Question:

One concept I do not understand of evolution, is that if change happens by
chance over time, how does it account for reproduction? That is, how is it
that species mutated to the differentiation we see today with the ability
to reproduce every step of the way? We have to assume fully functional
reproductive systems through every stage of change from a single celled
organism to what we see today.

Answer:

I am not an expert on evolution, being a chemist and physicist, but as I
understand it, this question you raise is not one of the big problems for
the theory of evolution (although there are some major problems with this
theory!). As species “evolve,” changes from generation to generation are
relatively small. One change in the genome–the set of hundereds of
millions or billions of base pairs of nucleotides–happens at a time. As
a general rule, different members of a single species are relatively
similar genetically and are able to reproduce together. In fact, any
genetic mutation which makes the succeeding offspring unable to breed with
the majority of the population is automatically eliminated from the gene
pool. Any change which made the reproductive system not function properly
is also automatically eliminated from the gene pool. If we can assume
that species can evolve, then the question you raise is not one of the big
problems with the theory.

Whether species can evolve from bacteria to elephants is another question
which is not settled or “proved” by the evidence to say the least, but the
fact that species do evolve (ie. change genetically) over time has been
proven by experiment. As this evolution occurs, new species emerge. For
example, I assume that lions, cheetahs, leopards, mountain lions, lynx and
house cats all evolved from a common ancestor over the course of millions
of years. The more different two of these species are, the less likely
they are to be able to produce viable offspring. As far as I know, lions
and tigers, for example, can produce live offspring, but those offspring
are sterile. This is evidence that as evolution occurs, eventually the
cumulative differences create completely separate species which have the
problem you anticipate–they cannot produce viable offspring.

Another question arises about reproduction and evolution. One good
question is how sexual reproduction arose in the first place. At first,
it may seem impossible for sexual reproduction to evolve out of asexual
reproduction. It is not likely that evolutionists will ever be able to
prove how this happened. Perhaps this example is a good argument against
bacteria-to-elephant evolution. Because we cannot reproduce evolutionary
change of this sort in the laboratory, it is wise for those on both sides
of this debate to be reserved about the confidence of their claims. Did
God intervene miraculously to create sexual reproduction, or did some
hard-to-imagine sort of dual sexual/asexual transition come about
spontaneously? I have my personal opinion on this, but cannot prove
either point to be true. The wise course is humility and open-mindedness.

John Oakes, PhD