Thoughts on Darwin's Finches (10 September, 2014, 15 Elul, 5774)
1. Introduction. Darwin Finds the Finches
(a) Galapagos Islands
(b) How Darwin's finches got their beaks. A gene's-eye viewÂ ofÂ evolution by William J. Cromie
3. Conclusion: Acquired Triggering of Changes is both Adaptative and Inherited
The Finches on the Galapagos Islands featured in the exposition of the Theory of Evolution by Charles Darwin. This theory, in our opinion, is false. It is however widely accepted. It is also somewhat useful as a theoretical construct in comparing different species. For those who do not know, finches are small birds. They are not Kosher, i.e. one should not eat them. On the other hand theyÂ chirp and can be somewhat attractive and amusing. Alongside budgerigars they are often kept as pets in cages. Darwin found different types of finches on different neighboring islands in the Galapagos. Sometimes there were more than one type on the same island. The different types were differentiated by variations in their shape of beak and in beak size.Â Â Different beaks were suited to different sources of food. Harder, sharper beaks are better for eating seeds with tougher coverings. Other kinds of beaks are good for softer foods, or insects, etc.
Darwin postulated that the finches had all originated in the one parent body whose offspring had changed their beaks according to different sources of food. Darwin considered this a proof of evolution. We disagree but the subject does bring up a point worth consideration.
(a) Galapagos Islands
From Wikipedia, the free encyclopedia
The Galapagos Islands... are an archipelago [chain of islands] of volcanic islands distributed on either side of the Equator in the Pacific Ocean, 926 km (575 mi) west of continental Ecuador, of which they are a part.
...The islands have a population of slightly over 25,000.
The islands are famed for their vast number of endemic species and were studied by Charles Darwin during the voyage of the Beagle. His observations and collections contributed to the inception of Darwin's theory of evolution by natural selection.
(b) How Darwin's finches got their beaks
A gene's-eye view of evolution
By William J. Cromie
Harvard News Office
Darwin's finches are the emblems of evolution. The birds he saw on the Galapagos Islands during his famous voyage around the world in 1831-1836 changed his thinking about the origin of new species and, eventually, that of the world's biologists.
Darwin wondered about the changes in shape of bird beaks from island to island. So-called cactus finches boast longer, more pointed beaks than their relatives the ground finches. Beaks of warbler finches are thinner and more pointed than both. These adaptations make them more fit to survive on available food.
Researchers at Harvard Medical School have taken the story one step further. Using modern genetic analyses, they found a molecule that regulates genes involved in shaping the beaks of Darwin finches. "Calmodulin is a protein that binds and activates certain enzymes, which triggers a signal that eventually turns specific genes on or off," explains Arkhat Abzhanov, an evolutionary biologist at Harvard. These signals alter the behavior of cells responsible for beak sculpturing.
"We found that calmodulin was indeed expressed at detectably higher levels in cactus finches compared to ground finches, and thus associated with their longer beaks," says Clifford Tabin, professor of genetics. "This higher level is both biologically relevant and functionally important for shaping of elongated beaks, which are used in a specialized manner to probe cactus flowers and fruit for pollen, nectar, and seeds." The same surge of calmodulin was not found in more blunt-beaked ground finches.
When Charles Darwin first saw the Galapagos Islands he described them as 10 islands "situated under the equator." He noted that they originated as volcanoes and were pockmarked with craters. "Some of the craters, surmounting the larger islands, are of immense size, and they rise to a height of between three and four thousand feet."
Noting differences in the feeding habits of the finches, Darwin wrote that cactus finches "may often be seen climbing about the flowers of the great cactus trees." Seeing the diversity of beaks and other structures in the closely related finches, he wrote in his notebook, "one might really fancy that one species had been taken and modified for different ends."
Darwin elaborated on this idea when he published his intellectual bombshell, the "Origin of Species," some 25 years later in 1859. He speculated that birds, resembling starlings, came to the Galapagos Islands by wind. Evolution took over and different groups developed different diets. When, he wrote, "an immigrant first settled on one of the islands, ... it would undoubtedly be exposed to different conditions in the different islands (where) it would have to compete with a different set of organisms. ... Then, natural selection would probably favor different varieties in the different islands."
In other words, beaks changed as the birds developed different tastes for fruits, seeds, or insects picked from the ground or cacti. Long, pointed beaks made some of them more fit for picking seeds out of cactus fruits. Shorter, stouter beaks served best for eating seeds found on the ground. Eventually, the immigrants evolved into 14 separate species, each with its own song, food preferences, and beak shapes. Warbler finches, for example, catch insects in beaks that are sharper and more slender than those of cactus eaters.
Asked about the possibility of calmodulin in the heads of humans, Abzhanov answers, "At this point we don't know whether mammals in general or humans in particular employ calmodulin during development of their skulls and faces. It is, however, very likely as calmodulin appears to be involved in very basic craniofacial developmental processes. We do know it is expressed at the right time and in the right place in the development of mice embryos. We will certainly pursue its role(s) during both mouse and chicken development."
In other words, they suggest:
Originally we had one parent finch body.
Offspring went to different islands with different possibilities.
Changes in beak size etc occurred in accordance to the environmental needs, (in this case of eating, i.e. the need to eat).
TheÂ change may have been effected through a mechanism thatÂ triggers turning specific genes on or off. The existence of this trigger had been there from the beginning.
Once the trigger was put into effect it became hereditary.
A similar chain of causation could explain the differences between humans as well as animals.
This does not mean that racial or biological differences do not exist between people.
They do and they are hereditary.
But they may not always have been like that.
Animals and humans can change in accordance to the environment. This happens by an already INBUILT Â mechanism being activated. Once the activation occurs it is passed on by heredity.