Brain Anatomy and Relations with Skull - Article Example

Most students should see that there are skulls which satisfy some of the criteria but not others; that is, there are forms intermediate between human' and non human' (Nickels, 1987). If the concept of a graduation of forms is accepted, then the further question what came first, a large brain or an upright stance' will bring out ideas on how and why this evolution occurred as it apparently did. Of course this approach concentrates entirely on fossil morphology. Modern ideas on human evolution are based on a variety of forms of evidence addition to morphology: molecular clocks' such 2 interspecies differences in DNA and haemoglol anthropological observations on apes and primitive hunter-gatherers; tools; preserved footprints; and considerations of climate and likely competitors.

These factors should all be mentioned, but from the classroom point of view they do not have the convenience and concrete appeal of the skulls. It is not intended to cover the topic of the human evolutionary pathway comprehensively here. Recent and interesting accounts of the fossil record and prehistory of man can be found in Day (1984), Leakey and Lewin (1977), Lewin (1984), Lambert (1987), Putnam (1988), Stringer (1985), and Weaver (1985). The skull casts used in this exercise need to be reasonably accurate copies of genuine fossils which are as old (with due allowance for experimental error) as claimed.

Some casts are partially restored and it is reasonable to accept restorations which are soundly based on drawings, photographs, and casts of related fossil material. Opponents of evolutionary theory may dispute this approach on the grounds that the fossils are forgeries or that the dating methods are in error. The history of Piltdown man' earlier this century lends some plausibility to the claims of forgery, but with recent advances in dating methods a modern Piltdown' would not survive for very long (Weiner, 1955).

And if dating methods are so inaccurate that an object only 6000 years old is dated at 600 000 years then the validity of the large areas of chemical, physical, and geological theory and practice that underpin those methods must be called into question. Of course, it must be emphasized that while the evidence currently available to us suggests that a special creation some 6000 years ago is improbable, it does not, and cannot, show that it is impossible. Nor does the evidence necessarily contradict the concept that the universe as a whole and the laws that govern it were created a long time ago.

There are large gaps in the fossil record and it is sometimes claimed that this shows that there is in fact no link between a recent animal and its postulated ancestor. However, it is hardly surprising that there are such gaps in the record. Consider the sequence of events in the formulation of a fossil. After the animal dies it is almost certain to be torn apart by carnivores and scavengers and its bones might be distributed widely. If the bones are