. Through all of these disproofs, the optimism of the true believers has remained invulnerable. In support of their conviction they quote statisticians who can prove that life must exist somewhere in the vastness of the universe. This debate, incidentally, remains vigorous, with some researchers postulating that millions of planets must support life, while others argue that we are most likely alone. Surely, these skeptics argue, if extraterrestrial life were at all common then the earth would have been colonized from space during its four-billion-year history. The doubters also dispute the value of spending the half-billion dollars that it will cost just to determine whether life exists on the latest frontier of the optimists—below the tens of kilometers of ice that cover Jupiter’s moon Europa.
The skeptics believe that the obsession with finding extraterrestrial life is unwarranted on other grounds, among them how poorly we understand life on our own planet. Steve Jones, in Darwin’s Ghost, does credit to their arguments, for he astonishes the reader with an analysis of life on Earth that makes Sagan’s Venusians look dull. Jones is an unabashed admirer and emulator of Darwin. “The Origin of Species is,” he writes, “without doubt, the book of the millennium… the high point of the literature of fact.” He describes his own work as an attempt “to read Charles Darwin’s mind with the benefit of scientific hindsight.” To do this, Jones uses the structure of Darwin’s Origin, filling out the arguments with modern examples, and reproducing verbatim Darwin’s own summaries of each of the chapters, along with Darwin’s recapitulation and conclusion.
Jones is not one to tolerate the slighting of his hero. We learn that in 1858, when Darwin and Wallace presented their ideas on evolution to the Linnaean Society of London, the society’s president, Thomas Bell, proclaimed that it had been a dull year, not being “marked by any of those striking discoveries which at once revolutionise…the department of science on which they bear.” Jones has made his own inquiries into Bell, describing him as “a dentist with an interest in reptiles” and later as a “reptilian dentist,” who published Kalygonomia, or the Laws of Female Beauty “with plates bound in a separate volume to allow them to be locked away from inquisitive eyes.”
Having disposed of Mr. Bell, Jones informs us that “science (unlike the arts) can be detached from those who do it,” and for that reason he includes the name of no living scientist in his book. Given the author’s adulation of Charles Darwin this is a curious decision, and one which makes it very difficult to track authority in this unreferenced work.
Apparently unafraid of appearing immodest, Jones tells us, “There is no obvious reason why the theory of evolution should attract the finest science writers, but it is so,” and Jones is indeed an entertaining writer, despite having spent thirty years studying snails. At his best he is capable of almost Johnsonian pronouncements, such as “age is a tax on sex, levied by natural selection.” Organization, however, is not his strong card, nor is continuity of argument or full explication of interesting facts. He moves through his material at such a breathtaking pace that the reader can feel that he or she is traversing a field of disconnected if sparkling examples on a runaway horse. Jones’s writing shares some characteristics with that of my favorite eccentric author, John Aubrey, for both are highly entertaining, yet somehow occasionally seem to miss the mark. (In Brief Lives Aubrey glosses William Shakespeare thus: “His father was a Butcher, and…when he was a boy he exercised his father’s Trade, but when he kill’d a calf, he would doe it in a high style, and make a speech… he had but little Latin, and lesse Greeke.”)
Darwin’s Ghost commences with a lambasting of American creationism, then jumps to a discussion of HIV-AIDS, which Jones informs us “contains in its brief history the entire argument of The Origin of Species: variation, a struggle for existence, and natural selection that in time leads to new forms of life.” Then on to the evolution of whales, where he includes a discussion of why Moby Dick was white (“an inherited defect in the ability to make the dark pigment called melanin”) and cetacean retroviruses. Next come our animal companions, where we learn in passing that in Darwin’s England “cats [were] not wholly despised as an article of diet” and that a notorious gang of cat-eaters in West Bromwich meant that fanciers couldn’t “keep a favourite a week.” Then Jones follows Darwin into the arcane world of the pigeon fancier (but not going so far as to join London’s smartest pigeon club, the Philoperisteron, as did Darwin). While a contemporary reader of Darwin lamented that The Origin had not included enough on pigeons (predicting that it “would soon be on every library table” if this section were lengthened), Jones cuts short discussion of the feathered tribes. Instead we get an exceedingly brief treatise on the domestication of wheat, followed by that of dogs. We learn that Linnaeus characterized man’s best friend by its possession of an upturned tail, the fact that it licks its wounds, is often infected with gonorrhea, and frequently urinates upon hearing certain music. Linnaeus clearly knew some strange dogs, among them, Jones informs us, the Naked Dog, the Fat Alco, and the Techichi.
Zoos also receive a cursory examination—“In one, the gorillas were given sausages and a pint of beer for breakfast…. When Philadelphia Zoo opened in 1874, its sloth was poked to death by umbrellas within a week”—in which is included an interesting discussion of how zoo animals respond to the selection imposed by their unnatural environment. Jones makes the point that zoo animals are under intense selective pressure for particular characteristics, not least of which is simply the ability to survive in such an alien environment. Human selective pressure can also be intense, as is made clear by the proliferation of albino tigers (with more than one hundred bred at Cincinnati Zoo alone), all of which are descended from a single male. The albinos are preferred by zookeepers simply because they draw such large crowds. Such selective breeding, along with the propensity of zookeepers to weed out savage, nervous, or intractable individuals, means that zoo animals are rapidly diverging from their wild ancestors.
It is perhaps inevitable that the great mass of material accumulated in Darwin’s Ghost includes some unfortunate errors, which become rather dense when Jones delves into the Southern Hemisphere. He tells us mistakenly that “dogs got to most of the world (except Africa…) as soon as humans did,” ignoring the 50,000-year gap between the arrival of dogs and humans in Australasia. He writes that “South Australia was once covered with a spiny scrub called the jarrah.” This “spiny scrub” is in fact a majestic, nonprickly eucalypt that reaches 135 feet in height and is restricted to high-rainfall areas in southwestern Australia. To state that South African fynbos, Australian kwongan, and Californian chaparral are “fire-resistant” is strange, for they are among the most fire-promoting plant communities known, with fynbos being reduced to little but ash after a blaze. Jones writes wistfully of the lungfish: “Now a mere half dozen kinds are left. They live a dreary existence,…shrouded in mud for much of the year. They are fossils, reminders of a universe now lost.” While it is true that the African and South American lungfish can spend considerable periods shrouded in mud, their Australian relative has no such ability and lives entirely in free water, as did many of its ancient relatives. By the time I reached the false assertions that “the southern beech of South America has close kin in…South Africa,” that “frogs are absent from all oceanic islands,” and that the aquatic form of the axolotl lacks legs, I was becoming skeptical of some of Jones’s more outlandish claims.
Despite its imperfections Darwin’s Ghost has a great deal of material to pique the reader’s interest and challenge the mind. Jones tackles the seemingly intractable problem of the evolution of imitation among butterflies. Some butterflies bear bright markings, which they have evolved as a warning to predators that they are poisonous or distasteful. Various nontoxic species of butterfly have come to imitate their intricate colors. They evidently evolved from well-camouflaged species that must have forsaken their protective coloring. Jones shows that both camouflage and mimicry offer protection, but any intermediate stage seems suicidal. “Quite how the insects traversed the valley of death…is not clear,” he writes with some understatement. In a more homely mood, Jones asks, “Why are twice as many left shoes as right washed ashore in Holland, while the opposite is true for Scottish beaches?” A curious fact indeed, and one for which Wills and Bada’s chromatographic potential of the tides might be invoked, but by this stage I was beginning to doubt whether even Jones’s basic “fact” is correct, and, if it isn’t, we are left with nothing to explain.
Charles Darwin once referred to his mind as “a machine for grinding general laws out of a large collection of facts.” Ever mindful of producing the most robust possible “general laws,” Darwin was careful about the “facts” he fed into his incredible machine, for their veracity was utterly essential to what he was trying to do. Here lies the greatest contrast between Darwin and his “ghostwriter” Jones.
A profound difference also exists between Wills and Bada’s The Spark of Life and Darwin’s The Origin of Species. Despite the fact that Darwin’s work would eventually open the way for removing the divine from the creation of life, nature and all of its creatures are treated with a sense of awe and wonder verging on reverence. “It is interesting to contemplate an entangled bank,” wrote Darwin at the end of his world-changing thesis,
clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been produced by laws acting around us…. There is grandeur in this view of life,…[that] from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
Wills and Bada’s The Spark of Life succeeds admirably in its goal of informing us of the state of research into life’s origin. Jones’s Darwin’s Ghost provides a witty, wide-ranging discourse on natural selection. In the end, however, neither combines erudition with humility and a sense of wonder at the world as Darwin did. Perhaps this is because our human society is becoming ever more like Darwin’s tangled river bank. It’s filling with highly specialized professionals, each capable of doing his or her job spectacularly well, but none able to view life as a whole, and wonder at it.