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What we can learn from biology's most important theory

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Introduction | The Population Paradox | Placebo Environmentalism | A Modest Proposal | Parenthood | Conclusion | References | Feedback

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In evaluating the human condition, it isn't possible to overemphasize the significance of evolutionary theory. This well-supported scientific theory influences our behavior in ways most of us can't begin to imagine. This article explores how evolution provides answers to questions we might not otherwise think to ask.

In the past 150 years evolutionary theory has moved from being a philosophical curiosity to becoming a precondition for understanding human behavior. There are certain aspects of our behavior that are easily explained and perfectly logical, while other aspects make no sense at all without the theoretical framework provided by evolution. This article reveals our connection with evolution, and through that connection, with all life on earth.

MRSA Timeline

1959: Methicillin is introduced as an antibiotic.

1961: Bacteriologist Patricia Jevons discovers first methicillin-resistant staphylococcus aureus (MRSA) in English hospitals.

1968: First report of MRSA in American hospitals in Boston.

1974: MRSA accounts for 2% of hospital staph infections in U.S.

1981: First reports of MRSA acquired in the community, while MRSA in hospitals increases steadily.

1997: MRSA accounts for 50% of hospital staph infections.

1998: University of Chicago researchers report a 25-fold increase in community-acquired MRSA from 1993 to 1995. During the same period, 35 kids in Chicago are hospitalized with community-acquired MRSA.

1999: CDC reports deaths of four otherwise healthy children from community-acquired MRSA.

2002: University of Chicago team finds that new cases of community-acquired MRSA are genetically distinct from hospital strains.

2007: CDC estimates that MRSA causes 94,000 severe infections each year, killing 19,000.

Sources: CDC, University of Chicago, Barry Kreiswirth for The Public Health Research Institute Center; Chicago Tribune: Jeremy Manier

Disease Dangers

When first discovered, antibiotics seemed to turn the tide against many historical infectious agents — they stopped tuberculosis (TB), Bubonic Plague and other deadly ailments in their tracks. These treatments appeared to represent an unqualified victory for modern medical practice. But more recently, doctors have seen new bacterial strains spring up that cannot be treated with existing antibiotics, and a variety of TB now exists that is, for all practical purposes, incurable, and so dangerous that some individuals must be locked up to keep them from infecting others.

In a related development, hospitals have aggressively used multiple methods including antibiotics to control germs that would otherwise attack patients while they were in the hospital. But those methods have backfired, and more Americans now die from hospital-borne Staph infections than from AIDS. As things now stand, for many patients the hospital environment itself poses a greater risk than the disease they're suffering from.

What's going on? Are drug companies producing less effective drugs? Have doctors failed to prescribe antibiotics often enough? The answer to these questions is that we haven't been paying attention to the role played by evolution in this and all biological issues. Here are some properties of evolution:

  • In response to environmental changes, organisms either adapt or become extinct.
  • The biological changes behind adaptation originate in random DNA mutations.
  • Most mutations are harmful and result in reduced fitness, but a minority happen by chance to meet new environmental challenges.
  • Organisms with beneficial mutations produce more offspring than those with harmful mutations until the fitter group represents the entire population, to be eventually replaced in a continuous process of adaptation.
  • The story of evolution is recorded in individuals and species that represent the best adaptation to their changing environments.
  • Evolution is not a gradual move from simple to complex, or from dumb to smart, but is a brutal filter that only notices survival and reproduction.
  • Evolution is not a plan, it is an algorithm, one in which random changes sometimes produce successful organisms by chance.
  • Evolution has no final objective or end-point — it is not a means to an end, but a process. In the evolutionary narrative, all species are temporary forms.

There are now incurable strains of TB, and dangerous Staph infections in hospitals, because the original infectious organisms evolved to meet the threat posed by antibiotics. To be specific, the antibiotics killed all the bacteria except a tiny minority that happened to be resistant to antibiotics, and that minority eventually became the entire surviving bacterial population.

The TB and Staph stories are examples where, by ignoring a powerful, well-supported scientific theory, we have exposed ourselves to incredible danger. Some people don't understand evolution but are willing to learn its role in shaping the modern world, while others, by rejecting the very concept of evolution, proactively defend a breathtaking personal level of ignorance that must be witnessed to be believed. Unfortunately for all of us, members of the latter group tend to sit on committees that decide what our children may learn in school.

Charles Darwin and Gregor Mendel

About the time Darwin shaped his ideas about evolution, an Austrian monk named Gregor Mendel was experimenting with pea plants and noticed certain predictable patterns of inheritance. At that early stage in the history of evolution it could be said that Darwin recognized the consequences of adaptation at the species level, while Mendel witnessed the result of mixing particular genotypes, but neither saw the big picture or identified the source of genetic information.

The true significance, and relatedness, of Darwin's and Mendel's work was not fully appreciated until long after their passing, in what is called the modern synthesis in biology, crafted between 1936 and 1947. Shortly thereafter Watson and Crick completed the picture by describing the structure of DNA.

It must be emphasized that the scientific evidence for evolution and natural selection is copious and widespread, and the above examples of quickly evolving bacterial strains, although headline news, are only representative of a large class of similar narratives. As time passes, those who doubt the reality of evolution must ignore a greater corpus of evidence, and accept greater personal risk, in order to defend their ignorance.

Artificial Selection / Monocultures

People were manipulating genetic outcomes long before genetics was itself understood. One example can be seen in dog breeding, where the wide variety of modern dog types were derived from the wolf by selective breeding. Another example is the selective breeding of optimal strains of corn, wheat and soybeans to maximize their yield, robustness and resistance to pests.

The dark side of artificial selection can be seen in the story of the Irish Potato Famine. In the 1800s Ireland became increasingly dependent on potatoes as a single crop to support its increasing population, and within that crop, a single genetic variety ("lumpers"), with tragic consequences. In retrospect it can be seen that, if a wider variety of potato strains had been allowed to exist, some of them would have been able to resist the blight that destroyed the entire crop for several successive years, resulting in about a million deaths by starvation.

The lesson of the Irish Potato Famine has yet to be learned. Many modern agricultural strains, seemingly the best choice for a particular growing environment, are monocultures (single genetic strains) and therefore represent ticking biological time bombs. One example is the widespread extinction of the U.S. corn monoculture in the 1980s, resulting in the loss of a billion dollars of agricultural output (but no loss of life). A hidden danger in modern agriculture is pressure to increase yields in order to feed growing populations, which can lead to dependence on a single optimal strain that produces the highest output per acre. It seems we've placed ourselves in the same position as the Irish of the 19th century, but because we understand what can happen, we have no excuse.

But the largest and potentially most tragic example of monoculture is the "Holocene extinction event". Although this sounds like one of those geological eras we identify by examining rock strata, the Holocene extinction event is happening now, and we are the cause — humans are selectively breeding ourselves in a way that excludes thousands of other species, and we are rapidly approaching a monoculture in which humans are the only surviving species.

When we look back at the Irish Potato Famine, it's easy to say, "Wow, that was stupid! How could those people not realize the risk they were taking in becoming more and more dependent on fewer and fewer biological species?" The unanswered question is whether we will recognize that we're repeating the same mistake on a much larger scale.

Many people now accept that we are placing ourselves in danger by extinguishing all species but ourselves, but it's much harder to figure out what to do about it. Before my readers say, "That's simple — all we have to do is reduce our numbers," I have to say no, it's not that simple. Read on.

The Population Paradox

To briefly recapitulate the first part of this article, evolution is morally neutral and only notices what survives and reproduces, nothing else. The evolution of distinctive traits, however much survival value they appear to have, cannot interfere with the bottom line, which is surviving offspring. The absolute priority of reproductive fitness places firm limits on physical size, resistance to disease, visual acuity, or any other trait one can name, including intelligence.

Intelligence and Survival

Evolution selects against overdesign — a physically large animal like a dinosaur may be able to dominate smaller creatures, but it can be (and ultimately was) outcompeted by smaller creatures who made up in number what they lacked in size. A bird with extraordinarily acute eyesight will only prevail against other species if it can see a mouse other birds cannot see, otherwise the energy cost of maintaining its eyes will select against the trait.

Just as with physical size and visual acuity, intelligence has an upper practical limit, beyond which the trait reduces fitness and is selected against. This is true at the level of species, but there is a version of this selection process in the lives of individuals that I call the "Population Paradox". The paradox works like this:

Former New York Governor
Eliot Spitzer before his
fall from grace
"OctoMom," a.k.a. Nadya Suleman,
single unemployed welfare mother
with a few of her 14 children
Courtesy INFdaily.com
  • An intelligent, educated individual explains to his tribe that there are far too many human beings on the planet and that, by increasing our numbers, we risk our own safety and that of our children.
  • On hearing this information, the more intelligent, sensitive, caring listeners resolve to have fewer children.
  • On hearing the same information, the less intelligent, sensitive, caring listeners don't change their behavior.
  • The result is fewer intelligent, sensitive, caring people in the next generation.

Yes, the Population Paradox really is as simple as that — to put it bluntly, people who care about the state of the planet are outcompeted by those who don't. (These facts cannot be used as an excuse for irresponsible behavior, and we all must think and accept responsibility for our actions. We just have to think more deeply.)

Transient Stupidity

Some readers may see what appears to be a flaw in the Population Paradox idea — there are some very intelligent people, those people have intelligent, healthy children at least some of the time, and this might stand as a counterexample to the paradox.

But because evolution's absolute priority is reproduction, it performs an end run around intelligence and common sense — intelligent people continue to have children on a very overcrowded planet by temporarily becoming stupid, and this is not my idea, it's an idea that has been put forth by many people including feminists. One name for this syndrome is "pregnancy brain," a temporary decline in reasoning and memory ability that accompanies pregnancy. But this evolution-mandated drop in intelligence is by no means limited to women. In my opinion and that of many others, we see its most extreme form in men, whose ability to reason plummets to near-zero around the topic of reproduction.

Consider two examples:
  • Eliot Spitzer, former Governor of New York, former sanctimonious prosecutor, was discovered to have regularly engaged the services of prostitutes in an almost public way, and resigned in disgrace. Some who hear this story are inclined to ask, "What was he thinking?" But that question includes an unwarranted assumption — that there was any measurable mental activity, at least above the equator.
  • Nadya Suleman, an unmarried, unemployed mother of six who lives on food stamps, decides six isn't enough and visits a fertility clinic. The fertility clinic, in a breathtaking violation of the Hippocratic Oath, impregnates her eight times over, and all of them live. As I see it, this is child abuse ipso facto — this woman's 14 children are, for all practical purposes, orphans of an apparent clinical narcissist. I can imagine future tell-all books in the tradition of Mommie Dearest, with memorable mommy-quotes like, "I really, truly, sincerely love you, number 11."

Free Will

This section is meant to emphasize the fact that we have no chance to understand human behavior without first understanding evolution. Evolution is such a powerful force in our lives that it offers a partial answer to the old question about the existence of free will: we may have free will in some parts of our lives, but as to procreation, we certainly don't.

Some readers will see an obvious objection to the above claim — many people make intelligent decisions about reproduction, and this supports the possibility of free will in all areas of human life, even the most basic and instinctive parts. I must agree that's true, such things do happen, but by making intelligent decisions about reproduction, we remove ourselves from the gene pool. Consider this example:

  • An intelligent person (for this example a person possessed of an absurd degree of intelligence with no imaginable practical application) sees a late-night advertisement that exhorts us to feed all the world's starving children.
  • She responds to the advertisement by saying, "That's absurd — a program to feed starving people, with no conditions or requirements? That can only lead to many more starving people in the future — how humane is that? Only the most superficial intellect could fail to see this program can only increase human suffering in the long term."
  • She thinks a bit more and says, "If I choose not to feed those starving people, but proceed to have my own children, then I am a despicable racist and selfish hypocrite. So for reasons of personal integrity I will not have any children."
  • True to her word, our intelligent test subject doesn't have any children.
  • After twenty years have gone by, we see another person watching another advertisement to feed all the world's starving children. Unencumbered by even a bit of extra intelligence, she says, "Yes! I'll show my compassion and humanity by feeding all those starving people!"

Conclusion? Free will may exist in some areas, but as to reproduction issues, it doesn't — we're animals, as Freud said (one of the few things he got right).

Placebo Environmentalism

The world is heating up — everyone can agree on that. Now let's just say for the sake of argument that this heating is at least partly caused by human activity (I respect the views of those who disagree, but this is just an example and I don't want to wander away from the topic) and that the consequences of warming may be harmful, so what shall we do about it?

Here are some recently proposed remedies:

  • Scatter iron oxide on the oceans. The iron oxide will support the growth of algae, which will sequester a lot of atmospheric CO2, the reduced CO2 will decrease global warming.
  • Launch a bunch of tiny reflectors into Earth orbit. The reflectors will bounce sunlight back into space, this will reduce the amount of sunlight that gets to the surface, this will reduce surface heating, which will cool the planet.
  • Spread huge reflective sheets across deserts. The sheets will reflect more sunlight back into space than the sand can, this will reduce surface heating, that will decrease global warming.

There are many similar proposals, ranging from humorous to harebrained, but I ask my readers to notice what is missing from the list and from environmentalism in general — any discussion of world population. To put this in the simplest terms, a warming world is a symptom, world hunger is a symptom, world wars and terrorism are symptoms — all symptoms of the underlying disease of overpopulation. We can treat the symptoms, or we can treat the disease.

Reality Testing

It is one thing to see that we are emotional hostages of our own fertility, and to notice that discussions of population tend to be profoundly hypocritical (it's always "them" that have too many children), but it is quite another to refuse to even acknowledge the problem. Environmental movements that do not address population treat symptoms while ignoring the underlying disease and have little reason to exist. Every sanctimonious, green, save-the-whales, recycle-your-cans, wind and solar power movement that won't address population is as much a placebo (a sham treatment with no real effect) as giving a cancer patient a more comfortable pillow instead of surgery.

Imagine that all the well-intentioned, properly organized environmental causes succeed and our environmental impact is reduced to half its present level — half the oil, half the coal, half the nuclear power, etc.. If we were to achieve that spectacular result, we would have to watch our victory be wiped out over the next 60 years as the world's population doubles from its present level. According to international population authorities and assuming the above optimistic environmental forecast, in 60 years we will find ourselves in exactly the same predicament, confronting the same problem we do now.

Does this sound pessimistic? Does it paint too bleak a picture? Well, no, not really. According to Wikipedia's article on population, "The last one hundred years have seen a rapid increase in population due to medical advances and massive increase in agricultural productivity made possible by the Green Revolution."

Translated into everyday terms, before the Green Revolution children were starving, but the Green Revolution allowed those starving children to have children of their own, so now we have ... more starving children than there were before (according to UNICEF, 10 million children under the age of five now starve annually). What an accomplishment. I should add that the Green Revolution depends to a large extent on monocultures and their attendant risks.

Within environmental causes, world population is the elephant in the room that no one cares to acknowledge. There are several reasons for this — one is that environmentalists who discuss population quickly lose public support (because people much prefer meaningless gestures to personal sacrifices). Another is that there is little purpose in discussing population with people who can't imagine their role in the process. A third reason is the perverse effect of the Population Paradox discussed above, in which open discussion of population issues only changes the composition of the future population, not its size.

But don't despair, dear reader — there are ways to address these issues. Read on.

A Modest Proposal

At this point in a typical essay, an author can be relied on to offer one or more hand-waving remedies for all the world's problems. But I don't intend to insult the intelligence of my readers, and this article's topic deserves a better, more realistic treatment.


First let's dismiss things that can't possibly work or that have been tried and failed. Racism and Eugenics are easy to dismiss because they pretend that we know more than nature and can substitute our own choices for those of evolution — if history teaches us anything, it is that we don't, and we can't.

Genetic Algorithms

Someone will surely object that the above represents a dismissal without substance, so in this digression I will give it a bit more depth. When computer scientists attack a truly complex problem, they sometimes push the programmers out of the way and assign the problem to a "genetic algorithm", a computer method that imitates natural evolution. Well-designed genetic algorithms are very effective at solving complex problems and choosing optimal strategies, in ways that even their designers may not fully understand when the process is complete, just as with evolution in nature.

Traditional software design and problem-solving is organized top-down, that is to say, a broad statement of a problem to be solved is recursively broken down into subtasks. But for many problems the top-down approach simply doesn't work, and a genetic/evolutionary approach produces better results by attacking the problem in a less organized, more bottom-up way.

As the discipline of genetic programming has become better-established, its similarity to natural evolution has been recognized by many, indeed much of genetic programming is consciously imitative of natural evolution. The key to the success of both natural and computer evolutionary algorithms is that all options are tested in parallel, without prejudgment, and the quality of the result depends on the algorithm's impartiality. To put this another way, the best evolutionary algorithms measure only results, not how the results are achieved. It would be nice if human societies worked this way, but we aren't there yet. Suffice it to say that impartial algorithms produce the best results.

Back to non-starters. In deciding what to do about certain human problems and in my opinion, we should avoid assuming that our choices can stand in for those of nature. This obviously can't work for all problems, but as to fundamental issues like the size of the human population, we need to stop assuming we can outwit nature.


Readers may recall an earlier comment about a measurable decline in reasoning powers during pregnancy. As it happens and for reasons of their own, some societies have assumed that women are always sort of stupid and their mental state during pregnancy is the norm for their gender. Unfortunately for this viewpoint and its adherents, there is no evidence to support it — indeed, all available evidence points in a different direction. In objective tests, women's intellectual abilities are the same as those of men, and in some areas (verbal reasoning and calculation, to name just two) women score higher than men.

Fertility and Education in Women
Courtesy The Population Reference Bureau

Is this issue germane to the topic of world population? You bet it is. First, women are the fulcrum on which the population issue turns. Second, in societies where they are free to speak out, women express a wish to control their fertility, and there is a strong worldwide correlation between womens' social standing and educational attainments, and low fertility. This means, when given a choice, women prefer smaller families, and the more intelligent and educated a woman is, the stronger this preference is.

Someone might object and ask if this idea collides with the Population Paradox — won't such intelligent, educated women with small families be outcompeted by others (the "OctoMoms" of the world) and disappear from the gene pool? Not if all women are guaranteed equal rights, equal educational opportunities, and equal access to fertility control measures. Where those rights are in place, the educated, intelligent woman isn't outcompeted by anyone.

Another possible objection: isn't this idea of equal rights for women just another example where people try to impose something unnatural on nature? Well, no, for two reasons. One, the present low standing of women is distinctly unnatural when compared to all of human history. Two, evolution works better when more options are available — or "degrees of freedom" to use the engineering term.

This isn't a panacea (there aren't any in nature), but it is a way for us to proactively coöperate with nature and respect her rules and methods. This idea deserves to be given a chance, as do women.

Professor Lisa Randall
Department of Physics
Harvard University


Now for my all-time pet peeve, the imaginary dichotomy between geeky, nerdy, pocket-protector-wearing, socially inept mostly-males on the one hand, and poised, highly social, well-groomed, earth-mother mostly-females on the other. There is no issue more influential in keeping women down than the imaginary divide between knowing how to think and knowing how to dance. Geekophobia exemplifies the worst kind of sexism — the kind women volunteer for.

More words have been printed on this one issue than I care to re-read, but most make the same point — there aren't many women in mathematics, science and engineering, and no one knows why. Those who offer theories about it tend to get it wrong, some falsely concluding that women have no aptitude for math and science. This commonly heard position suffers from a minor defect — there's no evidence for it and plenty of counterevidence. Up to a certain age, girls do just as well as (or better than) boys in technical subjects, then, at about age 13, poof! — in spite of their proven ability, we see far fewer girls in advanced math and science classes.

The simplest explanations tend to be the right ones, and in this case the simple explanation is ... choice. Most women choose not to enter these fields or develop an interest in these subjects. Some researchers argue that peer pressure and false social stereotypes play a part, and that seems likely. But innate ability is not the problem.

There is a supreme irony here — women who choose to stay away from mathematical subjects sometimes argue that they are making a more natural, earthy choice than their nerdy pocket-protector-wearing classmates, but in reality there is nothing more natural or earthy than mathematics, and the most accurate and reliable descriptions of nature take the form of mathematical equations. I must add that mathematics is sometimes very beautiful, but just as with fine art, one must train one's perceptions to see the beauty.

The Logistic Function

As an example, the "Logistic Function" describes the progress of biological colonies that are faced with limited resources (e.g. all of them). It's not important that my readers understand this function on sight, only that they recognize that to someone who understands mathematics, this equation tells us something profound and beautiful about nature, in a concise and rigorous way.

Growth in a Biological Colony

Now look at the graph of a typical biological colony as modeled by the logistic function. The area at the left of the graph represents a time when the colony is essentially unconstrained and creates new members as fast as possible. The area at the right represents a time when environmental limitations (e.g. starvation) prevent any significant increase in population. As it happens, the human colony is at about the "100" point on the horizontal scale, meaning we must do something or a lot more people are going to starve.

An amazing thing about mathematics is that one could write 100,000 words on the topic of evolution and not get close to what the logistic function tells us. Another, more general thing to know about mathematics is that, if you don't learn it, people will successfully lie to you for your entire life.

Image courtesy of makinglemonade.com

No life experience can compare to parenthood for disorientation, confusion and shock — it's almost impossible to picture in advance, and having an experienced person explain what's going to happen doesn't seem to do any good. Finally, even when warned, almost no one hesitates.

Veteran parents typically report that their childrens' teenage years were the unhappiest time in their lives (for both the parents and the teenagers). I doubt many parents have any idea what they're getting into, and I suspect some would have second thoughts if they could see their own future.

Most parents don't see the connection between evolution and childbearing — they expect to produce a miniature version of themselves, but, you know, better — smarter, nicer looking, more even-tempered. But childbearing is the moment when evolution rolls its dice, and if the outcome were in any way predictable, childbearing would not exist. To put this simply, parents expect something recognizable, but evolution requires something never seen before.

I can't think of a better moment to learn about evolution, but parents almost never consider the role of random mutation and natural selection in the development and behavior of their own children. They don't seem to realize that an unexpected outcome is the reason for childbearing — it's the point, not a side effect.

To put this in its simplest terms, when your child doesn't behave as you expect, that's nature talking. Parents' responsibility toward their children is properly limited to protecting them from obvious dangers, not for molding them in the parents' image. But for parents to understand this, they have to grow up.


I can see why religious fundamentalists want to outlaw the teaching of evolution — it is a powerful idea with plenty of supporting evidence, and it provides us with basic truths about ourselves that appear to contradict religious dogma. No educated person expects to be able to make an informed decision about anything remotely biological without understanding its evolutionary implications.

Since its inception, a number of bad actors have taken evolutionary ideas and distorted them to accomplish narrow, selfish ends, as in the example of Eugenics, which pretends that people can safely design our own future. But we aren't qualified to do that — we must allow nature to take her own course. Others have tried to use evolution as a cover for racism, but this requires another distortion, the idea that evolution has a preferred outcome (it doesn't).

Evolution is not a story with a fairy-tale ending, and it's not a plan with a goal. Properly understood, evolution is a bottom-up process that works best when all possibilities are included. The crowning irony of evolution is that it's often presented only as "red in tooth and claw," but in truth it's nature's way to give everyone an equal chance.

However my readers feel about evolution, whatever views they bring to the subject, before making a declaration or taking a position, my advice is to ... learn it first. Many people don't actually understand evolution and end up arguing about it from a position of ignorance.

A colleague once described physicist Stephen Hawking's work as "so beautiful that it has to be true." This is a comment one often hears in science, where theories that require only a few principles to explain a lot are particularly prized. Evolution is just such a theory — it uses a small handful of principles to explain a great deal of nature. Which leads me to this closing remark — if religious fundamentalists actually understood evolution, they would try to give God credit for it.


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