> Evolution may also refer to the change of one living thing to another, such
>>as reptiles into birds. This process, called macroevolution, has never been
>>observed and should be considered a theory.
Archaeopteryx, Confusciousornis, Ichthyornis, and many other Mesozoic birds
have features of both reptiles and of modern birds. This is an
observation. That they are transitional forms is an interpretation, but so
is the claim that they aren't, and I have not encountered credible
justification for the latter claim (but have not encountered it in a
context likely to have such).
> Evolution also refers to the unproven belief that random, undirected forces
>>produced a world of living things.
This is where the real problem lies, yet it only gets one sentence! The
difference between science and philosophical or religious views (in
particular, the presentation of the latter as the former) is the problem
here, yet most of the statement focuses on doubtful antievolutionary
arguements.
> There are many unanswered questions about the origin of life which are not
>>mentioned in your textbook, including:
If this said "Science is always subject to change in the light of new ideas
and discoveries. Several aspects of evolution are uncertain, and much
research is focused on questions such as:", it would not sound so much like
an accusation of conspiracy on the part of textbook writers. It would
still face the problem of selecting accurate questions; words like "many"
or "some" would help.
> - Why did the major groups of animals suddenly appear in the fossil record
>>(known as the "Cambrian Explosion")?
The phyla Porifera, Cnidaria, Mollusca, Echiura, and Chordata (plus
hyolithids, if they are considered a separate phylum) are relatively
well-documented from the late Precambrian; I heard rumor at the last GSA of
Precambrian trilobites (Arthropoda) as well, and there are many
problematica, trace fossils, etc. that may represent other phyla. There
are also myriad hypotheses as to why rapid diversification occurred around
the Precambrian-Cambrian boundary. The impression of a wild
diversification at this time is largely due to Steve Gould's attempt to
make it an example of the random nature of evolution, so it's ironic to see
it in anti-evolutionary circles.
>- Why have no new major groups of living things appeared in the fossil record
>>for a long time?
Several soft-bodied phyla do not appear in the fossil record until quite
late, if at all. I know of two explanations for the decreasing rate of
appearance of higher-level taxa. First, there may not be ecological room
for anything drastically different. If the basic niches are already full,
any novel organism must compete with established organisms. Secondly,
because most higher-level taxa include multiple lower-level taxa, they will
be as old as the oldest lower-level taxon included, making their average
age older. [E.g., the genus Homo must be as old as H. habilis and is older
than H. erectus or H. sapiens].
> - Why do major groups of plants and animals have no transitional forms in
>the >fossil record?
Animal phyla have few transitional forms in the fossil record because the
oldest known animal fossils are already assignable to phyla. If
transitional fossils exist, they are in yet older rocks. There are
transitional forms between several classes, orders, etc. known. Few
transitional forms are known in those groups with lousy fossil records.
>- How did you and all living things come to possess such a complete and
>>complex set of "Instructions" for building a living body?
If living things had a significantly incomplete set, they would not be
living. Clearly, the evolution of a decent set of instructions is strongly
favored by natural selection. Many, though not all, of the steps involved
in the transformation from abiotic chemicals to instruction suitable for
life have been carried out in labs; additionally, there is molecular
biological evidence on the evolution of some complex systems.
Picking out such a list of questions is unwise-new discoveries are
constantly happening (the list of well-established Precambrian phyla is
considerably larger after 1997), and all possible textbooks cannot been
read to check whether they address these. However, the main issue is the
presence of claims that science disproves the Bible, if not theism. Such
claims are not science and do not belong in a science textbook; encouraging
critical thinking and clearly defining what is and what is not science will
address these problems. The scientific data on biological evolution and
the age of the earth are side issues; the former has thoroughly distracted
this statement.
David C.