Thursday, September 29, 2011

A Serious Humorous Interlude

Please remember to visit my YouTube site for videos in which I explain evolutionary concepts in the guise of Charles Darwin. You’ll be glad you did!

This is a humorous poem that takes a backward look at human evolution. I first saw it when I was in high school, back when I was a creationist. I enjoyed it then and I enjoy it now.

Darwin’s Mistake
(Evolution—From the Monkey’s Viewpoint)

Three monkeys sat in a coconut tree Discussing things as they are said to be.

Said one to the others, “Now listen, you two, There’s a rumor around that can’t be true, That man descended from our noble race. The very idea is a great disgrace.

“No monkey has ever deserted his wife, Starved her babies and ruined her life. And you’ve never known a mother monk To leave her babies with others to bunk Or pass from one on to another Till they scarcely know who is their mother.

“And another thing you’ll never see, A monk build a fence round a coconut tree, And let the coconuts go to waste, Forbidding all other monks to taste. Why, if I put a fence around a tree, Starvation will force you to steal from me!

“Here’s another thing a monkey won’t do, Go out at night and get on a stew, Or use a gun or club or knife To take some other monkey’s life.

“Yes, man descended, the ornery cuss, But, brother, he didn’t descend from us!”

This poem has appeared in many places on the web, without attribution of authorship. One website, however, identifies the author as Gilliam S. Weaver and tells his story.

Friday, September 23, 2011

Are We the Inevitable Products of Mathematical Equations?

I have just finished reading Martin Nowak’s Super Cooperators, a book written with Roger Highfield. Nowak is a biomathematician at Harvard. He has spent a career designing mathematical models that demonstrate the conditions under which altruism can evolve. Altruism is when one animal is nice to another animal of the same species.

Nowak’s view of the world resonates with my spirit. He sees the natural world as full of cooperation. Cooperation is at least as important as the “survival of the fittest,” which Darwinism is often portrayed to be. I find his viewpoint inspiring just like the viewpoint of Lynn Margulis (whom Nowak hardly mentions). The fact that Nowak is a fellow devotee of the music of Gustav Mahler doesn’t hurt any either.

And some important results have emerged from Nowak’s mathematical models. I cannot summarize all of them, but one that I remember is the following. In simple, direct interactions, when a cooperator and a defector come in contact, the defector always wins. That is, the cooperator becomes a sucker for offering help that is not reciprocated. In large populations in which all the animals are equally likely to come in contact, altruism doesn’t have a chance. But in populations in which small groups can form, where animals can choose their friends, so to speak, altruistic groups can emerge. And when they do, they can beat out the pathetic defectors every time, at least temporarily. This is particularly the case in animal societies where the animals know the reputations of other animals, which is something they can do within small groups. This is, in fact, probably the most important way in which altruism evolved. It is an example of multi-level selection: selection among groups within a larger population.

However, in one sense, I consider Nowak’s work to be unrealistic. He begins the book by expressing his feeling that all of truth can be expressed precisely by mathematics. Toward the end of the book, he claims that his equations would be true anywhere in the universe. He admits that his conclusions are not too different from beliefs, such as the Golden Rule, found in traditional religions. But he still thinks he has made a monumental universal discovery. “Now, for the first time, aspects of these powerful ideas [from religion] have been quantified in experiments, captured in equations, and enshrined in science.” He seems to mean that ideas such as the Golden Rule are really true for the first time in the history of the universe as a result of his mathematical simulations.

Nowak’s mathematical approach is unrealistic because it omits all historical contingency. In Nowak’s models, animals are cooperators or defectors for logical reasons. So maybe his equations would work reliably on the planet Vulcan. But they cannot be relied upon for human behavior. The equations mirror many, but not all, aspects of human behavior. The primary historical contingency is religion. The memes of religion have parasitized the human mind to such an extent that, throughout human history, many people have considered it a religious duty, absent any benefit, and more important than life itself, to bring death and destruction to others. Nowak’s models do not include the thirst for evil that is so common in human motivation, in which loss is reward because it ensures eternal life in a heaven.

Friday, September 16, 2011

Almost Everything Evolves

The following appears in my book, Life of Earth: Portrait of a Beautiful, Middle-Aged, Stressed-Out World, published earlier this year by Prometheus Books. I also just finished lecturing about this subject in my evolution class this morning.

The process of natural selection involves these elements: variation; reproduction; limitation. We usually think of genes in this context: natural selection favors the best genes, which must cooperate with other genes to create the best organisms, within populations. But there is nothing about the process of natural selection that requires that the evolvers be organisms. As it turns out, almost everything evolves.

Evolutionary biologist Richard Dawkins pointed out that it is not just genes, but any kind of information, that evolve. Dawkins called non-genetic pieces of information memes, a counterpart to genes. The result is cultural evolution, the counterpart to biological evolution. Cultural evolution turns out to strongly affect biological evolution, because for most complex animals, the most important part of the environment is the culture of its species.

All that is necessary for something to evolve, according to Dawkins, is a faithful but imperfect copying mechanism for instructions, and a system that is ready to obey those instructions. DNA and the cell fulfill these requirements. So do computer programs and computers. And so do memes and the human mind.

A meme can be as simple as an idea. Somebody thinks of an idea, which is a mutant form of some earlier idea that somebody else had. This is the variation step. In the population of human minds, this new idea contributes to the memetic variation of ideas that is available in the culture. The person then tells the idea to another person, or publishes it or sends it. This is the reproduction step. The human mind has a limited capacity for recalling and using ideas. This is the limitation step. The result is that the most successful ideas get propagated in the culture. The less successful ideas remain rare, the arcane knowledge of a few people, or become extinct. The most successful ideas are not necessarily the best ideas, but just the ones that people like the most. For every good and true idea, there are probably a dozen bad and stupid ideas that rattle around in people’s brains. Many of us try to eradicate the bad ideas from our minds, but with only partial success.

Usually, memes are parts of complex sets. As a result, memetic selection not only favors the memes that are most useful to the animals that think or learn them, but work best as part of a memetic set. Human languages are sets of memes. All humans have an innate capacity for language, but they always learn their particular languages from other humans. The result is that languages evolve.

Evolution is like a branching tree. The branches become separate species when the animals no longer recognize one another as potential mates. Languages have the same pattern. The main Indo-European branch of evolution split into smaller branches, one of which was Latin, which then evolved into smaller branches such as Iberian and French, which evolved into twigs such as when Iberian evolved into Spanish, Portuguese, and Catalan. Mutations accumulate in languages, and memetic selection preserves the variations that are most useful or most appealing to the speakers. After awhile, so much divergence has occurred that the speakers may be mutually unintelligible, as when a speaker of Spanish tries to understand French, or when a Parisian pretends he cannot understand a Frenchman from Dijon. An awareness of the branching evolutionary pattern of languages grew during the nineteenth century at the same time as the awareness of biological evolution. A successful word-meme is one that functions best as part of a language, not necessarily by itself.

Friday, September 9, 2011

Let the Earth Bring Forth Plants

The first chapter of Genesis in the Old Testament is a hymn to an orderly and bountiful cosmos. Surprisingly enough, it begins by describing a universe that existed before God began to create. This universe had two problems: it was chaotic and empty (the old King James English says “formless and void”). During the six days of creation, according to this hymn, God solved these two problems. On the first three days, he brought order into the heavenly, the fluid, and the earthly realms: making light separate from darkness, air separate from water, and land separate from sea. On the last three days, he filled the heavenly, fluid, and earthly realms: filling the heavens with stars, the water and air with fish and birds, and the earth with “creeping things.” It is obvious to everyone except creationists that this chapter was never, even when it was first written, intended as an historical description of the history of the cosmos. It described the work of creation as categories, not as a timeline. Astronomy, geology, and biology now provide explanations for the processes of creation described poetically in Genesis.

As beautiful as it is, however, the first chapter of Genesis reflects the human-centered viewpoint of the time in which it was written (about 500 BCE), a viewpoint to which most modern people still cling, even if they are not particularly religious. This viewpoint puts humans at the pinnacle of creation, something that most people (including those who think they understand evolution) still do. The writer of Genesis did not praise humans as much as you might think, however: humans were created on the same “day” as all of the creeping things. Humans did not even get their own special day of creation. But Genesis clearly states that humans rule all of the creation, and uses terms that imply that humans have the right to conquer and rape the creation.

One example of this domination is the creation of plants. Plants appear on Day 3, along with the dry land. That is, in this hymn, plants are not considered to be living organisms; they are just a part of the landscape. In a sense this is true: any landscape without plants is quickly ravaged by erosion, as I have explained in my book Green Planet. But the God of Genesis does not give plants any role of their own other than to be eaten by animals. Behold, he says on Day 6, I have given you every green plant for food.

But plants are organisms. They’ve got to make a living like everybody else. Plants have populations that evolve. It is not in the interests of the plants to just sit there and allow themselves to be eaten by animals. The plants that natural selection favors are those that can avoid getting eaten by animals.

As a result, the world is not just a big salad bowl. Nearly every wild plant has several or many characteristics that make it unpalatable to animals. In some cases, plant defenses are clearly visible: spines on cactuses, stinging hairs on nettles. In other cases, the defenses are invisible but even more effective. Most plants have leaves that are at least mildly toxic. Plants produce thousands of different kinds of chemicals that are toxic to animals. Some of them accumulate poisonous mineral ions out of the soil and put them in little sacs (vacuoles) in the leaf cells, where the poisons will not harm the leaves but will harm any animal that chews the leaf, breaking open the sacs of poison.

Humans have bred crop and garden plants that are palatable, and this has created for most of us the illusion that plants are just waiting to be eaten. They are like Al Capp’s cartoon shmoos, which fall all over themselves in an attempt to get eaten, with stupid grins on their faces. Be warned: wild plants do not have brains, they are in fact stupid, but evolution has produced in them many defenses that appear to those who study them to be very clever. Wild relatives of crop plants, such as beans, tomatoes, and potatoes, are poisonous. Some tribal peoples subsist on wild cassava. But they have to boil and squeeze the cassava pulp to remove poisons first.

Even the parts of plants that are not poisonous are not simple gifts to feed animals. Many species of plants produce soft, colorful, sweet, fragrant fruits. These fruits make themselves very visible to animals, and reward the animals for eating them. Such fruits, abundant and hanging low, are in fact part of our image of paradise. (The word paradise itself comes from the Persian word pairidaeza, a walled garden.) But the plants have something to gain from this arrangement. The fruits have seeds in them. Animals usually eat the entire fruit, swallowing the seeds. It is just too much work for the animal to pick out the seeds, especially since the pulp clings closely to them. Plants cannot move around and carry their seeds to new locations, nor can the seeds move under their own power. Many plants therefore get animals to carry their seeds to new places by getting the animals to eat them. They pay the animals by feeding them the sweet and nourishing pulp of the fruit. The animals deposit the seeds, along with a pile of fertilizer, far away from the parent tree. Both the plants and the animals benefit. In other cases, plants take advantage of the animals. Seeds with spiky burs entangle the fur of mammals, which carry the seeds to a new location while they are trying to scrape the burs from their fur.

Plants and herbivores are involved in what has been called an arms race. Plants evolve defenses, and herbivores evolve ways of circumventing the defenses. Plants then evolve new defenses, and herbivores evolve ways of circumventing these as well. For both the plants and the animals, this interaction is expensive. The plants have to use their energy and molecules to make poisons rather than using them to grow new leaves and roots. Animals have to use energy and molecules to digest the plants despite their defenses. In human societies, spending more money on defense means spending less on growth (such as infrastructure and education). Plants and animals find themselves in the same predicament as humans do.

This is coevolution: natural selection favors plants that are prickly or poisonous, but not so much that they cannot grow, and animals that can tolerate or avoid the poisons, but not so much that they divert too much energy away from their own metabolism, movement, and growth.

One you have learned about the coevolutionary relationship between herbivores and plants, you can never again look at a serene natural landscape the same way as before. The Lord is my shepherd, said the psalmist, leading sheep into green pastures. The psalmist also said that God prepared a table for him in the presence of his enemies. But the psalmist could not have guessed that, to a certain extent, the green pastures themselves were one of the enemies. There never was a natural Garden of Eden in which all the plants were uncomplicatedly nutritious.

This entry was part of my book Life of Earth: Portrait of a Beautiful, Middle-Aged, Stressed-Out World, published earlier this year by Prometheus Books.

Thursday, September 1, 2011

Hurry Up and Wait

Both of my parents served in World War II, my father as a soldier (luckily, never deployed) and my mother as a dental hygienist. They told me that life in the military consisted of “hurry up and wait.” Others have described the military life as long periods of boredom interrupted by brief periods of terror.

And that is what evolution is like also. Most of the time, in most species, it does not seem to be occurring—fluctuating directional selection creates long-term stabilizing selection. But sometimes, rapid directional selection occurs. When? Just as you might expect, and as the Grants observed in the finch populations—it occurs when there is a major environmental change. The environment around a population may change, or a few members of the population might migrate to a new location that has different environmental conditions. When conditions change, directional selection gears up to make the population change along with it. On the Gal├ípagos Islands, the conditions changed back and forth. But sometimes environmental conditions change and then do not change back. Or the migrants do not go back home, remaining in permanently altered conditions. Under these circumstances, directional selection has permanent and rapid effects. It may lead to the formation of a new species, and do so rapidly. Such bursts of evolution have been called punctuations.

Scientists have a name for the overall hurry-up-and-wait pattern of evolution: punctuated equilibria. That is, long periods of equilibrium, during which stabilizing selection is the main process, punctuated by brief periods of rapid directional selection. New species usually originate during these punctuational events. A species comes into existence by a punctuation of directional selection, and then stays fairly unchanged until it either becomes extinct or experiences another punctuation. This pattern of evolution was first pointed out by evolutionary biologists Stephen Jay Gould and Niles Eldredge in the 1970s. It is the punctuations that demonstrate just how rapidly evolution can occur.

This entry appears in my book Life of Earth: Portrait of a Beautiful, Middle-Aged, Stressed-Out World, from Prometheus Books.