|Biology: Principles and Processes - Nelson|
Biology: Principles and Processes. Roberts, M., M. Reiss, and G. Monger. 1993. Nelson
This book has been replaced by Advanced Biology. Roberts, M., M. Reiss, and G. Monger. 2000. Nelson
This textbook contains a detailed account of the theory of evolution, in three substantial chapters. The authors are honest about some of the shortcomings of the evidence for evolution, and even admit that an element of faith in evolution is needed in order to believe it in certain areas. However, no other scientific theories of origins are presented, and the reader is left with the impression that despite its problems, the theory of evolution is the only possible explanation for how we came to be here.
Evidence for evolution
Most of the standard evidence for evolution is included in this textbook, and detailed at some length.
For many of these, the authors do highlight some areas of uncertainty. In the section on the origin of multicellular organisms, they write:
Like so many other aspects of early evolution, this is a controversial matter and we can do no more than touch on the possibilities (p. 815).
Evidence from fossils is covered in a manner which is baised towards gradualistic evolution:
Studying the fossil inhabitants of different [rock] strata...has made it possible to trace the evolution of successive groups of animals and plants during geological time…What kind of evolutionary sequences have been established from the fossil record? There are obviously far too many for us to look at all of them, so we shall choose one for detailed discussion: the evolution of horses (p. 778)
This makes it appear that there are many sequences similar to that of horses, but a few sentences later it becomes clear the apparent horses sequence mentioned is very unusual:
...compared with most fossil sequences, the record for horses is pretty complete.
For an analysis of the story of horse evolution presented in detail by this book, see the article on Horse Evolution on this website.
The problems of The Fossil Record are mentioned, but these are used to introduce the evolutionary theory of punctuated equilibrium:
Intermediate forms in the fossil record are surprisingly rare. The rarity of intermediate forms is seen by creationists, who believe in special creation rather than the in the evolution of species, as evidence that evolution has not occurred. However, two American palaeontologists, Niles Eldredge and Stephen Gould, put forward a different interpretation…” (p. 799)
The Miller-Urey experiment is used to show how amino acids first formed. The book claims that:
Geochemical evidence suggests that at this time the Earth’s atmosphere was dominated by four simple gases: methane, ammonia, hydrogen and water vapour
However, this is questioned a few paragraphs later:
...since Miller’s work, some earth scientists have questioned whether the Earth ever had a reducing atmosphere lacking oxygen. (p. 811)
Gene mutations are described as very important in generating evolutionary change and are illustrated by changes of single letters in English sentences which change their meaning (p. 794). However, the book fails to mention that the probability of any of the changes it shows is less than 0.0008, and that the vast majority of possible changes in the sentences would result in nonsense.
The authors' position on the evidence for evolution is summed up at the end of the chapter Evolution in evidence:
The theory of evolution is testable, and is therefore a scientific theory. However, the evidence in favour of it, although generally held to be convincing, is not foolproof.
EugenicsA section on artificial selection by humans develops into a discussion of eugenics, something which the textbook appears to advocate.
There is nothing intrinsically evil about wanting to improve the quality of the human race…The theory and practice of improving the human race by means of selective breeding is known as eugenics, and despite its sinister undertones many people feel it should not be dismissed as totally unacceptable provided of course it is carried out on a voluntary basis…If in vitro fertilisation is accompanied by suitable biochemical tests carried out at the 8-16 cell stage, doctors may be able to determine whether the embryo will develop into a healthy baby or show any genetic abnormalities. This information could then be made available to the woman before a decision has to be taken as to whether or not to implant the embryo into her womb. However, the majority of babies will no doubt continue to be conceived and carried to term as before. (p. 805)
Teaching the controversy?
The closest this textbook gets to teaching the controversy is a box entitled Scientific arguments against evolution (p. 781). This describes several doubts which may be held about evolution, such as the origin of the first replicating molecules, and the evolution of the human brain. It admits that an element of faith in evolution is needed. In the absence of good evidence, the book appeals to the great majority of scientists alive today who believe in evolution. No alternative theories are mentioned which pupils might want to consider.
Overall, school pupils using this book are left with little choice but to accept the theory which has been described to them.
Darwin's theory is generally held to have stood the test of time and, with certain modifications, is accepted today by practically all biologists (p. 760)
There is something remarkable about the thought that you, the person sitting reading this chapter, and we, the authors of it, are – if current scientific opinion is to be believed – the product of an evolutionary process that began some thirteen billion years ago with the birth of the Universe itself. (p. 808)
A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question.