Evolution: A Very Short Introduction
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This book illuminates the crucial role of evolutionary biology in transforming our view of human origins and our relation to the universe, highlighting the impact of this theory on traditional philosophy and religion. The authors introduce the general reader to some of the most important basic findings, concepts, and procedures of evolutionary biology, as it has developed since the first publications of Darwin and Wallace on the subject, over 140 years ago. They show how evolution provides a unifying set of principles for the whole of biology and sheds light on the relation of human beings to the universe and each other.
indicate the amounts of differences between species (ranging from 0.2% between the closest species to 16.5% between the most different). The tree shows that the Galapagos species form a cluster clearly having a common ancestor, and that they all have similar sequences of this gene, consistent with this ancestor being quite recent. In contrast, the other related species of finch differ much more from one another. As Darwin wrote, when describing the inhabitants of the Galapagos islands in The
different engineers over the evolution of a machine, and early car designers would have been astonished at modern cars. In natural evolution, it results from what has been called ‘tinkering’ with the organism, with minor changes that make their possessors survive or reproduce better than others. In the evolution of a complex structure, several different traits must, of course, evolve simultaneously, so that the different parts of the structure are well adapted to function as a whole. We saw in
53 mortality 77, 82, 85, 117–18, 119, 120, 121 mosses 34 moths 14, 82, 83 mountain building 42, 43 mules 92 multicellular animal life 50–1, 53 mutation 6–7, 7, 26 advantage 72–3 albinism 23, 24 antibiotic resistance 6, 66, 79–80 artificial selection 63 changing amino acids 104 disease caused by 73 effects of 35–8 genes 29, 85, 104–7, 120, 121 hearing loss 22, 26 hormone antagonism 23 limits of 74–5 in nerve cells 127 resistant 6, 66,
bacteria, are finite, so that genetic drift will always operate. The combined effects of mutation, natural selection and the random process of genetic drift cause changes in the composition of a population. Over a sufficiently long period of time, these cumulative effects alter the population’s genetic make-up, and can thus greatly change the species’ characteristics from those of its ancestors. We referred earlier to the diversity of life, reflected in the large number of different species
pathway is organized like an assembly line, with a succession of sub-processes. Each sub-process is carried out by its own protein ‘machine’; these are the enzymes for the different steps in the pathway. The same pathways operate in a wide range of organisms, and modern biology textbooks show the important metabolic pathways without needing to specify the organism. For example, when lizards tire after running, this is caused by the build-up of the chemical lactic acid, just as in our muscles.