Delaying crunch time

kw: book reviews, nonfiction, insects, natural selection

We once lived near a field that had much milkweed. One day in early spring I noticed some chrysalises of Monarch butterflies hanging on milkweed stems. I went out the next day with a box and gathered more than twenty of them, by cutting a substantial part of the plant so they would stand upright in the box. I left the box on the front porch, which was enclosed but was nearly as cold as outside. When a warm day came, I took the box out into the sun. Soon I could hear rustling from inside it. I opened the lid and watched as the butterflies struggled out of their pupa cases and stretched their wings. They all rested there, drying and moving slowly. Then they all took flight at once. For a minute or two I was surrounded by their beauty. We saw Monarch butterflies in the area for several weeks before they migrated out. I suppose at least some of them made it to Mexico. Near the end of that time, I saw a few orange butterflies that were a little smaller. I netted one, and thus made the acquaintance of the Viceroy butterfly. My "bug book" informed me it is a Batesian mimic of the Monarch.

Why does the Viceroy look like a Monarch? The Monarch tastes bad to birds, so a bird that has tried to eat one will avoid them. I don't know if birds learn from each other, but even if they don't, there are many more butterflies than there are birds. Once each bird has had a taste of Monarch, both Monarchs, and the Viceroys, that so resemble them, are pretty safe from being eaten.

Later I learned about another kind of mimicry. Many whole genera of tropical butterflies are inedible (or at least taste very bad), and look so much alike that naturalists have a hard time determining which species a particular specimen belongs to. Not only so, but other species, also inedible, look very similar to them. This is Müllerian mimicry. A bird that eats any of these species will avoid them all. By the way, this goes for mice, toads, snakes and other insectivores, as does the former principle.

The fate of nearly all insects is to be eaten. They aren't going to live very long in any case. Even in the tropics, adult insects seldom live a year, and in temperate climates, most overwinter as eggs or pupae. But the most insectivores prey on adults or larvae. For a species to survive, then, at least some individuals need to avoid, hide from, outrun or otherwise fend off predators long enough to reproduce. It must be hard to be a fly or moth in southern New Mexico. The millions of bats that live in the Carlsbad Caverns are estimated to eat a few tons of insects every single night.

Naturalist Gilbert Waldbauer relates the various ways that insects put off the inevitable in How Not to be Eaten: The Insects Fight Back, a highly informative and entertaining book. Of course, the author discusses mimicry of both kinds, and a few others lesser known. He also tells us of the ongoing debates about just how effective mimicry is. It turns out that trying to prove such a thing is close to impossible. How do you catch, mark, release, and re-capture hundreds of insects, so you can figure out how many are left? A few very clever experiments have been performed, with ambiguous results so far. In my view, the existence of mimicry, plus the known mechanism of natural selection, prove that it is effective.

The bulk of the book relates a number of other strategies insects use: hiding, fleeing fast, mimicking twigs and bird droppings and flower parts, using noxious chemicals either in their tissues or as sprays, making startle displays, and even literally fighting back. This last is not just the province of stinging insects, the ants, wasps and bees. One anecdote describes a fight between a sparrow and a praying mantis. The mantis put up a good fight, but was eventually killed and eaten.

Then there is the other side. A great many insectivores are insects. Robber flies consume bees; dragonflies captures bees, flies and moths; and fireflies eat mosquitoes (so don't let your kids catch them all to make light jars!). If a new kind of fly evolves that is twice as fast as the fastest dragonfly, it will multiply until most flies can outrun their predators. Dragonflies will be hard pressed to survive unless they evolve greater speed in return, and perhaps get more crafty also. Certain tropical mantises resemble orchids, only partly to fool birds, but even more to fool pollinating insects that they eat. Some species of moth and other bat pray have ears, not to hear one another but to hear a bat's sonar clicks so they can hide or fly erratically to avoid the bat. If the moths get better at this, the bats have to improve also, or die out. It has been called an arms race.

Of course, the primary reproductive strategy of most insects is to lay many, many eggs. They attempt to overwhelm the opposition. If an average female moth lays enough eggs so that two offspring survive to reproduce (one to replace her and one to replace her mate), the species will live on. If they somehow were to average three surviving offspring each, the population would explode, increasing by 50% per generation. For some insects, the population could easily increase by a factor of ten or more in a single season. Then, they'd be likely to outgrow their food supply, and many would starve. Starving insects are easier prey than healthy ones, so keeping the balance is also a way "not to be eaten."

An olive branch, or a slap in the face?

kw: book reviews, nonfiction, evolution, religion, controversy, natural selection

The opening paragraph of Chapter 1, titled "The Future Can Differ from the Past", is very hopeful:

"This is a book of tall claims about evolution: that it can become uncontroversial; that the basic principles are easy to learn; that everyone should want to learn them, once their implications are understood; that evolution and religion, those old enemies who currently occupy opposite corners of human thought, can be brought harmoniously together."

Doesn't that sound like the author is conciliatory, perhaps willing to admit that spiritually-minded people may know something that is not amenable to scientific study but is nonetheless valid? Sadly, after ten chapters of nice talk, we have this, in Chapter 11, titled "Welcome Home, Prodigal Son":

"First, we must abandon the notion that some special quality was breathed into us by a higher power. This does not require abandoning religious faith—many people manage to combine a vibrant religious faith with a fully rationalistic conception of the world—but it does require abandoning certain kinds of religious faith."

The author is David Sloan Wilson, whose book Evolution for Everyone: How Darwin's Theory Can Change the Way We Think About Our Lives is the latest attempt by a well-meaning scientist to bridge the cultural gap between (some) scientists and Christians who believe that the Bible is more than a story book. The arrogance of his position is extreme. I'd answer this way:

David, just who is the prodigal here? This parable is by Jesus, not by Ed Wilson! Jesus wants you to turn to faith in His Father. Religion and Darwinism enjoyed a century of amicable relations, until the sudden resurgence of "biblical inerrancy" views seventy years ago. The earlier, more reasonable Evangelical viewpoint was that the Bible tells us what God wants us to know about relationships, both horizontal and vertical, and that poetic language is not intended to convey exact knowledge of the natural world. This is still the position of the majority of Bible believing Christians. However, to "abandon" the inspiriation of a human spirit by God is simply apostasy. David, to eliminate the "certian kinds of religious faith" that you wish people to abandon would remove every genuine Christian from the planet. You are proposing spiritual genocide. How naïve! Paul wrote in 1 Corinthians 15:19, "If we have hoped in Christ in this life only, we are of all men most to be pitied." Christian faith and practice make no sense without a real God and without hope in His eternal Kingdom.

I distinguish faith from religion. To me the term "religious faith" is meaningless. Religion is practice, regardless of its motive. Faith is a motivation based on a spiritual experience. Christian faith is based on a revelation of God. According to both the Bible and the experience of millions of believers, the human spirit is an organ, distinct from the soul and body, that mediates contact with God and fellowship among His people. The Bible describes this in detail. If it is to be believed—and tens of millions do so believe—faith is the result of a direct revelation from God, an experience that forever changes how a person thinks about God. A Christian is someone who has met God, personally. One cannot "abandon" an experience.

The Bible contains a distinct definition of faith, in Hebrews 11:1, "Now faith is the assurance of things hoped for, the conviction of things not seen." Once faith is received (it isn't natural, not the Biblical kind), a person has an inner conviction of the reality of God and an expectation that the Biblical promises will be kept. Biblical writers even use special words for "know" and "knowledge" when referring to knowing the things of God.

I follow the progress of a number of scientific disciplines. I find today's cosmology quite interesting, if rather quizzical. Certain observations of star motions in galaxies have convinced astronomers that most of the gravitational force keeping the stars in their orbits is generated not by matter as we know it but some kind of "dark matter", and speculation abounds about what it might be. The only thing known is that this stuff has gravitational mass but is not affected in any way (that we yet know of!) by light or other electromagnetic radiation. Thus, something like 85% of the matter Universe is unseen, and perhaps unseeable. Interestingly, some scientists suggest that gravitons (or whatever it is that mediates gravitational force) travel at a speed different from that of light, which increases gravity's effect over galactic distances, thus no "dark matter" is needed. These folks are greatly disparaged, and they can't get funding to do the experiments necessary to determine if their idea has merit. This sounds like a religious controversy to me! The "establishment" scientists have great faith, do they not? They have little else to go on!

Guess what, it just might be religious after all. Some Christians, long before this controversy arose in recent decades, noticed Colossians 1:17, "He is before all things, and in him all things hold together." Could the power of God account for 85% of the Universe? To bring about "The End", perhaps all He need do is simply let go. Personally, I like the gravity idea better. Furthermore, the "dark energy" that seems to be speeding up the expansion of space requires the greatest, most astonishing leap of faith I've ever heard of. I've looked long and hard at the data. It is not yet conclusive. The error bars on every chart I've seen are larger than the effect. This idea is based more on the theory that space "just has to be flat" than on anything truly scientific. Speculation gone wild...or maybe "dark energy", which amounts to three times as much gravitational potential as "dark matter" plus ordinary matter combined, is a further manifestation of divine power. Again, I don't think so. I think it just shows that science is still too limited to deal with cosmology with anything like the precision and completeness that is so arrogantly claimed. Let's give it a century or so of further study and see what else shows up.

So, back to my exhortation: David, you require people who have met God to "abandon" their belief in Him, before you will allow us the right to an opinion. You have not met Him. I have experience and you have ignorance. You claim that "factual reality" is complete, that it is all there is. I claim that it is not. I have shown that many scientists cannot even agree on how much "factual reality" is presently in existence, or even detectable. You must at least admit that I might have actually met God. You must take an agnostic, not an anti-theistic stance, at the very, very least. Otherwise, you have no right to an opinion about faith. You are in a territory such that you are unable to have a valid thought about the subject.

Religion? Go ahead, have all the opinions you want. Religions need no gods. Indeed, a good friend who is a Hindu told me, "My Guru is primary, my family is next, and then come the gods." Another friend, a Buddhist, has explained their entirely godless religion, in which Karma and Reincarnation work blindly in an eternal cycle; their cosmogony could run as a computer program. In fact, any religion could. Religions are rule-based, and I often joke that "You can hang the rules of your religion on the wall, and a robot could do them, but you cannot." Religious practices are quite amenable to scientific study. The desire to (try to) conform to an ethical Rule is nearly universal (sociopaths excepted), so it is certainly an evolved trait (as is sociopathy).

So to evolution. I like 90% of the book. Great examples, a clear teaching method, and I suspect the EvoS project is well worth the undertaking. I may do so myself.

David's thesis is simple. It is worthwhile to bring evolutionary thinking to bear on any observed phenomenon. (As a Geologist and amateur in a number of disciplines including Astronomy, I write and speak of galactic, stellar, planetary, continental, mineralogic, and chemical evolution. Particularly with regard to the concentration and emplacement of ore minerals, a kind of natural selection takes place, but of course there is no genetic/hereditary mechanism to produce new variations [elements and minerals]. Nearly all of geology is a reworking of existing Earth materials...but not quite. The planet does intercept a few tons of new matter daily.)

For example, he shows that, on every level one may imagine, collective behaviors tend to increased prosperity, or fitness, of the group. Units that prefer to exploit the group decrease its overall prosperity and fitness, so groups develop mechanisms to limit such damage, or they vanish. Thus, societies with appropriate laws and sufficiently strong enforcement mechanisms succeed better than anarchic ones (so we can expect nations that support terrorists to decrease in relative prosperity). A metazoan animal, such as a coral polyp, a bandicoot, or a human, is a collective of many cells that usually behave according to strong rules, genetically encoded, that even tell certain cells when to suicide. Cancer results when cells become rulebreakers and self-seekingly abandon behavior for the collective good.

Each cell of a polyp, a bandicoot, or a human, or of a tree, grass blade, or amoeba, is also a collective. Probably 1.5 billion years ago, after 2+ billion years of experimentation with various kinds of collective agglomeration, groups of specific kinds of bacteria became something new, the eukaryotic cell. All the "organelles" in such a cell must originate from bacterial precursors, and groups thereof managed to enclose themselves in a larger lipid membrane derived from that of an extra-large species of bacteria. (Perhaps it was related to the "giant bacillus" found in all human mouths, a brownish critter as large as some eukaryotes: about 15-20 microns long and 2-3 microns in diameter. It has 40-100 times the cell volume of smaller bacilli like E. Coli.)

What usually prevents human cells from turning into tumors or cancers? A lot of our DNA is not for making proteins but for regulating gene expression, particularly genes that affect cell growth. You could call a cell a totalitarian state. There are "police forces" and "executioners" within each cell that detect and edit DNA that mutates in deleterious ways, most of the time. There are similar cellular police in our immune system, and most cells that try to take off on their own are marked "not me any more" and destroyed.

A lot of Evolution for Everyone is devoted to applying evolutionary thinking to human groups, from households to nations. In the process, as the organisms themselves become more able to develop culture, evolution of the culture proceeds more rapidly than that of the biological organisms, yet by similar means. This reaches an extreme level in nations and nationalism. David states that "modern nations represent the current frontier of multilevel cultural evolution." Here is how most nations behave:

Imagine starting a conversation with someone who turns out to be nakedly selfish. Not only does she care only about herself, but she talks to you as if she cares only about herself. You hear all about her schemes for gettint ahead while riding roughshod over other people. Then she reveals how you figure in her plans without the slightest concern for your welfare. You would be doubly amazed at such a person. Only a social idiot would first have such shrunken values and then make no attempt to disguise them.

Yet I have just described the average political speech on international relations.

To me this is evidence that natural selection hasn't been operating very long in the political arena.

Of more immediate interest to me is the idea that the rules, or laws, make a family, church, club, neighborhood, or society livable. I once read that the police cannot enforce any law that is not voluntarily obeyed by at least 85% of the populace. This is the big reason most cars on I-95 go 70 mph or faster: because they can get away with it. The police have determined than the 15% cutoff is about 75 mph, so by going after only the fastest 15%, they establish what the "practical" speed limit is. In any group, if compliance to a crucial rule or law vanishes, pretty soon the group breaks up or falls into anarchy: disfunctional family; churches that split and split again; clubs that disband or fail due to lack of interest; neighborhoods that become hellholes; nations that fail.

But I concern myself with the effect police work has on police. In a recent case, several police fired 30+ bullets into a handicapped man who had failed to "obey instructions" (turned out they were talking too fast, and he was slow of mind), and celebrated their "kill" with high fives and a kind of dance. What happened to them? "You can't wrestle with a skunk and come out smelling like a rose." Police spend all their time with criminals, and guess who influences whom the most?

I am in favor of citizen-deputies, and very few "professional" police officers. In fact, I'd favor universal police service, on a rotating basis. Only in this way would this beleaguered group, our "peace officers", be spending more time with lawkeepers than with lawbreakers.

Much is made by this author and others of the "two island" thought experiment. In one case, populate one island with "good" folks, and the other with "bad" ones. The good will get better and the bad will get worse. Then take one "bad" person to the "good" island: he or she will soon live in luxury, at the expense of the rest. Mix the two groups in equal numbers on one island and "good" behavior will vanish away.

This model supposes that the "good" are uniformly good and never bad, and the converse. Actual people are complex. Every one of us is both good and bad. I lead a church. In a recent church meeting, at a round table discussion, we were talking of the meaning of love, and testing some boundaries. The Va Tech massacre was fresh on our minds, as was a recent suicide bombing in the MidEast. At one point, I remarked, "If you put me in a room with an unarmed terrorist, I could talk to him. But if I saw the same person in an overstuffed trench coat heading for a schoolyard, I'd shoot him in the head." In the ensuing discussion, most agreed this would show the greatest love possible to the potential victims, at the expense of sending one person to his god a bit early. It is Audie Murphy's reasoning: initially somewhat reluctant to shoot at an enemy, he reasoned that killing an enemy soldier saved a larger number.

I hope David becomes willing to allow believers to believe. I've long deplored the lunatic fringe of "inerrancy" folks, but I don't begin a discussion with any of them by demanding that they abandon their most cherished beliefs. I am a Christian evolutionist. God isn't afraid of evolution, and those who think they are defending Him are really only defending their own insecurities. The Bible leaves plenty of room for the eons of planetary and biological evolution to mold Earth and its life into the enviroments we experience today.

God works with human hearts. He seldom messes with nature. I have elsewhere written of the nature of miracles: they are events for which science will not and cannot provide an explanation, because they are produced by One who does not take note of science or technical tests. Such events are few. Don't look for a natural explanation for the sun stopping in the sky when Joshua asked God for that. Either it didn't happen at all, or it happened by a non-natural agency. About such things, science and scientists can only say, "I don't know." Only a person who meets God and receives His faith is able to know. Let us be humble, even though we know God, because that knowledge alone doesn't go very far.

I find it encouraging that this author at least tries to be conciliatory. That is a step too few scientists have been willing to take.

Fit today, maybe fit yesterday, but fit tomorrow...?

kw: book reviews, nonfiction, science, biology, evolution, natural selection

A Creationist would view the appeal of the book as, "Come into my parlor, said the spider to the fly." It won't convince many. That is a pity, because Sean B. Carroll's new book is an outstanding presentation of the best material that shows how evolution by natural selection is such a powerful theory.

The book is The Making of the Fittest: DNA and the Ultimate Forensic Record of Evolution. Dr. Carroll believes in "Tell 'em what you're gonna tell 'em, then tell 'em, then tell 'em what you told 'em." The opening chapter explains the purpose and structure of the book, and the closing two chapters, which he coyly calls "an after-dinner conversation", reiterate the main points and emphasize that "fittest" is a moving target.

It is a pity that so many use the phrase "survival of the fittest" without giving it much thought. If "the fittest" meant what we commonly mean, there would be but one superorganism on Earth, consuming inorganic material as it grows, subject only to the limits the planet can sustain. But with a little thought we realize that "the fittest" refers to a population of organisms that take best advantage of the resources offered by a particular ecological niche in one restricted ecology or other...or a limited set thereof. (Generalists like H. sap. can thrive in a large number of ecologies, but by no means all).

A knowledgeable person means a lot by the term "natural selection". Selection by itself just narrows the range of variation within successive generations of a population. Should the characterisics of the niche that population is adapted to change too much, it will die out. Selection implies that something supplies a range of possibilities from which to select. That "something" is mutation, a catch-all term for several mechanisms that change DNA. In brief, single "letters" (bases we label A C G or T) in the long "text" of a genome may be exchanged for other letters; one or more letters may be deleted; one or a few letters may be inserted; and bigger blocks may be duplicated.

The last item on the list is facilitated by certain sequences that say "cut here", which happen to occur about every 10,000 bases. "Restriction" (i.e. DNA-cutting) enzymes—used by viruses that need to insert their DNA into ours—cut apart DNA at such points, and other enzymes re-seal the cuts. Such a mechanism can copy a gene right next to itself. Then you have two copies, and further, smaller, mutations followed by selection (i.e. death of offspring for which a mutation is deleterious) will change one of these copies over many generations. New functions, new proteins, and perhaps new physiology arise by this mechanism.

One consequence of this cut-and-copy activity is that a copied gene is typically accompanied by some extra stuff that surrounded its original. Pieces of noncoding DNA (often called "junk") are also often copied to new places. These are called "interspersed elements", or INEs; long and short ones are called LINEs and SINEs, respectively. SINEs that precede genes can be easily extracted from DNA, and their presence in various organisms give us a good idea how closely they are related. They are easy to tell apart because they differ in length if their original source is different. Also, because they do not affect one's life or that of one's offspring, there is no selection pressure on them; they stay put over long stretches of time, slowly degrading as smaller mutations occur, but very rarely eliminated.

One of Carroll's illustrations (Fig. 4.3, p 100), shows the SINEs associated with three genes common to eight primates: Human, Bonobo, Chimp, Gorilla, Orangutan, Siamang, Green Monkey, and Owl Monkey. The SINEs for one gene are just over 500 bases long in Humans, 200 in all other apes, and quite a bit longer for the two monkeys (too long to show in the illustration; not present visibly). Another SINE of length ~750 bases is common to Humans, Chimps and Bonobos, ~450 for other apes, and again not shown for the monkeys. A third is ~475 bases long for all apes, and ~125 for the two monkeys.

Let's call these three SINE varieties alex, barb, and chip; and use -long to denote the longer version of each. Alex-long is found only in humans, so the gene in question was greatly modified in humans, but not in other apes. Barb-long must have been inherited by humans, chimps, and bonobos from their common ancestor, and chip-long from the common ancestor of all apes. The copy of some noncoding DNA that produced alex-long happened only after humans split off from the chimp-bonobo line. And so forth.

The SINEs and LINEs that we all carry, by the thousands, last lots longer than some genes. However, the longest-lasting features of our genome are seemingly immortal genes, the subject of Chapter 3. There is a protein called "elongation factor 1-alpha" that is used in every cell of every living creature yet studied. The DNA that produces it is one of about 500 immortal genes that are almost identical in every living being. Here is a portion of the amino acid (AA) sequence of this 1-alpha protein (we use capital letters for the twenty amino acids in proteins), for five very different organisms:

DAPGHRDFIKNMITGTSQADCAVLIV Human
DAPGHRDFIKNMITGTSQADCAVLII Tomato
DAPGHRDFIKNMITGTSQADCAILII Yeast
DAPGHRDFVKNMITGASQADAAILVV Archaea
DCPGHADYVKNMITGAAQMDGAILVV Bacteria
D-PGH-D--KNMITG--Q-D---L-- "Immortal" letters

Those that differ from the Human sequence are bolded (Although there is an A that doesn't change here, it does change for other organisms not shown. The "immortal" ones never do). The KNMITG is particularly interesting. These six AAs fold into a shape that is critical to the operation of the protein. Any change to any of them is invariably fatal. Thus, natural selection has preserved them, because every cell in which any of them was changed by a mutation has died straight off.

I will touch but one other area, one I find fascinating: color vision. The author presents it in detail in Chapter 4, and returns to it frequently in later chapters. First, a study of color vision throughout the animal kingdom indicates that early animals had at least five different color receptors; the lamprey and other very primitive animals have five. Most birds and many fish and reptiles have four, primates either two (New World monkeys) or three (apes and Old World monkeys), and most other mammals and many more primitive animals (but not the most primitive) have two.

Humans actually have a fourth receptor, the "night vision" rods, which do not produce color vision. However, there is a twilight region of near-dark for which the rods begin to work, and the "green" (medium wave) cone still works, though the "red" (long wave) and "blue" (short wave) have quit working. Under a quarter moon, objects that are brightly colored by day take on deep blue-to-yellow/brown hues. It takes near-total darkness to produce entirely monochromatic rod vision. But by day our vision is trichromatic, because of three color receptors...for most of us. For about one man in fifty (but very few women), either the long or the medium cones are missing. It takes both to distinguish colors in the red-yellow-green area of the spectrum. So such men are red-green color blind. They can still distinguish "yellow" from blue.

However, there are three sites in the opsin pigment protein sequence that make most of the difference between the long and the medium (red and green) cones. When all three are one way, we have the green variety, and the other way, the red variety. More than 90% of us have "green" pigment that is "really green" and "red" pigment that is "really red." But for some people, there is a mixed case. One of these sites in particular makes half the wavelength difference in a pigment's peak sensitivity. Mix it wrong, and half of one's color discrimination is gone. For most people with such "anomalous color vision" there is no problem. They are still able to see all the colors, the experience is just less intense.

Now, WHY do we and our closer primate relatives need to tell red from green? Most mammals get along with two colors (dogs and cats included). Why, because we eat fruit. It is a major part of the diet, and ripe fruit is usually red. A dog can't tell a ripe raspberry from a green one, and doesn't need to, because dogs don't eat raspberries...and house pets that have learned to like them can tell more from the smell than the color anyway. Primates have poor noses! (That is another story...)

Old World primates with 3-color vision descended from 2-color ancestors. How? By duplication of an opsin gene, and a gradual shift of one copy to detect redder things, compared to the other. We can tell which came from which by comparing sequences with the long wave opsin in 2-color vision primates. Areas that don't determine color vision, that are primarily structural, are more similar in the more closely related genes. There's lots more here, but that's enough for now.

The author's principal aim is to prove, as closely as one can come to proof, that natural selection is a correct theory. While we know that theories are really only falsifiable, never totally provable, a sufficient mass of favorable evidence coupled with an absence of contrary evidence is as close as one can come. A theory is considered strong, not because it explains phenomena known at the time of its inception, but when it makes correct predictions of observations yet to be made, and even more if unexpected findings are found to fall under its explanatory umbrella. Very few theories currently reign as Very Strong Theories: Quantum Electrodynamics, Special Relativity, General Relativity, and Evolution by Natural Selection are the top four.

His secondary aim it to show that "intelligent design", the latest offshoot of creationism, is not a scientific theory. He actually expends little effort to this end, because ID is an unwitting straw man very easy to demolish, and because Christians have already done a good job of it. Here is part of a statement by Richard Harries, the Bishop of Oxford, as quoted on p. 242: "The theory of evolution, far from undermining faith, deepens it. This was quickly seen by Frederick Temple, later Archbishop of Canterbury, who said that God doesn't just make the world, he does something more wonderful, he makes the world make itself. ... biblical literalism brings not only the Bible but Christianity itself into disrepute." The simple fact is that ID makes no statement that can be scientifically tested, so it isn't science, it is just a myth, not even a biblical one.

This reminds me of a joke I first heard as jibing certain fundamental baptists, but here:

A devout Episcopal appears at the gate of heaven and Peter admits him. He is assigned an angel to show him around. The angel tells him there is just one place he must avoid, and shows him a walled compound, without windows, and a fence far from the wall, guarded by armed angels. "Who is in there?" the gentleman asks. The angel replies, "The creationists. They think they're the only ones here!"

When did human evolution stop?

kw: book reviews, nonfiction, paleoanthropology, archaeology, historical linguistics, primatology, social anthropology, evolutionary psychology, population genetics, human origins, natural selection

The simple answer to this post's title: It hasn't. Among those who accept evolution of the human animal, it is common to think that we've reached some kind of pinnacle, and no evolutionary change has taken place in the last ten or twenty thousand—or perhaps 100,000—years (For those who don't, of course no evolution has ever taken place). The book Before the Dawn: Recovering the Lost History of Our Ancestors by Nicholas Wade presents a synthesis of what is known and strongly inferred in the disciplines related to human origins. The picture is full of surprises.

Item: When did people begin to wear clothing? Fabrics are so rarely retained in "fossil" deposits, we can't begin to guess. Body lice provide the answer (yuck!). Head lice, equivalent to head-and-body lice in apes, live in the hair. Body lice live only in clothing, and move to the skin to feed, but lay eggs in clothing, because there is too little hair on most human bodies to reliably protect the nits. So when did body lice evolve? Genetic dating from modern head and body louse populations provides the surprising answer: about 70,000 years ago. Such dates currently suffer from large uncertainties, so the actual development of the body louse, shortly (a few thousand years) after clothing became common, occurred before 40,000 years ago, and most likely 80,000 or later.

Item: When did proto-humans lose their body hair? Both chimps and bonobos (once called "pygmy chimps") both have fair skin under that black hair. Only the face, hands and feet are dark, because of a permanent tan. Dark skin over the body probably arose as hair was lost, to protect the skin from the sun. "Black" Africans can be sunburned, but it takes a lot more sun exposure compared to lighter-skinned people. When did darker skin over the whole body evolve? Genetic dating again provides an answer, this time from the genes that produce skin pigments: about 1,200,000 years ago.

Strangely, I looked for information on the "first use of fire", but Wade doesn't mention it. A BBC News article of 22 March 2004 states that early African humans, possibly Homo erectus, seem to have had hearths as early as 1.5 million years ago. Another article, dated 29 April 2004, about H. erectus in Israel, has them using fire in sophisticated ways 790,000 years ago. It seems to me that nakedness arose primarily as a result of fire use. Other explanations, such as sexual selection, seem less compelling.

What is interesting, though, is the million or more years that passed between the loss of hair and the development of clothing. Production of textiles must require a change in thinking that didn't occur earlier. The Acheulian "toolkit" was used by at least three species of Homo from 1.7 million years ago until it was supplanted 250,000 years ago by Mousterian (H. Neanderthalensis in Europe) and Middle Paleolithic (H. Ergaster in Africa) technologies. These related technologies show two things: that there was contact between African and European species of Homo; and that one had attained sufficient brain power to greatly improve their use of stone tools, which the other quickly adopted (it takes less wit to copy than to invent). So, apparently, clothing other than cured skins was an invention later yet.

I've known the term "anatomically modern human" (AMH) for decades. I confess that I didn't think about it much. But later, the term "behaviorally modern human" (BMH) gave me pause. Is there a difference? Sure is, by tens of thousands of years. It seems AMH's, which arose in Africa 100,000 years ago, could pass for human today, as long as they didn't do anything. But they didn't live like BMH's, who lived like the hunter-gatherer groups of today, such as certain "primitive" tribes in South America or New Guinea. Evidence of BMH living appears just after 50,000 years ago in Africa, and about 45,000 years ago in Europe.

AMH living was by foraging and minor hunting. Family groups stayed together, in bands of related families that scattered and coalesced on a daily basis, numbering 50 or fewer. Few activities other than food gathering and preparation, procreation, and sleeping, occurred.

BMH living included much more hunting, of larger game, and specialized plant gathering. A great increase in the use of ornaments and artful trinkets arose. The stone toolkit, called Upper Paleolithic, was much more complex, with specific tools for specific uses, and complex tools made of bone, antler, and ivory. Musical instruments, such as bone flutes, are found for the first time in BMH leavings. The people ritualized burial. And they traded among groups, much more than AMH's, to obtain materials and products found far from their home ranges.

Add one item: About 50,000 years ago, BMH's from the "ancestral human population" (AHP) in Africa migrated beyond Africa, apparently for the first time since 1.8 million years ago, and established themselves eastward and northwestward to the limits of the Eurasian continent in a few thousand years. They seem to have supplanted and replaced Neandertals in Europe and "archaic Homo" people in Asia, in less than ten thousand years. During this time, some reached Australia, something the archaics didn't do.

When I saw all these together, I was convinced for the first time that the "multiregional" hypothesis, which requires persistent gene flow among the African, European, and Asian species of Homo, must be wrong. What was it that kept Africans from continuing to migrate to Eurasia, at least successfully, between 1.8 million and 50 thousand years ago? The most likely answer is that the land was occupied by Neandertals and archaics, who either drove out or destroyed invaders. In the same way, the AHP in Africa filled at least the Northeast part of that continent and kept the other species from invading.

Once the AHP developed BMH living, they could make better use of resources, had better weapons, and could stay together in larger groups, compared to the other species, and could successfully invade Eurasia. However, even with these advantages, it wasn't a simple walkover. The number of BMH's who became the ancestors of all non-African people was less than 500, and possibly as few as 150.

OK, so what happened since 50,000 years ago? Are we BMH's who have somehow adapted to settled life? Are today's remaining hunter-gatherer (H/G) groups BMH's? Not really. Although BMH's were anatomically very nearly the same as AMH's, there are differences between today's people, both in Africa and Eurasia, and the people of the African AHP. If you were to take a range of modern people, of all races, of various sizes and ages, and pair them up with AHP folks of similar size and age, you'd find the earlier people had thicker skulls and heavier bones at all ages. They were not as heavily built as Neandertals, but were definitely more like American Football players than like Soccer (European Football) players. The AHP's also stayed in smaller groups than members of modern H/G groups do.

The main reason is inter-group combat. There has been a strong tendency among anthropologists to understate the level of aggressiveness and prevalence of warfare among "innocent savages." An unbiased look at the record reveals that the greatest single danger to humans through all ages was and is other humans. Xenophobia is the natural state of the H/G mind, the BMH mind, and the AMH mind, as it was for all earlier species of Homo.

It is now known that groups of chimps engage in wars of extermination against neighboring groups, and that the leading cause of death among males is "chimpicide". Bonobos, with a female-dominated society, do not engage in such warfare...a good reason for turning over all politics to women!

The greatest single cause of both male and female death in most H/G groups is warfare and killing raids between groups. So, while trade arose at least 50,000 years ago, it probably occurred primarily among groups that couldn't exterminate one another, just as it does today among all the mutually warring tribes in New Guinea and South America, for example. "You aren't my brother or cousin, but unless I judge I can destroy you, I'll call you friend...for a while."

My father's cousin, while a missionary in New Guinea in the 1950s, saw frequent warfare and some cannibalism. Two groups of men might trade one day, and slaughter one another the next. A smaller village might have all its men killed, whereupon all their children would be killed, plus most of the women, and the rest taken as concubines.

Let's look at a few numbers. About a third of adult male chimps die in combat. The number is the same among the Yanomamo, a Brazilian tribe of H/G's. One study showed that a typical tribal society lost, on average, 0.5% of its population yearly to warfare (that's ~1% if the men and a smaller proportion of women; and among men, that's a 26% loss per thirty years). However, averages tend to hide incidents. Most inter-tribe warfare is carried out by small battles and raids a few times per year, or perhaps monthly. Pitched battles are much less frequent, but cause huge carnage: A 30% loss on both sides is typical. Modern societies prior to 1900 AD could produce similar death tolls: At the battle of Gettysburg, the Union side lost 21%, and the Confederates lost 30%.

However, the two World Wars of the 20th Century resulted in losses of less than 10% among the soldiery, and a percent or less of the engaged nations' total citizenry. Stalin's purges of the 1940s and '50s were actually worse than either World War in terms of pure carnage...they were wars of another sort. But in 2002, though a number of wars were in progress around the globe, including America's war in Afghanistan, 0.3% of deaths were due to warfare.

But these latter figures are comparing recent wars among settled societies, with wars among H/G societies, BMH societies...and apes! They are probably not entirely fair. Wade doesn't go into this, but by my own study, I find the following: History is full of war stories, from Troy to Sparta to Carthage and so on. But it seems the total toll of warfare among settled societies is typically about half that among H/G societies.

I wonder what is cause and what is effect? Did settlement and agriculture result in a preference for negotiation? Or did the development of more negotiation-prone people—perhaps first among those who profited most from trading—allow settlement to occur?

I'd say it is a coevolutionary change. Our skeletons reflect the fact that we have less reason to fear being bonked on the head some random night, compared to the AHP, and less need for face-to-face combat. Although today's H/G members live very similarly to the AHP, a Yanomamo or Dani person can be socialized to live in a city. I suspect a person brought in a time machine from 40,000 years ago would be unsocializable, or only partly so.

The brain has changed since that time. So far, two genetic changes that determine brain size, and probably size in specific areas, have been found and genetically dated. One occurred 37,000 years ago, the other 6,000 years ago. The people of 50,000 years ago were, from archaeological evidence, able to live in larger groups than earlier peoples. They were able to extend the idea of "kin" to a larger group than before. But each change to the brain seems to have increased the number of "others" a person could tolerate.

By 15,000 years ago, when settlement began, it seems people could tolerate even greater numbers, and additionally, accept direction from leaders. Both are required for a few hundred people to live in continuous close proximity. It seems strange that these first settlements were not primarily agricultural. They seem instead to have been "places to be" between hunting and collecting expeditions, and trade centers. Specialized skills proliferated; the best hunters got their spear and arrow points from the best stoneworkers, as the best clothing makers got needles and other tools from bone workers...and in turn traded clothing to those less skilled.

The later development of agriculture led to much larger settlements, about the time of the 6,000-year-ago bump in brain size. A larger brain adapts one to the need to remember a larger number of people. It was not much later than this that lactose tolerance evolved among those who kept herds of large mammals. To this day, lactose tolerance or intolerance indicates whether your ancestors were farmers or ranchers.

Now think, today an office worker can step out of an apartment and essentially vanish into a city of millions of strangers, and return safely hours later! Rather extraordinary, wouldn't you say?

What other genetic changes have arisen recently? Malaria resistance among those living in subtropical areas has evolved at least twice since 10,000 years ago (one such change causes sickle-cell disease). Our sense of smell is much reduced compared to just 15,000 years ago, because most of the olfactory gene set has become inactive. Whether this is because of the stench of early cities, of because of less need to smell out game, I forbear to speculate!

The changes to brain and body that occurred prior to 50,000 years ago are found in all humans. Those that arose later are found in larger or smaller numbers depending on where a mutation arose and how strong a benefit it ensured.

This leads us to the most visible differences among human populations, those that correlate best with the continent one's ancestors inhabited: we call them races. While skin color is often considered to be the main indicator of race, it is not really the best. The Caucasians in southern India are darker than some Africans; some Japanese (and I don't mean Ainu, which are very pale) are paler than most Caucasians; many Australians (aboriginals not Austro-Brits) are darker than most Africans or Indians. If you take almost anyone, and paint their skin white (or any solid color of your choice), most people can tell at a glance what continental type they typify, and often the subtype (pygmies and Inuit are quite distinctive, for example).

Regardless how extensive "racial" differences are, it seems they arose no more than 12,000 years ago. They reflect, as do many other indicators, that most people in history seldom moved far from the place they were born. The subtypes within continental groups emphasize this. So, rather than the "not politically correct" attitude toward any mention of racial genetics, it would be better to look upon the diversity of human types as a library of the history of humanity.

One thing is sure: We continue to evolve. We are more gracile than the AHP. Gracility may continue, but it has probably already reached it logical limit among East Asians. Even though Chinese fed a "Western" diet grow taller than their parents, they remain on average much slenderer than Europeans. The continually increasing complexity of modern life will, unless civilization collapses, lead to people with larger brains and more multitasking skills, first behaviorally, and over a few generations, genetically. We won't become the bare brains of science fiction, but we may become smaller, thinner, quicker, and less aggressive in the future. Should Homo sapiens survive another 50,000 years, no doubt our descendants will look back at us as quizzically as we look back at the people in Africa, 50,000 years ago, some of whom managed to escape that continent to colonize the rest of the planet.