Is Natural Selection Losing its Appeal?
Some recent science reports sound like they are ready to cast Darwin’s key phrase natural selection overboard, or at least demote it from its leading role in evolution. These articles each hint that long-held beliefs are being challenged.
- Make room: Science Daily asked, “Natural Selection Not The Only Process That Drives Evolution?” Scientists at Uppsala University are finding a bigger role for neutral genetic drift. They examined “fast-evolving” human genes by comparing them with those of other primates, and claim that many did not show signals of natural selection. “The research not only increases our understanding of human evolution, but also suggests that many techniques used by evolutionary biologists to detect selection may be flawed,” the article said. They may have trouble selling this idea: “many of the genetic changes leading to human-specific characters may be the result of the fixation of harmful mutations.” It’s not clear how a degrading process led to human language, civilization and fast-food restaurants, but “This contrasts the traditional Darwinistic view that they are the result of natural selection in favour of adaptive mutations.”
- Tree pruning: A “dramatic” rearrangement of Darwin’s tree of life reported by Science Daily claims that “evolutionary relationships among animals are not as simple as previously thought.” The new tree developed by researchers at the American Museum of Natural History appears to have two trunks near the base. All the sponges, comb jellies, jellyfish and placozoans are on one branch, and all other animals on another. Placozoans look like slimy multicellular amoebas that glide along the surfaces of household aquariums. Nature News titled this, “Humans and sponges may share a slimy ancestor.”
What are the implications of this approach? For one, it means the “genetic tool kit” for complex organs appeared before the split, and for another, convergent evolution was widespread after the split. “Some people might initially be shocked to see that nerve cells in cnidarians and higher animals (Bilateria), the group of animals that includes humans, evolved independently,” a researcher commented, claiming that the nervous systems are not that similar. “It is the underlying genetic tool kit that is similar amongst these basal animals,” another said. “Placozoa have all of the tools in their genome to make a nervous system, but they just don’t do it.” On the face of it, this would seem to raise questions about natural selection. Why would selection invent tools that are not used?
Nature News understood the difficulties the new tree presents. One “difficult implication” means that nervous systems evolved independently in the two branches. “This is hard to swallow,” one biologist remarked. The supporters of the new tree just brushed it off. “The placula already had all the genes necessary to make all the building blocks [of a nervous system], but it didn’t have to make it because ecology didn’t force it to do so,” said Bernd Schierwater [University of Veterinary Medicine Hannover in Germany]. For him, this problem is “not too complicated at all.” His answer begs the question, though, of why natural selection would produce a genetic tool kit in the first place, if “ecology” did not “force” it to use it.
Nature News quoted others who remain wary of the way these trees are calculated. “Small alterations in the settings of some of these analysis tools can make major differences to the outcomes,” one said. Another worried about adequate taxon sampling. “I am tired of these molecular papers that don’t make sufficient controls to check the reliability of the phylogenetic inferences. The other critic remarked, “This certainly isn’t the last word on the scheme of animal evolution.”
- White eyes: If the environment forces evolutionary change, as Darwin insisted, why would some white-eyed birds diversify quickly across multiple habitats while others stay the same? PhysOrg reported on this biological puzzle. It claims that bird members of the family Zosteropidae are among the fastest diversifying species ever found, even faster than the cichlid fishes in African lakes. What’s more, the diversification does not appear to be related to geographical features, because other species in those areas do not diversify so quickly. “As we started to compile the data, we were shocked,” one researcher said about how similar the genetics of these diverse white-eyed birds were across a wide range. To her, this represented “a recent origin and incredibly rapid diversification.”
The article claims this confirms a hypothesis by Ernst Mayr 80 years ago that certain species are intrinsically better at diversifying than others. Mayr’s “Great Speciator” hypothesis proposed that internal factors like sociability, the ability to survive in a variety of habitats, and a short time between generations relative to other animals can be more important than geography in generating changes. Although the article did not mention natural selection, it seems to relegate it to a lesser role. Darwin had emphasized environmental factors as drivers for natural selection. Researcher Christopher Filardi recognized the debate: “This leaves the question: are the white eyes really special, or have we simply caught them at a special time in their evolution? That we don’t know, but our results indicate that high rates of diversification may have as much to do with a species’ ‘personality’ as they have to do with more classical geographic or geological drivers of speciation.” Filardi did not characterize what “personality” might mean in biochemical or genetic terms, or why this bird family would have such a different “personality” than other families that would cause rapid diversification. The word is foreign to evolutionary nomenclature. He seemed to use it as a place-holder for ignorance of the cause of diversification.
The ability of some species to diversify can be dramatic. Science Daily reported on a catfish found in Venezuela that can climb trees. Its modified pelvic fins (see picture on National Geographic News) allow it to inch up tree trunks. Furthermore, this ability is seen in three separate species, suggesting the common ancestor lived upstream. Nevertheless, they are all catfish, and not members of any groups that evolutionary charts show as ancestors of land animals. The fins are modified fins, not bony limbs.
Natural selection has long been the fulcrum of controversy in evolutionary thinking. Historians agree that Darwin succeeded best in making the general idea of evolution acceptable – but he failed to win the case for natural selection as the mechanism of evolution. Natural-selection theory was almost moribund by 1900. It was revived by the neo-Darwinian synthesis in the 1940s, but that was more by peace treaty between disagreeing groups of scientists (fossil hunters, field naturalists and geneticists) than by demonstration – and the peace treaty signers knew nothing of the revolution in molecular biology just around the corner.
Since the last major Darwin drum-beating celebrations in 1959 (the centennial of Darwin’s black book), natural selection has been treated like a truism, rarely questioned. Some are still objecting to it, though. One reason is that the phrase portrays nature operating with a purposeful hand, choosing traits it wants for a purpose. As Darwin envisioned it (aware of the inherent personification in the phrase), it could only operate on small variations in the immediate present. No foresight or planning was involved. Another problem recognized later was that it conveys no information. If fitness is measured by what survives, and survivors are assumed to be the fit ones, then it is a tautology: survivors survive. Evolutionists have squirmed around this problem with lots of bellowing and bluff, but their answers merely shield the tautology with synonyms (example: 10/29/2002).
The most serious and enduring objection to natural selection theory has been its insistence on randomness. Natural selection is supposed to produce endless forms most beautiful from an unguided, purposeless mechanical process. But chance is not a process! Oh, but the randomness in variation is selected by the environment, the Darwinist says. Well, guess what: the environment is random, too, so this reduces to chance acting on chance. Folks, chance is not a law of nature. Chance is not a mechanism. Chance is not an explanation. Chance is nothing. Darwin is celebrated because he liberated biology from theology and supposedly brought it under the reign of “laws of nature.” Big deal. What kind of law is it to say that Stuff Happens? (09/15/2008). It’s like calling Brownian motion a force. There is no vector. Moreover, natural selection has never been shown to be creative. One major impetus for the intelligent design movement has been the lack of evidence that natural selection is capable of originating the complex, interacting organs that permeate biology. Nobody questions the reality of mutations, and not even young-earth creationists disagree with the ability of selection to conserve and adapt existing genetic information to changing conditions, but how could a blind process that can only respond to immediate circumstances build a wing, eye, kidney or brain? Imagining it, or making up stories, is not evidence.
If Darwinism is true, abandon all hope of purpose, meaning and values. Darwin could not endure the theistic evolutionary views of his friend and supporter Asa Gray, who promulgated Darwin’s ideas in America but tried desperately to cling to a role for God in the process. Darwin understood that any designing intelligence would contradict his central tenet. Stuff Happens. Take it or leave it. Darwin wanted pure, unadulterated chance in his biology, not “God makes stuff happen.” He could allow for God creating the dice in the foggy past, perhaps, but every roll from then on was hands off. William Provine has been among the few Darwinists willing to go all the way to the bitter consequences of the Stuff Happens law: there is no purpose, no meaning, and no free will, and when you die, you are dead, dead, dead. (It never seems to enter his attention that he shoots his view in the foot when he says this.)
Darwin Day would be a good time to point out to the world that “Stuff Happens” is no law at all, and believing in this anti-law has bitter consequences. As a kicker, point out to them that the scientific evidence contradicts it. Above you have three examples.
Exercise: Assuming philosophical naturalism for the sake of argument, is natural selection as arbitrary and vacuous a scientific explanation as its nemesis, vitalism, the idea of a “life force” in living things? Defend your answer.
Discussion Question: Are laws about chance different than calling chance itself a law? For instance, there are well-known Laws of Probability that can predict the outcomes of probabilistic events to high degrees of certainty in some cases. Is natural selection like one of these laws, or would that be confusing subject and object? In light of the commentary above, see if probability theory can rescue natural selection from the charge that it reduces to Stuff Happens.