Darwinians have gotten into the habit of taking it from all sides--from Christian fundamentalists who dismiss Charles Darwin’s evolutionary theory out of hand, to the new wave of cyber-techies and their fuzzy “post-Darwinian” notions.
Well, the Darwinians can fight back, and biologists Peter and Rosemary Grant have provided the ammunition.
In the season opener of PBS’ “The New Explorers” tonight, host Bill Kurtis allows the Grants’ stunning work to speak for itself in “What Darwin Never Saw.”
The cumulative effect of the Grants’ 22 years of researching finches on Daphne Major, a virtual desert island in the Galapagos archipelago, is to prove Darwin’s theories of natural selection and species adaptation. No more theories, no hemming and hawing. Proof--pure, undiluted proof.
This is, in essence, an hourlong distilling of Jonathan Weiner’s book on the Grants’ work, “The Beak of the Finch,” but there is nothing like the camera for taking us to the islands where Darwin’s scientific quest began.
Like Darwin, the Grants didn’t start trying to make a major statement. Just as Darwin nearly stumbled upon his observations of physical variations within a species (depending on its environs), the Grants were here to investigate finches, and no more. And just two finch types at that, among the Galapagos’ 13 finch species.
Nature, though, got in the way. It was one thing to observe and measure the medium ground finch, using its short, deep beak to feed on underground seeds, and the large-beaked cactus finch. The Grants’ thorough study made them experts on the lifestyles of nearly every finch on the island--made easier by the finches’ extremely tame and friendly disposition.
But with the drought of 1977, followed by the El Nin~o-triggered eight-month rain of 1983, the couple became privy to dramatically fast species adaptation.
The drought favored the larger-beaked finches, physically able to search and find the most plentiful kinds of seeds in extreme, 100-degree-plus weeks and months. The El Nin~o storms, however, reversed the process; the large-beaked birds’ prime food was harder to find in the tall, thick grasses that sprouted everywhere, while the small-beaked birds thrived. Natural selection was no longer a speculation of million-year-long processes, but immediately observable.
It doesn’t stop there. The Grants are now studying how the medium ground finches have mated with smaller and larger species, producing hybrids that are measurably different. It’s all in the beak, and the beak has proved Darwin right.
“What Darwin Never Saw” sometimes loses focus, drifting off to a Galapagos research facility and its program for preserving the Galapagos tortoise. That’s another story in this amazing archipelago; the Grants’ story is enough for an hour, and is surely enough to give people pause to reconsider their beliefs.
* “What Darwin Never Saw” airs on “The New Explorers” at 8 tonight on KCET-TV Channel 28.