From: L.A. Moran
To: All Msg #271, May-05-93 12:42PM
Subject: Teaching macroevolution (sic)
Organization: UTCC Public Access
From: firstname.lastname@example.org (L.A. Moran)
Bill Rawlins (email@example.com) has written,
"Science has only speculation. So, why, I asked, is the Miller-Urey
experiment put into most biology textbooks claiming to explain the
origin of amino acids, and later down-the-line, DNA?
My objection here is not so much the experiment as it is to wasting
time teaching speculation. AND, having reviewed many of these texts,
and references to speculation of this sort, THE AUTHORS GENERALLY
GLAZE OVER AND/OR DO NOT MENTION THE SPECULATION INVOLVED,
MAKING IT APPEAR TO THE TYPICAL READER THAT SUCH SPECULATIONS ARE
FACTS. This is called "distortion"."
This is a serious charge so I decided to investigate by examining the leading
textbooks of introductory biology (note that these are the most popular and
widely read textbooks - I can't vouch for more obscure works). The following
quotes demonstrate conclusively, in my mind, that these textbooks writers are
fully aware of the distinction between fact and speculation. It is simply not
true that our students are being taught that abiogenesis is a proven fact.
I challenge Bill Rawlins to support his accusation or withdraw it.
Campbell, Neil A. in BIOLOGY 2nd ed. Benjamin/Cummings, 1993
"Historical study of any sort is an inexact discipline, dependent
as it is on the preservation, reliability, and interpretation
of past records. The fossil record of past life is generally less
and less complete the farther into the past we delve. Fortunately,
each organism carries traces of its evolutionary history in its
molecules, metabolism, and anatomy. As we saw in Unit Four, such
traces are clues to the past that augment the fossil record, much
as similarities and differences between extant cultures help social
scientists understand historical relationships between the cultures.
Still, the evolutionary episodes of greatest antiquity are generally
the most obscure. This chapter is the most speculative of the unit,
for its main subject is the origin of life on a young Earth, and no
fossil record of that seminal episode exists. The chapter sets the
stage by briefly discussing the origin and early existence of the
Earth, in keeping with the theme of the intertwining of geological
and biologial evolution, and then describes theories of how natural
processes on the youthful planet could have created life."
from the introduction to
Chapter 24 "Early Earth and
the Origin of Life" p.510
Raven, Peter H. and Johnson, George B. in BIOLOGY 2nd ed. Times Mirror/
Mosby College Publishing, St. Louis 1989 (I don't have the 3rd ed. on hand.)
"The question of the origin of life is not simple. It is not possible
to go back in time and watch how life originated; nor are there any
witnesses. There is testimony, in the rocks of the earth, but it is
not easily read, and often this record is silent on issues crying out
for answers. Perhaps the most fundamental of these issues is the
nature of the agency or force that led to the appearance of the first
living organisms on earth - the creation of life. There are, in
principle, at least four possibilities:
1. An unknowable agency. The first life-forms may have possessed
genetic systems very different from those characteristic of
the organisms we know now, and they might even have lacked
cellular organization. What we think of as 'life' may be a
secondary stage of some earlier process, about whose origins
we can learn nothing because no trace remains.
2. Natural outside agency. Life may not have originated on earth
at all, but instead may have been carried to it, perhaps as
an extraterrestrial infection of spores originating on a
planet of a distant star. How life came to exist on that
planet is not a question we can soon hope to answer.
3. Supernatural outside agency. Life-forms may have been put on
earth by supernatural or divine forces. This viewpoint, common
to most religions, is the oldest hypothesis and the most widely
4. Evolution. Life may have evolved from inanimate matter,
associations of molecules achieving ever-greater degrees of
complexity. In this view, the force leading to life was
selection; changes in molecules that increased their stability
also caused them to persist longer.
In this book we deal only with the fourth possibility, attempting to
understand whether the forces of evolution could have led to the origin
of life and, if so, how the process might have occurred. This is not to
say that the fourth possibility is definitely the correct one. Any one
of the four possibilities might be true. Nor does the fourth possibility
exclude religion: a devine agency might have acted via evolution. Rather,
we are limiting the scope of our inquiry to scientific matters. Of the
four possibilities, only the fourth permits testable hypotheses to be
constructed ad so provides the only *scientific* explanation, that is,
one which could potentially be disproven by experiment, by obtaining
and analyzing information."
from Chapter 4, The Origin
and Early History of Life p.63
Purves, William K., Orians, Gordon H. and Heller, H. Craig LIFE, THE SCIENCE
OF BIOLOGY 3rd ed. Sinauer Associates/W. H. Freeman, New York 1992
"Today there is a substantial body of information on which to base
plausible theories on the origins of life on Earth. The preserved
remains of many early organisms have been found and described, and
a number of laboratory experiments have studied chemical reactions
under conditions similar to those believed to have prevailed on the
early Earth. We know that all organisms have very similar basic
cellular metabolic pathways. This strongly suggests that all living
organisms are descendants of a single common ancestor. This does not
imply that life originated only once, but it does suggest that only
one of these origins led to all successful lineages of organisms. We
will first examine the evidence, and then explore its implications
for the ways life may have originated.
[four pages of evidence and theory deleted]
The fact that we cannot clearly choose among such strikingly different
theories indicates how much is yet to be learned. On the other hand,
the fact that there are such theories and that we can test at least
parts of them shows we have made progress in our attempts to understand
the origins of life."
form Chapter 17, Origins
pp. 387 and 390
Curtis, Helena and Barnes, N. Sue BIOLOGY 5th ed. Worth Publishers Inc.
"Until very recently, the earliest fossil organisms were a mere 600
million years old, and for a long time after publication of 'The
Origin of Species', biologists regarded the earliest events in the
history of life as chapters that would probably remain forever
closed to scientific investigation.
Two developments, however, have greatly improved our long-distance
vision. The first was the formulation of a testable hypothesis about
events preceding life's origins. This hypothesis generated questions
for which answers could be sought experimentally. The results of the
initial experiments led to the formulation of further hypotheses and
to additional experiments, a process that continues today as scientists
in many laboratories explore the question of life's origins. The second
development was the discovery of fossilized cells more than 3 billion
[description of Oparin's and Miller's experiments]
These experiments have not proved that such organic compounds were
formed spontaneoulsy on the primitive earth, only that they could have
formed. The accumulated evidence is nevertheless, very great, and most
biochemists now believe that, given the conditions existing on the
young earth, chemical reactions producing amino acids, nucleotides,
and other organic molecules were inevitable."
from Chapter 4, pp. 85 and 87
Here is what I wrote in PRINCIPLES OF BIOCHEMISTRY, Horton, R.H., Moran,
L.A., Ochs, R.S., Rawn, J.D. and Scrimgeour, K.G. Neil Patterson Publishers/
Prentice Hall, Englewood Cliffs 1993.
"Gradually, populations of similar organisms diverge from each other
and new species evolve. Biological evolution can be traced through
the fossil record or by directly comparing the sequences of genes
and proteins. These observations suggest that all of the millions
of species that exist today have descended from a single ancestor
that lived several billion years ago. This ancient ancestral cell
was undoubtedly capable of glycolysis (the breakdown of glucose)
and many of the other fundamental biochemical processes that are
common to all cells. It could synthesize amino acids and lipids
and almost certainly used ATP as the fundamental unit of energy.
It used the same genetic code that we find in its modern descendants.
How the ancestral cell evolved from simpler organsims is an unsolved
problem. The origin of life itself, an event that ocurred more than
three billion years ago, is the subject of much speculation."
from Chapter 1, p.24
I hope that t.o. readers will find this helpful in refuting another of the
spurious charges of the anti-evolutionists.
Laurence A. Moran (Larry)