I'm in Chicago with Ms. Sandwalk and another couple who we hang out with. We have a wonderful time at the art gallery, took the architectural boat tour and ate delicious deep dish pizza.
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Only the mature male Moschus produces musk. The substance occurs in only one location on the deer's body: on its abdomen, just in front of its penis, is a hairy pouch known as the musk gland. This sac is about the size of a golf ball. It is composed of several layers of skin, with two openings immediately above the animal's urethra.I'm told that humans of both sexes get turned on by this smell. If so, the woman on the subway is not only going to attract female musk deer but she's also going to get a lot of attention from both men and women of a different species. I guess it's a good thing that I freed up the seat next to her.
In the early summer, unripe liquid musk drains into the gland from the surrounding tissues, and is stored there for some weeks or months. During the course of this time, the musk - 30 grams of it or so - "matures" into a granular, waxy, reddish-brown substance with an extremely potent and familiar smell.
When the musk has ripened - shortly before the autumn rutting season - the deer begin to discharge it mixed with their urine, apparently to mark their territory and attract females. (This behavior is familiar to anyone who has come in contact with a tomcat that "sprays.") Even in winter, male musk deer have been reported to leave behind fragrant red snow, rather than yellow.
When the neutral theory of molecular evolution was first proposed by, among others, the great Japanese geneticist Motoo Kimura, it was controversial. Some version of it is now widely accepted and, without going into the detailed evidence here, I am going to accept it in this book. Since I have a reputation as an arch-"adaptationist" (allegedly obsessed with natural selection as the major or even only driving force of evolution) you can have some confidence that if even I support the neutral theory it is unlikely that many other biologists will oppose it!I can't think of any serious biologists who would deny that neutral mutations exist. The essence of Neutral Theory, or Nearly Neutral Theory as it is currently called, is undoubtedly correct. The fact that Richard Dawkins accepts it in this book is not remarkable. What's remarkable is that he has to tell us that he accepts it, especially in a book about the evidence for evolution.
It is a remarkable fact that the greater part (95% in the case of humans) of the genome might as well not be there, for all the difference it makes. The neutral theory applies even to many of the genes in the remaining 5%—the genes that are read and used. It applies even to genes that are totally vital for survival. I must be clear here. We are not saying that a gene to which the neutral theory applies has no effect on the body. What we are saying is that a mutant version of the gene has exactly the same effect as the unmutated version.In other words, the vast majority of the DNA in our genome is junk. Mutations that occur in junk DNA will become fixed in spite of the fact that they are not seen by natural selection. This is what he means when he says that most mutations are neutral and it's equivalent to saying that the dominant mechanism of evolution, in terms of overall frequency, is random genetic drift and not natural selection. I just wish he'd come right out and say it.
As it happens, it is probably true to say that most mutations are neutral. They are undetectable by natural selection, but detectable by molecular geneticists; and that is an ideal combination for an evolutionary clock.This is the way the adaptationist dismisses non-adaptive evolution. It's not really of interest to real biologists. It's only interesting to molecular geneticists. And we all know that those people are not real evolutionary biologists!
None of this is to downgrade the all-important tip of the iceberg—the minority of mutations that are not neutral. It is they that are selected, positively or negatively, in the evolution of improvements. They are the ones whose effects we actually see—and natural selection "sees" too. They are the ones whose selection gives living things their breathtaking illusion of design. But it is the rest of the iceberg—the neutral mutations which are in the majority—that concerns us when we are talking about the molecular clock.
As geological time goes by, the genome is subjected to a rain of attrition in the form of mutations. In that small portion of the genome where the mutations really matter for survival, natural selection soon gets rid of the bad ones and favors the good ones. The neutral mutations, on the other hand, simply pile up, unpunished and unnoticed—except by molecular geneticists.
It is also possible (although "ultra-Darwinists" like me incline against the idea) that some mutations really do change the body, but in such a way as to have no effect on survival, one way or the other.
The adaptationism controversy is quite different. It is concerned with whether, given that we're dealing with a phenotypic effect big enough to see and ask questions about, we should assume that it is the product of natural selection. The biochemist's "neutral mutations" are more than neutral. As far as those of us who look at gross morphology, physiology and behavior are concerned, they are not mutations at all. It was in this spirit that Maynard Smith (1976) wrote: "I interpret 'rate of evolution' as a rate of adaptive change. In this sense, the substitution of a neutral allele would not constitute evolution ..." If a whole organism biologist sees a genetically determined differences among phenotypes, he already knows he cannot be dealing with neutrality in the sense of the modern controversy among biochemical geneticists.Finally, in 2009, Richard Dawkins admits that it is "possible" that visible mutations could be neutral. Hallelujah!
1. Jerry Coyne's View of Random Genetic Drift
Genomic changes underlie evolutionary adaptation, but mutations—even those substituted (fixed) in evolving populations—are not necessarily beneficial.Variation in the rate of genomic evolution is also subject to many influences and complications.On the one hand, theory predicts that neutral mutations should accumulate by drift at a uniform rate, albeit stochastically, provided the mutation rate is constant. On the other hand, rates of substitution of beneficial and deleterious mutations depend on selection, and hence the environment, as well as on population size and structure. Moreover, the relative proportions of substitutions that are neutral, deleterious and beneficial are usually difficult to infer given imperfect knowledge of any organism’s genetics and ecology, in the past as well as in the present.At 20K generations, there were 29 single nucleotide polymorphisms (SNP) and 16 deletions, insertions, and chromosomal rearrangements (DIP) for a total of 45 different events (see figure). Not all of these contributed to adaptation and the rapid growth phenotype but many of them did. Some were mutations that inactivated a gene and some were amino acid substitutions that change activity of an enzyme.
Experiments with tractable model organisms evolving in controlled laboratory environments minimize many of these complications and uncertainties15,16. Moreover, new methods have made it feasible to sequence complete genomes from evolution experiments with bacteria. To date, such analyses have focused on finding the mutations responsible for particular adaptations. However, the application of comparative genome sequencing to experimental evolution studies also offers the opportunity to address major conceptual issues, including whether the dynamics of genomic and adaptive evolution are coupled very tightly or only loosely.
Despite his understandable desire to spin the results his way, Lenski’s decades-long work lines up wonderfully with what an ID person would expect — in a huge number of tries, one sees minor changes, mostly degradative, and no new complex systems. So much for the power of random mutation and natural selection. For his work in this area we should be very grateful. It gives us solid results to point to, rather than having to debate speculative scenarios.I don't think I need to comment on such stupidity.
Barrick, J.E., Yu, D.S., Yoon, S.H., Jeong, H., Oh, T,K., Schneider, D., Lenski, R.E., and Kim, J.F. (2009) Genome evolution and adaptation in a long-term experiment with Escherichia coli. Nature Oct 18. [Epub ahead of print] [PubMed] [doi: 10.1038/nature08480]
Is everything a skeptic believes something which is a conclusion reached by scientific methods?
No. Much of what we believe, we believe on the basis of testimony from other people who we trust, including our knowledge of our own names and date and place of birth, parts of our childhood history, the history of our communities and culture, and knowledge of places we haven't visited. We also have various beliefs that are not scientifically testable, such as that there is an external world that persists independently of our experience of it, that there are other minds having experiences, that certain experiences and outcomes are intrinsically or instrumentally valuable, that the future will continue to resemble the past in various predictable ways, etc. If you did believe that skeptics should only believe conclusions which are reached by scientific methods, that would be a belief that is not reached by scientific methods.
Thinking of science as a religion that worships truth as it god enables me to praise its virtues and criticize its shortcomings at the same time. In my previous blogs, I have played the role of scientific reformer for two major issues. The first is the "new atheism" movement spearheaded by the so-called four horsemen: Richard Dawkins, Daniel Dennett, Samuel Harris, and Christopher Hitchens. Isn't it wonderful how scientists and rationalists reflexively adopt religious imagery? I am an atheist in the sense that I regard religion as 100% a human construction, but I'm here to testify that the "new atheists" depart from factual reality in their own way. So did Ayn Rand, the "new atheist" of her day, as we are learning to our sorrow from the collapse of the free market belief system that she helped to create. If we worry about religions for their departures from factual reality, then we should really worry about "stealth religions" that do the same thing without invoking the gods, because they do a better job of masquerading as reality. As someone who is seriously committed to studying religion from a scientific and evolutionary perspective, I'm here to say that the new atheists can't bring themselves to accept the facts about religion as a human construction. Read my six-part series on "Atheism as a Stealth Religion", now archived on my ScienceBlog site, for more. Even better, start acquainting yourself with the emerging field of evolutionary religious studies, whose members are more serious about holding each other accountable for what they say about religion.Hmmmm ... my sympathies lie with Dawkins et al so I guess this is aimed at me. I was completely unaware of the possibility he mentions; namely, that I don't accept the facts about religion as a human construction. I'll have to think carefully about that one. Is it possible that, as an atheist, I was secretly thinking that religion might actually have been constructed by supernatural beings? Nope, I don't think so.
The second major issue that requires scientific reform is group selection, a theory that explains how groups can become well adapted to their environments in the same sense that individuals do. The theory of group selection began with Darwin and involves a simple set of issues that anyone can understand. Yet, it remains endlessly controversial. Next year marks the 35th anniversary of my first publication on group selection and I'm confident that the controversy will continue for decades more unless something is done. That "something" is a truth and reconciliation process, similar to the resolution of political conflicts that otherwise might continue forever. The idea that a scientific controversy might require a truth and reconciliation process similar to a political controversy speaks volumes about science as a fallible and culturally influenced process.I don't have a dog in this fight. It will be interesting to watch and learn.
Researchers have offered many theories about why women are religious in greater numbers than men. Most are inconclusive; all are fascinating. Some investigators locate the engine of belief in our very brain chemistry, and find the female brain far more apt to sense the divine. Canadian cognitive neuroscientist Michael Persinger, the reigning cleric of the neurology of belief, has asserted that the “experience” of God, or feeling the presence of the divine, is literally built into the brain, specifically in the limbic system or the temporal lobe. When Persinger applied magnetic fields over the temporal lobe to mimic the reaction he found in electromagnetic studies, the gender difference was “quite impressive”—that women sensed the presence of a “sentient being” in greater numbers than men.It's not their fault that women fall for superstitious nonsense. Their brains are built differently and evolution is to blame.
“Belief,” Persinger told me, “relates more to how the person relates, interprets, and reconstructs the experience.” In other words, even when men and women had the same response in the brain, women were more apt to attribute it to something divine, “out of body.” Other scientists have found these limbic tendencies particularly pronounced in adolescent girls, concurrent with the final stages of brain development. As Barry Kosmin, a coauthor of the new Trinity College study says, “That's why when anybody sees the Virgin Mary, it's a couple of young girls on a mountainside in Southern Europe.” ....
Some researchers hypothesize that women are hardwired to believe because of evolutionary imperatives. Belief in God—or the Mount Olympus ensemble cast, or a phalanx of wood spirits, and so on—has long been connected with tribal ritual, and formed the center of communities. Women relied on these communities for the survival of their children, while men were off spearing buffalo, pillaging neighboring settlements—or whatever the caveman business trip furnished. The relationship between belonging and belief is an ancient one. It may have resulted in the development of certain alleles connected to a sense of God, or at least a commitment to religion.
[Hat Tip: Friendly Atheist: Science or Sexism?]
Recently a group of biologists has offered a theory that they say explains, if not tube socks, then nearly everything else. In a series of high-profile papers, Corey Fincher and Randy Thornhill, both at the University of New Mexico, and Mark Schaller and Damian Murray of the University of British Columbia argue that one factor, disease, ultimately determines much of who we are and how we behave.Dunn expresses some skepticism using appropriate language but he goes on to describe "data" (correlations, actually) that supports the idea. The tone of the article is quite supportive of the idea that evolution is behind this behavior.
Their theory is simple. Where diseases are common, individuals are mean to strangers. Strangers may carry new diseases and so one would do best to avoid them. When people avoid strangers—those outside the tribe—communication among tribes breaks down. That breakdown allows peoples, through time, to become more different.
Differences accumulate until in places with more diseases, for example Nigeria or Brazil, there are more cultures and languages. Sweden, for example, has few diseases and only 15 languages; Ghana, which is a similar size, has many diseases and 89 languages. Cultural diversity is, in this view, a consequence of disease.
Then Fincher and colleagues go even further. Where people are more xenophobic and cultures more differentiated from one another, wars are more likely. Democratic governments are less likely because the tribe or group comes first; the nation and individuals in other tribes within the nation come second. And finally, poverty becomes nearly inevitable as a consequence of poor governance, hostility between groups, and the factor that triggered this cascade in the first place—disease.
[Hat Tip: a skeptical John Hawks]
PETER MITCHELL was an eccentric figure. For much of his career he worked in his own lab in a restored manor house in Cornwall in the UK, his research funded in part by a herd of dairy cows. His ideas about the most basic process of life - how it gets energy - seemed ridiculous to his fellow biologists.I wish this weren't so but I'm afraid the last statement is correct. It's not only biologists who fail to grasp the implications, there are even biochemists who don't understand chemiosmotic theory and don't teach it correctly in undergraduate courses.
"I remember thinking to myself that I would bet anything that [it] didn't work that way," biochemist Leslie Orgel wrote of his meeting with Mitchell half a century ago. "Not since Darwin and Wallace has biology come up with an idea as counter-intuitive as those of, say, Einstein, Heisenberg and Schrödinger."
Over the following decades, however, it became clear that Mitchell was right. His vindication was complete when he won a Nobel prize in 1978. Even today, though, most biologists have yet to grasp the full implications of his revolutionary ideas - especially for the origin of life.
That hyperbole has reverberated throughout the evolutionary biology community, putting Pigliucci and the 15 other participants at the forefront of a debate over whether ideas about evolution need updating. The mere mention of the "Altenberg 16," as Mazur dubbed the group, causes some evolutionary biologists to roll their eyes. It's a joke, says Jerry Coyne of the University of Chicago in Illinois. "I don't think there's anything that needs fixing." Mazur's attention, Pigliucci admits, "frankly caused me embarrassment."Jerry Coyne was wrong. There are some things that need fixing. Anyone who has read Stephen Jay Gould's The Structure of Evolutionary Theory should know that.
Well it seems our feedback to the University of Toronto about the upcoming Autism One conference has had an effect. As I noted earlier, Autism One is hosting a conference on autism in Toronto in October. The original brochure listed boldly that the conference was being presented with the Dalla Lana School of Public Health. Understandably concerned, I, along with many of you, contacted the university to register our concerns. Why would a school of public health support a program that touts dubious biomedical treatments for autism, and the ultimate quackery, homeopathy?I don't excuse the SickKids Foundation for their stupid attitude and support for this kind of quackery but the situation with respect to the University of Toronto is a bit different.
Well it turns out the school has acted – quickly and decisively. I’ve heard directly from the school, and have been assured that they were never an official supporter of the program. The brochure and website suggested that the school was actually co-hosting. The school has asked for its name to be removed – and the organizers have complied, as Orac noted earlier this week. The online version of the brochure no longer lists the school’s name.
But what about the SickKids Foundation? Well, this event has brought to light that the SickKids Foundation “takes a neutral stance on complementary and alternative health care” and seems satisfied to remain a sponsor of antivaccination pseudoscience. Their name is still on the brochure.
Which brings me to the topic of the post. Universities never have the funding that they think they need, and do whatever they can to bring in other types of revenue. So the Univeristy of Toronto has rented its space to AutismOne for the conference, and the brochure correctly notes that the address is the Medical Sciences Building on campus. Has a nice ring, doesn’t it? Despite the agenda clearly lacking both valid medicine or science, the conference has bought an air of legitimacy by locating itself on campus. It’s clearly a problem that needs to be addressed, as there’s stuff happening elsewhere on campus…
If a homeopathy manufacturer is providing sponsorship dollars for this symposium, the likelihood of the content being science-based is, well, probably homeopathic.There's no excuse for this. The Faculty of Pharmacy should be ashamed. All members of the University of Toronto community should be embarrassed. I know I am.
It pains me to point this out, as U of T is my pharmacy alma mater, and the school is filled with superb faculty, students, and researchers. So why is the Leslie Dan Faculty of Pharmacy willing to tarnish its good name by offering a continuing education program containing pseudoscience, sponsored by a company that makes homeopathy? Do they really need the money? Or have they run out of science-based topics to teach?
If this is the state of pharmacy continuing education, we should all be dismayed. Because when academic institutions that should know better are facilitating pseuodoscience like homeopathy, and accepting sponsorship from homeopathic manufacturers, what chance does pharmacy really have to be a science-based profession? And what does it mean for patient care, when pharmacists are learning how to use elaborate placebo systems to treat chronic pain?
HMB434H1I've spoken to the person who runs the Human Biology Program (Valorie Watt). She helped organize this course and she hired the lecturers. She doesn't see a problem.
Complementary and Alternative Medicine [20L, 4S]
Integrative health care is a phenomenon that is developing in health care systems in North America, China, India, and Vietnam, among others. It involves the coordination of multi-disciplinary and culturally-specific health services in the treatment of illness and disease, and an expanded concept of health, illness, and wellness.
[Photo Credit: Peter Macdiarmid/Getty: A kind of magic?]
The influence of this process on important evolutionary change, though, is probably minor, because it does not have the moulding power of natural selection. Natural selection remains the only process that can produce adaptation. Nevertheless, we'll see in chapter 5 that genetic drift may play some evolutionary role in small populations and probably accounts for some non-adaptive features of DNA.Okay, so it's not perfect, but at least he isn't confused about the difference between "evolutionary theory" and "Darwinism". Right?
Such random change in the frequency of genes over time is called genetic drift. It is a legitimate type of evolution, since it involves changes in the frequencies of alleles over time, but it doesn't arise from natural selection. One example of evolution by drift may be the unusual frequencies of blood types (as in the ABO system) in the Old Order Amish and Dunker religious communities in America. These are small, isolated, religious groups whose members intermarry—just the right circumstances for rapid evolution by genetic drift.1This sounds like a typical adaptationist speaking. As a general rule, adaptationists admit to random genetic drift but confine it to small populations. They also make sure you understand that drift can't cause adaptation. Finally they state their opinion that drift only affects neutral alleles.
Accidents of sampling can also happen when a population is founded by just a few immigrants, as occurs when individuals colonize an island or a new area. The almost complete absence of genes producing the B blood type in Native American populations, for example, may reflect the loss of this gene in a small population of humans that colonized North America from Asia around twelve thousand years ago.2
Both drift and natural selection produce genetic change that we recognize as evolution. But there's an important difference. Drift is a random process, while selection is the anti-thesis of randomness. Genetic drift can change the frequencies of alleles regardless of how useful they are to their carrier. Selection, on the other hand, always gets part of harmful alleles and raises the frequencies of beneficial ones.
As a purely random process, genetic drift can't cause the evolution of adaptations. It could never build a wing or an eye. That takes nonrandom natural selection. What drift can do is cause the evolution of features that are neither useful nor harmful to the organism.
At this point, some evolutionists will protest that we are caricaturing their view of adaptation. After all, do they not admit genetic drift, allometry, and a variety of reasons for non-adaptive evolution? They do, to be sure, but we make a different point. In natural history, all possible things happen sometimes; you generally do not support your favorite phenomenon by declaring rivals impossible in theory. Rather, you acknowledge the rival, but circumscribe its domain of action so narrowly that it cannot have any importance in the affairs of nature. Then you often congratulate yourself for being such an undogmatic and ecumenical chap. We maintain that alternatives to selection for best overall design have generally been relegated to unimportance by this mode of argument.This describes the views of many adaptationists but Jerry Coyne does not exactly fall into that mode of thinking—at least not when his attention is focused on the issue.
In fact, genetic drift is not only powerless to create adaptation, but can actually overpower natural selection. Especially in small populations, the sampling effect can be so large that it raises the frequency of harmful genes even though selection is working in the opposite direction. This is almost certainly why we see a high incidence of genetically based diseases in isolated human communities, including Gaucher's disease in northern Swedes, Tay-Sachs in the Cajuns of Louisiana, and in retinitis pigmentosa in the inhabitants in the inhabitants of the island of Tristan da Cunha.This is very important and Jerry Coyne is one of the few adaptationists who get it. Random genetic drift doesn't just work on neutral alleles. It can also lead to high levels of deleterious alleles. Even their eventual fixation.
Because certain variations in DNA or protein sequence may be, as Darwin puts it "neither useful nor injurious" (or "neutral" as we now call them), such variants are especially liable to evolution by drift. For example, some mutations in a gene don't affect the sequence of the protein that it produces, and so don't change the fitness of its carrier. The same goes for mutations in non-functioning pseudogenes—old wrecks of genes still kicking around in the genome. Any mutations in these genes have no effect on the organism, and therefore can evolve only by genetic drift.It's impressive that Coyne admits to the possibility that externally visible features could be neutral and could evolve by random genetic drift. However, he immediately qualifies the statement by pointing out that it's very difficult to prove whether a trait has absolutely no selective advantage. This is true, but adaptationists usually forget to mention two things about natural selection that weaken this argument. First, they forget to mention that it's often just as difficult to prove that a trait has a selective advantage. Second, traits with small advantages are most often lost before they are fixed. Natural selection is not random but neither is it as much of a sure thing as most people believe.
Many aspects of molecular evolution, then, such as certain changes in DNA sequence, may reflect drift rather than selection. It's also possible that many externally visible features of organisms could evolve via drift, especially if they don't affect reproduction. The diverse shapes of leaves of different tree species—like the differences between oaks and maple trees -- were once suggested to be "neutral" traits that evolved by genetic drift. But it's hard to prove that a trait has absolutely no selective advantage. Even a tiny advantage, so small as to be unmeasurable or unobservable by biologists in real time, can lead to important evolutionary changes over eons.
The relative importance of genetic drift versus selection in evolution remains a topic of hot debate among biologists.
1. This is technically correct. Individual alleles will be fixed much faster in small populations than in large populations ... if they are fixed. But this does not mean that random genetic drift only fixes genes in small populations.
2. The founder effect is an important feature of evolution by accident.
There are two ways that modern evolutionists approach the Cambrian explosion, or what has been called “Darwin’s dilemma”:Here's another option.
A. Some freely acknowledge that the Cambrian fossil evidence essentially shows the opposite of what was expected under neo-Darwinian evolution.
B. Others deal with the Cambrian explosion by sweeping its problems under the rug and trying to change the subject.
Thanks for asking for my reaction to Behe’s post on our recent paper in Nature. His interpretation of our work is incorrect. He confuses “contingent” or “unlikely” with “impossible.” He ignores the key role of genetic drift in evolution. And he erroneously concludes that because the probability is low that some specific biological form will evolve, it must be impossible for ANY form to evolve.
Behe contends that our findings support his argument that adaptations requiring more than one mutation cannot evolve by Darwinian processes. The many errors in Behe’s Edge of Evolution — the book in which he makes this argument — have been discussed in numerous publications.
In his posts about our paper, Behe’s first error is to ignore the fact that adaptive combinations of mutations can and do evolve by pathways involving neutral intermediates. Behe says that if it takes more than one mutation to produce even a crude version of the new protein function, then selection cannot drive acquisition of the adaptive combination.
[Photo Credit: Joe Thornton by Jack Liu Photographer]
[Image Credits:
Charlemange Empire map
Emperor Charlemagne]