In considering the origins of Man, the Bible and evolutionary theory are generally considered to be rivals; although in actuality they are in one sense incommensurable and in another (deeper) sense the Christian account includes the biological while the biological is metaphysically-incoherent when detached from divine revelation.
But a puzzle is the actual function of the scientific, biological discourse of human evolutionary origins: what work does this discourse actually do?
This is a necessary question because all sciences must be rooted in wider reality if they are to be valid.
Much of biology is rooted-in, and tested by, practical disciplines (involving prediction and intervention) such as medicine or agriculture; much of chemistry and physics is rooted in engineering.
The performance of scientific theories (and the relevance and validity of experiments) is thus underwritten by some practical field of endeavour, which 'keeps it on the rails'.
(A complementary example is concern over 'superstring' theories in physics, in that this discourse has perhaps detached itself from such practical roots, hence stopped being a science.)
So what, if anything, is the practical application of the biology of human evolution?
My suspicion is that there is no significant practical application for human evolutionary theory - but rather than supplying useful answers, biological evolutionary theory serves primarily to assert itself as the proper method for establishing (or rather denying) the place, function, purpose, meaning of humanity in the larger scheme of things.
The reason I doubt the practical relevance of biological accounts of human origins (having worked in precisely this field over a couple of decades, and been observing it for much longer) is that nobody in general society takes any practical notice of the findings.
The genre of semi-popular accounts of human evolution is a well-established one...
Nevertheless, the successive stories perform a regular series of U-turns in what is put forward as accepted fact.
The same fossil homonids (australopithecines and Homo Habilis) are portrayed in quick succession as daring hunters of big game, peaceful vegetarians, and nimble scavengers from carnivores...
Others (Neanderthals) are described one year as sensitive and religious people who buried their dead with flowers while speaking human language, the next as animals whose difference from chimpanzees and gorillas would not be immediately obvious to us...
Yet other homonids (homo erectus) have often been envisaged as fire-making dwellers in caves; but according to some new versions the caves were merely where their bones were brought by scavenging animals, and the ash of their hearths just debris of occasional natural bushfires.
The examples sound so far-fetched, when put like that, that it might be thought I have invented them. I have not. What has happened in each case is that a careful re-examination of apparently convincing evidence has shown some 'association' to be a product of randomness...
These errors were not malicious or even foolish at the time; they are just what must be expected when so much theory has to rest on so little evidence.
Each discovery of new fossil bones is liable to cause dramatic revision in the story offered... the resulting changes of story are embarrassing and are not often pointed-out, but they are obvious to anyone whose interest in this fascinating area lasts more than a couple of years.
Richard Byrne - The Thinking Ape, Oxford University Press, 1995.
I was, for several years, interested by the implication that distinctive human cognition (approximately everything that makes humans different from chimpanzees) probably evolved in the past two and a half million years (when the differential size of the brain grew) and that this meant an awful lot had to happen in not many generations (if there were 4-5 generations per century, then this would mean a maximum of about 100K generations - which is many-fold less then used to be assumed to be necessary for the evolution of consciousness, language and all the rest of it)
But the fact is that nobody really, seriously, does anything, as a consequence of these rapidly-changing theories of human origins.
Therefore, I infer that their purpose is not scientific, nor practical, but popular.
It seems that genre of semi-popular accounts of human evolution is well-established because that is the 'bottom line' (insofar as there is a bottom line) for biological theorizing about human origins.
That this is plausible is confirmed by the fact that, since Darwin, the fossil hunters have always gone straight to the general public with their theories - whether real or (as with Piltdown Man) fake. The evolution of Mankind is indeed the first most enduring, and always present genre of popular science.
But why this link between evolutionary accounts of human evolution and the mass media?
It cannot all be about funding and fame - the public must be getting something from it as well.
Yet, if the story of Man's History is continually changing and reversing, then it cannot be the specific content which is important: it must, by elimination, be the process at which the content is generated that is important - and the continually changing content merely serves as a way to supply novelty and keep public interest going.
What people get from this field is continual affirmation that this (i.e. evolutionary biology) is the way to understand the nature of the human condition.
No matter how often the story is changed or contradicts itself, the one thing that does not change are the assumptions of the field - that scientific disciplines such as paleontology, archaeology, geology, anthropology, primatology, genetics and so on... that these are the way in which we understand what made us human, and what it is to be human.
The specific sciences involved matter little - because all of them exclude the divine, and indeed the transcendental as matters of assumption.
Therefore, the discourse of human origins is a prime domain, perhaps even the prime domain, for establishing and enforcing the 'primacy of science' and the elimination of religion from public discourse.
On scientific grounds it certainly made sense to eliminate divine will from the study of evolution - after all, it has never been precisely or in detail known what is the divine will, so that is disputed; and the way in which divine will opertes is likewise a matter of continual debate.
How straightforward and clarifying, therefore, to eliminate the divine from the business of science.
But this elimination is not, of course, evidence that the divine will is not real, nor that it is of no effect. It is just a pragmatic, an heuristic, which simplifies things - just as it simplifies ballistics to ignore wind and air resistance and potentially changing effects of gravity.
However, that does not mean that wind and gravity don't exist - and sometimes they need to be taken into account.
Most evolutionary biologists, and almost all those who read and 'believe' the stories of human origin, have forgotten that Darwin did not discover that God did not exist, nor did he discover that God was un-neccessary - he simply made the a priori decision to try explaining things without God.
Did this work? Well, it depends what you mean by 'work'.
If by 'work' you mean something practical and tangible like medicine or technology, then evolutionary theories of human origin seem to make no difference either way - they change and they change, and nobody seems to care.
But if by 'work' you mean 'effectively destroy Christianity'; then sure, the theories of human origins have worked; they have worked very well indeed.