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Wednesday, December 22, 2010

How much of the body plans of organisms can be explained by laws of form, not Darwinism or design?

Quite a bit, say Jerry Fodor and Massimo Piatelli-Palmarini, in What Darwin Got Wrong.

They offer an interesting example, the 'fourth dimension' of living systems,
The body masses of living organisms vary between 10^-13 grams (bacteria) to 10^8 grams (whales), that is, by 21 orders of magnitude. It's interesting to see how other physico-chemical and biological properties and processes, and their ratios, scale with mass. How, for instance, surfaces and internal rates of transport, rates of cellular metabolism, whole organism metabolic rate, heartbeat, blood circulation, time and overall lifespan scale with mass. Thee are, of course, all three-dimensional systems, so it seems astounding that all the scaling factors, encompassing microorganisms, plants and animals, are multiples of a quarter, not a third. ^16

 Jerry Fodor
Physicists and biologists at Los Alamos, Santa Fe and Albuquerque institutes attribute the "fourth dimension" to the fractal-like architecture of the organisms' vascular networks. The guiding criteria, they found, was "the maximization of the inner and outer exchange surfaces, while minimizing distances of internal transport (thus maximizing the rates of transport)." They quote West et al. (1999),
“Although living things occupy a three-dimensional space, their internal physiology and anatomy operate as if they were four-dimensional. Quarter-power scaling laws are perhaps as universal and as uniquely biological as the biochemical pathways of metabolism, the structure and function of the genetic code and the process of natural selection.
They comment,
In the words of these authors, natural selection has exploited variations on this fractal theme to produce the incredible variety of biological form and function', but there were severe geometric and physical constraints on metabolic processes.'

The conclusion here is inescapable, that the driving force for these invariant scaling laws cannot have been natural selection. It's inconceivable that so many different organisms, spanning different kingdoms and phyla, may have blindly 'tried' all sorts of power laws and that only those that have by chance 'discovered' the one-quarter power law reproduced and thrived.
Of course, the Darwinist puts questions like down to an entirely misguided reason for doubting Darwin, that their theory sounds unbelievable and  doesn't add up. Richard Dawkins might say of Fodor, as he has of Mike Behe, that it is Fodor's job to get back to work and show how Darwinism indeed accomplishes this feat.

On the other hand, Fodor could be on to something.


Note 1: Quotations from Jerry Fodor and Massimo Piatelli-Palmarini, What Darwin Got Wrong (London: Profile Books, 2010), p. 78-79.

Note 2: The image is from Wikimedia Commons.


New papers confirm: Sorry Mr. Dawkins - No free lunch today

Molecular biologist Douglas Axe, whose specialty is proteins, has published TheLimits of Complex Adaptation: An Analysis Based on a Simple Model of Structured Bacterial Populations in BIO-Complexity, assessing whether current standard models of evolution are plausible.

A friend writes to explain,
This is a very important paper. It takes on a major problem in population genetics, a problem that has provoked a number of recent papers from our opponents, precisely because they know this issue must be solved before neo-Darwinism can work on any level except the trivial.

Warning: heavy sailing ahead, but the introductory section that challenges Lynch and Abegg is worth reading carefully.

The take home message: gene duplication and recruitment as a model for the evolution of new genes is very limited. It works only if very few changes are required to reach a new selectable function. If the duplicated gene has a slightly negative fitness cost, the maximum number of mutations (in addition to the duplication itself) that a new innovation in a bacterial population can require is two or fewer. If the duplication is cost-free the number of mutations jumps to six or fewer.
Ann Gauger at the Biologic Institute draws attention to this paper as well:
Evolutionary Algorithms: Are We There Yet?
Yes, heavy sailing - in more senses than one, as trolls armed with their iron rice bowls pile on. Author Axe takes a relaxed view of the smoke, mirrors, and noise:

For more, go here.

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We've completed the set!: All phyla of life appeared in the Cambrian

Confronting the impact of the Cambrian explosion of life 550 million years ago, British physicist David Tyler notes that
All skeletalised metazoan phyla appeared in the Cambrian

Until this year, the Bryozoa were missing from the list of Cambrian organisms. Although some had been previously reported, critical scrutiny showed that they were misidentified and that the oldest known bryozoans came from Lower Ordovician strata. This year, however, Upper Cambrian bryozoans were reported from the lower Tinu Formation, southern Mexico. They were said to be about 8 Ma years older than the oldest Ordovician fossils. This means that Cambrian strata can be said to record examples of all the skeletalized metazoan phyla.
For more, go here.

The obvious lack of fit between the actual Cambrian event and the popular saga of the"long slow evolution of life" has sparked surprisingly little curiosity, compared to exercises in creative explanation of the "so-called" explosion, suppression of information, dunno-what-hit-us shock and reassurances about ongoing research. Too bad we can't just get past all that, to a genuine wish to know what happened.

Note: Illustration shows Bryozoan membranipora membranacea, US Geological Survey


Coffee with the squirrels today: They don't give their kids mating advice

Red squirrel, Tamioscurus Hudsonius
Staff writer Lesley Ciarula Taylor explains for Toronto Star readers "Why female red squirrels aren’t choosy about their mates":
Guelph scientists have solved the puzzling question of why female squirrels are rampantly promiscuous, sleeping with an average of 10 males in one day.

It almost entirely depends on how many guys show up.
That's the finding reported by University of Guelph researchers from their study of 85 female North American red squirrels. Female squirrels do not pass any specific mating tendencies (one, some, or many guys) on to their daughters.
"A lot of folks who have looked at this before looked at whether it’s good or bad for a squirrel to be promiscuous," [lead investigator Eryn] McFarlane told the Star on Wednesday. "I wanted to look at whether it was genetic, regardless of whether it was good or bad."

What she found is that risks and benefits don’t have much to do with how females behave.

[ ... ]

This is the first study that says genetics or heredity have little to do with a female squirrel’s sex life.
Goodbye, selfish gene. Or, to put it in the vernacular, none of the ladies are chaste, but some are more chased than others. It depends on how many guy squirrels are around to chase them.

For the tale of how the Washington Post thought it had discovered natural selection among squirrels, go here.

Look, squirrels are, well, squirrelly, but anyway here's the Abstract:
The tendency of females to mate with multiple males is often explained by direct and indirect benefits that could outweigh the many potential costs of multiple mating. However, behaviour can only evolve in response to costs and benefits if there is sufficient genetic variation on which selection can act. We followed 108 mating chases of 85 North American red squirrels (Tamiasciurus hudsonicus) during 4 years, to measure each female's degree of multiple male mating (MMM), and used an animal model analysis of our multi-generational pedigree to provide what we believe is the first estimate of the heritability of MMM in the wild. Female red squirrels were highly polyandrous, mating with an average of 7.0 ± 0.2 males on their day of oestrus. Although we found evidence for moderate levels of additive genetic variation (CVA = 5.1), environmental variation was very high (CVE = 32.3), which resulted in a very low heritability estimate (h2 < 0.01). So, while there is genetic variation in this trait, the large environmental variation suggests that any costs or benefits associated with differences among females in MMM are primarily owing to environmental and not genetic differences, which could constrain the evolutionary response to natural selection on this trait.

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