21st Century Science: GCSE Foundation. Penny Johnson (ed.). Pearson-Longman. 2006.

This book is part of a new series of GCSE science texts, designed to promote scientific literacy for all future citizens.

Evidence for Evolution

Module B3.1, Life on Earth, begins with a double-page spread about extinction, sent from an 'Intergalactic Federation' of aliens. This introduction describes evolution over 3500 million years as an objective, unquestionable fact, confirmed through extra-terrestrial contact with another evolved intelligence. Human beings are put on trial by the aliens for crowding out other species and producing harmful waste!

Under the heading 'How did life on Earth start?', the text claims that the early Earth contained no atmospheric oxygen, the text uses the Miller-Urey Experiment as evidence for chemical evolution.

The next section is perhaps the most relevant to this discussion. 'What is the evidence for evolution?' begins by tentatively suggesting:

We can link related fossil and living species in an evolutionary tree to show how later organisms may have evolved from earlier ones. Page 168.

The text then presents a cartoon reconstruction of a large, extinct amphibian named Eryops, stating that Eryops was most closely related to modern toads and frogs. This is followed by a diagram of an evolutionary tree showing one ancestor species splitting into two. What this text fails to present is any evidence of the transitional fossils that should exist between Eryops and modern frogs and toads. No transitional form is presented. Instead, the bird-like Archaeopteryx is shown, and pupils are asked:

...which living animal does the fossil of Archaeopteryx look most like?

After a brief mention of Comparative Genetics, and a diagram of a phylogenetic tree for animals, the text makes an interesting reference to fossilisation by asking pupils:

Why must dead organisms be buried quickly if they are to turn into fossils?

This is a departure from teaching about fossilisation in many other textbooks, which strongly imply that fossils are buried slowly over millions of years of erosion and deposition. For instance, under the heading 'Deep Time', GCSE Science: Higher [OCR] states that:

What Hutton described was the rock cycle. 'Processes such as erosion and deposition of sediment take place slowly.'

Hutton's powerful legacy is also found in GCSE Biology by Mackean (2002):

...a skeleton of a fish might become embedded in mud or sand...settling down on the bottom of a lake. After a few million years, with the pressure of more layers building up on top of it, the mud or sand becomes rock.

Which textbooks are right, the ones which state that fossilisation takes place slowly, or the ones which state that it is rapid?

B3.4 - 'How does evolution happen?' - contrasts the ideas of Jean-Baptiste Larmarck to Darwin's mechanism of natural selection. However, no modern theories which contrast to Darwinism are mentioned, so pupils do not gain knowledge to allow them to understand current controversy.

B3.5 - When does a hypothesis become a theory? - gives the example of the Galapagos Finches as evidence for Darwinism. This section also notes:

Darwin's hypothesis caused great argument. At that time the main explanation for all the different species on Earth, and all the fossils, was that God had created them. This is not an idea that can be tested scientifically.

This statement is oversimplistic. Most prominent geologists of this time did not believe that God directly created fossils in the rocks, but rather, that fossils were a record of the death and burial of living creatures.

Toward the end of this section, the text strongly implies that Darwinism is proven and that dissent is entirely due to religiously motivated resistance to learning:

Since Darwin's time studies of animals in the wild for long periods have shown evolution happening. However, some religious people still do not believe that evolution happens.

This statement is rather misleading. Few long-term studies of evolution in the wild have been undertaken. Perhaps the best example is an excellent study on the Galapagos Finches by Peter and Rosemary Grant. This shows fluctuations in the shape of beak finches over time, partly due to environmental selection. To that extent, they have "shown evolution happening". However, few people, religious or otherwise, would disagree with their findings. What many people, religious or otherwise, have difficulty believing is that all life has evolved from a single-celled common ancestor, and that an undirected natural process has resulted in an appearence of design in the natural world. It is this different meaning of "evolution" that is often not believed. This textbook sentence therefore exploits a flexibility in the definition of "evolution" give the reader a false impression.

Finally, B3.8 - 'How have humans evolved?' - states that:

...the first hominid (human-like) species evolved from an ape-like ancestor around 7 million years ago.

The data presented to back up this assertion are a collection of fossil skulls including: Australopithecus africanus, Homo habilis, and Homo erectus.

Teaching the Controversy

The blurb on the back cover describes this text as the 'best preparation for the scientific citizen of the future'. We disagree, since there are no real opportunities for students to understand contemperory scientific objections to Darwinism. The scientific citizen of the future needs to understand debate over the answer to the question "Where do I come from?"