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> An Invitation to the Facts < Response to Chapter 3 of The Evolution Deceit 'Imaginary Mechanisms of Evolution' Part 2: Are all mutations harmful? Andya Primanda Evaluation of Harun Yahya's arguments The core of HY's arguments in Chapter 3 of the Evolution Deceit is these following statements: 1: Mutations are harmful Some useful mutations have also been observed among humans. Lactose intolerance (the inability to digest lactose in milk) is a universal feature of adult mammals. Genes for lactase (lactose-digesting enzyme) is turned off in adults. However, some human individuals do not have their lactase gene switched off, so they can digest lactase as adults (lactose tolerance). In hunter-gatherer populations, this variation offers no selective advantage, but in pastoral societies which kept cattle and goats, lactose tolerance has an advantage, in which the lactose-tolerant individuals can effectively use nutrients from the milk they drink. Nevertheless, usefulness itself is a vague concept. Consider large size vs small size as examples of heritable variation within a population. Can we tell which is more useful? Larger plants, for example, can outcompete small plants for light. However, smaller plants can better cope with some harsh conditions, such as impoverished soil or strong winds. Another example is coloration. Polar bears with their white coats are successful in the Arctic. However, their adaptation is only good in their native land. Put a polar bear in a rainforest and it will not survive, because its white coat will not give it an advantage. There are no absolutes in variation usefulness; a variation that is useful in one environment might not be useful in other. Every individual organism is unique. There is variability in their genotype and phenotype. Most of these variations are the result of neutral mutations. Kimura (1983) defined neutral mutations as changes within the genotype that have no effect to the fitness of the individual. For instance, mutations in 8000 Drosophila genes have no effect to the phenotype (Mayr 2001: 105). This example shows that not all mutations are harmful. Most are neutral, while some are harmful and some are beneficial. Mutations that decrease the fitness of the phenotype (harmful mutations) will not remain in the gene pool of a population, because the individuals which have them has decreased fitness and less descendants. Harmful mutations have small chance of heritability in the population, while those enhancing the fitness (useful mutations) will be kept because they have a larger chance of heritability. It should always be remembered that fitness is defined by the surrounding environment. How many mutations are useful? Remold & Lenski (2001) cultured three E. coli bacteria strains (derived from a parent culture grown for 10.000 generations in glucose-containing media) in a new environment, maltose-containing media. They found that 12% of the mutations improved the ability to utilize maltose. Their results suggest that some mutation are indeed beneficial.
Considering the facts mentioned above, it should be obvious that mutations are not always harmful. Most are neutral and some are even beneficial. There are no absolute criteria of fitness; a weakness in one environment might be a useful adaptation in another, and vice versa. Therefore, the claim that all mutations are harmful has been disconfirmed. REFERENCES Hawkey, P.M. 1998. The origins and molecular basis of antibiotic resistance. BMJ 317: 657--660. Mayr, E. 2001. What evolution is. Basic Books, New York. Remold, S.K. & R.E. Lenski. 2001. Contribution of individual random mutations to genotype-by-environment interactions in Escherichia coli. PNAS 98 (20): 11388--11393. Yahya, Harun. 2001. The evolution deceit 6th ed. Kültür Publishing, Istanbul (Online pdf version at www.harunyahya.com) FEEDBACK Send feedback to: andya_p@postmark.net Previous page: Introduction
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