As biologists we are not overly concerned about whether an observation or theory supports or contradicts religious writings. Science works on a simple, but strict, assumption, namely that the world is explicable solely in terms of natural forces - matter and energy. Whether this is in fact "True" is not particularly important. What is demonstrably true is that this assumption "works", i.e. it leads a logically and internally consistent body of theory that enables us to predict the behavior of the "real world". We see this in our ability to design and build quite amazing technologies - ranging from genetically re-engineered organisms to the first quantum computers, liquid crystal displays, magnetic resonance imaging systems, etc -- all based on the "naturalistic" and secular assumptions of science.

These are generally cases of co-evolution. An obvious example, based on human -directed artificial selection, are the domesticated strains of plants and animals that are, in many cases, dependent upon human intervention for their survival (see here).

On the other hand, there are many natural examples of co-evolution. Consider the smallpox virus that infects only humans. The absence of an alternative animal host made smallpox relatively easy to eradicate, once a sufficient percentage of the human population had been immunized. A similar fate appears to await poliovirus and hopefully other human viral pathogens.

But one could argue that viruses are not really organisms? No matter, a number of microorganisms are restricted to living on humans. For example, the bacteria that causes syphilis, Treponema pallidum,and gonorrhea, Neisseria gonorrhoeae appear to infect only human beings.

There are also larger organisms, such as the head louse (Pediculus humanus) that appears specialized for life on people.

Why is this? Basically, people represent an attractive ecological niche, and this niche has been populated by numerous organisms -- some of which have adapted via natural selection so well that they could no longer survive without people.