©2002  by Gerard Wakefield
(This article may be copied for educational purposes only.)

"Darwin’s Finches"

In the 1970’s, evolutionary biologists Peter and Rosemary Grant went to the Galapagos Islands to observe the evolution and speciation of Darwin’s finches in the wild — one of the central pillars of Darwin’s theory. In 1977, a severe drought wiped out 85% of a particular species on one island (Wells 2002: 78). This island, Daphne Major, was struck so severely that regrowth of most of the seed-producing plants was prevented. The island’s population of seed-eating medium ground finches (Geospiza fortis) suffered from this loss of their food: small-beaked G. fortis died off more quickly than large-beaked ones, because the ones with the larger (hence stronger) bills were able to crack open large, tough seeds that had withstood the drought. The survivors reproduced, and the Grants found that their offspring had larger beaks (Grant & Grant 2002: 136). They concluded:

“This was a clear example of natural selection that led to evolution in the next generation because the variation in beak size that we measure largely reflects an underlying variation in genetic factors” (Grant & Grant 2002: 136).

What they failed to mention was that the “evolution” to which they referred was not transpecific macroevolution (one species turning into another), but intraspecific microevolution (small changes within a species), since G. fortis did not evolve into a new, superior species of finch. The Grants never actually witnessed this species evolve into a completely new, improved life-form, better able to crack tough seeds and thus survive droughts. Instead, the opposite happened, thus defying Darwinian predictions: when the drought ended, average beak size returned to normal. Since then, beak size has oscillated as the food supply has increased or decreased with the climate. In fact, a drought on the same island nearly 10 years later demonstrated that microevolution, not macroevolution, was occurring. For some reason, plants that bore the large, tough seeds suffered, while plants that bore the small seeds favored by small-beaked finches flourished, thus making life miserable for large-billed specimens of G. fortis, but joyful for their small-beaked comrades. The result was that average beak size returned to pre-1977 levels. The Grants reported:

“Observing selection and evolution when environmental conditions fluctuate in the short term affects our views of evolution in the long term. In the short term of a few decades, the oscillations cancel out, leaving the population with a beak size that’s, more or less, in dynamic equilibrium. Over the long term of many decades, centuries or even millennia as food resources change, a vector of directional change runs through the oscillations toward a larger or smaller overall beak size…” (Grant & Grant 2002: 136).

Again, what the Grants failed to point out is that what they witnessed with their own eyes only covers intraspecific microevolution, and provides absolutely no proof that, had drought conditions continued, G. fortis would have macroevolved into an entirely new species. The Grants have no ability, in their own words, to witness what changes might occur to these finches over “decades, centuries or even millennia,” thus demonstrating that belief in macroevolution rests on assumption, not hard data. Research biologist Dr. Jonathan Wells, professor of biology at California State University, comments on these findings:

“Darwin’s finches and many other organisms provide evidence that natural selection can modify existing features — but only within established species. Breeders of domestic plants and animals have been doing the same thing with artificial selection for centuries. But where is the evidence that selection produces new features in new species?” (Wells 2002: 78 [italics original]).

Grant, P. R., and B. R. Grant. 2002. “Adaptive Radiation of Darwin’s Finches.” American Scientist 22, no. 2.
Wells, J. 2002. “Elusive Icons of Evolution.” Natural History 111, no. 3.

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