Archive for April, 2007

Evolution of sex roles

Saturday, April 21st, 2007

invisiblesex1.jpgThe Philadelphia Inquirer published an article on April 2 reporting research findings on the sex roles of our hominid ancestors. It includes a reference to a new book, The Invisible Sex: Uncovering the True Roles of Women in Prehistory by James Adovasio, Olga Soffer and Jake Page. Perhaps the most prominent message in the article is that current paleoanthropology research is invested in studying human evolution from an equal-rights-minded perspective, while past research has chauvinistically and perhaps inaccurately emphasized the machismo of early man’s big-game hunting achievements. No doubt this enlightened effort to consider the importance of early woman’s labors to our extant existence reflects our recent cultural evolution towards gender equality. Bravo in this regard. And while I’ll never criticize the popular media for reporting on, nor researchers from researching, the evolutionary history of the species we’re all most interested in (our own), the fact remains that inferring evolutionary dynamics from ancient fragments of bones and tools is nearly impossible. The opacity of this problem is well illustrated by just how easily influenced the scientific perspective is by the social politics of our culture at large.

Still, there’s a big difference between making the most of the data you’ve got—and the validity of these researchers’ scientific conclusions should be evaluated by the rigor of their scientific method—and flat-out naivety or, worse, disingenuousness. At the end of the article, Stanford anthropologist Richard Klein is reported as saying that a mutation in the lineage of early humans may be responsible for our eventual success, as opposed to the eventual extinction of the related Neanderthal lineage. This point comes after a dramatic description of humans emerging into a “cultural” and “artistic” existence of sophisticated “conceptual thinking,” the implication being that our superior intellectual powers should be credited with saving us from extinction. (There’s no way to know this, either: another example of human bias?) But hand-waving aside, there are some things we DO understand rather well, and the extraordinarily complex, quantitative nature of human biology is one of them. No geneticist or evolutionary biologist would ever think that a single mutation could induce such a dramatic new phenotype, so why should an anthropologist (or reporter)? The truth is almost certainly that multiple mutations distinguished our early human ancestors from their Neanderthal neighbors. This may be less easily dramatized to a non-scientific audience, but I argue strenuously that an accurate representation of the scientific process is as critical in an agenda for general science education as is whether scientific research is reported at all.

Yup, still a problem

Thursday, April 19th, 2007

NOTE: This post was originally published on February 28, 2007, on an old version of this site.

In discussing Stephen Jay Gould and Richard Lewontin‘s article “The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme” with a group of undergraduates the other day, one of the students asked if this critique, published in 1979, is still relevant. Gould and Lewontin’s basic thesis is that too many biologists fall prey to the seduction of describing everything they see as an adaptation. They accuse their colleagues of inappropriately dissecting organisms into discrete traits, then conjuring adaptive explanations for the existence of these traits—a process that not only neglects to provide evidence to justify such an adaptive explanation, but that also fails to consider how evolution is a whole-organism process. Well, today I have a definitive answer: it is as relevant as ever.

moalembook.jpgToday Marty Moss-Coane interviewed guest Sharon Moalem on her show Radio Times. Dr. Moalem, author of Survival of the Sickest, a book about how many human diseases are in fact adaptive “complicated blessings,” paraded a series of sophomoric explanations for how susceptabilities to many human diseases have in fact been selected for over our evolutionary history.

For example, Moalem argues that the relatively high frequency of genes that underlie the disease hemochromatosis in populations of European descendants may be the result of selection for these genes during the plagues of Europe. Hemochromatosis is a disorder in which iron accumulates in body tissue, and macrophages—which are a part of the immune system—suffer an iron deficiency. Because some pathogens may depend on iron to escape attack by the immune system, and because descendants from countries with high plague casualties show high frequencies of hemochromatosis, Moalem makes the argument that Europeans with iron-deficient macrophages were more likely to survive the plague… and thus we see a disproportionate representation of hemochromatosis in European descendants. But wait a minute! Correlation must not be confused with causation. If the genes that cause hemochromatosis are so detrimental, why were they not purged from the population before the plagues began? Maybe new mutations are popping up, or maybe selection is too weak to purge these alleles from the population. Or perhaps there has been positive selection for some of these genes, but we have no direct evidence that it was to avoid dying from the plague. It may be the case that the genes that underlie hemochromatosis also perform a beneficial function elsewhere in the body.

Furthermore, Moalem uses spurious scientific data to spin his adaptation stories. For example, he reports that fewer boy babies than girl babies were born in New York city after 9/11. Apparently there are some data suggesting that gestation of a male fetus incurs a higher cost to the mother, and that under stress, a mother will be more likely to miscarry if she’s carrying a high-cost son. Nevermind that this phenomenon deserves skeptical examination—the statistics that claim a significant gender skew in New York births can be easily dismissed, thus debunking Moalem’s claim that the 9/11 attacks stressed out pregnant mothers and caused a slight decrease in the boy/girl newborn ratio. The failure of this study is quite straightforward. The authors compute birth ratios for 81 different time intervals in New York city: 71 intervals leading up to 9/11, and 10 inervals after 9/11. The authors claim that the lowest boy/girl ratio occurred in one of the 10 post-9/11 intervals, and that it deviated “significantly” from the average ratio over all 81 intervals. Their data do show that the lowest ratio occurred post-9/11, but it is not significant. Fluctuations in birth ratios, just as in any natural phenomena, will occur due to randomness. (And in fact, the sex ratio went up more often than it when down in the 10 intervals after 9/11!) Statistics allow us to infer whether a fluctuation differs enough from the average to suggest something unusal, and when looking at multiple events, a statistician must correct for multiple tests. Quite simply, these authors performed the correct test but utterly failed to adjust the type I error value to accommodate the type of data they were examining. The truth is that there is absolutely no evidence that birth ratios changed at all in response to the 9/11 attacks. To see what p-values should have been reported, see this criticism.

Radio Times is broadcast every weekday from the Philadelphia NPR station WHYY, 90.9 FM. You can listen to this particular show from the Radio Times archive.

Yes, THIS is why conservatives should love evolution

Thursday, April 19th, 2007

NOTE: This post was originally published on February 27, 2007, on an old version of this site.

An article by David Brooks recently published in the Philadelphia Inquirer offers a tantalizing morsel of controversy, which is begging for a good swipe. Brooks’ essay starts out with a thesis: The notion that humans are fundamentally good, and that our virtuous natures are made venal by corrupt institutions, has been gradually eroded and replaced with science’s sinister declaration that we’ve evolved from conflict-stricken, status-contesting ancestors and we thus embody inherently animalistic, not-so-good predispositions. He makes an intriguing case. The zinger comes at the end: “Many conservatives resist the theory of evolution even though it confirms many of conservatism’s deepest truths.” Yikes.

So taking this argument apart, we have:

  1. Science teaches us that we are wicked by evolutionary inheritance.
  2. Many who advocate the philosophy of a fundamentally wicked human nature are conservative.
  3. Perversely, many conservatives reject evolution.

barbedwire.jpgWell, I agree that rejection of evolution is perverse, no matter who you are. And the claim that conservatives prefer a world view of inherit wickedness, while perhaps endlessly debatable, does obviously coincide with the Christian concept of original sin. But there is a problem with distilling the evidence-based truths of science into an argument that we’re bad by nature. In a wider context (and to be fair, one that Brooks outlines), perhaps it’s notable that science motivated a sea change against the naive and hopeful philosophy that things in their most natural form will make peace and exhibit good behavior. So long as we’re talking about shifts in broad, popular perspectives, this makes a lot of sense.

However, in precisely this kind of broad, popular perspective, science offers so much more. After the initial crushing disappointment that we are, after all, vulgar animals, shouldn’t we realize the liberation this invites? If evolution can teach us anything, it’s that things are the way they are due to natural forces—not good, not bad. Moreover, these natural forces have shaped an ever-shifting, diversifying and changing biological landscape. After all, evolution is a reactionary force—it can only act on existing variation. There’s no destiny involved. How liberating! Don’t like that your ancestors developed a ravenous preference for simple carbohydrates? At least it’s not your destiny to consume nothing but bread and pasta. Lessons from science suggest an exploration of gastronomical preferences to find a diet that sates both your inherited appetite and your modern self-interest in being skinny. Along these lines, I think that discerning our natural, human instincts within an evolutionary context can be liberating: as we come to understand why we are the way we are, we can develop agency for becoming who we want to be.

Brooks’ whole point about conservatives and evolution is interesting compared to Michael Shermer’s point about how liberals and conservatives understand the basis for sexual orientation.

Not just science, but civics…

Thursday, April 19th, 2007

NOTE: This post was originally published on December 18, 2006, on an old version of this site.

constitution2.jpgThe New York Times published an article today reporting that a Kearney, NJ high school student has criticized his history teacher for proselytizing evangelical Christianity. David Paszkiewicz has been accused of telling his 11th-grade public school class “that evolution and the Big Bang were not scientific, that dinosaurs were aboard Noah’s ark, and that only Christians had a place in heaven.” Sixteen-year-old student Matthew LaClair was uncomfortable with these statements and brought the teacher’s actions to the attention of the administration.

Perhaps somewhat surprising is the amount of support for the teacher, who has clearly violated the First Amendment, and the amount of criticism for the complaining student. Another student and member of Mr. Paszkiewicz’s youth group, Greice Coelho, criticized Matthew LaClair, erroneously claiming that he is “ignoring the First Amendment to the United States Constitution, which gives every citizen the freedom of religion.”

This comment tidily demonstrates a warning Judge John Jones made in the December 13 panel discussion, in which he observed that many Americans are deficient in their civics education. He said the Dover case revealed that many people don’t understand their rights, and when they don’t understand them, they are much more likely to lose them.

“Sectarianism”

Thursday, April 19th, 2007

NOTE: This post was originally published on December 13, 2006, on an old version of this site.

Twice in the last two days I have heard the word “sectarian” used to describe the efforts to dissolve the separation church and state and the zealous promotion of fundamentalist Christianity.

In yesterday’s panel discussion on Science, Faith and Darwin at the Franklin Institute, panelist Stephen Harvey argued that, far from being valid science, “intelligent design is not just religious, it is sectarian.”

And in today’s cover story for Salon, former Air Force officer Mikey Weinstein argues that the unconstitutional proselytizing of evangelical faith within the military is “as much of a national security threat to this country as al-Qaida” and calls a video of senior officers promoting their faith “blatantly and vociferously sectarian.”

I think the use of this word is appropriate and smart. The arguments of the very conservative Christian right are not representative of most Americans, nor even most American Christians, and the word denotes the political motivation and connotes the perilousness of their agenda.

Panel discussion on Science, Faith and Darwin

Thursday, April 19th, 2007

NOTE: This post was originally published on December 13, 2006, on an old version of this site.

Today the Franklin Institute held a panel discussion on “Science, Faith and Darwin.” A recording of the discussion can be found here. Participants included:

  1. Dr. Arthur Caplan, Director of the Center for Bioethics at the University of Pennsylvania, moderator
  2. Dr. Michael Weisberg, Assistant Professor of Philosophy at the University of Pennsylvania, panelist
  3. Dr. Michael Shermer, author and founder of the Skeptics Society, panelist
  4. Eric Rothschild, Esq., Pepper Hamilton LLP, panelist
  5. Stephen Harvey, Esq., Pepper Hamilton LLP, panelist
  6. Judge John Jones III, U.S. District Court, Middle District of Pennsylvania, panelist

darwin.jpgMichael Weisberg opened the panel with a powerful point about our history of accepting scientific explanations in the context of religion. By the middle of the 19th century, Newtonian physics had provided a spectacularly successful unifying explanation for the movement of the heavens and the motions of objects on earth. Both scientists and the public agreed on these explanations, and God’s role was somewhat displaced—though not necessarily removed, as the religious perspective remained that God initiated, for example, the movement of the solar system. However, these powerful physical theories simply could not explain the intricate complexities of biology, and a sort of pseudo-scientific set of explanations, invoking God as a creator, were established. Thus when Darwin proposed the first fully satisfactory scientific explanation for biological diversity, in which God was no longer required to explain certain mystifying gaps in our understanding, some people felt that the actual concept of God was being challenged. Weisberg concludes by saying that it is perfectly reasonable to accept the position that the Anglican Church held at Darwin’s death, and still holds: that biological science can illuminate truths about the world, without threatening a conventional religious belief in God.

Stephen Harvey tidily summarized the achievement of the prosecution in the Kitzmiller vs. Dover Area School District case, for which he and Eric Rothschild were the lead attorneys:

  1. The prosecution proved that the Dover area school district acted with the purpose of promoting religion.
  2. The prosecution proved that intelligent design is religious.
  3. The prosecution proved that intelligent design is not science.

Harvey mentioned that when he and Rothschild first took the case, their colleagues joked that the case was “Harvey and Rothschild vs. God.” But he emphasizes that actually, following the facts of the case itself, Kitzmiller vs. Dover was not a case of faith versus science, and that their position was not anti-religion or anti-God. “Religion thrives in this country, not despite the separation of church and state, but because of it.” Really, the case was about making sure that a public school science classroom was not used as a pulpit to promote anyone’s specific religious perspective. Judge John Jones, who presided over the case, made the startling point that Kitzmiller vs. Dover made it apparent to him just how deficient the American public is in their civics education, not just their science education.

Of particular note, I think, is that each of the panelists emphasized frustration at the anti-evolution argument that science and theism are mutually exclusive, not just frustration at attacks on evolution. These authorities are clearly devoted to respecting both science the possibility of God. Michael Shermer openly declared himself an agnostic (like Darwin), and in fact a militant one: “I don’t know and you don’t either!” Stephen Harvey described himself as a Roman Catholic, and deconstructed the fallacy of one of the major arguments in intelligent design. Irreducible complexity is a fundamental concept in ID, and Harvey explained that, like other religiously motivated attacks on evolution, it is not proof of an intelligent designer, but instead an illogical, contrived dualism that posits that there are only two mutually exclusive possibilities: science or creationism, and that evidence against one is proof for the other.

One of the best questions of the evening inquired where, exactly, can religion be raised in a public school? The complexity of the answers by the panel reflects the overwhelming tension over religion in our culture. Michael Shermer was enthusiastic about the idea of discussing religion in history or philosophy class, he maintained only that it may not be incorporated into a science curriculum. John Jones pointed out that trouble begins when any teachings in this area become mandatory. Eric Rothschild was also enthusiastic about the idea of a comparative religions class at the high school level, much as they exist in higher education, but conceded that they must be non-biased and non-proselytizing and the potential for abuse is high given that school boards are governed at the local level. Stephen Harvey also pointed out that the potential for divisiveness in a school district would be tremendous.

Radio Times guest: Michael Shermer

Thursday, April 19th, 2007

NOTE: This post was originally published on November 23, 2006, on an old version of this site.

Today Marty Moss-Coane interviewed Michael Shermer, author of Why Darwin Matters: The Case Against Intelligent Design. In his book, Shermer writes, “Darwin matters because evolution matters. Evolution matters because science matters. Science matters because it is the preeminent story of our age, an epic saga about who we are, where we came from and where we are going.” Shermer is a former creationist who now defends evolution and explains that it makes “good theology” and that we need not find it contradictory to religious belief. He is the publisher of Skeptic magazine, columnist for Scientific American and founder of the Skeptics Society. Marty Moss-Coane is the host of Radio Times, a daily radio show from NPR radio station WHYY, 90.9 FM in Philadelphia, PA. You can listen to this show from the Radio Times archive.

whydarwinmatters.jpgMichael Shermer makes an intelligent and educated case for integrating science with religious belief. He points out that the theory of gravity, which explains the formation of planets and our solar system, is not contradicted by Christians in our country; it is largely accepted that this is “how God did it.” I agree perfectly with his argument that evolution need not challenge faith either. Science simply offers explanation of the world we live in. I particularly like Shermer’s insistence that, fundamentally, science can’t contradict faith, because science is the best tool we have for illuminating the world we live in, and no one should feel threatened by that.

Shermer directly confronts intelligent design as a guise for creationism and points out that the anti-evolution philosophy suffers from a specific fallacy of pseudoscience. Intelligent design abandons the quest for knowledge at the precise point at which it is most critical: while science seeks to investigate those things that we don’t understand, intelligent design invokes the “irrevocably complex” cause when our knowledge of a system is incomplete. He points out that this pseudoscientific process of “chasing the gaps” and using God as an explanation for those things that we do not fully understand is the opposite of how science works. Hence these arguments for God or a creator may be philosophical or theological, but not scientific.

Shermer also made an interesting point that I had never heard before. In explaining Charles Darwin’s argument that the evolutionary environment of our ancestors, which included important social interactions and group cooperation, may have played a role in developing a natural moral code, he points out that most conservatives and Christians do believe that we all have innate dispositions. It is typically liberals who try to explain human behavior by external influences. However, these perspectives are perfectly reversed when it comes to an explanation of sexual orientation! Conservatives and Christians are more likely to believe that homosexuality is environmentally influenced or chosen, while liberals typically argue that sexual orientation is innate.

Interview with Warren J. Ewens

Wednesday, April 18th, 2007

NOTE: This post was originally published on November 21, 2006, on an old version of this site.

warren.jpgDr. Warren J. Ewens is an internationally recognized mathematician whose contributions to population genetics earned him membership in the Australian Academy of Science in 1981 and membership in the Royal Society in 2000. He has been a professor of biology at the University of Pennsylvania since 1972, and has motivated unquantifiable numbers of students and colleagues with his warmth and extraordinary ability to explain things you thought you didn’t understand.

I spoke to him in his office in Philadelphia.

How has math been important in advancing the field of evolutionary biology?

Mathematics quantifies a subject. If you don’t have some kind of quantification, you are relying on purely verbal arguments. So mathematics would come into it if you asked, Has there been enough time for the observed evolution that we see to have occurred? How does the observed amount of genetic variation relate to mutation rate? Is it consistent with the population sizes that we observe? What is the effect of natural selection? In my view, all of these questions can only be answered by a mathematical approach.

Some people reject the idea of evolution because they argue that the world as we know it can’t be due to just “random chance.” Can you explain the role of stochasticity in biology, particularly in evolution?

I think it’s a good idea here to make an analogy. Let’s imagine a casino. Clearly there is random chance with respect to which slot the ball lands in on a roulette wheel, and so on. Thus the amount of money which the casino owners make on any one day or in any one year is random. But you can be pretty sure that they’ll make money in the long run. In other words, even though there’s randomness, there’s something like a deterministic process at work, in that the casino is quite sure to be making a profit overall. Now in the genetical context, the analogy might be something like this: certainly there is randomness in the sense that the mutations which arise are assumed to be random with respect to their fitnesses; they just arise spontaneously. Perhaps 99.9% of them are unfit mutations, they are bad mutations that are then lost from the population. But a small fraction, perhaps 0.1%, happen to be good mutations and they are the ones that will eventually spread through a population and make that population in some sense better. So even though mutations arise from a random process, just as a casino has a random process, you can be certain that in the long run, enough good mutations will accumulate for evolution to occur.

Population genetics is an important component of evolutionary biology, because of the theoretical framework it provides. How would you characterize the important contributions to population genetics?

Quite a few of the formulas in population genetics have found applications in other areas of science, like physics and mathematics. But I would say, perhaps unfortunately, almost nothing of mathematical population genetics has made its way into the outside world, because so very few people understand it, want to understand it… perhaps some want not to understand it! Overall the greatest contributions to population genetics have stayed inside the theory. But within the field, it has led to a substantial quantification of the procedure, and to the extent that quantification is important in any scientific activity, it’s been important in that regard.

Do you have a philosophy on teaching?

Well, that is a very hard question to answer. I don’t think I have a philosophy that is at all unusual. I would say the main thing is you have to let the students see, especially in biology, the amazing things we are discussing: the structure of the body, the evolutionary process, things like this; and try to transfer that amazement and wonder to them so that they will be enthused themselves to become interested in those areas.