Pseudogenes are DNA sequences that resemble functional genes but seem to have no purpose. The presence of similar eta globin pseudogenes in humans and chimps has been used as an argument for common ancestry of the two species.

The philosophical context in which biology is presented can make an important difference in its meaning for the student. The philosophical worldview of the biblical Christian is quite different from that of the non-Christian; thus, the biology teacher may have a profound influence on the development of worldview by the student.

In the early development of the theory of evolution by natural selection, two men stand out as having played a central role: Charles Darwin and Alfred Wallace. Both men traveled widely and were keen observers of nature. For both men, visits to islands played an important role in developing their understanding of nature. Darwin's visit to the Galapagos Islands is of special interest.