A change in population size does not constitute evolution, yet it is also a sort of biological change.

It is likely that natural selection on a population will often increase efficiency, of feeding, say, and so increase population size.  A disease-causing bacterium will increase in abundance after evolving antibiotic resistance.

However, it is possible to imagine evolution that is not "good for the species", and that even causes a decline in efficiency and in population size.

So evolution by natural selection is really not "for the good for the species" or for population size, instead it is improves competitive ability, usually between individuals within and between species.

Dawkins has suggested that natural selection improves the fitness of individual genes.  However, this seems a little circular to me, because this may lead to a confusion between

Dawkins' ideas seem to me to be tantamount to arguing genes are fitter if they increase in populations, thereby conflating natural selection with evolution.

But this is all philosophy ... What do you think?


Creationists view evolution as a theory.  However, the whole of science is theory.  In science, we don't actually "know" anything for certain.  We leave "perfect knowledge" for religion. Nevertheless, scientific theories that have been tested a lot and have been found to make useful and correct predictions are generally regarded as "certain", or "facts".  In this sense, Evolution is a fact.  You are of course free to disagree; we don't mind what you believe in this course.  However, to pass exams on this course, we expect you to be aware of the arguments and evidence in favour of evolution vs. creation.  You do need to learn about evolution, even if only to help you produce arguments against it!