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Reply #15: I do not know what PZ Meyers beef is - probably professional jealousy [View All]

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althecat Donating Member (1000+ posts) Send PM | Profile | Ignore Sat Jul-12-08 05:18 PM
Response to Reply #12
15. I do not know what PZ Meyers beef is - probably professional jealousy
....

Here is a take on the discussion from a conservative periodical - published yesterday - without the ad-hominnem and including discussion of the subject matter....


AAAS' Science magazine/Elizabeth Pennisi 7/10/2008


Massimo Pigliucci is no Jimi Hendrix. This soft-spoken evolutionary biologist from Stony Brook University in New York state looks nothing like that radical hard-rock musician whose dramatic guitar solos helped revolutionize rock nroll. But to Suzan Mazur, a veteran journalist who occasionally covers science,
Pigliucci is the headliner this week at a small meeting she believes will be the equivalent of
Woodstock for evolutionary biology. The invitation-only conference, being held in Altenberg, Austria, promises to be far more transforming for the world than the 1969 music festival, Mazur wrote online in March for Scoop.co.nz, an independent news publication in New Zealand.

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.

Its a joke, says Jerry Coyne of the University of Chicago in Illinois. I dont think
theres anything that needs fixing.

Mazurs attention, Pigliucci admits, frankly caused me embarrassment. Yet Pigliucci and others argue that the so called modern synthesis, which has guided evolutionary thought and research for about 70 years, needs freshening up. A lot has happened in the past half-century. DNAs structure was revealed, genomes were sequenced, and developmental biologists turned their sights on evolutionary questions. Researchers have come to realize that heredity is not simply a matter of passing genes from parent to offspring, as the
environment, chemical modification of DNA, and other factors come into play as well. Organisms
vary not only in how they adapt to changing conditions but also in how they evolve.

Evolution is much more nuanced than the founders of the modern synthesis fully appreciated, says Pigliucci. That doesn't mean that the overall theory of evolution is wrong, as some intelligent design proponents have tried to assert using Mazur's story as support, but rather that the modern synthesis needs to better incorporate modern science and the data revealed by it. More than genes pass on information from one generation to the next, for example, and development seems to help shape evolutions course.

"Many things need fixing," emphasizes one invited speaker, Eva Jablonka of Tel Aviv University in Israel. I think that a new evolutionary synthesis is long overdue. Modern tradition The modern synthesis essentially represents a marriage of the 19th century concept of evolution with Mendelian genetics, which was rediscovered at the beginning of the 20th century; the birth of population genetics in the 1920s added to the intellectual mix. By the 1940s, biologists had worked out a set of ideas that put natural selection and adaptation at evolutions core.

Julian Huxleys 1942 book, Evolution: The modern synthesis, brought together this work for a broad audience. Simply put, the modern synthesis holds that organisms have a repertoire of traits that
are passed down through the generations.

Mutations in genes alter those traits bit by bit, and if conditions are such that those alterations
make an individual more fit, then the altered trait becomes more common over time. This process is called natural selection.

In some cases, the new feature can replace an old one; in other instances, natural selection also leads to speciation.

However, several concepts have arise since then that make the modern synthesis seem too simplistic to some, Pigliucci among them.

In a 2007 Evolution paper, he called for the development of an "extended evolutionary synthesis." His plea coincided with a similar one made that year by Gerd Muller, a theoretical biologist at the University of Vienna. Together, with support from the Konrad Lorenz Institute for Evolution and Cognition Research in Altenberg, they organized this week's conference, inviting many who share theviewthat the modernsynthesis is incomplete. "What's happening now in evolutionary theory is as exciting and foundational as during the early days," says David Wilson of Binghamton University in New York, another attendee.


Beyond genes

Insights from ecology, developmental biology, and genomics in particular are nudging evolutionary biology away from a focus on population genetics---how the distribution of genes changes across groups of individuals---and toward an understandingof the molecular underpinnings of these changes. Better family
trees that give researchers greater confidence about the relatedness among organisms have helped promote a credible, comparative approach to these mechanisms, says invitee Gnter Wagner, an evolutionary developmental biologist at Yale University.

Some studies, for example, indicate that development constrains evolution. From the modern synthesis perspective, Wagner explains, "the body plan is a historical residue of evolutionary time, the afterglow of the evolutionary process" such that more closely related organisms share more features. The alternative view, he says, is that "body plans have internal inertia," and evolution works around this stability.

Austrias Konrad Lorenz Institute for Evolution and Cognition Research is hosting a much-discussed evolutionary biology meeting.

Massimo Pigliucci (right) and Gerd Muller want to update the modern synthesis.

Daring Duo

This perspective fits in well with that of Stuart Newman, another invitee to the conference. A developmental biologist at New York Medical College in Valhalla,Newman and Mller have focused on physical processes that guide how cells organize limbs, livers, hearts, and other tissues. The stickiness, elasticity, and chemical reactions within and between cells, for example, all influence where cells wind up in an organism.
The duo thinks these processes helped define early multicellular life, a time when genetic systems were still quite primitive and body shapes were presumably more plastic than now. Their work suggests that body plans with interior spaces, segments, appendages, and multiple layers of tissue are inevitable. That's "heresy for the modern synthesis but inescapable if you incorporate physics into the picture," says Newman.

Studies of development that suggest how evolution proceededthe so-called evo-devo approachhave yielded other insights, among them that genes and proteins are arranged in networks that have their own set of properties. "There are lots of interdependencies that allow only certain patterns of evolution to happen," says Wagner.

Much like networks, regulation is a new buzzword in biology circles; yet its another concept virtually ignored in the modern synthesis. Scientists now grasp that gene activity, RNAs, and proteins are all under regulatory controls and that shifts in those controls likely drive evolution as much as traditional gene
mutations that alter a proteins form. Harvard Universitys Marc Kirschner, for example, contends that organisms have long possessed core componentsthe machinery for energy metabolism, pattern formation during development, making cytoskeletons, or cell signalingthat have persisted relatively
intact through time. But he proposes that genetic changes that alter when and where in the developing body these components are used have helped create modern diversity.

Wagner thinks that by virtue of the breadth of genes they influence, transcription factors may be central to the type of evolutionary shifts Kirschner proposes. Changing the regulation of a few factors, even one, could help coordinate the systemic changes needed to make a new trait, helping to ensure that larger muscles
coevolve with bigger jawbones for a more powerful bite, for example. Bottom line: New traits contain very little that is new in the way of functional components, whereas regulatory change is crucial, Kirschner
and John Gerhart of the University of California, Berkeley, wrote in a supplement to the 15 May 2007 issue of the Proceedings of the National Academy of Sciences.

The modern synthesis also doesnt take into account epigenetics A small chemical modification of a DNA basethe addition of a methyl group, for examplecan turn a gene off or on as easily as a mutation. Molecular biologists have long known about such epigenetic effects, but only recently have they demonstrated that methylation tags and other epigenetic marks that silence or activate genes can travel from
one generation to the next. That potentially creates a "bewildering increase in the complexity of the entire inheritance system," Pigliucci asserted in his 2007 call to arms.

Certain environmental conditions, such as diet during gestation, can alter the epigenetic patterns of the resulting offspring, and new traits that result can last for generations, says Jablonka, who has been striving to get recognition for this mode of inheritance for years. For example, in a study conducted several years
ago, pregnant mice injected with an endocrine disrupter gave birth to males with reduced fertility,
whose subsequent sons, grandsons, and even great-grandsons were likewise affected.

Each generation had inherited the same altered methylation pattern of DNA (Science, 3 June
2005, p. 1466). "It's beginning to be accepted that may actually have something to contribute to evolution," says Jablonka. She argues that because these chemical modifications change how tightly wound DNA is, they also influence other properties of a genome that are relevant to evolution. The coiling of a DNA strand, she points out, can alter the rate of mutation, the ease by which mobile elements can move around, the duplication of genes, and even how much gene exchange occurs between matching chromosomes.

Beyond reason?

As the Altenberg 16 seek to modernize the modern synthesis, other unconventional ideas will be on the table. One is evolvability, the inherent capacity of an organism or a population, even a species, to respond to a changing environment. Introduced about 20 years ago, the concept can help explain why certain groups of organisms readily and rapidly diversified. Consider vertebrate toes: Amphibians have a wider range in digit number than, say, reptiles, which may indicate that the former are more evolvable for that trait, Pigliucci points out. But the question remains whether natural selection favors more evolvable organisms. If the idea of
evolvability wasnt radical enough, a few researchers have proposed that organisms can stock up mutations whose effects manifest themselves only when the right circumstances arise.

Both ideas have their skeptics. I dont believe organisms have a closet where they maintain all this genetic variation, says Douglas Schemske, an evolutionary biologist at Michigan State University in East Lansing.
Even among those coming to Altenberg, theres far from universal agreement.
Wagner finds epigenetic inheritance hard to swallow. "I haven't been convinnced," he says. And some
outside the Altenberg 16 dont see what all the fuss is about.

Im happy with the modern synthesis, says George Weiblen, an evolutionary biologist at the University of Minnesota, Minneapolis. Others note that some of the items on the meetings agenda, such as the role
of plasticity in looks and behavior in evolution, have fallen in and out of favor for decades. Its like selling old wine in new bottles, says Thomas Flatt of Brown University.

But these criticisms dont faze Altenbergs organizers. The modern synthesis emerged from at least a decades worth of discussions. The crucial point of the workshop is bringing these concepts together, says Mller. And no one truly expects a scientific Woodstock.

Woodstock was an immensely popular event celebrating a new musical mainstream, says Newman. I imagine this will be more like a jam session circa 1962.
ELIZABETH PENNISI

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