Darwin's Dangerous Idea (46 page)

adaptationists.

They soon turned these handicaps to good uses, however, or at least made Consider the greater honey guide,
Indicator indicator,
an African bird that compensations for them: their upright, bipedal posture, their subcutaneous owes its name to its talent for leading human beings to wild beehives hidden layer of fat, their hairlessness, perspiration, tears, inability to respond to salt in the forest. When the Boran people of Kenya want to find honey, they call deprivation in standard mammalian ways, and, of course, the diving reflex—

for the bird by blowing on whistles made of sculpted snail shells. When a which permits even newborn human infants to survive sudden submersion in bird arrives, it flies around them, singing a special song—its "follow-water for long periods with no ill effects. The details—and there are many, many more—are so ingenious, and the whole aquatic-ape theory is so shockingly antiestablishment, that I for one would
love
to see it vindicated.

That does not make it true, of course.

attention to the rhetoric than the arguments: "The critique by Gould and Lewontin has The fact that its principal exponent these days is not only a woman, Elaine had little impact on practitioners, perhaps because they were seen as hostile to the whole enterprise, and not merely to careless practise of it" (Maynard Smith 1988, p. 89).

Morgan, but an amateur, a science writer without proper official credentials 6. Kipling began publishing the individual stories in 1897.

244 SEARCHING FOR QUALITY

The Leibnizian Paradigm
245

in spite of her substantial researches, makes the prospect of vindication all the responded with admirable clarity, however, to the objections that had been more enticing.7 The establishment has responded quite ferociously to her lodged to date, and usefully contrasted the strengths and weaknesses of the challenges, mostly treating them as beneath notice, but occasionally aquatic-ape theory to those of the establishment's history. And, more recently subjecting them to withering rebuttal.8 This is not necessarily a pathological still, a book has appeared that collects essays by a variety of experts, for and reaction. Most uncredentialed proponents of scientific "revolutions" are against the aquatic-ape theory: Roede et al. 1991. The tentative verdict of the kooks who really are not worth paying any attention to. There really are a lot organizers of the 1987 conference from which that book sprang (p. 324 ) is of them besieging us, and life is too short to give each uninvited hypothesis that, "while there are a number of arguments favoring the AAT, they are not its proper day in court. But in this case, I wonder; many of the sufficiently convincing to counteract the arguments against it." That judicious counterarguments seem awfully thin and
ad hoc.
During the last few years, note of mild disparagement helps ensure that the argument will continue, when I have found myself in the company of distinguished biologists, evo-perhaps even with less rancor; it will be interesting to see where it all comes lutionary theorists, paleo-anthropologists, and other experts, I have often out.

asked them just to tell me, please, exactly why Elaine Morgan must be wrong My point in raising the aquatic-ape theory is not to defend it against the about the aquatic-ape theory. I haven't yet had a reply worth mentioning, establishment view, but to use it as an illustration of a deeper worry. Many aside from those who admit, with a twinkle in their eyes, that they have often biologists would like to say, "A pox on both your houses!" Morgan (1990) wondered the same thing. There seems to be nothing
inherently
impossible deftly exposes the hand-waving and wishful thinking that have gone into the about the idea, other mammals have made the plunge, after all. Why couldn't establishment's tale about how—and
why
—
Homo sapiens
developed biped-our ancestors have started back into the ocean and then retreated, bearing alism, sweating, and hairlessness on the savanna, not the seashore. Their some telltale scars of this history?

stories may not be literally as fishy as hers, but some of them are pretty Morgan may be "accused" of telling a good story—she certainly has—but farfetched; they are every bit as speculative, and (I venture to say ) no better not of declining to try to test it. On the contrary, she has used the story as confirmed. What they mainly have going for them, so far as I can see, is that leverage to coax a host of surprising predictions out of a variety of fields, and they occupied the high ground in the textbooks before Hardy and Morgan has been willing to adjust her theory when the results have demanded it.

tried to dislodge them. Both sides are indulging in adaptationist Just So Otherwise, she has stuck to her guns and, in fact, invited attack on her views Stories, and since
some story or other
must be true, we must not conclude we through the vehemence of her partisanship. As so often happens in such a have found
the
story just because we have come up with
a
story that seems to confrontation, the intransigence and defensiveness, on both sides, have begun fit the facts. To the extent that adaptationists have been less than energetic in to take their toll, creating one of those spectacles that then discourage anyone seeking further confirmation (or dreaded disconfirmation) of their stories, this who just wants to know the truth from having anything more to do with the is certainly an excess that deserves criticism.9

subject. Morgan's latest book on the topic (1990)

But before leaving it at that, I want to point out that there are many adaptationist stories that
everybody
is happy to accept even though they 7. Sir Alister Hardy, the Linacre Professor of Zoology at Oxford, who originally proposed the theory, could hardly have been a more secure member of the scientific establishment, 9. The geneticist Steve Jones ( 1993, p. 20 ) gives us another case in point: There are more however.

than three hundred strikingly different species of cichlid fish in Lake Victoria. They are so different; how did they get there? "The conventional view is that Lake Victoria must once 8. For instance, there is no mention at all of the aquatic-ape theory, not even to dismiss have dried up into many small lakes to allow each species to evolve. Apart from the fish it, in two recent coffee-table books that include chapters on human evolution. Philip themselves, there is no evidence that this ever happened." Adaptationist stories
do
get Whitfield's
From So Simple a Beginning: The Book of Evolution
(1993) offers a few disconfirmed and abandoned, however. My favorite example is the now-discredited ex-paragraphs on the standard savanna theory of bipedalism. "The Primates' Progress," by planation of why certain sea turtles migrate all the way across the Atlantic between Africa Peter Andrews and Christopher Stringer, is a much longer essay on hominid evolution, in and South America, spawning on one side, feeding on the other. According to this all-The Book of Life (Stephen Jay Gould, ed., 1993b), but it, too, ignores the aquatic-ape too-reasonable story, the habit started when Africa and South America were first begin-theory—the AAT. And, adding insult to oblivion, there has also been a wickedly funny ning to split apart; at that time, the turtles were just going across the bay to spawn; the parody of it by Donald Symons (1983), exploring the radical hypothesis that our ances-distance grew imperceptibly longer over the eons, until their descendants dutifully cross tors used
to fly
—"The flying on air theory—FLOAT, as it is acronymously (acrimonian ocean to get to where their instinct still tells them to spawn. I gather that the timing ously, among the reactionary human evolution 'establishment')." For an overview of the of the breakup of Gondwanaland turns out not to match the evolutionary timetable for reactions, see G. Richards 1991

the turtles, sad to say, but wasn't it a cute idea?

The Leibnizian Paradigm
247

246 SEARCHING FOR QUALITY

The answer—which makes beautiful sense, in retrospect—is that, by having have never been "properly tested," just because they are too obviously true to a large prime number of years between appearances, the cicadas minimize be worth further testing. Does anybody seriously doubt that eyelids evolved the likelihood of being discovered and later tracked as a predictable feast by to protect the eye? But that very obviousness may hide good research predators who themselves show up every two years, or three years, or five questions from us. George Williams points out that concealed behind such years. If the cicadas had a periodicity of, say, sixteen years, then they would obvious facts may lie others that are well worth further investigation: be a rare treat for predators who showed up every year, but a more reliable A human eye blink takes about 50 milliseconds. That means that we are source of food for predators who showed up every two or four years, and an blind about 5% of the time when we are using our eyes normally. Many even-money gamble for predators that got in phase with them on an eight-events of importance can happen in 50 milliseconds, so that we might miss year schedule. If their period is not a multiple of any lower number, however, them entirely. A rock or spear thrown by a powerful adversary can travel they are a rare treat—not worth "trying" to track—for any species that isn't more than a meter in 50 milliseconds, and it could be important to per-lucky enough to have exactly their periodicity (or some multiple of it—the ceive such motion as accurately as possible. Why do we blink with both mythical Thirty-four-Year Locust-Muncher would be in fat city). I don't eyes simultaneously? Why not alternate and replace 95% visual attentive-know whether Lloyd and Dybas' Just So Story has been properly confirmed ness with 100% ? I can imagine an answer in some sort of trade-off balance.

yet, but I don't think Gould is guilty of Panglossianism in treating it as A blink mechanism for both eyes at once may be much simpler and cheaper established until proven otherwise. And if he really wants to ask and answer than one that regularly alternates. [G. Williams 1992, pp. 152-53]

"why" questions, he has no choice but to be an adaptationist.

The problem he and Lewontin perceive is that there are no standards for Williams has not himself yet attempted to confirm or disconnrm any hy-when a particular bit of adaptationist reasoning is too much of a good thing.

pothesis growing out of this exemplary piece of adaptationist problem-How serious, really, is this problem even if it has no principled "solution"?

setting, but he has called for the research by asking the question. It would be Darwin has taught us not to look for essences, for dividing lines between as pure an exercise in reverse engineering as can be imagined.

genuine
function or
genuine
intentionality and mere
on-its-way-to-being
function or intentionality. We commit a fundamental error if we think that if Serious consideration of why natural selection permits simultaneous blink-we want to indulge in adaptationist thinking we need a license and the only ing might yield otherwise elusive insights. What change in the machinery license could be the possession of a strict definition of or criterion for a would be needed to produce the first step towards my envisioned adaptive genuine adaptation. There are good rules of thumb to be followed by the alternation or simple independent timing? How might the change be prospective reverse engineer, made explicit years ago by George Williams (

achieved developmentally? What other changes would be expected from a 1966). ( 1) Don't invoke adaptation when other, lower-level, explanations are mutation that produced a slight lag in the blinking of one eye? How would available (such as physics). We don't have to ask what advantage accrues to selection act on such a mutation? [G. Williams 1992, p. 153]

maple trees that explains the tendency of their leaves to fall
down,
any more than the reverse engineers at Raytheon need to hunt for a reason why GE

Gould himself has endorsed some of the most daring and delicious of made their widgets so that they would melt readily in blast furnaces. (2) Don't adaptationist Just So Stories, such as the argument by Lloyd and Dybas invoke adaptation when a feature is the outcome of some general (1966) explaining why cicadas (such as "seventeen-year locusts") have developmental requirement. We don't need a special reason of increased reproductive cycles that are prime-numbered years long—thirteen years, or fitness to explain the fact that heads are attached to bodies, or limbs come in seventeen, but never fifteen or sixteen, for instance. "As evolutionists," Gould pairs, any more than the people at Raytheon need to explain why the parts in says, "we seek answers to the question, why. Why, in particular, should such GE's widget have so many edges and corners with right angles. ( 3 ) Don't striking synchroneity evolve, and why should the period between episodes of invoke adaptation when a feature is a by-product of another adaptation. We sexual reproduction be so long?" (Gould 1977a, p. 99 ).10

don't need to give an adaptationist explanation of the capacity of a bird's beak to groom its feathers (since the features of the

10. Gould has recently ( 1993a, p. 318) described his antiadaptationism as the "zeal of the Gould's attitude towards adaptationism is not so easily discerned, however.
The Book of
convert," and elsewhere ( 1991b, p. 13) confesses, "I sometimes wish that all copies of
Life
( 1993b) is packed with adaptationist reasoning that made it past his red pencil, and
Ever Since Darwin
would self-destruct," so perhaps he would recant these words today, thus presumably has his endorsement.

which would be a pity, since they eloquently express the rationale of adaptationism.

248 SEARCHING FOR QUALITY

The Leibnizian Paradigm
249

bird's beak are there for more pressing reasons), any more than we need a in drawing up and criticizing various legislative regimes. They are just not special explanation of the capacity of the GE widget's casing to shield the being Darwinian enough in their thinking. Better adaptationist thinking soon innards from ultraviolet rays.