A nice game, with lovely goals all around. The scrappy Uruguayans fought to the end.

Over at Pharyngula, PeeZee describe new kerfuffles involving tea partiers and creationists who weasel about the age of the Earth.  He links to one of his earlier posts about Earth’s age, but I thought I’d add a useful link.  It’s a nice short paper by geologist Robert Hazen, “How old is Earth, and how do we know?” published in Evolution, Education and Outreach (online access is free).  All the dating methods are there: dendrochronology, varves, plate tectonics and—the method for determining Earth’s age—radiometric dating.  There’s a good list of references, too.

If you’re a teacher, or someone who just wants a short precis on how we know that life has been around more than the Biblical few thousand years, bookmark Hazen’s piece.  And, as I do, have a look at the journal from time to time.

In yesterday’s New York Times, ace critic Michiko Kakutani reviewed a new novel, Lucy, by Laurence Gonzales. The premise sounds pretty dire:

Lucy is part human, part ape, the result of an experiment in which a British scientist named Stone managed to artificially inseminate a genetically altered female bonobo named Leda. Lucy is reared and home-schooled by Stone in the heart of the African jungle. His plan is to send her off to college in England, where she will presumably meet a mate. He envisions her as “the universal Eve” for a new and improved race of people that will preserve the best qualities of bonobo genetics.

For one thing, Kakutani doesn’t like the science, and rightly so:

Not only does Mr. Gonzales fail to explain how Stone might have managed the unprecedented feat of cross-species breeding in the middle of the jungle without any real laboratory or medical facilities, but he also sidesteps the question of why Lucy’s looks are so utterly human and why her bonobo genes are evident mainly in traits like her unusual physical strength and highly acute hearing.

Yeah, the reviewer should have given the salacious details!  But what Kakutani doesn’t realize is that this experiment has been tried before.  As I mention in WEIT, the Russian biologist Ilya Ivanovich Ivanov inseminated female chimps with human sperm in Africa in the 1920s and failed.  His reciprocal plans to inseminate humans with ape sperm were mercifully aborted by the Russians.

Could human-ape hybrids (called “humanzees” or “chumans”) be viable? Maybe Ivanov just didn’t do the experiment enough times; after all, even humans who try to have human babies often fail.  The chimp and human lineages are diverged by about 7 million years, and that’s almost exactly the same distance between the horse and donkey lineages. Horses and donkeys, as we know, can produce viable (but sterile) offspring—mules. So maybe humanzees like Lucy (obviously named after Donald Johanssen’s A. afarensis fossil) could survive.

Kakutani’s question about why Lucy has human appearance but some bonobo behaviors is a good one, though.  She goes on to criticize the novel on nonscientific grounds:

Unfortunately, Mr. Gonzales’s orchestration of these developments is increasingly hurried and perfunctory as the book hurtles along. He rushes through the momentous decision to create a YouTube video explaining Lucy’s story in her own words, making the whole scenario sound thoroughly hokey, and does much the same thing with the scenes depicting Lucy’s flight from home and efforts to elude a mysterious stalker who may or may not work for the government. . .

. . . To make matters worse, his depictions of Lucy’s enemies — fundamentalist bigots who want to send her to a zoo; conservative politicians who want to pass a bill that would officially render her “a nonhuman animal” — grow increasingly cartoonish, to the point where any real sense of threat is removed. It seems preposterous that the United States government or its agents would throw this teenage girl into a cage on an Air Force base. And it seems equally preposterous that they would allow a Mengele-like veterinarian to perform sadistic experiments on her.

Oy, gewalt! That sounds like a biologized version of The Da Vinci Code.  I’ll give this one a grateful pass, but if anyone here reads it, do report back.

Fig. 1.  Ilya Ivanov (1870-1932), renegade biologist

Rabbi David Wolpe has engaged in a series of debates on faith with Christopher Hitchens. In yesterday’s Washington Post he gives his reaction to these debates and offers a touching tribute to Teh Hitch.  He ends the piece with some grudging admiration:

Later we sign copies of our books for the audience. Five or 10 kindly souls stand in my line. His stretches out as long as the eye can see. He looks up at me and winks.

The smart money, he seems to be saying, is in heresy.

I’d say “atheism” instead of “heresy.”

Something weird is going on over at BioLogos.   It’s becoming less and less scientific and more and more evangelical, to the point where its writers blatantly expound the most extreme and Jebus-loving form of babble.  Here’s part of a post by Kenton Sparks, a professor of Biblical studies at Eastern University.  Sparks tries to explain why the Bible, supposedly the word of God, has errors and contradictions.  He starts by explaining another contradiction: why a God-created world has problems:

Let us begin with God’s creation. It is beautiful … in fact, unbelievable beautiful. Yet it also includes terrors and evils that are unspeakable … rapes, murders and wars … famine, disease and disaster … pain indescribable. Given that God has created everything that exists, how do Christians avoid the possible (some skeptics would say inevitable) implication that the blame for creation’s evils and horrors can be pinned on God? Following Paul’s lead in Rom 8:20-22, Christians dogmatically assert that the cosmos is broken because of human sin.²² So it is not God, but human beings, who are finally culpable for the messy side of creation. Creation is good and beautiful because it is God’s creation, but warped and broken because of human influence.

To make the point clearer, imagine with me a beautiful painting by Renoir or Monet. And then imagine that someone seizes the painting, rips it from its frame, crumples it up and stomps on it for about ten minutes. What does one end up with? One ends up with a beautiful painting that is everywhere warped and twisted. In some places the former beauty of the unmolested painting is more visible than in others, but there is no quarter of the painting that has escaped the damage. This, I would say, suitably describes God’s creation. It is beautiful but also broken, and in such a way that one cannot really separate what’s beautiful from what’s not. Because it is the good thing itself that is warped and damaged.

Is this “dogmatic assertion” supposed to comport with science? If so, then how exactly did human sin cause earthquakes, disease, tsunamis, and other acts of God that kill innocent people or make them suffer?  And if those imperfections were caused by human sin, did they not then exist before humans? Did tectonic plates only start moving when our ape-ish ancestors somehow acquired a soul?  And what about those diseases that were long present in animals but jumped to humans? Did the Irish potato blight, caused by a fungus, really result from human sin?  Couldn’t God have stopped it before it killed so many children and families?

Sparks’s theodicy is of course complete nonsense, raising far more questions than it settles.  More important, it’s disproven by science.

And here’s the president of BioLogos, Darrell Falk, trying to explain to his flock how hard it is to reconcile science with their faith.  But first he lays out what that faith involves:

We at BioLogos believe that Jesus, fully God and fully man, walked on this earth 2,000 years ago in order to show humankind how to live life to the full. Jesus died in order that we, sinful humankind, might be clean. His shed blood has made us clean. We need not live under the power of sin any longer. We are called to an infinitely better life that is made possible because we have been forgiven through the event of Calvary, and because of the resurrection power that raised Jesus from death to life. That death to death at the tomb near Calvary was not metaphorical, and the new life we live in Christ is not metaphorical either. We are empowered to live fully gifted lives; we are empowered to live out our calling, enabled by the resurrection-power of God’s Spirit which dwells in us. The Church has existed through these past 2,000 years because the Power of God’s Spirit is alive in God’s Church. We believe the Bible, a living document through which the Holy Spirit continues to speak today, is the divinely inspired Word of God.

At least he declares unequivocally that the Resurrection was not metaphorical.  But given that BioLogos thinks that Genesis and the idea of Adam and Eve as the parents of humanity are metaphorical, it would be nice if Falk could tell us how he manages to discriminate between those parts of scripture that are empirically true and those that are just instructive stories.  And how can he be so sure that Jesus was the real prophet and not Mohamed? Is this discrimination based on evidence?  Or is it just what Falk wants to be true?

Things don’t look good at BioLogos.  The science, always in an uneasy equipoise with faith, is now being pushed aside by evangelism.  I predict that Templeton will withdraw its support; at least that’s what they should do if they want to retain any credibility with scientists.

h/t: Butterflies and Wheels

Now here’s a fair debate!

h/t: Richard Dawkins Foundation website

Many species have bright and conspicuous colors. When these colored individuals are dangerous or distasteful, the pattern is called warning coloration or, as biologists call it, aposematic coloration.   These patterns act (and presumably evolved) to cause predators to avoid attacking the individuals, which either taste dreadful or could hurt the predator.  Predators (often birds) do indeed learn to avoid the colors after an initial experience with them.  You, for example, have learned to avoid insects having black and yellow stripes, so you won’t go near anything that looks like this:

Here are some examples of aposematic colors and patterns in diverse species:

The striped skunk (Mephitis mephitis), which squirts a nasty fluid from anal glands

The poisonous coral snake (Micrurus fulvius)

The ladybug (Coccinella septempunctata); not a bug but a beetle.  When grabbed by a predator, they secrete a foul-tasting fluid from their leg joints

The noxious caterpillar of Eupackardia calleta (the calleta moth).

The blue-ringed octopus (Hapalochlaena lunulata). It’s one of the deadliest sea animals, with a venomous bite that’s killed many people.

The yellow banded poison dart frog (Dendrobates leucomelas), which secretes toxic alkaloids through the skin.

Now scientists have shown that lots of these species are indeed toxic or dangerous to predators, and that the predators do indeed learn to avoid the patterns and colors (sometimes, as we’ve discussed before, the predators can even evolve a hard-wired aversion to the pattern).  So this system is good for both the aposematic species and its predator.  But there’s always been a big problem with this system: how did the coloration evolve in the first place?

You can show from phylogenetic analysis that many of these brightly-colored species evolved from camouflaged (“cryptic”) ones.  This lead to the evolutionary problem:  the first mutant individual that was toxic but had a new, bright color would call attention to itself.  Since no predator has yet learned, since the pattern is new, that individual would be more likely to be eaten than its camouflaged conspecifics, and so there would be a penalty attached to the new mutation.  Only when those aposematic individuals were sufficiently common—and thus could be encountered often enough by predators who would remember the pattern and avoid the next aposematic individual—could they enjoy the protection afforded by their color.  The problem of aposematic coloration, then, is that at very low frequency it would seem to be disadvantageous and could not invade a population. Only when it gets above a certain frequency would natural selection then act to fix the trait in the species. (This kind of natural selection, in which the advantage or disadvantage of a mutation depends on its frequency in the population, is called frequency-dependent selection.)

Various solutions have been offered to this puzzle, but all of them suffer from problems. I won’t recount these, but want to briefly highlight a paper that offers a possible solution.  In the June issue of Evolution, Michael Speed and his colleagues suggest a way to get aposematism off the ground.

The solution is this: although the first mutant aposematic individuals are more likely to be detected by predators, they have another feature that more than offsets this advantage: they forage more openly, enabling them to get resources that their cryptically colored (and presumably hidden) conspecifics don’t share.  This could increase the fitness of aposematic individuals above that of their cryptic kin.  Speed et al.’s paper conducts numerical simulations, involving “optimization” of the color and foraging traits, that show (as you might guess), that if these foraging advantages (which of course make them more conspicuous to predators) are sufficiently large, they can outweigh the deleterious effects of being seen and attacked by a predator.

Under this model, then, the evolution of warning coloration is associated with a niche shift.  Speed et al. show that their model makes several predictions, which preliminary data seem to support:

• Species that are aposematic should expose themselves more often to predators (because they’re out seeking resources) do their non-aposematic relatives.  Speed et al. show that there is indeed evidence for this in poison-dart frogs and Lepidoptera: aposematic species forage during the day more often than do their cryptic relatives.  And, of course, skunks are perhaps the noisiest and most conspicuous foraging mammals in North America!
• Aposematic species should, because they are able to get more resources, be able to evolve larger body sizes than their relatives.  There are preliminary data supporting this in insects and amphibians
• For species with very different life stages, like Lepidoptera, the mobility of a life stage should correlate with its degree of warning coloration.  Speed et al. cite some supporting evidence: “Pupal forms of lepidopteran species that are aposematic in larval or adult stages are often cryptic. . . consistent with the fact that they are completely stationary and hidden away from predators.
• Aposematic species should “make use of a greater range of food plants than closely related, but cryptically colored species.”  This prediction has not been tested.

This model sounds good, and may well obviate the problems with getting warning coloration off the ground, but there’s one problem.  It is an optimization model in which several traits are simultaneously “optimized” by natural selection.  But evolution has to work on genes, and a gene-based model of Speed et al.’s theory seems a bit problematic.  Which mutation came first, the one for bright color or the one for foraging more openly? (Presumably these two types of traits—behavioral and morphological—are based on different genes.) If the aposematic mutation came first, it would still encounter the problem of being more visible to predators without the compensating benefit of getting more food.  If the foraging-openly mutation came first, it would be disadvantageous because it would expose itself to predators more (and if there were an advantage to foraging more openly if you were cryptically colored, the species would already be doing it).

In other words, the theory seems to depend on the concatenation of new mutations for two traits, each of which is individually disadvantageous at low frequencies but which become advantageous when they occur together.  But, given the rarity of mutation, this seems to be improbable. Indeed, I know of only a few cases of evolution that involve two mutations that are useful together but individually disadvantageous. (For you evolution fanatics, one example is the evolution of compensatory mutations in the loop structure of transfer RNA.)

This shows a persistent problem with optimization models: what looks optimal from an evolutionary standpoint may not be attainable when you deal with the messy genetic details.  And, after all, anything that evolves has to obey the rules of population genetics.

I may be missing something, and perhaps the authors will correct me, for I really want this idea to be true. It fits the facts about nature so well!

_______

Speed, M. P., M. A. Brockhurst, and G D. Ruxton.  2010.  The dual benefits of aposematism: predator avoidance and enhanced resource collection.  Evolution 64:1622-1633.