GOD'S UTILITY FUNCTION
- Richard Dawkins
Chapter from River Out of Eden
My clerical correspondent of the previous chapter found faith through a wasp.
Charles Darwin lost his with the help of another: “I cannot persuade myself,”
Darwin wrote, “that a beneficent and omnipotent God would have designedly created
the Ichneumonidae with the express intention of their feeding within the living
bodies of Caterpillars.” Actually Darwin’s gradual loss of faith, which he
downplayed for fear of upsetting his devout wife Emma, had more complex causes. His
reference to the Ichneumonidae was aphoristic. The macabre habits to which he
referred are shared by their cousins the digger wasps, whom we met in the previous
chapter. A female digger wasp not only lays her egg in a caterpillar (or
grasshopper or bee) so that her larva can feed on it but, according Fabre and
others, she carefully guides her sting into each ganglion of the prey’s central
nervous system, so as to paralyze it but not kill it. This way, the meat keeps
fresh. It is not known whether the paralysis acts as a general anesthetic, or if it
is like curare in just freezing the victim’s ability to move. If the latter, the
prey might be aware of being eaten alive from inside but unable to move a muscle to
do anything about it. This sounds savagely cruel but, as we shall see, nature is
not cruel, only pitilessly indifferent. This is one of the hardest lessons for
humans to learn. We cannot admit that things might be neither good nor evil,
neither cruel nor kind, but simply callous-indifferent to all suffering, lacking
all purpose.
We humans have purpose on the brain. We find it hard to look at anything without
wondering what it is “for”, what the motive for it is, or the purpose behind it.
When the obsession with purpose becomes pathological it is called paranoia-reading
malevolent purpose into what is actually random bad luck. But this is just and
exaggerated form of a nearly universal delusion. Show us almost any object or
process, and it is hard for us to resist the “Why” question-the “What is it for?”
question.
The desire to see purpose everywhere is a natural one in an animal that lives
surrounded by machines, works of art, tools and other designed artifacts; an
animal, moreover, whose waking thoughts are dominated by its own personal goals. A
car, a tin opener, a screwdriver and pitchfork all legitimately warrant the “What
is it for?” question. Our pagan forebears would have asked the same question about
thunder, eclipses, rocks and streams. Today we pride ourselves on having shaken off
such primitive animism. If a rock in a stream happens to serve as a convenient
steppingstone, we regard its usefulness as an accidental bonus, not a true purpose.
But the old temptation comes back with a vengeance when tragedy strikes-indeed, the
very word “strikes” is an animistic echo: “Why, oh why, did the
cancer/earthquake/hurricane have to strike my child?” And the same temptation is
often positively relished when the topic is the origin of all things or the
fundamental laws of physics, culminating in the vacuous existential question “Why
is there something rather than nothing?”
I have lost count of the number of times a member of the audience has stood up
after a public lecture I have given and said something like the following: “You
scientists are very good at answering ‘How’ questions. But you must admit you’re
powerless when it comes to ‘Why’ questions.” Prince Philip, Duke of Edinburgh, made
this very point when he was in an audience at Windsor addressed by my colleague Dr.
Peter Atkins. Behind the question there is always an unspoken but never justified
implication that since science is unable to answer “Why” questions, there must be
some other discipline that is qualified to answer them. This implication is, of
course, quite illogical.
I’m afraid that Dr. Atkins gave the Royal Why fairly short shrift. The mere fact
that it is possible to frame a question does not make it legitimate or sensible to
do so. There are many things about which you can ask, “What is its temperature?” or
“What color is it?” but you may not ask the temperature question or the color
question of, say, jealousy or prayer. Similarly, you are right to ask the “Why”
question of a bicycle’s mudguards or the Kariba Dam, but at the very least you have
no right to assume that the “Why” question deserves an answer when posed about a
boulder, a misfortune, Mt. Everest or the universe. Questions can be simply
inappropriate, however heartfelt their framing.
Somewhere between windscreen wipers and tin openers on the one hand and rocks and
the universe on the other lie living creatures. Living bodies and their organs are
objects that, unlike rocks, seem to have purpose written all over them.
Notoriously, of course, the apparent purposefulness of living bodies has dominated
the classic Argument from Design, invoked by theologians from Aquinas to William
Paley to modern “scientific” creationists.
The true process that has endowed wings and eyes, beaks, nesting instincts and
everything else about life with the strong illusion of purposeful design is now
well understood. It is Darwinian natural selection. Our understanding of this has
come astonishingly recently, in the last century and a half. Before Darwin, even
educated people who had abandoned “Why” questions for rocks, streams and eclipses
still implicitly accepted the legitimacy of the “Why” question where living
creatures were concerned. Now only the scientifically illiterate do. But “only”
conceals the unpalatable truth that we are still talking about an absolute
majority.
Actually, Darwinians do frame a kind of “Why” question about living things, but
they do so in special, metaphorical sense. Why do birds sing, and what are wings
for? Such questions would be accepted as a shorthand by modern Darwinians and would
be given sensible answers in terms of the natural selection of bird ancestors. The
illusion of purpose is so powerful that biologists themselves use the assumption of
good design as a working tool. As we saw in the previous chapter, long before his
epoch-making work on the bee dance Karl von Frisch discovered, in the teeth of
strong orthodox opinion to the contrary, that some insects have true color vision.
His clinching experiments were stimulated by the simple observation that bee-
pollinated flowers go to great trouble to manufacture colored pigments. Why would
they do this if bees were color-blind? The metaphor of purpose-more precisely, the
assumption that Darwinian selection is involved-is here being used to make a strong
inference about the world. It would have been quite wrong for von Frisch to have
said, “Flowers are colored, therefore bees must have color vision.” But it was
right for him to say, as he did, “Flowers are colored, therefore it is at least
worth my while working hard at some new experiments to test the hypothesis that
they have color vision.” What he found when he looked into the matter in detail was
that bees have good color vision but the spectrum they see is shifted relative to
ours. They can’t see red light (they might give the name “infra yellow” to what we
call red). But they can see into the range of shorter wavelengths we call
ultraviolet, and they see ultraviolet as a distinct color, sometimes called “bee
purple”.
When he realized that bees see in the ultraviolet part of the spectrum, von Frisch
again did some reasoning using the metaphor of purpose. What, he asked himself, do
bees use their ultraviolet sense for? His thought returned full circle-to flowers.
Although we can’t see ultraviolet light, we can make photographic film that is
sensitive to it, and we can make filters that are transparent to ultraviolet light
but cut out “visible” light. Acting on his hunch, von Frisch took some ultraviolet
photographs of flowers. To his delight, he saw patterns of spots and stripes that
no human eye had ever seen before. Flowers that to us look white or yellow are in
fact decorated with ultraviolet patterns, which often serve as runway markers to
guide the bees to the nectaries. The assumption of apparent purpose had paid off
once again: flowers, if they were will designed, would exploit the fact that bees
can see ultraviolet wavelengths.
When he was an old man, von Frisch’s most famous work-on the dance of the bees,
which we discussed in the last chapter-was called into question by an American
biologist named Adrian Wenner. Fortunately, von Frisch lived long enough to see his
work vindicated by another American, James L. Gould, now at Princeton, in one of
the most brilliantly conceived experiments of all biology. I’ll briefly tell the
story, because it is relevant to my point about the power of the “as if designed”
assumption.
Wenner and his colleagues did not deny that the dance happens. They did not even
deny that it contains all the information von Frisch said it did. What they did
deny is that other bees read the dance. Yes, Wenner said, it is true that the
direction of the straight run of the waggle dance relative to the vertical is
related to the direction of food relative to the sun. But no, other bees don’t
receive this information from the dance. Yes, it is true that the rates of various
things in the dance can be read as information about the distance of food. But
there is no good evidence that the other bees read the information. They could be
ignoring it. Von Frisch’s evidence, the skeptics said, was flawed, and when they
repeated his experiments with proper “controls” (that is, by taking care of
alternative means by which bees might find food), the experiments no longer
supported von Frisch’s dance-language hypothesis.
This was where Jim Gould came into the story with his exquisitely ingenious
experiments. Gould exploited a long-known fact about honeybees, which you will
remember from the previous chapter. Although they usually dance in the dark, using
the straight-up direction in the vertical plane as a coded token of the sun’s
direction in the horizontal plane, they will effortlessly switch to a possibly more
ancestral way of doing things if you turn on a light inside the hive. They then
forget all about gravity and use the lightbulb as their token sun, allowing it to
determine the angle of the dance directly. Fortunately, no misunderstandings arise
when the dancer switches her allegiance from gravity to the lightbulb. The other
bees “reading” the dance switch their allegiance in the same way, so the dance
still carries the same meaning: the other bees still head off looking for food in
the direction the dancer intended.
Now for Jim Gould’s masterstroke. He painted a dancing bee’s eyes over with black
shellac, so that she couldn’t see the lightbulb. She therefore danced using the
normal gravity convention. But the other bees following her dance, not being
blindfolded, could see the lightbulb. They interpreted the dance as if the gravity
convention had been dropped and replaced by the lightbulb “sun” convention. The
dance followers measured the angle of the dance relative to the light, whereas the
dancer herself was aligning it relative to gravity. Gould was, in effect, forcing
the dancing bee to lie about the direction of the food. Not just lie in a general
sense, but lie in a particular direction that Gould could precisely manipulate. He
did the experiment not with just one blindfolded bee, of course, but with a proper
statistical sample of bees and variously manipulated angles. And it worked. Von
Frisch’s original dance-language hypothesis was triumphantly vindicated.
I didn’t tell this story for fun. I wanted to make a point about the negative as
well as the positive aspects of the assumption of good design. When I first read
the skeptical papers of Wenner and his colleagues, I was openly derisive. And this
was not a good thing to be, even though Wenner eventually turned out to be wrong.
My derision was based entirely on the “good design” assumption. Wenner was not,
after all, denying that the dance happened, nor that it embodied all the
information von Frisch had claimed about the distance an direction of food. Wenner
simply denied that the other bee read the information. And this was too much for me
and many other Darwinian biologists to stomach. The dance was so complicated, so
richly contrived, so finely tuned to its apparent purpose of informing other bees
of the distance and direction of food. This fine tuning could not have come about,
in our view, other than by natural selection. In a way, we fell into the same trap
as creationists do when they contemplate the wonders of life. The dance simply had
to be doing something useful, and this presumably meant helping foragers to find
food. Moreover, those very aspects of the dance that were so finely tuned-the
relationship of its angle and speed to the direction and distance of food-had to be
doing something useful too. Therefore, in our view, Wenner just had to be wrong. So
confident was I that, even if I had been ingenious enough to think of Gould’s
blindfolded experiment (which I certainly wasn’t), I would not have bothered to do
it.
Gould not only was ingenious enough to think of the experiment but he also bothered
to do it, because he was not seduced by the good-design assumption. It is a fine
tightrope we are walking, however, because I suspect that Gould-like von Frisch
before him, in his color research-had enough of the good-design assumption in his
head to believe that his remarkable experiment had a respectable chance of success
and was therefore worth spending time and effort on.
I now want to introduce two technical terms, “reverse engineering” and “utility
function”. In this section, I am influenced by Daniel Dennett’s superb book
Darwin’s Dangerous Idea. Reverse engineering is a technique of reasoning that works
like this. You are an engineer, confronted with an artifact you have found and
don’t understand. You make the working assumption that it was designed for some
purpose. You dissect and analyze the object with a view to working out what problem
it would be good at solving: “If I had wanted to make a machine to do so-and-so,
would I have made it like this? Or is the object better explained as a machine
designed to do such-and-such?”
The slide rule, talisman until recently of the honorable profession of engineer, is
in the electronic age as obsolete as any Bronze Age relic. An archaeologist of the
future, finding a slide rule and wondering about it, might note that it is handy
for drawing straight lines or for buttering bread. But to assume that either of
these was its original purpose violates the economy assumption. A mere straight-
edge or butter knife would not have needed a sliding member in the middle of the
rule. Moreover, if you examine the spacing of the graticules you find precise
logarithmic scales, too meticulously disposed to be accidental. It would dawn on
the archaeologist that, in an age before electronic calculators, this pattern would
constitute an ingenious trick for rapid multiplication and division. The mystery of
the slide rule would be solved by reverse engineering, employing the assumption of
intelligent and economical design.
“Utility function” is a technical term not of engineers but of economists. It means
“that which is maximized.” Economic planners and social engineers are rather like
architects and real engineers in that they strive to maximize something.
Utilitarians strive to maximize “the greatest happiness for the greatest number” (a
phrase that sounds more intelligent than it is, by the way). Under this umbrella,
the utilitarian may give long-term stability more or less priority at the expense
of short-term happiness, and utilitarians differ over whether they measure
“happiness” by monetary wealth, job satisfaction, cultural fulfillment or personal
relationships. Others avowedly maximize their own happiness at the expense of the
common welfare, and they may dignify their egoism by a philosophy that states that
general happiness will be maximized if one takes care of oneself. By watching the
behavior of individuals throughout their lives, you should be able to reverse-
engineer their utility functions. If you reverse-engineer the behavior of a
country’s government, you may conclude that what is being maximized is employment
and universal welfare. For another country, the utility function may turn out to be
the continued power of the president, or the wealth of a particular ruling family,
the size of the sultan’s harem, the stability of the Middle East or maintaining the
price of oil. The point is that more than one utility function can be imagined. It
isn’t always obvious what individuals, or firms, or governments are striving to
maximize. But it is probably safe to assume that they are maximizing something.
This is because Homo sapiens is a deeply purpose-ridden species. The principle
holds good even if the utility function turns out to be a weighted sum or some
other complicated function of many inputs.
Let us return to living bodies and try to extract their utility function. There
could be many but, revealingly, it will eventually turn out that they all reduce to
one. A good way to dramatize our task is to imagine that living creatures were made
by a Divine Engineer and try to work out, by reverse engineering, what the Engineer
was trying to maximize: What was God’s Utility Function?
Cheetahs give every indication of being superbly designed for something, and it
should be easy enough to reverse-engineer them and work out their utility function.
They appear to be well designed to kill antelopes. The teeth, claws, eyes, nose,
leg muscles, backbone and brain of a cheetah are all precisely what we should
expect if God’s purpose in designing cheetahs was to maximize deaths among
antelopes. Conversely, if we reverse-engineer an antelope we find equally
impressive evidence of design for precisely the opposite end: the survival of
antelopes and starvation among cheetahs. It is as though cheetahs had been designed
by one deity and antelopes by a rival deity. Alternatively, if there is only one
Creator who made the tiger and the lamb, the cheetah and the gazelle, what is He
playing at? Is He a sadist who enjoys spectator blood sports? Is He trying to avoid
overpopulation in the mammals of Africa? Is He maneuvering to maximize David
Attenborough’s television ratings? These are all intelligible utility functions
that might have turned out to be true. In fact, of course, they are all completely
wrong. We now understand the single Utility Function of life in great detail, and
it is nothing like any of those.
Chapter 1 will have prepared the reader for the view that the true utility function
of life, that which is being maximized in the natural world, is DNA survival. But
DNA is not floating free; it is locked up in living bodies and it has to make the
most of the levers of power at its disposal. DNA sequences that find themselves in
cheetah bodies maximize their survival by causing those bodies to kill gazelles.
Sequences that find themselves in gazelle bodies maximize their survival by
promoting opposite ends. But it is DNA survival that is being maximized in both
cases. In this chapter, I am going to do a reverse-engineering job on a number of
practical examples and show how everything makes sense once you assume that DNA
survival is what is being maximized.
The sex ratio-the proportion of males to females-in wild populations is usually
50:50. This seems to make no economic sense in those many species in which a
minority of males has an unfair monopoly of the females: the harem system. In one
well-studied population of elephant seals, 4 percent of the males accounted for 88
percent of all the copulations. Never mind that God’s Utility Function in this case
seems so unfair for the bachelor majority. What is worse, a cost-cutting,
efficiency-minded deity would be bound to spot that the deprived 96 percent are
consuming half the population’s food resources (actually more than half, because
adult male elephant seals are much bigger than females). The surplus bachelors do
nothing except wait for an opportunity to displace one of the lucky 4 percent of
harem masters. How can the existence of these unconscionable bachelor herds
possibly be justified? Any utility function that paid even a little attention to
the economic efficiency of the community would dispense with the bachelors.
Instead, there would bee just enough males born to fertilize the females. This
apparent anomaly, again, is explained with elegant simplicity once you understand
the true Darwinian Utility Function: maximize DNA survival.
I’ll go into the example of the sex ratio in a little detail, because its utility
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