s the hot volleyball players were sitting in the creek cooling off, they noticed all the layers in the rock wall on the other side of the creek. Someone remembered that those layers are called “strata,” and somebody else wondered if they contained any fossils. That got several people interested in searching for fossils. Some searched for fossils in those rock strata while others leisurely walked along the creek looking for fossils among the loose rocks that were on the creek bed. Indeed, several fossils were found, the most interesting of which was a fossilized cephalopod shell that was about 7 or 8 cm long.
In discussing the fossils they found, someone mentioned the
word “evolution,” which of course, started a big conversation. During that
conversation, it became apparent that some of the students who had taken
freshman biology knew what it was all about, while some other people at
the picnic, who never had that explanation, had developed some incorrect
ideas as to what the Theory of Evolution is all about. Some people
mistakenly thought that the Theory says that monkeys turned into people,
while others thought that if environmental conditions change, then organisms
can also change to match their new environment. Somebody else said she
had been told that the fossils were put in the rock strata and made to look
older than they really are, just to test people’s religious beliefs. The
biology students who were present did their best to explain to everyone else
just what the Theory of Evolution actually
says.
At its simplest level, the word “evolution” means “change.”
Thus for example, I could say something like, “The Web pages for this course
have evolved as I have taught the course.” In terms of biology’s Theory of
Evolution, a more formal definition might be, “the series of changes that
have transformed life on Earth from its beginnings until now,” or even more
specifically, “changes, over time, in the percentages or frequencies of the
various alleles of the genes in a
population.”
Once again, recall the discussion of multiple-drug-resistant
bacteria on the
immune system
Web page. Due to our overuse of antibacterial agents, the percentages of
bacteria with genes that make them drug-resistant have increased within the
population over time, or more directly, those bacterial populations
have evolved to be more drug-resistant. Note carefully what that is and
is not saying. That is NOT saying that individual bacteria have changed
to become drug-resistant! Rather, those individual bacteria whose genes
just happened
to make them more drug-resistant survived and produced offspring to whom
they passed on their resistant genes, while those bacteria whose genes
did not enable them to be drug resistant died as a result. Thus, what this
is saying that, in the population as a whole, the incidence of, the frequency
of, bacteria that possess drug-resistant genes has increased, or put another
way, the frequency of drug-resistant genes within the population, has
increased.
Similarly, we humans have caused changes in other organisms.
Due to heavy use of insecticides, especially in urban areas, the cockroach
populations living in those areas have become insecticide resistant.
Silkworms have been reared in captivity for nearly 5000 years, now, and
during that time, through artificial selection, we have bred a whole
population of silkmoths with wings that are too short and stubby to fly.
It is thought that the ancestors of our modern domestic dog(s) looked much
like a wolf (so perhaps, German Shepherds have changed the least), but
from that, we have selectively bred for everything from St. Bernards and
Great Danes to Chihuahuas and Toy Poodles. (Note that “selective breeding”
or “artificial selection,” which depends on naturally-occuring mutations in
the DNA of an organism/population, is not the same as “genetic engineering,”
which involves directly manipulating/changing the DNA within a cell.) Due
to artificial selection by humans, the wheat we grow/eat, now, has much
larger seeds than the wheat grown/consumed by humans several thousand years
ago. These are just a few examples of how we, via artificial selection,
have changed the gene frequencies in populations of organisms over time,
and Charles Darwin, among others, argued that if this is true of artificial
selection, then logically, the same would also be true of natural
selection – environmental, rather than man-made, “pressures” which only
allow organisms with certain traits, certain genes, to mate and produce
offspring.
Thus, Darwin said that:
Darwin summed this up in the phrase, “descent with
modification due to natural selection.” As an example of natural selection,
consider the gene that causes sickle-cell anemia. This gene causes abnormal
hemoglobin, which in turn, causes a red blood cell containing that
hemoglobin to crinkle up (“sickle”) when stressed. Those pointy, crinkled
RBCs often get stuck going around corners in capillaries and small arteries
and veins, causing blood clots, therefore strokes, heart attacks, etc., which
often end up killing the person. There is, however, an interesting twist to
this story. The gene for sickle-cell is more common (higher frequency) in
populations of people who live in tropical, malaria-infested areas. When a
malaria parasite tries to invade a RBC with normal hemoglobin, it is
successful, enabling it to live and reproduce, invading and killing more RBCs
until the
person dies from malaria. However, if a malaria parasite tries to invade a
RBC with abnormal (sickle-cell) hemoglobin, that stresses the RBC, so it
sickles, which kills the malaria parasite (so it is unable to reproduce
and leaves no offspring to invade other RBCs). Thus, people with totally
normal hemoglobin (2 copies of the “make normal hemoglobin” gene) end up
dying from malaria, and people with totally abnormal hemoglobin (2 copies of
the “make abnormal hemoglobin” gene) are almost immune to malaria, but end up
dying from sickle-cell. Thus, the people who are best suited to that
environment are those with one gene for normal hemoglobin and one gene for
abnormal hemoglobin, so they make some of each. That way, there’s not as
much of a chance of their RBCs sickling and causing blood clots, and if a
malaria parasite happens to try to invade a RBC with abnormal hemoglobin,
that RBC sickles, killing the parasite before it can reproduce (thus they are
resistant, but not totally immune, to malaria). Therefore, in that
environment the sickle-cell gene is not totally “bad,” and due to
natural selection by both the malaria and the sickle-cell, that sickle-cell
gene is kept in the population and not eventually “weeded
out”.
Biologists have noted other evidence that supports the Theory of Evolution. For example, it has been noticed that the fossils in upper, more recent layers of rock are more similar to modern, living organisms, while fossils in lower, more ancient rock are more dissimilar. The embryos of organisms that are more closely related are also more similar to each other, and the developmental stages through which those embryos pass are believed to be parallel to the evolutionary history of that/those species. The fancy, technical phrase which is used to describe that is “ontogeny recapitulates phylogeny,” which means that the embryonic development of a species replays/follows its evolutionary history.
The idea is, then, that if enough genetic change accumulates,
speciation may be a result of that. As a hypothetical example, suppose
prior to the ice ages, there was a population of a type of mouse-like
animal that occurred throughout all of North America. Then, during the ice
ages, the glaciers came down through North America like “fingers,” separating
areas so the species in those areas could no longer get to nearby areas to
interbreed. If one of the “pockets” thus formed was a cool, dry, upland
area, those conditions might have put selective pressure on the population
there to accumulate genes for a short, hairy tail, long, thick, fluffy, body
hair, and small ears.
If another of the “pockets” was a warm, moist, swampy, lowland area, those
conditions might have put selective pressure on the population there to
accumulate genes for a long, naked tail, short, scant, oily body hair, and
large ears.
Perhaps, over time, these two populations might accumulate so many more
genetic changes that, when the glaciers receeded and they came back into
contact with each other, the mice might be so different that they would
be unable to breed with members of the other population, and thus, would be
considered to be two separate species.
In recent history, we have seen an actual, similar situation with a species
of moth called the Peppered Moth, which lives in England. These moths are
white with black speckles (hence their name), which is thought to provide
them with camouflage so they cannot be seen by predators. It is thought that
predation
by birds is a major source of natural selection for these moths — those
that are seen get eaten while those that are well-camouflaged survive.
During the early part of the Industrial Revolution when much coal was burned
in the cities, resulting in a lot of pollution and soot, the urban Peppered
Moth populations consisted of predominantly black moths, whereas the rural
populations remained speckled. While people got tired of the soot and
cleaned up the pollution in the cities, resulting in a Peppered Moth
population that now is a mix of black and speckled moths, it has been suggested
if the moth populations would have remained “separated” for a longer time,
that enough genetic change might have accumulated to result in two different
species.
On a sort-of related note, here’s an interesting theoretical
thing to ponder. Back in the 1950s, a poor black woman named Henrietta Lacks
had cervical cancer, from which she died, but not before doctors and researchers
had obtained a sample of her cancer cells and grown them in
tissue culture. Her cancer cells were the first to be grown successfully in
tissue culture, and resulted in lots of money for the biotech companies who
subsequently began to mass-produce and sell cultures of these cells (called
HeLa cells) to other researchers (note: none of this money ever got back to
her family). Since then, of course there have been some mutations in some
of those cells, so the biotech companies are now selling a number of
different HeLa cell lines with slightly different properties. Recently, an
interesting question has arisen: “Are these cells still human?” Considering
that these were cancer cells, not normal human cells, to begin with, and
considering all the genetic mutations which have occurred since then, can
we still consider these to be “human” cells?
Since the Biblical book of Genesis is shared in common by
all the Jewish, Christian, and Moslem people in the world — that’s a lot of
people, and since, in this country there is currently a lot of debate over
the so-called “Creation vs. Evolution” issue, I will offer a few comments
and thoughts, here.
That whole debate is fueled by our human misunderstandings: many of the
scientists who I’ve heard criticize the idea of “creation” are
self-proclaimed atheists who have never had any theology courses or studied
what that idea really says, many of the theologians who I’ve heard criticize
cosmology and the Theory of Evolution have never had any biology and/or
physics/astronomy courses, and don’t really know just what those theories are
and are not claiming, and many of the theologians who claim to be using a
“literal interpretation” of Genesis 1 are, instead, ignoring and/or
explaining away significant differences in the verbs used there, based on
their own, personal biases.
The Biblical account is written from the standpoint of recording what happened
and why, while modern science seeks to understand the mechanisms and processes
to explain how it all happened.
When I was in college, one of my professors shared his
viewpoint, which I have found helpful: there are two ways of looking at the
idea of creation — discontinuous creation, in which everything new
was only created at the beginning, and nothing new has ever been created
since then, and continuous creation, in which new things are still
being created; and there are two ways of looking at the idea of evolution —
atheistic evolution, which says that everything evolved totally by
chance and was not guided, and theistic evolution, which says that
everything under the guidance of some supreme being; and while the ideas of
discontinuous creation and atheistic evolution cannot be reconciled with
any of the other ideas, on the other hand, the ideas of continuous creation
and theistic evolution fit very nicely, hand-in-hand.
A number of scientists who are also Christian or Jewish have very carefully
compared the the order in which Genesis 1 says things were created with
modern cosmology (study of the origins of the universe) as accepted by many
astronomers and physicists, today, and have noted that the two are almost
exact parallels.
In the ancient Hebrew creation account as recorded in the book of Genesis,
the Earth was given the ability to produce plants and animals. In Genesis
1: 11, the Creator says, “Let the land produce vegetation.” Verse 12
says, “The land produced vegetation.” Genesis 1:24 adds, “Let the
land produce living creatures.” Notice that what’s being created here is
not the plants and animals, themselves, but the process whereby they
will arise, the Laws of Nature, the “rules of the game” by which the Earth
will produce the plants and animals — what a modern biologist would refer to
as the Theory of Evolution. These verses stand in sharp contrast to earlier
verses which say, “Let there be.”
For those of you who may find this of interest, the General Biology
History of Science
Web page contains further details, including some of the actual Hebrew text.
In terms of the debate over how long it took or how long ago it all happened,
several authors have suggested that Einstein’s Theory of Relativity can
easily account for that seeming discrepancy: as physicists now know, time flows
differently depending on one’s point-of-view, and thus from the Creator’s
viewpoint (the only one possible before humans came on the scene, and thus,
the one recorded in the book of Genesis) it may,
indeed, have taken 6 days, yet from our, very-different point-of-view looking
back with our radioactive dating tools, etc., that very same time
period may look, to us, like millions of years.
Thus, I sense that there seems to be a growing group of scientists, theologians,
and other people who are taking the “middle ground,” and saying that there is
no “debate,” no discrepancy, and that the ideas of creation and evolution are
not only compatible, but are just two ways of looking at the same events,
ideas which may help to enlighten and inform each other.
Links to Related Information on Our Web Server
The following Web pages contain information related to
the Theory of Evolution.
There will be one, combined assignment for the topics of Taxonomy, Evolution, Ecology, and Human Intervention. Thus, even though this will appear on each of those pages to remind you, you only need to do it once. You will need to go somewhere where there are lots of living organisms. Assuming you’re here in the Cincinnati area, you might go (with your family?) to the Cincinnati Zoo, Krohn Conservatory, the Newport Aquarium, one of the local parks, or someplace similar to that. If you’re not in the Cincinnati area, there are probably similar places to visit near wherever you are. However, if finances are tight and/or you’re short on time, your back yard would work, too! Then, you need to try to find organisms in as many taxonomic groups/categories as possible. You need to observe and take notes on each organism you find — you do not need to try to catch them or pick them up, but rather, observe their natural behavior — then go look up further information on each of those organisms. The grading criteria for this assignment are given below, and you should also refer to those as you work on the assignment. A total of 26 points is possible.
1. Taxonomy: | ||
---|---|---|
2 | — | Representatives of 4(+) kingdoms were included |
1 | — | Representatives of 2-3 kingdoms were included |
0 | — | Representatives of only 1 kingdom were included |
2 | — | Representatives of 4(+) plant divisions were included |
1 | — | Representatives of 2-3 plant divisions were included |
0 | — | Representatives of only 0-1 plant division were included |
2 | — | Representatives of 4(+) animal phyla were included |
1 | — | Representatives of 2-3 animal phyla were included |
0 | — | Representatives of only 0-1 animal phylum were included |
2 | — | Representatives of 4(+) arthropod classes were included |
1 | — | Representatives of 2-3 arthropod classes were included |
0 | — | Representatives of only 0-1 arthropod class were included |
2 | — | Representatives of 4(+) vertebrate classes were included |
1 | — | Representatives of 2-3 vertebrate classes were included |
0 | — | Representatives of only 0-1 vertebrate class were included |
2 | — | 11 or more total organisms were included |
1 | — | 6-10 total organisms were included |
0 | — | 5 or less total organisms were included |
2 | — | 5(+) scientific names were included |
1 | — | 2-4 scientific names were included |
0 | — | 0-1 scientific names were included |
2. Ecology: | ||
2 | — | Descriptions of the organisms’ traits/characteristics were thorough and showed that the student was extremely observant |
1 | — | Descriptions of the organisms’ traits/characteristics were adequate and showed that the student was fairly observant |
0 | — | Descriptions of the organisms’ traits/characteristics were too sketchy and showed that the student wasn’t very observant |
2 | — | Descriptions of the organisms’ habitat and environmental conditions were thorough and showed that the student was extremely observant |
1 | — | Descriptions of the organisms’ habitat and environmental conditions were adequate and showed that the student was fairly observant |
0 | — | Descriptions of the organisms’ habitat and environmental conditions were too sketchy and showed that the student wasn’t very observant |
2 | — | Descriptions of the organisms’ interactions and behaviors were thorough and showed that the student was extremely observant |
1 | — | Descriptions of the organisms’ interactions and behaviors were adequate and showed that the student was fairly observant |
0 | — | Descriptions of the organisms’ interactions and behaviors were too sketchy and showed that the student wasn’t very observant |
2 | — | Descriptions of the human impact on these organisms’ environments were thorough and showed that the student was extremely observant and thoughtful |
1 | — | Descriptions of the human impact on these organisms’ environments were adequate and showed that the student was fairly observant and thoughtful |
0 | — | Descriptions of the human impact on these organisms’ environments were too sketchy and showed that the student wasn’t very observant and/or gave little evidence of putting much thought into it |
3. Overall: | ||
2 | — | The student, obviously, went beyond the minimum requirements of the assignment |
1 | — | The student adequately completed the assignment |
0 | — | The student completed considerably less of the assignment than what was required |
2 | — | It is evident that the student used much insight, thoughtfulness, and critical thinking when completing this assignment |
1 | — | The student adequately thought about the assignment – there was, perhaps, a bit of “fuzzy thinking” in a couple places |
0 | — | The assignment gives the appearance of being “slapped together” just to get it done, with little evidence of thoughtfulness |
Total Possible: | ||
26 | — | total points |
Some References Pertinent to the Creation-Evolution “Debate”:
Note: these are listed as examples of the many books that are available.
Campbell, Neil A., Lawrence G. Mitchell, Jane B. Reece. 1999. Biology, 5th Ed. Benjamin/Cummings Publ. Co., Inc. Menlo Park, CA. (plus other editions)
Campbell, Neil A., Lawrence G. Mitchell, Jane B. Reece. 1999. Biology: Concepts and Connections, 3rd Ed. Benjamin/Cummings Publ. Co., Inc. Menlo Park, CA. (plus other editions)
Curtis, Helena. 1983. Biology, 4th Ed. Worth Publ. New York, NY.
Darwin, Charles. 1859. The Origin of Species. (reprinted numerous times since then)
Heath, Thomas L. 1991. Greek Astronomy. Dover Publ., Inc. New York, NY.
Lewis, C. S. 1964, 2007. The Discarded Image. Cambridge University Press. New York, NY.
Lewis, C. S. 1966, 2007. Studies in Medieval and Renaissance Literature. Cambridge University Press. New York, NY.
Lewis, C. S. 1970. The Laws of Nature. God in the Dock. Walter Hooper, Ed. Wm. B. Eerdmans Publ. Co. Grand Rapids, MI.
Lewis, Ricki. 1992. Life. Wm. C. Brown. Dubuque, IA.
Parker, Andrew. 2009. The Genesis Enigma. Dutton/Penguin. NY.
Schroeder, Gerald L. 1990. Genesis and the Big Bang. Bantam Books. NY.
Schroeder, Gerald L. 1997. The Science of God. Free Press. NY.