The theory of evolution is outlined in an extensive chapter which surveys a variety of evidence. No alternatives to evolution as a theory of origins are mentioned, and no possibility of doubting the theory of evolution is mentioned by the authors. The authors see this as justified because the majority of scientists believe in evolution.

Evidence for evolution

This textbook has a chapter on evolution, which starts with a general introduction to the theory, and ends with a detailed account of the hypothesised evolution of humans from apes.

Evolution is introduced in theoretical terms, with an outline of Darwin’s argument. The different types of selection are illustrated with a hypothetical mammal which is selected for different fur length according to its environmental conditions.

Polymorphism is illustrated using the real world examples of human blood groups, the colouring of the land snail Cepaea nemoralis, and The Peppered Moth Biston betularia. Antibiotic resistance in bacteria is used as an example of mutation and selection.

There are sections on artificial selection and on isolating mechanisms which can lead to speciation. Few real world examples are given for these processes.

This textbook assumes that humans have evolved from ape-like creatures. The question in the authors’ minds is not whether evolution of humans has occurred, but which path it took, as this extract shows:

9.6 Evidence for human evolution

It is important to realize that we are faced with many difficulties when trying to sort out fact from fiction in the evolution of mankind. (p. 182).

Three lines of evidence on human evolution are used:

1. The first set of evidence used for human evolution is homology.

We can test relationships between species by looking for characteristics that are similar in different species because they have been inherited from a common ancestor. Such similarities are called homologies. (p. 182)

This is used, not to show that evolution has occurred, but by what pathway:

we can look for similarities…and try to decide which apes are our closest relatives. (p. 182)

2. The fossil record, but this section begins with a very significant admission:

All fossil records are very incomplete and that of primates is no exception: far more forms must have lived than are represented as fossils. In addition the record is geographically imbalanced with few examples from the Oligocene period (around 23-35 million years ago) in Africa, even though there is good reason to suppose it was a major centre of primate evolution.

In other words, there is no evidence for key steps in the evolution of primates.

3. Lastly, comparative physiology and biochemistry – another argument for homology, this time relying on similarities between primates in protein and DNA sequences. The text does admit that such studies sometimes give conflicting results, but favours the view that humans are most closely related to chimpanzees.

The textbook then surveys a range of fossil “man-apes”: australopithecines, Homo habilis, Homo erectus, Neanderthal man, and Cro-Magnons. These are all contested as genuine examples of hominid intermediates.

Teaching the controversy?

This book does not teach any scientific controversy over evolution. The only controversies taught are those within the evolutionist camp. The authors’ appear to see this as justified because most scientists are evolutionist:

Evolution is the process by which new species are formed from pre-existing ones over a period of time. It is not the only explanation of the origins of the many species which exist on earth, but it is the one generally accepted by the scientific world at the present time” (p. 168).

Most people now agree that the first man-apes were the australopithecines which lived between 5 million and 1.2 million years ago and that Homo arose in Africa 2.4 million years ago” (p. 188)

This textbook makes no mention of the significant number of credentialled scientists who do not believe in molecules-to-man evolution. The strongest reason given by this textbook for belief in evolution as a theory of origins is that it is generally accepted by the scientific world. This is questionable, and the absence of good evidence presented in the book may leave the reader wondering why scientists believe in evolution. Is the textbook missing out the best evidence, or is there really a paucity of hard evidence for evolution?