Dinosaurs triumphant!

 kw: book reviews, nonfiction, history, fossils, geologists, victorian era, dinosaurs, evolution

As a fun retirement job I work at a natural history museum. A few years ago the exhibit hall was being redesigned. Several of us were discussing the plans, and the kinds of exhibits to be included. One experienced scientist—like me, retired, and a volunteer in the research division—said primarily one thing, persistently and steadily, every couple of minutes: "Dinosaurs." It was true when I was a child and it remains true that having several dinosaur skeletons on display will bring the crowds.

As told by Edward Dolnick in Dinosaurs at the Dinner Party: How an Eccentric Group of Victorians Discovered Prehistoric Creatures and Accidentally Upended the World, people had found big fossilized bones for millennia, and fitted them into whatever worldview they had, usually as prehistoric, or sometimes contemporary, giants. For example a fossil elephant skull, with its large central hole for the trunk, is behind the myths of Cyclops with a single, giant eye. As the Industrial Revolution cranked up in the late 1700's, with all the digging of canals, tunnels, and deep foundations, many more large bones were unearthed. A few chapters are devoted to Mary Anning, the most productive fossil finder of her generation. Comparative anatomy became a thing, and by the early-middle 1800's a great number of the animals to which these bones had belonged were being likened to reptiles with certain mammalian characteristics, such as upright legs rather than the sprawling legs of a crocodile.

The word "dinosaur" was coined by Richard Owen in 1842. Not long after, marine reptiles such as plesiosaurs and ichthyosaurs, and aerial reptiles such as pterosaurs, were recognized as parallel to dinosaurs, but not included. By this time it was also becoming more and more clear that the Earth was a great deal older than the comfortable assumption of "around 6,000 years", or the more specific "created in 4004 BC", based on Biblical interpretation of the time. Also, the geological principle of superposition—rock layers and their fossils found below more shallow layers and their fossils are older, and a succession of layers represents a succession in time—showed that most creatures from long, long ago had gone extinct, even that there had been entire assemblages of living things that vanished from the scene, to be succeeded by other assemblages that then became extinct, several times.

This upset the simple theology of the time. Then when Darwin published On the Origin of Species in 1859 the faith of many was shaken. Time was impossibly long (about 750,000 times as long as they had thought), the vanishing of 90+% of all living species (more than once!), and the sudden insignificance of humans and human history seemed to relegate God to the status of a minor, and indifferent, demigod.

Side note: How is it that so many people retain Biblical faith to this day? I was taught from a very early age about The Gap: that verse 1 of Genesis 1 describes an original creation, which was damaged and became chaotic, such that verse 2 and onward describe a restorative creation. Hebrew has certain complications in its grammar. One is this: the past tense of the verb "created" in Genesis 1:1 is different from the past tense used for the verbs in the rest of the chapter that describe God's actions on the Six Days. Therefore, whatever one may think of the six days (such as whether they were 24-hour days or eons or something in between), the time of the first verse is not in any way constrained. In the Scofield Reference Bible (1909), the second note on Genesis 1:1 (using "but" to mean "only") is, "But three creative acts of God are recorded in this chapter: (1) the heavens and the earth, v. 1; (2) animal life, v. 21; and (3) human life, v. 26, 27. The first creative act refers to the dateless past, and gives scope for all the geologic ages." This last sentence is the key to understanding that God's focus is on His relationship with humans, and that is the emphasis of the entire Bible. It is not a text of natural history.

In this very entertaining book we learn how the people of the Victorian era (~1837-1901) were practically dragged out of their comfortable, small and short-lived world into a dramatic, vast and eons-long spectacle. Once dinosaurs had been discovered, many thought they and their flying and swimming kin might be found in the unexplored parts of the Earth. Eventually they understood, this was not to be.

In the next-to-last chapter, "Dinner in a Dinosaur" we learn of a fantastical dinner party held New Year's Eve 1853 inside a life-size model of an iguanodon. By the late 1800's dinosaurs had thunderously earned a seat at the table.

The last sentence of the Epilogue ends, "…with no warning, no foreboding, they vanished." I would add the proviso that today's birds are dinosaurs. If you are ever in the presence of a Cassowary or Ostrich in the wild—and you'd be in mortal danger in either case—you'll understand.

Innovation can take its sweet time

 kw: book reviews, nonfiction, biology, culture, sociology, evolution, innovation

The cover of the book really catches the eye, being decorated with lovely shells of the Cuban land snail Polymita picta. Interestingly, these snails are never mentioned in the text. These golf-ball-sized snails are considered by many to be the most beautiful snails in the world.

For your delectation, here are some more, from one lot in Berlin's Museum für Naturkunde. 

I happen to consider a different species the "most beautiful", and I'll show some examples below.

The term Sleeping Beauties is used by practitioners of scientometrics (measuring the effectiveness of scientific ideas), to describe articles or monographs that receive few or no citations by other scientists, for years or decades, until they suddenly become "popular", possibly receiving hundreds or thousands of citations in literature. A real "blockbuster" idea might then be cited, and even enter the popular press, for many years. One learns this rather late in the book Sleeping Beauties: The Mystery of Dormant Innovations in Nature and Culture by Andreas Wagner.

The thesis of the book is that innovations crop up all the time but are seldom "on time". They may need to arise a few times before factors in the environment permit them to spread. The first example in the book is grass. Grass evolved about 70 million years ago, but widespread grasslands did not appear until about 25 million years ago in South America and Asia, and 10-15 million years ago in North America. From that time, grasses radiated into thousands of species, from cm-high Alpine grasses to 20-meter-high timber bamboo. Although grasses had several innovations that made them more efficient—growth from the base rather than the tip; drought and heat resistance; SiO2 granules in the tissues—these did not favor them when Earth was mostly moist and tropical. Only in certain isolated areas did the environment favor grasses over other plants. Then the environment changed, and so did the kind of plant cover found on the major continents. The evolution of C4 photosynthesis, which makes plants that use it well adapted to CO2 levels below 1000 ppm, and a change of climate to warmer and drier across large swathes of continents, favored grasses even more over shrubs and trees. Today, even though many decry the rising CO2 level—it is more than 400 ppm now—trees and shrubs are struggling and grow more slowly than they did while dinosaurs were around, while grasses do quite well.

Similar cases are found throughout the natural world. About one-third of the book explains what has happened in evolutionary, cellular, and molecular terms. Basically, every biological entity undergoes many small DNA mutations in various cells yearly. Some are damaging and cause the cell to die. Some affect how a cell grows and it becomes cancerous, which can cause the entire animal to die a few weeks or months later. Most seem to be neutral, in that they don't change the protein a gene makes or the way a regulatory sequence works. Finally, some improve the lot of that cell; as it divides, whatever it is doing (making digestive enzymes, making muscle move, releasing a hormone) might be done a bit better so that daughter cells attain that advantage. In a multicellular animal or plant (a metazoan) a mutation must arise in a germ cell, one that will become an egg or sperm, for the trait to enter the next generation. 

The author argues that small mutations such as SNPs (Single Nucleotide Polymorphisms) occur with great frequency. Some mutations can affect larger things. A SNP in just the right place can disable a regulatory sequence, so that a key protein is no longer made. Sometimes an error in DNA copying causes a whole gene to be duplicated. Then if you have copy A and copy B of that gene, and copy B is the next one to incur a SNP or other mutation that changes its function (usually decreasing it), the organism can get along fine as long as copy A works well. Then further changes to copy B might occur until it is sufficiently modified that it might take on another function. However, let us be clear that this doesn't happen all in one organism, but over several generations. In prokaryotes (bacteria and archaea), where the entire organism is a single cell, it is easier to see how this can lead to rapid evolution. In eukaryotes (protozoa and all metazoa, including almost everything big enough to see), a mutation, beneficial or not, must pass through the bottleneck of reproduction, occurring in a germ cell, or it will not affect the next generation. I think this is not made clear enough in the text. The author deals almost exclusively with single-celled organisms.

I'll step aside from the book's content for a moment. The statistics of metazoan reproduction are such a steep hill for new mutations to climb that it would seem that their evolution must almost come to a complete halt. But there is a "third sex" that transmits genetic information horizontally between organisms, including across species boundaries: viruses, retroviruses in particular. Although some retroviruses (such as HIV) cause disease, others do not. Let's call one of these apparently harmless viruses Friendly Human Virus, or FHV. You'd never notice an infection by FHV, it is so low-level. For a period of time the infected cells would produce FHV particles, and in the process they would incorporate the FHV genome into the cell's DNA. Not all infected cells die. About 8% of human DNA consists of hundreds of "endogenous retroviruses", stored more-or-less intact in our "noncoding DNA" (it used to be called "junk DNA"). Some of the FHV particles your body sheds will include copies of some of your own DNA that the new virus particles picked up during their manufacture, which is a rather sloppy process. When someone is infected with FHV that came from you, cells in that person's body get some of your DNA incorporated into their genomes. The "Viral 8%" is part of a "library" of potentially useful genes that may get activated by other mutations later on. Contrast this 8% with the amount of your own DNA that is actually used to make proteins (2%) and regulatory sequences including ribozymes (another 2%).

There is a lot of terminology in the chapters that form the "meat" of the author's argument. It's OK, it's all well described and defined. By the middle of the book a reader can understand how certain kinds of innovation in evolutionary traits occur over and over, until other factors in the environment one change or another something favorable, something that will spread in a population.

The second half of the book discusses similar concepts as they relate to culture. Culture is not only a human thing, although until a generation or two ago, everyone thought only humans had culture. Consider certain small British birds with bills that can puncture the heavy foil lid of a milk bottle. For many years the milkman left milk bottles on people's porches once or twice weekly. At some point, a bird managed to cut its way into a milk bottle to get a beak-full of milk. Birds observe one another, and when another bird saw the feat, it tried it. Soon, the practice spread throughout the British Isles. Milk is now dispensed in a different way, which thwarts the birds. This is an example that seems to have spread rapidly, but the details are interesting. A little records-gathering has shown that the practice was confined to a small area for a few years, and then spread rapidly after that delay. I haven't learned if it happened more than once, but the author of Beauties posits that every time an innovation is researched in detail, it is found to have occurred several or many times, but only the most recent is usually remembered. He discusses the use of citrus fruits to combat scurvy: it was discovered several times during a period of two centuries before finally "taking hold" in the British Navy, to the point that British sailors are still called Limeys.

In general (but see below), the book is a great pleasure to read. There is a lot to think about, a lot to learn. Evolution has more going on than I'd have thought.

As promised, here is an example of what I consider the most beautiful species of snail, the Splendid Jewel Snail, Liguus fasciatus splendidus. The next picture has a few examples of other subspecies of jewel snails.

These are found primarily in Florida, on the trees and shrubs of "hammocks" (the local pronunciation of "hummocks", elevated, shrubby places in the Everglades).

I have a quibble. On page 181 the author discusses writing systems that were studied in detail by Mark Changizi and colleagues, including Latin, Arabic, Hebrew, Greek, Cyrillic, Chinese and Cherokee. They sorted the characters in a script according to the number of strokes. For example, "O" and "I" have one stroke (when written without serifs), while "M" and "W" have four. Analyzed this way, there are great similarities among writing systems, and he states, "Most characters can be written with three strokes, some with one or two, but none has more than four, regardless of the writing system." I think Dr. Wagner missed something. This is ridiculous if one includes the logographic scripts, primarily Chinese, Japanese and Hangul (Korean). The image at right is scanned from the spine of my Japanese wife's "big dictionary". It reads "Complete Kanji Dictionary Ocean", where "ocean" is an emphatic modifier of "complete"; the corpus deals with more than 80,000 logographs. From top down, the number of strokes are 17, 13, 13, and 10. If one wishes to separately treat the portions that don't touch, dividing a single logogram into its root and "the rest", many of those still have more than four strokes each. Hangul characters usually have fewer strokes than Chinese, but seldom fewer than 5 or 6. I dug around among other languages of Asia. A "swirly" script like Tamil may have letters with few strokes in the formal sense, but some single strokes swirl around so much they may as well be three or four, to which another stroke or two are added. I don't know how one even counts strokes in Sanskrit! And then there's classical Mayan. The characters are very complex, and quite variable depending on the writer. Dozens of strokes are typical. A key concept when looking at a Mayan stela: the carved glyphs are intended to appear a though they were written with a brush in a paper codex (of which few survive).  Probably 95% of the world's scripts follow the "4-or-less" tendency, but it is not universal.

Secondly, as to the structure of the book. The endnotes occupy 38 pages, and more than half the space is devoted to long notes that could have been incorporated into the main body of text, which is 240 pages. Such asides take off from the main text in a way that it's often necessary to go back to the original page and re-read what came before the superscript, to get the thread of the discussion. Bad practice. Dear authors, don't put "asides" in endnotes, just keep them in the main text or leave them out. If something is worth saying, that's where to say it. Reserve endnotes for citations or very (very!) brief elucidations.

Behavior is as behavior does

 kw: book reviews, nonfiction, natural history, animals, behavior, evolution, nature-nurture debate

A fellow showed up half an hour late for his regular poker game with friends, and found they'd started without him. For a fourth, they'd recruited the host's dog. The man told the host, "Wow! That's some talented pup!!" "Oh," he replied, "Old Groaner isn't so great. Whenever he has an ace he wags his tail."

We are amused by pictures or stories of animals doing "human" things (or the converse!). Yet until recently, while most people with pets seem to easily understand that the animals have feelings and purposeful behaviors, scientists have been slow (by centuries!) to come around.

Marlene Zuk's new book, Dancing Cockatoos and the Dead Man Test: How Behavior Evolves and Why it Matters, drives lots of new nails into the coffin of the Animal-as-Automaton view. Let me state at the outset that, for two good reasons I hold that animals, even the rather elementary ones we call "bugs", all fit along at least three scales (none of them is the scala naturae, the "natural ladder" so beloved of ignorant biologists). Firstly, as to consciousness, one end might be called "Human-level self consciousness" (assuming it's truly the end point; maybe toothed whales are beyond us, for example); the other end we can call "barely conscious of more than the basic drives of hunger and the 'urge to merge'". Secondly, as to emotion, just as some animals have abilities we don't, there ought to be some that can have feelings we don't have. Thirdly, considering behavior, which is often divided into "purposive" (the scientific jargon for "purposeful") and "instinctive" (which really means "purely genetic"): everything living behaves. Animals are practically defined by behavior. It is what they ARE. "Lower animals" are the product of 4 billion years of evolution, the same as humans. So are the things that they DO.

Somewhere on my bookshelves I have the seminal volume, Purposive Behavior in Animals and Men by E.C. Tolman, published in 1932. This book is not referenced by Dr. Zuk, more's the pity. If she's not an intellectual descendant of Tolman, she's at least a grandniece. He was far ahead of his time, as witness the still-nearly-pervasive use of the canard "anthropomorphism" to discredit much work on animal behavior.

My two reasons: To hard-line creationists, many of whom also hold the Calvinist position that God has no emotions, I would say, "Are we not created in the image of God? Did our emotions and behaviors come from nowhere? Are they not part of that image?" Of course, some would double down to say that all such things are part of "original sin" or whatever Protestants call it. (Though I am a believer, I am neither Catholic nor Protestant.) They are fools. To take a further step, "If we have feelings and behaviors that are something other than automatic, why would God deny such abilities to animals?"

To hard-line Skinnerian scientists I would say, "I subscribe to evolution, as carried out by natural selection. Do you? If so, you must realize that our feelings came from somewhere. Where? Of course, from our nonhuman ancestors. We emote and behave because they did." So much for anthropomorphism. And as I said before, animals that are attuned to greatly different environments than humans could survive (without costly technology) are likely to have feelings and behaviors that are so foreign to us that we are unlikely to recognize them as such.

So, a bit about the book—which I urge everyone to read!—what is the Dead Man Test? Some, wishing a less macabre moniker, call it the Teddy Bear Test: If a Teddy Bear can do it, it isn't behavior. Substitute Dead Man for Teddy Bear if you prefer. Definition by exclusion.

How does behavior evolve? Just like anything else! Behavior is a physical attribute. It is just as real as height, eye color, and whether your ring finger is longer or shorter than your middle finger. These things, plus all other "genetic traits" are influenced by environmental factors. This is the central emphasis of the book. Genes alone don't determine anything. Neither does environment alone. Everything is a mix, an intertwining of the two. She has to say it over and over, because many folks won't get it otherwise!

For an example of this intertwining: One of my great-grandfathers was prone to drink. The family was Methodist, and Methodists were, until the 1960's, required to sign a Pledge that they would not touch alcohol. Great-grandpa Joe fought his addiction mightily, but he would go on a bender on occasion. His daughters kept their Pledges; it helped that they never tasted "the sauce" as young people, and that they took their father as a cautionary example. Having a strict mother helped. My mother was also raised to be a teetotaler, as was I. But in college some friends persuaded me to have a beer to celebrate my 18th birthday (I lived in a state that allowed 18-year-olds to drink "low beer"). I soon found a way to get harder stuff, and I was off, headed for a life as an alcoholic! Except, I couldn't afford it. Also, returning home after the school year, back in a teetotaling home, I took a hard look at myself, and decided not to use "anything that hinders thinking clearly". At that time I didn't know about Joe. Later one of my brothers became more of an alcoholic than I had been. His own story is fascinating, but won't fit here. He and I are both "recovering"; one never fully "recovers".

Why weren't my mother and her mother alcoholics? In a different environment they'd have been so. We have a kind of protein that turns ethanol into a heroin-like addicting substance. Fortunately, it is kind of rare. Yeah, I know there are lots of alcoholics; some of them have this same genetic situation. But they are a small fraction of the whole of humanity.

I'll leave it to you to get the book and allow Dr. Zuk to lead you down many a lane and garden path, with her stories of dancing cockatoos (do they have something to dance to in nature? Neither do elephants, and I've also seen videos of them responding to music); of octopuses punching fish, apparently out of irritation; of how animals from flies to flying foxes vary in their behaviors based on still-inscrutable combinations of their genetic endowment and their past and present environment. This sure is an enjoyable book!

Mechanisms of evolutionary saltation

 kw: book reviews, nonfiction, evolution, development, evo-devo, dna, molecular biology

It took Stephen Jay Gould twenty years to write The Structure of Evolutionary Theory. It will take me longer than that to read it. I bought a copy when it was released in 2002, and I am only one-third of the way through it. I intend to read it all.

You may know that Dr. Gould is one originator of the hypothesis of Punctuated Equilibrium: fossils show that species tend to persist almost unchanged for periods of a million years to tens of millions of years, and then undergo rapid change, during which new species arise quickly. His book discusses this matter, and much more, in a historical context. I probably haven't come to the "good bits" yet. But others have, and scientists continue to discover new aspects of genetics and evolution, so I read widely in the field.

A stellar new volume is Some Assembly Required: Decoding Four Billion Years of Life, from Ancient Fossils to DNA, by Neil Shubin, a researcher and professor of Organismal Biology and Anatomy. His book outlines certain events in the history of evolutionary thought and genetic discovery, with an emphasis on a seminal thought expressed by one of his mentors, "Things didn't start when you think they did."

For example, he discusses wings and flight. Flight arose at least four times, in insects, pterosaurs (reptiles), bats (mammals), and birds. In each case, wings didn't appear all at once, but we find that earlier tissues and structures with different functions were co-opted to become wings, in a rather short time span. Furthermore, by digging into the genetics of wing development, he and others have found that the precursors to wings have similar origins in these very different types of animals. I can't do justice to an explanation of this. The book's discussion is brief yet illuminating. Bottom line: structures that could later become wings were developed long ago, for other purposes, and only millions of years later did the new function of "catching air" arise, requiring comparatively modest further development.

Another example every school child of my generation learned (do they still?): lungs developed from flotation bladders in fish. Whether the bladder developed a connection to the mouth by accident or for another reason, once that occurred, the already-existing practice many fish had of gulping air when the oxygen supply in the water was low, when combined with a new place to put that air, allowed these fish to survive better. Also, fins in some fish species were modified with "lobes", and these precursors of legs were used to move along the bottom of a lake or stream. "Walking" in this way keeps the animal below the worst of currents that it wants to move against; only later were the "legs" used to move onto and across the land, and eventually they were strengthened into legs strong enough to support amphibian bodies.

The pace of evolutionary development was very slow long ago, but has been accelerated over time with various developments. The first living things were like bacteria, or perhaps their cousins, the archaea. These together are called prokaryotes ("before the nucleus"): a prokaryote cell's DNA is a loosely-wound loop that runs throughout the interior of the cell. After a half billion years of gradual proliferation, some prokaryotes developed photosynthesis. Before that all life was chemosynthetic, using processes such as robbing sulfur from metal sulfides for energy. There are several kinds of photosynthesis; only one, initially, used CO2 and water to produce sugar, with oxygen (O2) as a waste product. Today's cyanobacteria (also called blue-green algae) are descended from O2-producing bacteria that arose about 3,500 million years ago.

At first, all the excess oxygen was used up by oxidizing sulfides into oxides and sulfates. This slowed down after another billion years, and oxygen began accumulating into the atmosphere. From 2,500 million to 1,500 million years ago, during the "boring billion", O2 slowly increased to about 2%. Then things began to change more rapidly. About that time, or perhaps a few hundred million years earlier, more complex cells developed. The DNA was encapsulated inside its own membrane, and at least two events of engulfment happened. Most probably the first "guests" invited into a larger cell (or they were invaders that were subdued and enslaved) were cyanobacteria, which were put to work turning air into sugar, while being kept safe inside the cell. Now they are called chloroplasts. Almost immediately, the second event was the capture of certain small, energy-efficient bacteria that probably looked a lot like E. coli. These became mitochondria. These larger, compound types of cell are called eukaryotes ("good nucleus"). A discussion of this process on pp 195-6 seems to imply that plants have chloroplasts but not mitochondria; not so, they have both. They need both!

Single-celled eukaryotes are still with us, most familiarly in the form of protozoa such as Amoeba and Paramecium. Some time before 1,000 million years ago, molecular mechanisms that were being used to attach to a substrate or to food particles before "swallowing" them, were re-purposed to allow cells to cling together. In the book a lovely discussion of choanoflagellates discusses how this works. The earliest multi-cellular creatures, whether they were proto-plants (with chloroplasts) or proto-animals, had a variety of shapes, but mostly looked quilt-like or mat-like. Some time around 600 million years ago an organizing principle arose. To introduce it, we must look into segmentation.

The prototype of segmented animals is the earthworm. You can see the segments, a lot of them. We vertebrates are segmented also. Our spine expresses the segmentation. Not all animals are segmented; in fact most phyla are not, but all have some kind of body plan. The Homeobox, or HOX, genes are controllers of body plan development. Every animal species has them. The HOX genes are organizers, and represent a kind of meta-control. The simple idea that we have "a gene" for this or that is a big distortion. Even in a simple animal such as a 1mm nematode, there are HOX genes that make the difference between front and rear and so forth. The more complicated sets of HOX genes found in more complex animals arose from reduplication.

Reduplication is a big theme in genetics. The added sets of HOX genes we need are an example. Mutation isn't a matter of creating a new, complex function out of whole cloth. It proceeds by various errors of copying, which will usually just kill the animal, but occasionally are at least mostly harmless, and over time, the odd bit can gain a new function. The most common mutations are single-point changes, such as from an A to a G in the genetic code. But whole segments can be duplicated, particularly during the "crossover" that occurs during the production of eggs and sperm. If an extra set of HOX genes is produced, one set can go its merry way, controlling the body's development, while the other set is modified and can lead to an extra function or body part or even whole section. Again, this isn't usually good for the animal, but it can be.

Segmentation arose by reduplication. In some cases, many identical segments were produced (earthworm). In others, the segments became specialized. The HOX genes control all this. The illustration, from this article at Socratic.org, compares the HOM genes (as they are called for insects) with the multiple sets of HOX genes in humans and mice. The segmentation of the insect's body is emphasized in the drawing.

It may seem strange that we share this organizing principle with fruit flies, mice and everything else. From an evolutionary perspective, it makes sense. The system works, and we can see that it works, for it has produced millions of species of animal.

Now to the matter of saltation, as in this review's title. Saltation is a dirty word to most evolutionists. It has come to mean things like a rabbit suddenly "evolving" into a dog or a horse. That's ludicrous.

In a proper sense, saltation means "jumping", and the concept (if not the term) had to be coped with once Barbara McClintock discovered jumping genes in corn. They have since been found in every species, and certain kinds of them form much of the "junk DNA" found between the genes in our genome. But others have been put to use, and HOX may be an example.

Just by the way, there's a lot less "junk" in our DNA than early reports claimed. Just 2% of it codes for proteins. An additional 2% (perhaps much more) consists of regulatory sequences that control when and how the genes make those proteins, a further 8-10% consists of deactivated viruses, which form a "library" of stuff gathered from everywhere, that can be re-purposed. Some is apparently second- and third-level regulatory stuff. About 2/3 is "palindromic repeats" (such as AATTGCACGTTAA) that consist of head-to-toe copies of "stuff", which at the moment, is at least useful for landmarks used by CRISPER/CAS gene editing.

All these things, and many more discussed in the book, are mechanisms for more rapid evolutionary change, compared to waiting for single-letter mutations to accumulate. Even over millions of years, that process is dreadfully slow. The beauty of these mechanisms, still being discovered, is that they allow big changes to occur without disaster.

The Earth would seem quite full of many species, were there only a few tens of thousands of them. It is astonishing that there are millions! I work in the "shell room" of a museum, and every time I open a cabinet I see something new, just among the mollusks! That room contains specimens for more than 20,000 species...of seashell! Nearly 100,000 are known. It seems that life, having figured out how to spin out new kinds of creatures, is still ramping up. While we may be driving thousands of species to extinction, it is likely that new species are arising even faster. If we attain wisdom enough to let nature alone and "live lightly", we may see even more variety in the multiplicity of life in the future.

Should evolution matter to evangelicals?

kw: book reviews, nonfiction, evolution, debunking, polemics

My wife is Japanese. She came to the US at age 25. Prior to age 30, she lived in California, though she made one brief trip to another state to visit a friend. Japan's total land area is slightly less than 90% of that of California, and California's land area is 5¼% of the area of the "lower 48" states. This is background for this story:

Just before our first anniversary I was sent on a temporary assignment to Texas. We planned to drive, and I told my wife that we would do some sightseeing along the way. She said she preferred to go to Texas as quickly as possible. I said, "We can't go past the Grand Canyon without stopping to see it." Our first day's driving took us from southern California to Williams, Arizona. The driving time is only about seven hours, including a meal and a pit stop. After a night in a motel we drove north; it is about an hour's drive to a side road and a parking lot right on the South Rim. Most of the way the road slowly climbs a tilted plateau, flat in all directions. About halfway there she asked, "Where are the mountains?" I innocently asked, "What mountains?" She asked, "How can there be a canyon without mountains?" I said, "This is a different kind of canyon." We parked next to a railing. Only after we got out of the car and went to the railing could we see the canyon. She didn't make a sound. She just stood there, for a long time, hanging on tight (the railing really was very close to the edge).

From that location, one can see to the North Rim, which is 14 miles away in three directions, to the northwest, the north, and the northeast, and is 21 miles away to the north-northeast. After many minutes of looking back and forth at the wonderful Grand Canyon through the clear, June air, she said in a small voice, "How long can we stay?"

Until she saw the Grand Canyon, my wife could not imagine it. I don't know if she had even seen pictures of it. It didn't fit in her mind. The four national parks in central Japan are each about half a square mile in area. The largest one on-land, in Kyushu, encompasses 13 square miles of land and a much larger area of surrounding ocean. Compare that with Yellowstone at 3,471 square miles and Grand Canyon National Park, with 1,902 square miles. The main canyon of the Grand Canyon is more than 200 miles long, and it simply can't fit in Japan.

We are limited by what we are used to. Until seeing the Grand Canyon, followed by the Painted Desert and Petrified Forest, my wife had no room in her imagination for such things.

This concept applies to time as well as space. Until we are adults and have lived twenty or thirty years, most of us cannot really imagine a century, let alone a millennium. If we have been lucky enough to get acquainted with a grandparent or great-grandparent who is 80-100 years old, and listen to some of their stories, a century can come to have some meaning for us. This underlies a crevasse of understanding between those of us who have studied a natural science such as geology or astronomy, and everyone else. I made a telescope, with much help from my father, at age 11. It is small but works well and I still use it. My mother had studied geology and we were rockhounds together. She also taught me of The Gap between Genesis 1:1 and Genesis 2:2 (I read the Bible through for the first time at age 12-13).

With my small telescope I can see a dozen or more globular clusters and several galaxies. By the time I entered college I was comfortable with the great distances of these objects, and had learned clearly how such distances are determined. The closest globular cluster, M4 in Scorpio, is 5,500 light-years away. Another that is even easier to see, being much larger and brighter, is M3 in Hercules, which is nearly 34,000 light-years away. These are objects within our own galaxy, the Milky Way. The easiest galaxy to see outside the Milky Way is the great galaxy in Andromeda, at a distance of two million light years. The Whirlpool galaxy in Canes Venatici (the Hunting Dogs), not too far from the Big Dipper, is 23 million light years away. In my (smallish) telescope I can see this one also.

A light-year is the distance light travels in one year, about 63,000 times the distance from the Earth to the Sun. The Sun's light gets here in about 8 minutes. The light we see from the Whirlpool galaxy started on its way to us 23 million years ago. So by practicing amateur astronomy for many years I became comfortable with great spans of time.

I earned two-and-a-half degrees in geology (The "half degree" is known as ABD, "all but dissertation," because the results of my work contradicted the beliefs of a powerful professor on my dissertation committee. He took offense, and I left without my PhD. My work was later shown to be correct by others' work. That professor died without admitting he'd been wrong). I almost majored in paleontology, but went for geophysics instead. I still love paleontology, which is the study of fossils. For one of my summer field camps, I worked in Nevada on ancient reefs, aged about 300 million years. The semi-cliff I climbed almost daily was a sequence of reefs that covered a time span of several million years. The point is, I grew comfortable with time spans thousands of times greater than the kind of time that fits in most people's imagination.

During my time in graduate school I led a fellow student to Christ. He wanted to believe in Jesus but he didn't know what to do with the idea he'd heard from other Christians that the Earth "had to be" no more than 6,000 years old, "…or at most, maybe 8-10 thousand years," as some would say. He was as familiar as I was with Specimen Ridge in Wyoming, a series of more than twenty petrified forests, on atop another. They record this series of events: a forest would grow for several hundred to 1,000 years. A volcano would cover the area in twenty-to-200 feet of ash and kill the forest. A new forest would grow in the mineral-rich ash. This happened over and over. Tree rings can be counted in the petrified standing stumps. The total sequence covers more than 20,000 years. There is no room for Specimen Ridge in the imagination of a Young Earth Creationist. When I explained The Gap to him, and some other concepts that indicate Scripture can "handle" deep time, he received Jesus and was a good spiritual companion for several years, until we moved elsewhere.

Of course, along the way I also became very familiar with evolution. Fossils show that life has changed over time, which is the definition of the Fact of Evolution. Life is still changing, which means that evolution, as a process, continues, even affecting humans. Two books I reviewed recently, The 10,000 Year Explosion and Before the Dawn, demonstrate this.

Many may be guardedly okay with recent evolutionary processes, but don't care at all for the idea that all the millions of species arose by the same means. It is a hard pill to take when one's biological imagination is limited to occasional visits to zoos. People ask about mutations, and how a rabbit can turn into a horse. It can't. But some early animal had descendants that had descendants, and so forth, and one line became rabbits while another became horses. That "early animal" probably lived 100 million years ago. You don't make rabbits or horses overnight.

Such notions are the fruit of popular media, in which "Mutants" such as the X-Men or the Fantastic Four are radically changed in an instant. Hardly anyone knows that every one of us is a mutant, carrying DNA in our cells that is different from what we were born with, because of many small, "silent" (or near-silent) mutations that occur in us daily. Among all those, only the ones that occur in our germ cells (sperm or ova, depending on our sex), have a chance to make it to the next generation, but our children are born with 50-100 such small mutations that we were not born with.

Such small mutations, which occur with great frequency overall (but only affect a very tiny percentage of our total DNA because there is so much of it), can have several causes. These include chance copying errors, because the DNA copying machinery is very, very good but not perfect; and damage caused by radiation or free radicals, for example. We are a little bit radioactive. About 1/85 % of the potassium in our bodies is the radioactive isotope K-40. All the rest is either K-39 or K-41, which are stable.

Where such a mutation is not silent, it is usually because it changes the function of a protein, which is usually bad, but not always. In severe cases, the cell in which that mutation arises will die, and we never know it. There are lots of reasons cells in our bodies die by the millions daily; this is only one.

Larger mutations, with possibly greater effects, are rare, and usually harmful, but not always. They can include losing a small chunk of DNA (from a few "letters" to a few thousand), or the duplication of a little DNA, or a piece getting "loose" and being put back in place backwards or somewhere else. Very rare events include the duplication of a whole chromosome; Downs' Syndrome is the result of such a duplication. In the past, changes in the number of chromosomes have occurred with sufficient frequency that the various creatures on Earth have as few as two or as many as a thousand chromosomes.

A study of the DNA of many organisms of many types shows that all are related by common machinery to reproduce DNA, which is the first step to biological reproduction. All mutations, properly understood, that get into the germ line and are inherited, have the potential to change an organism's descendants, and if that organism's progeny multiply, over time a whole species can change a little.

The fact of evolution is plain to see. The process is not. The paragraphs above just touch the surface of the way mutations arise. How do they either increase to become common, or die out? Enter the prevailing theory of evolution, natural selection. When Charles Darwin proposed the mechanism of natural selection as a theory of evolution a century-and-a-half ago, he didn't know how new characteristics arose, nor what mechanism might "record" our characteristics. His original theory was a theory of how different characteristics could be favored or disfavored because of environmental factors, and thus give rise to disparate groups of animals from a population that once were all about the same. 

A classic example is a certain English moth that is usually light gray with dark spots, which make it hard to see on tree bark. During the early Industrial Revolution, the coal smoke in the air darkened tree bark in forests near the cities, and the moths were easier to see. Most of them. Some were darker and harder to see. Birds ate the light gray moths, so the darker ones became more common, and some of those had offspring that were even darker. As the smog got worse and trees got darker, eventually in some areas one could only find dark moths, and farther from the cities the lighter gray moths were still to be found. After the English quit using so much coal and more natural gas and liquid fuels, the bark of the trees gradually got lighter in color, and the darker moths became rare again. In this case, no new species was formed, but it could have been so had the burning of coal gone on for hundreds or thousands of years (and the average life span of an Englishman would have become shorter also).

Now that we know what DNA is and how mutations work, we have a mechanism for new characteristics to arise. They arise gradually, over long spans of time. But the example of the English moths shows that "long" can be measured in decades or centuries; it doesn't have to mean millions of years. But it is definitely numerous generations.

So here are the pieces that make natural selection work:

• Variation in a population of interbreeding organisms (a species) arises because of mutations in the DNA, mostly small but not always.
• Among the offspring of these organisms, for nearly all species, most die without reproducing.
• If a variation in the DNA of one organism makes it less likely to die young, and more likely to reproduce, that variation is more likely to "make it" into the next generation.

Consider some animals that live in grasslands near the edge of a desert, but not in the desert. They will vary in many characteristics, including the efficiency with which their bodies retain water. Some will be able to tolerate forays into the desert better than others. Over time, some number will be able to spend most of their time in the desert, and less in the nearby grasslands. Furthermore, prey animals in the desert will be different from those in the grasslands, and variants that can catch and eat "desert critters" will have a little advantage among the desert tolerant ones. Give it more time: a desert-dwelling species can be produced, leaving behind the grassland-dwelling species. They are very similar, and for a time they could even hybridize, but eventually that also will end. Now, it is not likely that the entire suite of characteristics that allow the new species to live full-time in the desert were present in the original species. Some variations were developed over time by the accumulation of small and smallish mutations. For animals with a life span of several years, this can all occur in 1,000 to 10,000 generations, say between 5,000 and 50,000 years.

If you read some books on anthropology, you'll find out that "early modern humans" were different from modern people in a few subtle ways, such as having thicker skulls and stronger bones. They lived as recently as 14,000 years ago. And, assuming they are our ancestors (anthropologists put us and them in the same species, Homo sapiens), in that time they underwent the changes that produced "modern humans". Counting four or five generations per century until rather recently, they lived 600-700 generations ago. The species Homo sapiens arose about 48,000 years ago, or 2,000 to 2,400 generations back.

Some who may have read this far, who are evangelical Christians, who have been taught that evolution is the greatest heresy, will have been poo-poohing this all as I went along. That's okay. This is leading up to my contention that whether evolution happened, and whether its mechanism was natural selection or not, has no effect on Biblical truth or the faith of the Gospel of Jesus Christ. No effect. None.

I am a scientist. I am also an ardent Christian. I learned long, long ago (half a century) that these are compatible. Sadly, there is a large and vocal cadre of evangelicals who claim the opposite. Or, at most, some of them will say that science, compatible with (their interpretation of) the Scriptures is acceptable; otherwise it is not and is even nonsense.

I wrote this piece after reading a certain book written by a young-earth creationist, a book intended to give younger Christians ammunition to shoot down evolution wherever they find it. I have decided not to name the book or its author, not to censor it (it is one of a great many), but to protect my brother, a man nearly my age whom I greatly respect as a teacher of the Bible and Biblical truth. However, in this area, he is quite incorrect, yet I don't care to pillory him publicly. So I'll just call him Bob.

The book is around a dozen years old. A lot can happen in a decade or so. For example, Bob makes a big deal about feathers. His discussion of how feathers are thought to have developed from scales (as he imagines it being thought of) is not Darwinian, it is Lamarckian. That is, he describes scales getting frayed in certain environments, and then this fraying is found to be beneficial, and is somehow passed on to descendants (that is, he thinks evolutionists think that). 

The Darwinian explanation is different: Scales come in many variations. Some of these have ribs or bumps. Ribbing can be very pronounced, or less so. In a particular sort of lizard, the ribbing was so pronounced that over many generations it resulted in scales with parallel sections, like a fan palm leaf. This was beneficial so the process continued. Later developments included cross-ribbing, and stage by stage a downy feather was produced. Maybe at first it wasn't "that downy", but wherever it was useful for retaining heat, in generation after generation these former-scales-now-downy-feathers became more like the goose down used in down jackets and sleeping bags. Once feathers of any sort arose, they could be modified over time to become the great variety of feather types we see today. 

A dozen years ago, the very few fossils that showed feathered non-avian dinosaurs were hotly contested and hardly known among the public. After 2007, a host of discoveries have resulted in a better understanding of feather evolution, which apparently started more than 200 million years ago. The first feathers were for thermal insulation. Developing feathers with aerodynamic properties, leading to flight, took tens of millions of years.

Another aspect of Bob's discussion is the "God of the Gaps" dilemma, or the problem of intermediate forms. See this illustration:

Let's consider this vaguely illustrative of the family tree of the apes, with its "root" some 25 million years ago. The tree on the left represents knowledge of paleoanthropology when I was in college; that on the right, something closer to current knowledge. The topmost orange block in each tree is Homo sapiens. The topmost blue blocks are Bonobos and Chimpanzees. The green block would be the common ancestor of all three, although we have no fossils of it at present. The purple blocks are various species of Australopithecus; one on the left, a few on the right. The orange blocks are various species of Homo. On the left, below sapiens, we have H. neanderthalensis, H. erectus, and H. habilis. I don't know how many fossils are currently included in the genus Homo, so I just added a few small blocks (small so they wouldn't overlap) at the right, with the Neanderthals replaced by two blocks to include the Denisovans.

Are the species on the "orange" branch all our ancestors? Some are and the rest are close cousins to our ancestors. Are they transitional forms? A paleoanthropologist would say Yes, as I do. But the strong creationist argument is, "Where are the transitional forms in between?" The complexity of this tree is probably less than the complexity of the actual situation through time with all the apes. What would it take to find "all" the transitional forms?

Terrestrial fossils are much more rare than marine fossils. There are tons and tons of fossil shells and corals for each person on Earth. The total number of fossils of genus Homo would fit in a footlocker. Someone like Bob (or at least like Bob a dozen years ago) will not be satisfied if we can't fill in every blank. Otherwise, he would say we haven't proved the case. Remembering that a time span of 48,000 years in human history represents as many as 2,400 generations, Bob is asking us to find a fossil to represent every generation over a span of millions of years; perhaps as many as a quarter to a half million generations from the time genus Homo split from genus Pan (chimps and bonobos). The number of fossils of early humans so far found represent 6,000 individuals. There are a lot of gaps to fill!

It's best to not belabor these points further. Where do these things fit in the Bible? God didn't inspire His prophets to write the books of the Bible to generate a natural history textbook. Moses was inspired to write for bronze age herdsmen at a time 3,000 years before it was even known that the shell-shaped things in rocks represented animals that died long ago. God's intention is to develop a relationship with people. The two "creation hymns" found in Genesis chapter 1 and chapter 2 show different characteristics of God and different aspects of His relationship with the first humans. Most importantly, if they are to be taken as word-for-word literally and scientifically accurate, both cannot be true. Important things happen in different orders. But we can discern a few key items:

• In Genesis 1, God created man in his image, "Male and female He created them." This creation was of a number of persons.
• In Genesis 2, The Lord God "formed man of the dust of the ground, breathed into his nostrils the spirit (or breath) of life, and man became a living soul." The woman was "built" from a portion of the man and brought to him later.

Taken together, these show that the created part of man is not the body, which was "formed", but the spirit. The word "living" in Genesis 2:7 is emphatic, indicating that without the spirit, the soul is dead, not able to contact God.

Numerous Bible students have written about "pre-Adamic men". Some have written pretty crazy stuff. But the best, including G.H. Pember, consider that there were non-spiritual humans on Earth in the distant past that rebelled against God along with Lucifer, and were punished by God when Lucifer was defeated and became Satan. After that God put a spirit in some, or all, remaining men to become "man" with a living soul. This makes sense to me. 

Is the foregoing literally true? I don't know. Here is the point, though. If the Adam of the Bible was an individual person (some Bible teachers consider that Adam represents a corporate group of men living in God's presence six or more thousand years ago), he lost direct fellowship with God because of a sin of disobedience. The Bible from Genesis 3 to Revelation 20 is the result: God working through the generations to gain people who will fellowship with Him and become His bride, described as the New Jerusalem in Revelation 21.

The origin of the pre-Adamic men, if they existed, is not described. The fossils of Earth indicate that they did exist, and that they came about by evolution. Other geological work shows that the Earth is indeed a few billion years old (4.543 billion, according to the most recent work). The universe has a definite origin, which was about 13.7 billion years. It's nice to think that "Let there be light" refers to the Big Bang, which was indeed a burst of unimaginably bright light. However, that verse refers to the first step of God's re-ordering the Earth after the primordial battle with Lucifer.

The Bible tells us that Lucifer was originally the Archangel, the leader of all the angels. In Job an enigmatic passage (38:4-7) tells that the angels were present when God "laid the foundations of the Earth", singing their praises. Did God wait until there were men on earth before putting Lucifer in charge? We don't know.

For God to have a relationship with us, however, little of this matters at all. Evolution is a part of the history before Adam, long before, and although its processes continue, they don't affect us or our relationship with God. At least when the book was written, Bob was of the opinion that one could not be a faithful Christian and believe that any part of evolution is true. This is not so.

Rather, the notion of evolution as heresy is a red herring, successfully used by Satan to keep myriads of ardent children of God distracted from the important work of bringing closer and closer the Kingdom of God, of being built up as the Body and Bride of Christ (see Ephesians in particular), and casting aside all doctrinal and personal divisions so that the longest prayer of Jesus Christ, recorded in John 17, can at long last be fulfilled. He prayed, "…that they may be perfected into one, that the world may know." Jesus prayed this three different ways within this long prayer. It has never been fulfilled. The world does not yet know. This is the great shame of Christianity. How can we be one if we let such matters divide us?

Among the saints with whom I fellowship, I am a rather rare bird. Most of those who were raised as Christians would look askance at my understanding of evolution and the great age of the earth and universe. I seldom mention it because I don't care to fight with them. If it comes up, I try to keep things thus, "It doesn't matter. Whether evolution happened or not has no bearing on the Bible or on our salvation." It takes someone quite persistent to get more than that out of me.

So why go into it at such length here? Because I am comparatively anonymous in this blog, for reasons that are as valid now as they were 15 years ago when I started it. Those who care enough can find out who I am.

If you can stomach it, learn this as a slogan worth keeping:

Evolution doesn't negate any truth of the Bible, nor does it threaten our salvation.

More on continued human evolution

kw: book reviews, nonfiction, anthropology, paleoanthropology, evolution, human evolution

In March I reviewed The 10,000 Year Explosion, by Gregory Cochran and Henry Harpending, which presents convincing evidence and discussion about how the human species continues to evolve. In one chapter they refer to a colleague's work and his book, Before the Dawn: Recovering the Lost History of Our Ancestors by Nicholas Wade. Naturally, I obtained the book and read it carefully.

To be up front here: Though I am a Christian, of a very evangelical and Biblical tradition, I am also a scientist, with perhaps way too much education in all the physical sciences; I finished my formal education at age 37. I wrote software for scientists for forty years. In retirement, I work for a natural history museum part time, both as a computer scientist and a biologist. At a young age I learned the "Gap theory" of interpreting Genesis and other parts of the Bible that refer to prehistory such as Job 38:4-7, Zechariah 12:1, and Isaiah 45:18. By careful study I determined that cosmology and deep time (13+ billion years of it), plus the facts of evolution and the theory of natural selection that describes how it operates, are no threat to Biblical faith nor to any revelation in the Bible.

Therefore, concerning people, the extreme Biblical literalist view is that humans (and all other living species) were created ex nihilo less than 10,000 years ago, and are the same now as they were then, barring various kinds of catastrophe and degeneration. Their creation was very shortly after that of the universe and Earth.

The scientific view is that once life on Earth began, natural selection operated for about two billion years to produce multicellular life from unicellular life, then the multicellular creatures continued evolving until all living forms we see today were produced, along with some ten, to 100, to even 1,000 times as many species that went extinct in past eons; then among the tiny twig on the "tree of life" known as Great Apes, one ape species split into three species, which continued to evolve and adapt to different environments to become humans, chimpanzees, and bonobos; along the way other species such as H. erectus and Neanderthals arose and later became extinct.

The combined view I have (following G.H. Pember and others) is that Genesis 1:1 occurred "in the dateless past", to quote C.I. Scofield, and that the first verb in Genesis 1:2 is "became": "The earth became waste and empty", where Isaiah 45:18 tells us the original formation of the planet was "not waste". Prior to historical time, "anatomical" humans, that were not "behaviorally modern", experienced a big change. Their worldwide spreading from a homeland in Africa began during a warm spell between ice ages about 50,000 years ago. That behavioral change probably marks a point in time that God intervened, as recorded in Genesis 2:7, "And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul." (King James Version). The grammatical emphasis is on the word "living". This does not describe a creation ex nihilo. "Dust of the ground", a metaphor for humanity, existed already, but when God breathed a spirit into "the man", the animal soul became a "living soul," a soul that is now able to contact God. The rest of the Bible describes contact after contact between God and various people. The Septuagint translates "living soul" as ψυχὴν ζῶσαν , "psuchen zosan", which refers to divine life, not biological life. 

With all that in mind, I consider two questions:

1. Do the mechanisms of natural selection still operate on humans?
2. Do any changes thus wrought continue to improve our adaptation to modern environments, or are they only degradations from a formerly more perfect humanity? (as many Christians believe)

I look for well-researched books like Before the Dawn and The 10,000 Year Explosion to find answers to those two questions. With new genetic tools made available in the past twenty years, there is evidence aplenty that humans are still evolving, and that we continue to become better suited to the environments into which our travels have taken us. Further, genetics has led anthropologists and archaeologists to look more keenly at their own studies for things that were overlooked under an older paradigm that stated, "once humans developed culture, physical evolution came to a halt." It most assuredly did not!

I'll begin by discussing a few items I bookmarked. I can tell which chapter these are in, but the "page" numbers of the eBook don't correspond to printed pages. In the first chapter, after defining two periods of prehistory, the 5 million years since pre-humans split from other apes, and the 45,000 years between the time some left Africa and the development of writing, they ask,

"Why should the human genome, specifically shaped for survival in the present, have so much to say about the past?" (early in Chapter 1, "Genetics & Genesis")

I immediately thought, "Only if 'the present' means 'the past 500-1000 years' can this question be meaningful." Actually, as the author goes on to discuss, our genome contains material that supported survival over the entire span, including some important genes that have been kept nearly unchanged for tens or hundreds of millions of years; also others that arose in the past few thousand and even the past few hundred years, and some that are "works in progress" right now.

More to the point, an allele (a specific form of a gene) that arose and became frequent long ago will contain "silent mutations" that can inform us of our history. Time for a side trip.

The Central Dogma of Genetics states that DNA is copied to RNA, and RNA is transcribed to chains of amino acids, which are peptides and proteins. Transcription takes place in a molecular machine called a ribosome. There are 64 3-letter codons of DNA or RNA. There are 20 amino acids. Thus, the "translation table" to convert an RNA codon into an amino acid has multiple entries for each amino acid. Only one amino acid, methionine, has a single code. The other 19 have two, three, or four codons that "mean" them. Thus, the codons GGU, GGA, GGC, and GGG all code for glycine. If something changes a GGG in your DNA to GGA, it won't change the amino acid that results. That is an example of a silent mutation. 

We won't get into any of the many things that can cause such a change, but we all accumulate many in each of our cells in our lifetime. There are also other kinds of mutations, and some lead to new proteins. A mutation that is helpful in any way will be kept; one that is harmful will usually cause the death of the cell. Mutations that wind up in our gametes (sex cells), that didn't cause them to die already, can get into our children. We typically pass on about 50 mutations to each child. In a genome of a billion codons, 50 is not many.

The studies of what might have happened in the past depend on the rate at which silent mutations accumulate. Of course, it is possible for a silent mutation to re-mutate back the way it was, but the number of these will be very small, since point mutations are rare to start with (50 out of a billion per generation, per person). This principle is brought out numerous times in the book. End of side trip.

If we first look back 5,000,000 years or so, to the ancestor of humans, chimps, and bonobos, what would we see? There is scant fossil evidence. Central and east-central Africa were warm and humid then as they are now; there were no ice ages yet. In conditions like that, even teeth rot too quickly to leave fossils for us to find today. What little we know matches what we can infer by taking an "average hominin": the size of a chimp or smaller (males 50-100 kg, females 30-60 kg), furry like modern chimps, brain size similar to a chimp (450 cc) or maybe a bit smaller, promiscuous in sexual habits, possibly patriarchal but maybe not, and probably violently territorial and xenophobic. Today, bonobos are a little smaller than chimpanzees, equally furry, with a brain the same size, even more promiscuous, matriarchal, but less xenophobic and much less violent. Humans have become a little larger overall, and a foot or two taller, mostly hairless, but with much larger brains (1,400-1,600 cc), sexually more private but not necessarily less promiscuous, usually patriarchal (sorry, feminists), and with a great range of xenophobia and territorial aggression.

While chimps and bonobos are so physically similar that they were thought to be the same species until a generation ago, they are behaviorally very different. Further, humans are very, very different from both in many ways, but we can see our behavior reflected in theirs. It is almost as if we have a range of cultural expressions that encompasses all the variations found in bonobos and chimps.

Now look back 50,000 years, to the "behaviorally modern humans" (BMH) who left Africa to spread the world over. The archaic human species they encountered and what happened as a result are stories for another day. What were these "moderns" like? Between 100,000 (maybe 150,000) years ago and 50,000 years ago, the species (still called Homo sapiens) is called "anatomically modern humans" (AMH), and is physically very similar to "us, today", but with more archaic behavior. We will set aside for the moment the theological implication I made earlier about what may have happened 50,000 years ago. What is the difference between AMH and BMH? As I found upon reading later chapters, it's probably best to not consider us, today as BMH, but just "modern humans", MH, after another transition between 15,000 and 10,000 years ago. Both behavior and anatomy changed after that.

So, to get a BMH person, start with a very well-conditioned person, not quite an Olympic athlete, perhaps…or, what the heck, let's go with a couple of Olympians. We can pick the runner Usain Bolt (6' 5", 207 lb/195 cm, 94 kg) for the male, and gymnast Kylie Dickson (5' 6", 110 lb/167 cm, 50 kg) for the female. The BMH's were bare-skinned and lived in Africa, so the skin would be black. Shorten the male by several inches while leaving his weight the same. Double the strength of his muscles and bones, and add 20% to the thickness of his skull. Add 10-20 kg to the weight of the female, and make her bones and muscle proportionally greater. Both this man and this woman would look like modern weightlifters (the ones who don't use steroids). You wouldn't want to meet either one in a dark alley, unless perhaps you had a 5th degree Black Belt in Aikido. I have a Korean friend who is a 4th degree black belt; he doesn't need a weapon, he is a weapon. But he might not prevail against an average BMH male.

What else might be different? "Modern" behavior, to an anthropologist, is the more sophisticated late paleolithic toolkit that showed up about 50,000 years ago, along with sophisticated art (cave paintings being a stellar example), and more group interaction, including some tolerance of strangers so trading could be carried out. The story told by their bones, however, is of frequent and persistent combat and warfare. Although the women were also stronger than we'd find usual today, they didn't engage in combat, but had harder domestic work (like pulling hides off animals), than would have been usual later on.

So, back to, what differed between AMH and BMH? Not the anatomy, except perhaps in fine details. From 100,000 (or so) years ago until 15,000 years ago, the anatomy remained very similar. But better group dynamics, probably fostered by the development of language, seems to be a crucial step. It seems to me that sophisticated art had to follow language; once symbolic representation of thought was possible, other symbolisms including artistic artifacts could follow. The 10th chapter "Language" goes into this very comprehensively. Language seems to have appeared shortly before 50,000 years ago, and much else followed.

Chapter 7, "Settlement", brought out something that surprised me: the author's contention (he is far from alone in this) that people began to settle down into communities as much as 5,000 years before agriculture. I'd thought it was the other way around, and I've read that numerous times. I can't debate the point, so I'll leave it to you to read what the author has to say. But it convinced me. Starting before 15,000 years ago, a few thousand years of warming were followed by more cold, that broke about 11,500 years ago. The coldest bit was the Younger Dryas period, which lasted 800 years. Settling down apparently marks the major psychological transition between BMH and MH. People had to learn to tolerate the presence of unrelated strangers, and not try to kill them on sight; some cultures today are still prone to do that! They could then engage in long-range trading.

Midway in the chapter I find the statement, "Specialization in roles may have occurred for the first time." I think not. Even in a kinship group of 50-150 persons, someone will be a little better than most at making tools, and another will be a little better than most at accurate throwing of weapons, or at climbing of trees. One woman's more nimble fingers might weave a better, stronger basket more quickly than others'. So intrafamily trading probably began way, way back. Once you are able to converse peaceably with people in the family nearby, interfamily trading can get rolling, and that will naturally grow into trade networks that span continents.

Looking through my notes, I find a number of interesting items about settlement and socialization. But I'll skip a few to get to the critical point. How much of all this has genetic underpinnings? The author thinks, quite a lot. We can see in our more slender skeletons, compared with "Cro-Magnon" of 10-12,000 years ago, that MH's have changed over that time. We aren't quite as likely to club one another over the head. It makes me wonder, how warlike were BMH's? The Dani in New Guinea and the Yanomami in Brazil, until the past few decades, were used to losses of around 30% of each generation to inter-village warfare. What was warfare like 40,000 years ago, when skulls were thicker and bones twice as robust (muscles also, one must presume)? Shudder!

But what is happening now? Human skin changed from pale to black after hair was lost from the body. [Just by the way, my personal notion is that hair loss had to soon follow the domestication of fire. Think of a furry month-old baby falling into the fire, or an ember blowing onto it. In my twenties I had a beard; it caught fire once, and only very quick thinking by my father kept me from suffering disfiguring burns (I still have a couple of tiny scars). I have read that the most popular theory for hair loss is running. Humans can run down anything except a thoroughbred horse; and maybe over a day or two, the horse would also get too tired to keep going. Perhaps both influences played a part.] The people that made their way from Africa to northern Europe and northern Asia became pale again. This seems to have happened primarily in the past 5,000 years. Europeans and north Asians have different genetic mechanisms for skin coloration, so paler skin evolved at least twice. Lactose tolerance evolved at least four times, at different times in different places. Our jaws are smaller than was average for earlier MH's, which is why so many of us have to have our wisdom teeth pulled. Suffice it to say, the sore back many of us wake up with is also evidence that 2-3 million years has not been enough for a truly functional and robust erect spine to finish evolving.

The author has numerous added examples. Physically we are still evolving, and those of our behaviors that have a strong genetic element are evolving also. Where will it all take us? The presence of five "races" (we need a better word now; this one is too political) indicates that the human species is partway along a path toward splitting into multiple species. If sea-spanning ships and jet planes had never been invented, in another 50,000 years, would there be three or four or five species of human? It's possible. If we plant a colony on (better, underground) Mars, how long will they remain the same species? Since there would be a much smaller number of them, genetic drift, along with a very few novel genetic alterations (mutations), could render them genetically incompatible with "the folks back home"; that is, a new species of human. Homo arensis?

Are humans evolving faster than ever?

kw: book reviews, nonfiction, evolution, anthropology, human evolution, civilization

Consider a plant of the desert southwest of the U.S., the creosote bush, Larrea tridentata. It is host to several species of insects that can live nowhere else. One is the creosote bush walkingstick, Diapheromera covilleae. You can read at arizonensis.org that, while the creosote bush has inhabited North American deserts for less than 12,000 years, these species endemic to it, including the walkingstick shown here, evolved their special adaptations to life only on this plant within that time frame. The image is from that article.

In the book The 10,000 Year Explosion: How Civilization Accelerated Human Evolution, authors Gregory Cochran and Henry Harpending use this insect and others endemic to the creosote bush to demonstrate that evolution can happen on scales that correspond to recorded history. About the time that humans began farming in the Middle East, members of a species of American walkingstick already present began to prowl the newly-invasive creosote bushes for prey. While people were learning to live with agriculture, and developing it over and over again around the world, these insects evolved better and better camouflage, and habits better suited to the way the plant's twigs move in the wind, so that they are now unable to live elsewhere.

The aim of these authors is not, however, to provide a catalog of rapidly-evolving insects, but to set a few of them, and other creatures including birds and mammals—all of which show evidence of rapid evolution—alongside humans, to indicate that we, also, can evolve on such time scales.

Accepted dogma among most scientists has been that humans stopped evolving when they developed civilization. Civilization is thought to protect humans from the selective pressures that drive evolutionary changes. People who once would have died from many causes now live because of better sanitation, medical care, and a richer food supply. For me at least, long ago, a moment's thought was sufficient for me to realize that this just changed the style of selective pressure we experience. I concluded that in the past several thousand years, humans have most likely been evolving in a direction more dependent on such systems of care than before. These authors reach the same conclusion.

When I was young, the early humans just prior to the modern era were called Cro-Magnon, and I got the impression that if you put one is a suit or dress, it would be hard to distinguish that person from anyone else. Cro-Magnon humans are now called "Early Modern Humans" (EMH's), which encompasses a wider array of fossils than those that were known in the late 1800's through the early 1900's, when the textbooks I read were published. I have since learned that the average EMH was stronger than 99.9% of us (even the women were stronger than most modern men!), with heavier bones, thicker skulls, and a brain about 10% larger than the modern average. They had slightly larger jaws, with teeth of very similar size to ours, so they would not have had problems with wisdom teeth, as so many of us have. (FYI: I had no trouble with wisdom teeth, but more than half of my classmates in high school had to have theirs removed).

We have been taught that it takes a few hundred thousand, or millions of years, for significant evolution to take place. But some scientists, including one of my favorite science authors, Stephen Jay Gould, promoted "punctuated evolution": as long as the environment is comparatively stable, the species that live within it don't change, but when environment changes, such as at the beginning or end of an ice age, species then evolve rapidly so that new species develop which are better adapted to the new situation. I read almost everything by Gould, and I don't recall that he put a time frame on "rapid". The authors of this book come closer to doing so, contending that measurable changes in various human groups have taken place in "a few" thousand years, probably less than 5,000.

What could drive evolution at a more rapid pace? How could new and favorable mutations be gathered at a rate that would allow a group of humans to adapt to something new and different, in just 50-100 generations, and perhaps much less in some cases? One key factor that these authors stress repeatedly is the great expansion of population that resulted from agriculture. A larger number of people means that the little, random mutations that happen in every one of us are equally larger in number. Apparently, this is not too hard.

Consider lactose tolerance. The default condition is that adults and adolescents don't drink milk, so they don't need to digest lactose. Thus the enzymes needed to do so aren't produced in most adults and teens. But the domestication of cattle by various groups of people made quantities of cow milk available, and other animals' milk, such as horse or goat, were also available among other groups. At least four times, in different places, a mutation or two occurred that allowed the continued production of enzymes that carry out digestion of lactose throughout life. All occurred within the past 10,000 years.

Think about it. A herder might gather some milk to nourish an orphaned calf or kid. He might taste it himself; it would be a little sweet and taste good. But he would usually suffer discomfort or indigestion soon after, and would not try that again. But maybe not. Initially, scattered families here or there would be able to digest milk. This added source of nutrition would result in larger families for such folks. Over time, such a favorable genetic trait would become widespread and could even dominate a population. However, populations that never developed ranching or herding have very few members who can digest lactose. All of my relatives are milk drinkers. My wife is Japanese, and she and her family also drink milk. Most Japanese don't, and they can't without discomfort. My wife's family must have ancestors that were herders. The primary milk used in Japanese households is soy milk, and most people of the generation that is now in their 60's and older know how to make it. Younger folks buy it at the store because they are too busy earning a salary to learn traditional skills.

Lactose tolerance is one of many examples of recent evolutionary changes in many human populations. And this matter brings up a wider view: If a large cohort of people look distinctive, there is a genetic reason for it. Although the human species is one species, and there are no "breeding barriers" between any human groups, the concept of "race" is really an oversimplification of a blatant reality. Any cohesive group ("Tribe" is a common term) that doesn't outbreed with other groups will become a distinctive group (better adapted to a different environment, perhaps), and it isn't hard for people in "Tribe A" to recognize people of "Tribe B" on sight alone, even if all cultural accouterments and accessories are removed.

The last chapter touches on a sensitive subject: can there be a "Tribe" of humans that are smarter than average? Consider the controversy that erupted over The Bell Curve, by Herrnstein and Murray. This is a very non-PC subject! But, face it, folks, facts are facts and truth is truth. There does happen to be a group of people whose average IQ is 12-15 points above the average for all people. Though they number only about 11 million worldwide, about 1/7th of a percent of the human race, their members have earned more than 20% of all Nobel Prizes. Of course, an average implies a range of values. There are dumber ones also, just not as many of them. The proportion of them that are smarter than average is larger than that proportion in humanity generally.

Who are these people? The Ashkenazi Jews, usually just called "European Jews". They comprise 3/4 of the total Jewish population of the world. Einstein was one. So was Stephen Jay Gould.

The authors present the case for a history that could have produced such a result. One key element is almost total in-group marriage; they strongly discourage marriage to non-Jews. They experienced nearly a thousand years of persecution in Europe. For much of that time they were forbidden from engaging in most trades. They were allowed to have certain "professional" occupations, and money-lending was but one. Those who were most adept at managerial and accounting skills prospered and had larger families. Both the Jews and their neighbors favored large families, but a more prosperous family will raise more children to adulthood than a poor one, even if the number born is the same. This factor alone could result in a "smartening" of the European Jews over those centuries.

There is another factor that the authors don't touch (maybe they avoided it purposely): the Holocaust under Nazism. Many, many Jews left Nazi-controlled, areas, or countries they were soon to control, before the end of the 1930's. I reckon they tended to be the smarter, better-educated ones. Of those left behind, half or more were murdered by the Nazis and left no descendants. This probably boosted the average IQ even more.

Whether or not such processes were the deciding factors, the fact remains that worldwide IQ testing has shown that average IQ and the spread of IQ scores are practically universal, with the glaring exception being the Ashkenazi Jews. (Just by the way, the letters n-a-z-i "Ashkenazi" are in no way related to "Nazi", which is an acronym formed from German words meaning National Socialism.)

For those who think there is no evolution anyway, don't sweat it. I'd be surprised if you read this far anyway. But for those who accept evolution as "the way biology works", this book helps us understand that humans haven't been somehow extracted from Nature, but still form a part of it. The environments that we have built for ourselves haven't made us "not natural", just natural in a different way. We continue to evolve, and it would be interesting to be able to look forward another 10,000 years, to see what directions have been taken by the various tribes of mankind.