Wednesday, September 30, 2015

Paging Dr. Pangloss

20 years ago...
Neo-Darwinism has failed as an evolutionary theory that can explain the origin of species, understood as organisms of distinctive form and behaviour. In other words, it is not an adequate theory of evolution. What it does provide is a partial theory of adaptation, or microevolution (small-scale adaptive changes in organisms). It is partial in two senses. First, Neo-Darwinism assumes random genetic variation followed by selection, whereas there is now evidence for a role of directed mutation in adaptive response. That is, genes can evidently respond to environmental circumstances by non-random, adaptive mutation. And second, many of the adaptive "explanations" advanced for biological characteristics simply cannot be taken as serious science. In 1979, Steven Jay Gould and Richard Lewontin published a classic paper that ridiculed much of the adaptationist literature as constituting a "panglossian paradigm", Just So Stories of such dubious scientific value that they discredit the subject. For a few years after that, adaptationists watched their p's and q's more closely. However, the salutary influence of that paper has unfortunately diminished to the point where Just So Stories are again proliferating wildly. A recent example is why the hour-glass shape in women is an adaptive trait, determined by genes. Men select women with large hips and breasts because these are indicators of reproductive potential, or at least men think they are. Women who satisfy these criteria but do not have a small waist are simply fat, which, we are told, is not a good indicator of reproductive potential. Hence the selection of the hour-glass shape. You might think I overheard this in a pub, but it is in fact advanced as a serious proposition by Matt Ridley in The Red Queen following the original proposal by Low, Alexander, and Noonan in Ethology and Sociobiology. If this is science then Rudyard Kipling was a great scientist.  -- Brian Goodwin, biologist, "Neo-Darwinism Has Failed as an Evolutionary Theory"

Wednesday, September 16, 2015

Not-So-Simple Origins (or The Fortuitous Labyrinth Ball Game)

From "A Simpler Origin of Life" by Robert Shapiro (emphases mine):

The [speculated] exceptionally high urea concentration was rationalized in the Nature paper by invoking a vision of drying lagoons on the early Earth. In a published rebuttal, I calculated that a large lagoon would have to be evaporated to the size of a puddle, without loss of its contents, to achieve that concentration. No such feature exists on Earth today. 
The drying lagoon claim is not unique. In a similar spirit, other prebiotic chemists have invoked freezing glacial lakes, mountainside freshwater ponds, flowing streams, beaches, dry deserts, volcanic aquifers and the entire global ocean (frozen or warm as needed) to support their requirement that the "nucleotide soup" necessary for RNA synthesis would somehow have come into existence on the early Earth. 

The analogy that comes to mind is that of a golfer, who having played a golf ball through an 18-hole course, then assumed that the ball could also play itself around the course in his absence. He had demonstrated the possibility of the event; it was only necessary to presume that some combination of natural forces (earthquakes, winds, tornadoes and floods, for example) could produce the same result, given enough time. No physical law need be broken for spontaneous RNA formation to happen, but the chances against it are so immense, that the suggestion implies that the non-living world had an innate desire to generate RNA. The majority of origin-of-life scientists who still support the RNA-first theory either accept this concept (implicitly, if not explicitly) or feel that the immensely unfavorable odds were simply overcome by good luck.
 But this is what all evolutionary plausibility arguments invoke.  We are here, so evolution happened.  So whatever unlikely natural event  needed to occur to make it happen must have happened.

To say that the events invoked must be a priori not ridiculously unlikely is to threaten the whole edifice of evolution.  Unless, of course, the self-organization people are able to pull a rabbit out of their hat with concrete results on origin of life (not just interesting ideas).

Think of a labyrinth ball game (pictured).  The ball can always get from start to finish without any intelligent maneuvering, as long as the right fortuitous conditions occur (ground vibrations, air gusts, etc.).  In fact there are innumerable such scenarios that can account for the ball getting from start to finish on its own.  They are so outweighed by the far more innumerable ways that the ball never gets there.