Thursday, 29 November 2012

The Beak of the Finch: Dawkins vs Gould

Posted ImagePosted ImagePosted Image

I had the opportunity to take pictures of a Kingfisher from my living room and was fascinated by its beak design solution and the Japanese Bullet Train which was designed is a form of Bio-mimicry in engineering and the train travelled 10 percent faster, consuming 15 percent less energy and it no longer created a sonic boom after adopting this design into the Bullet Trains.

Birds have always been an interesting genera of organisms to study evolution from Ring species on how mating songs among a population change over time and induce reproductive barriers and there by speciation to their adaptations of beaks for different environmental niches. These examples of finches show that evolution can occur in our life time which we call as micro-evolution. Even though everyone agrees that evolution is happening there are minor disagreements on how it happens and what are the mechanisms that underlie it and this brought me to The Beak of the Finch: A Story of Evolution in Our Time

This seems to be an important study for both neo-darwinists as well as proponents of punctuated equilibrium theory and I think both the 'gene-selectionist view' as well as many of the tenets of the punctuated equilibrium view of the palaeontologists should be considered seriously because natural selection acts at both the gene level as well as at the ecological level and also on local scales and also on longer time scales of hierarchical evolution.

The current battle between these two different schools of thought can be right summed up as Dawkins vs Gould and Sterelny clearly summarizes the different points of view of these two evolutionary biologists where Dawkins identifies more with the gene-selectionist view and Gould and others identifying themselves with punctuated equilibrium.

This particular study like some of the many other studies seem to question the cumulative nature(cumulative selection) of how evolution was normally thought to operate by the neo-darwinists i.e. a gradual series of accumulation of good designs but as said there are cases where this normally not how evolution seem to work and this is where species selection comes into picture for the accumulation of novel design solutions. One such case is this -

Kim Sterelny (2007) cites this rapid natural selection as illustrating an important point about periods of relative stasis in the punctuated equilibrium hypothesis of Niles Eldredge and Stephen Jay Gould: "In claiming that species typically undergo no further evolutionary change once speciation is complete, they are not claiming that there is no change at all between one generation and the next. Lineages do change. But the change between generations does not accumulate. Instead, over time, the species wobbles about its phenotypic mean. Jonathan Weiner's The Beak of the Finch describes this very process".


The Grants observed that drought conditions led to larger average weight, wingspan, and bill size, whereas flooding experienced a few years later resulted in reduced measurements: "Everything the drought had preferred in size large . . . the aftermath of the flood favored in size small" (Weiner, p. 104). Rather than continuing "to shoot like an arrow in the same direction" (p. 104), evolution had turned back. "Natural selection had swung around against the birds from the other side. . . . Selection had flipped. . . . Not only can evolution push a species fast in one direction. Evolution can reverse direction and push it back just as swiftly" (pp. 104, 106).


It is indeed an wobbling over its phenotypic mean within a generations of species lineages where suddenly the large beak sizes where replaced by smaller ones and hence showing that novel designs doesn't necessarily accumulate over time with in a species and that certain species specific characteristics need to be transferred to daughter species and only then the novel design might have a chance that it gets accumulated over time.

I think species selection, non-adaptive change, uncoupling of macroevolution and microevolution and species stasis and mosaic evolution which are some of the main views of Gould on evolutionary biology along with the functional constraints of the phenotypes in developmental biology should be seen as well accepted tenets of evolutionary biology.


And there will always be people who still doubt evolution by natural selection without understanding how it works.

"Darwinism in the West is in much the same condition as was Soviet Marxism in its last days. Its power and prestige rest not on any real scientific accomplishments but on the theory's role in upholding the ruling philosophy. Obscure scientists who go to a remote island to measure finch beaks can become the subjects of television documentaries and Pulitzer Prize-winning books, because the intellectual elite relies on finch-beak variation to convince the public that materialism is true."

- Philip Johnson, a proponent of ID              

No comments:

Post a Comment