Evolution - Radical Changes in Morphology

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Ken Wilber has taken a lot of flack for his views on evolution over the years, especially for his views on quantum evolution, which is not really his idea, but one that has been floating around the world of evolutionary biology for quite some time. It appears that the evidence is growing in support of the position Wilber holds.

This morning I stumbled over an article by Olivia Judson at the New York Times called, The Monster is Back, and It’s Hopeful.

The title makes reference to the "hopeful monster," a term created by "Richard Goldschmidt (1878-1958), who believed that small gradual changes could not bridge a hypothetical divide between microevolution and macroevolution." At the time, his views were universally rejected, but things in science have a tendency to change with time.

In 1977 Stephen Jay Gould argued[1] that instances of rapid evolutionary change in brief geological timespans neither undermine Darwinian theory (as Goldschmidt believed) nor await discreditation (as many rigid neo-Darwinians at the time thought). The gradualism that Darwin inherited from anti-catastrophic geologists—especially Sir Charles Lyell—was never, Gould insisted, essential to his theory of evolution. In Darwin's own time his most passionate defender T. H. Huxley warned that this unnecessary element of "natura non facit saltum" would only dishearten those who believed that major leaps and cataclysms played significant roles in the natural history of life on Earth. Gould also wished that with the recent discovery of regulatory genes Goldschmidt's reputation and perhaps some of his contributions might now be seen in a favorable light.

So, back to Judson's article (this is just a piece, read the whole thing):

A quick survey of nature shows a variety of traits likely to have evolved in one jump, rather than gradually. For instance, many species of vulture lack feathers on their head and neck. (This is thought to be an advantage, as it stops them getting their feathers dirty when they stick their heads into a rotting carcass.) Did the loss of feathers happen because in generation after generation individuals with the most receded feather line had more children? Or did it happen through a single jump?

I haven’t been able to find out — I’m not sure the answer is known — but I’m betting on the jump. The reason is that chickens with a bare head and neck often appear spontaneously: a single mutation blocks feather production from shoulder to beak. My guess is that if it can happen in chickens, it can happen in vultures — and that in vultures, it gave an advantage.

But it’s only as our ability to dissect genomes has been transformed — a change that has really happened within the last ten years — that the idea of the hopeful monster has begun to stage a comeback. (Note, however, that few modern biologists use the term. Instead, most people speak of large morphological changes due to mutations acting on single genes that influence embryonic development.)

The reason for the comeback is accumulating evidence that, in nature, some of the big changes in morphology that we see appear to be underpinned by changes to single genes. For example, one of the big differences between insects and their close relations, the crustaceans, is that insects usually have six legs (some butterflies have only four) whereas crustaceans are typically leggier, sometimes having more than twenty (lucky they don’t have to buy shoes). The difference seems to be due to a mutation in a gene known as Ultrabithorax. In fruit flies, this gene represses leg growth: in the parts of the embryo where the gene is turned on, you don’t grow legs. In crustaceans, the gene doesn’t repress leg growth. A series of elaborate experiments involving man-made gene products that are part-insect and part-crustacean has shown that the insect version of Ultrabithorax has acquired the ability to repress legs.

Another example: sexy leg bristles in male fruit flies. In some species of Drosophila, males have fancy bristles on their legs; in others, the bristles are absent. The difference seems to be entirely due to changes in the way that a single gene, Sex combs reduced, is expressed in the front legs of the developing adult. High levels of expression give a nice bristly leg; low levels of expression do not. (It’s probably no coincidence that both Sex combs reduced and Ultrabithorax are members of a class of gene known as the Hox genes, which are important in laying out animal body plans.)

I'm no evolutionary biologist, but this view feels "right" intuitively, except that as I have argued before (here, and more recently here), I tend to think these genetic changes are not random mutations, but rather, intelligent responses to environmental conditions at the genetic level.

That remains pure speculation on my part, but the evidence is beginning to grow that evolution is not generally random -- if it were, I suspect it would hardly be as success as it has been.

Tags: Evolution, Radical Changes, Morphology, genetics, hopeful monster, Olivia Judson, Richard Goldschmidt, Ken Wilber, biology, Science, biophotons, intelligent evolution, random mutations, quantum evolution