As the hot volleyball players Rock Strata 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.

Human Biology Natural Selection and Evolution

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.

Change 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. Silkmoths 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:

  1. In any population of organisms, there is variation. For example, look at the variety of hair colors, eye colors, and skin colors (to list just a few traits) in humans. This also applies to things we can’t see. For example, some people can drink milk with no problem while others are lactose-intolerant.
  2. Those variations can be passed on. As parents mate and have offspring, they will each give half of their genes to each child. For example, maybe there is a maple tree whose genetic makeup just happens to cause it to grow much deeper roots than average, and thus, it survives better through a long, dry summer. When that maple tree produces seeds, those seeds will likely contain the gene for deep roots, and therefore the trees into which those seeds grow will also be drought-resistant.
  3. More offspring are produced than the environment can support, so there is competition for resources. Note here that “competition for resources” usually does not mean an out-and-out battle. Our maple tree with deeper roots will better be able to get enough water to survive in a dry year than another, nearby maple tree with more shallow roots. Note that the resources in question might be anything from food to water to hiding places to not being seen and eaten by a predator, etc., etc.
  4. Thus, this leads to survival of the fittest. “Fittest” does not necessarily mean the strongest when/if it comes to a fight. Fittest might mean anything from best able to survive a drought, best able to eat and/or deactivate toxic antibiotics, smartest and best able to figure out how to get food, best camouflaged, etc., etc. For example, in Charles Dickens’ book, Oliver Twist, it might be said that the most “fit” boy would have been the one who was the sneakiest, best pick-pocket. Those organisms whose genes just happen to make them best suited for their particular environment will live and produce offspring, thereby passing on their genes. Those organisms whose genes make them unsuited to their environment will probably die and will not produce offspring or pass on their genes.

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. Moths on Trees 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.


Background Information

Links to Related Information on Our Web Server

The following Web pages contain information related to the Theory of Evolution.

Bio Lecture History of Science
Information on the history of science, including the beliefs of the early Hebrew people
Bio Lecture Human Genetics
Includes information on sickle-cell and malaria
Bio Lecture Early Models of “Evolution”
Some of the ways people used to think organisms came into being, and some of the ideas that led up to the formulation of the theory of evolution
Bio Lecture Origins of Life
One of the leading theories put forth to explain how life first arose on planet Earth
Bio Lecture Darwin and Darwinian Evolution
Information on Charles Darwin and his ideas
Bio Lecture Natural Selection
Information on how Natural Selection can lead to speciation, and a discussion of the major groups of life forms living here on Earth
Bio Lecture Arthropods
Pay special attention to the section on arthropod evolution.
Bio Lab Biometrics Lab
An activity to illustrate the variation in height, weight, and age of college students

Your Assignment
A Scavenger Hunt

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. Kingdoms: Finding organisms in Kingdoms Fungi, Plantae, and Animalia should be fairly easy. If you look in just the right place, you might also be able to see some of the larger organisms from Kingdom Protista. You probably will not be able to see any of the organisms in Kingdom Monera without a microscope.
  2. Phyla (Divisions): Figuring out to what phylum (botanists use the word “division” instead of “phylum”) organisms in Kingdoms Protista and Fungi belong would be difficult, but there are a number of Phyla/Divisions in Kingdoms Plantae and Animalia that are fairly easy to identify. These includethe following.
    Within Kingdom Plantae it should be fairly easy to find representatives of
    plus, if you are fortunate enough to be in just the right place, you may see representatives of Division Lycophyta or Division Sphenopytya.
    Within Kingdom Animalia, you can probably find representatives of
    plus, if you go to the Aquarium or the Zoo, you may also be able to find representatives of Phylums Porifera, Cnidaria/Coelenterata, and/or Echinodermata.
  3. Phylum Arthropoda: Finding members of the following classes is possible, but you probably will not find representatives of all of these groups at once unless you are able to go somewhere like the Insect World at the Zoo. These include
    plus, if you are able to go to the Zoo or the Aquarium, you might also be able to find members of Class Xiphosura.
  4. Phylum Chordata, Subphylum Vertebrata: If you’re using your back yard, several of these might be difficult to find if you live in an urban area, but in general, the possibilities include
    plus if you are able to go to the Zoo or Aquarium, you can probably also see members of Class Chondrichthyes.
  5. Note that because the taxonomic heirarchy is “nested,” a given organism may represent several taxa. For example, a cat would represent Kingdom Animalia, Phylum Chordata–Subphylum Vertebrata, and Class Mammalia. Also, note that you will only get credit for organisms that are correctly placed — for example, credit would not be given for a domestic dog listed as a plant.
  6. For as many as possible of the organisms you find, look up and include their scientific names. The list of species seen on campus may be of help. Do not expect to find scientific names for everything you see. For example, there are so many kinds of flies that look so similar, it takes a PhD to identify them to species, but if you would see something like a Monarch butterfly, that species name is “easy” to find.
  7. For each organism, take notes on their characteristics: what do they look like, do they have any “unusual” body parts, what are they doing, how do they move, etc.
  8. Describe the habitat/environment in which each organism is found. If you’re at the Zoo, Aquarium, etc., these habitats may be very different, but if you’re in your back yard, it may seem, at first glance, like all the same habitat. Look more carefully, then — for example, the habitat in a flower bed would be different than the habitat in the middle of a lawn area. Notice (and take notes on) the amount of light (shady under trees and plant leaves vs bright sun in open lawn area), temperature/heat (cooler under trees, really cold in a penguin exhibit at the Zoo), humidity, soil conditions, etc. in the organism’s environment.
  9. Describe the organisms’ interactions with other organisms that share their habitats: what do they eat or how do they get food, who eats them, how do they defend themselves from predators (chemical defenses, camouflage, teeth and claws, or whatever). Do you see anything that looks like mating behavior? If they eat food, how do they eat their food (chew it up, suck it up, etc.)? How do they communicate with other members of their species and with other organisms? Are they solitary organisms or do they typically live in a social group such as a colony or pack? What is each organism’s “job” within its environment — what does it do there? Do you see any other interesting behavior patterns?
  10. Describe how human intervention, “good” or “bad,” has influenced each organism and its environment. For captive organisms, you may wish to consider both their normal, natural environment as well as the artificial or display environment in which they are currently living. Is there anything that we could/should be doing to improve and/or properly manage those environments?
  11. At this point, if you are a registered student, you should submit your work.

Grading Criteria

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.


Copyright © 2006 by J. Stein Carter. All rights reserved.
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