BIOL 112 – YOUR Opinions, Comments and Questions on Evolution

Spring 2008

Support of Darwin's Theory	MWF Section
YES	56%
NO	0%
CONFLICTED*	12%
No Answer	32%

 Fall 2007

Support of Darwin’s Theory	MWF Section	TR Section
YES	83%	76%
NO	3%	14%
CONFLICTED*	11%	10%
No Answer	3%	0%

 

* "No, although I know things do and can evolve….", "Yes, but my religion says no....." and similar responses.

 

 Your Comments about Evolution; my responses:

 

1.      Nature is so complex that it allows for the process to happen, yet simple enough that it could happen.  Very nicely stated!

2.      Honestly, I’m not that interested in how it all began.  I am more interested in what we do know about organisms and the environment, how they work, and what we should do to preserve.  This is a perfectly valid point of view, and we are coming to the nuts and bolts of structure and function soon.  But re-consider the value of learning about the processes that produce diversity.  It puts the whole picture into perspective.  Remember that evolution is an on-going process, and what we “do” might alter the process.

3.      I also believe that we as people have been responsible for most of the adaptive changes we see in animals to day.  Our pollution, destroying of wetlands, etc have all contributed.  These are relatively recent events and have occurred over very short time frames from an evolutionary perspective….  There is no question we are changing the environment.  The consequences are hard to predict, and will probably include both extinction and adaptation.

4.      I am just wary that the way we live may have a negative impact on our biological evolution or that of other species.  Well, we are certainly the cause of many extinctions, and we are certainly altering some very basic processes on the planet.  Where that will take us all – no one knows.

5.      …there are many holes in the theory so I don’t claim it as true.  Holes?  Not really.  Many processes remain to be fully understood, and few lineages are fully understood, but the basic premises behind the Modern Synthesis are sound and supported by the evidence.

6.      My uncle is not a monkey.  Of course not.  Modern humans and modern monkeys emerged from lineages that separated 6-10 MILLION years ago.

7.   Spring 2008 - A surprising number of you thought it was OK to teach Intelligent Design in the public schools.  ID is a faith-based approach to explaining diversity.  It provides no testable hypotheses.  The Raelian Movement is essentially a joke.

 

Your Questions about Evolution; my responses:

 

1.      Can you be a Christian and still believe in evolution?  Many Christians do.  Many religious people think that a god caused evolution to start.  Many consider the timelines in the Christian Bible allegorical (ie: a “Biblical Day” doesn’t have to be 24 hours long).

2.      Did Darwin talk about the evolution of humans from monkeys or is that a modern assumption?  From Dr. Hillenius:  He wrote a follow-up book, “The Descent of Man,” published in 1871, in which he outlines how he thinks his theory would apply to humans.  But this was published before the discovery of most fossils of human ancestors (Neanderthals had been known since the 1820s, but were not particularly instructive as to human origins.  Eugene Dubois found the first “missing link,” Java Man (now considered to be an example of Homo erectus) in 1891, but the significance of that find was not generally recognized at the time.  Raymond Dart, in 1928, found first widely recognized ape-man fossils: the Taung child from South Africa)

3.      What was Darwin’s religion?  Could his theory be based on a higher power?  What did the religious community say when Darwin published the theory?  Apparently Darwin was a Unitarian, later losing faith, and even later becoming agnostic.  I found a lot of very interesting information about Darwin’s personal life, and both social and scientific reactions to his work, on two websites.  Check them out if you are interested:   http://darwin-online.org.uk/ and http://www.aboutdarwin.com/index.html

4.      Are there any theories that refute evolution, or evidence that contradicts Darwin’s theory of evolution?  Not to my knowledge.  The only alternate explanations are faith-based and not testable.

5.      If the mechanism of evolution is natural selection, why do species that are less adapted still exist?  Species that continue to persist on this planet are adapted to their current conditions.

6.      What is the main component of evolution?  Change over time.  Review the Modern Synthesis and the agents of micro-evolution that we discussed.

7.      I would like to see the facts behind this theory.  I would like to know exactly how scientists came up with the theory of evolution and did one specific organism make scientists think of this theory.  No one organism.  Darwin made many observations of different species on his voyage on the Beagle that led him to develop the basic theory.  Other scientists were beginning to draw the same conclusions.  One big factor was the developing understanding amongst geologists that the earth was much older than previously thought; the concept of geological time was influential in Darwin’s thinking.  Again, review the Modern Synthesis, and if you are interested, read that section in your text that covers the historical aspects of Darwinism.

8.      Could a seemingly random event, like the death of only a few organisms, bring about a major setback in evolution?  Evolution doesn’t really experience “setbacks” – change is constant.  With species that are being bottlenecked, the loss of a small number of individuals could certainly have a big impact, but I would not call that a setback.  Even extinction is a natural process – change is constant.

9.      Several of you asked about mutations, and wanted to know if there are any animals that underwent mutations that changed their populations?  Remember, mutation is the only source of new alleles….  From Dr. Hillenius:  Other than “all of them?”  How about AZT-resistant HIV virus (the population of which evolves within a single patient), antibiotic-resistant bacteria (the population of which usually evolves as they spread between multiple patients), and pesticide-resistant insects (the populations of which evolve over multiple years)?  Larger animals?  How about smallpox sensitive vs smallpox-resistant humans in North America?  Prior to Columbus, the population here consisted mostly of smallpox-sensitive individuals, now the population consists mostly of smallpox-resistant individuals.  This is due obviously to migration – prior exposure in the old world had selected for smallpox resistance among the colonists.  But even if you limit this question to just the population of native descendants, I’ll bet there is a greater frequency of smallpox resistance now than there was then.  Other examples: hawthorn flies, banded water snakes, Darwin finches in the Galapagos, etc.  Details can be found in Freeman & Herron.

10.  Several of you are still confused about the random nature of meiosis and recombination, how those processes affect allele distribution, how alleles (DNA) change, and how all these processes affect the genetic structure of a population over time.  Review the section on meiosis (Chapter 13) in your text to understand the processes, and especially the very last concept section.  One random part occurs when the replicated, homologous chromosomes line up on the metaphase plate for the first “big split” – where the maternal set goes one way and the paternal set goes the other way.  That line up is random – there is no force that makes maternal go one way and paternal the other.  Plus, every homologous pair lines up independently of every other pair.  With recombination, the homologous chromosomes randomly fuse at the same gene, at several points along the chromosomes.  When the homologous pair splits apart in Anaphase I, the “maternal” chromosome contains some sections of the paternal chromosome, and vice versa.  The result of both processes is a vast shuffling of the alleles that end up in the gametes – every gamete has a random combination of maternal and paternal alleles.  The frequency of each allele in the whole population has not changed – but every offspring has a different combination of maternal and paternal contributions.  Lots of variation.  Alleles change only through mutation.  Mutations are random changes in the nucleotide sequence in a gene.  Sometimes they produce a phenotypic change, sometimes they don’t.  Sometimes the change is adaptive, sometimes it is neutral, and sometimes it is harmful.  Natural selection acts to preserve the helpful and eliminate the harmful.  Change may be slow, but it is constant.

11.  I don’t understand how DNA just changes to help animals survive.  It doesn’t!!!  Mutations are random.  Some result in traits that help an organism (not just animals) be more fit in its local environment.  Positive changes tend to persist and accumulate.  Organisms do not “need” to evolve, and humans are not in the position where we “don’t need to evolve any more”.  Natural variation x natural selection leads to change.  There are no “perfect” organisms.  Change is the only constant.

12.  How has “uniformity and diversity” influenced evolution?  Helpful changes persist.  The structures and processes that are shared across so many organisms, what we call the “uniformity of life” (DNA, ATP, respiration, etc….), emerged early in the development of life on earth, and have persisted – they have been conserved in all subsequent lineages.  Diversity has emerged as the basic format – life – has adapted to the myriad ecological niches on the planet.

13.  Several of you expressed interest in learning more about homologous structures.  We’ll bring up examples of homology and analogy throughout the semester.  It’s good to keep thinking of this and to try to draw your own questions and conclusions about both the material we will be discussing, and what you see in the world around you.  If you are really interested, plan on taking Evolution (BIOL 350) later in your college career

14.  Several of you were interested in learning more about transitional species and to see more examples.  Plan on taking Evolution (BIOL 350) or Dr. Hillenius’ wonderful Maymester course on dinosaurs.  Also, do the optional National Geographic quiz – lots of fascinating examples there.

15.  I’m still confused about genetic drift and gene flow.  Genetic drift occurs when only a sub-set of the parent population reproduces, which can lead to a “drift” away from the allele structure of the parent population.  Gene flow tends to homogenize the allele structure of a meta-population, as alleles are exchanged by immigration and emigration between partially segregated sub-populations.

16.  Why are bottlenecked species such as the cheetah more at risk of extinction?  Because their genetic diversity is so limited.  They are a “small sample”.  Change is constant, and if the available alleles are not adequate in a changed environment, the species takes a hit.

17.  Can two species mate to produce a new species?  Sometimes, but the essence of our definition of species is reproductive isolation.  Review the pre- and post-zygotic barriers to successful reproduction.

18.  Several of you expressed interest in learning more about the big bang theory and the very beginning of life.  You will learn more in 211 about our understanding of how the earth formed and when life emerged.  One thing we simply do not know, and may never, is how the first truly living organism formed.  We do know, from fossil and other evidence, that it was single celled, prokaryotic, with replication possibly RNA-based.

19.  How did single celled creatures eventually evolve into multicellular organisms?  This, too, you will learn about in 211.  The best hypotheses so far are based on symbioses, gene exchanges, and pinched off bits of functional membranes.  It took a long time - complex multicellular organisms emerged only about 700 million years ago.

20.  Are humans still evolving or have we stopped and now we only influence the world around us?  Evolution is a constant.  Many evolutionary changes are not big and obvious from the phenotype.  From Dr. Hillenius:  Evolution is a change in the allele frequency in a population between successive generations.  More people survive infection with AIDS if they possess the CCR5-D32 allele, which is a mutant form of the CCR5 gene that codes for a co-receptor on the T-cells.  People die from AIDS.  The global population of people that don’t die (whether or not they were infected with HIV), and which continues to have babies, tends to have an increasing frequency of the CCR5-D32 allele.  Thus, the population of humans evolves.  Similar evolutionary events happen any time humans survive any other infectious diseases because they have a particular beneficial allele.  And also any time death and fecundity are predictably correlated with a particular genetic makeup.

21.  I would like to know how the human species is going to evolve, but no one can say that for sure.  I think you answered your own question there!

22.  Why do monkeys not still evolve into humans?  They never did.  I hope this is more clear now that we have discussed human evolutionary pathways a little bit.  See also comment #6 above.

23.  It would be interesting to look at the actual time scale of a specific species’ evolution.  Yes, fascinating.  I think this is another reason to take BIOL 350.

24.  How are birds and dinosaurs related?  From Dr. Hillenius, a noted expert in this very field:  Both are archosaurs, a specific group of “reptiles.”  Birds and dinosaurs share a common ancestor.  Possibly, birds and theropod dinosaurs (the bipedal meateaters) have a more recent, more exclusive ancestor than the more distantly related dinosaurs, and many paleontologists think that birds ARE theropod dinosaurs.  Others think they are no more closely related than, say, rabbits and rodents.  Crocodiles and alligators are also archosaurs, but more distantly related to the other two.  However, since dinosaurs went extinct, crocs are the closest LIVING relatives of birds.

25.  What is technology doing to us?  The technological revolution is considered by many to be the most recent major shift in human cultural evolution (as in the Industrial Revolution, Agriculture, etc).  Cultural shifts may have an evolutionary impact, but I think those are hard to predict.  From Dr. Hillenius:  It allows us to live longer and have fewer babies.  Or more babies, if we choose.  It lets more of us survive otherwise fatal conditions (such as diseased lungs or kidneys), but it also kills more of us due to high speed impacts with hard objects).  It allows us to get more stuff, food, nutrients, for less effort, so it costs more to live: we use more stuff and nutrients for the same number of humans as a result.  It allows us to live in times and ecosystems that were otherwise much more inhospitable, and to live in much greater population densities. 

26.  Why is the Hardy-Weinberg theorem used if it doesn’t happen in nature?  It provides a null hypothesis – something we can use to compare against natural populations to see if change is occurring.

 

 

Your Comments and Questions about the Course; my responses:

 

1.      I have to teach my self the material for me to understand it.  This is EXACTLY the way it’s supposed to work!  Keep up with that and you will gain true understanding.

2.      Can we get the images back in the PowerPoints on the web?  No, I’m sorry – there are serious issues of copyright infringement and also the file sizes would be way too large.

3.      Would I summarize the material from the day before?  I try to do this, and will continue to try.  It will also help if you all review your notes as you are waiting for class to begin.  I’ll also try to repeat the Key Concepts slide at the end of each lecture, but remember, you can always get those from the website.

4.      Quiz questions are not straightforward.  No, many of them are not.  As I’ve been saying from the very first day, memorization is not enough to do well in this class.  We are trying to prepare you for your upper-division classes, where synthetic thinking is key.  My questions are designed to make you use the information you know in a little different way, or to answer a new or different question.  Analyze the quiz questions until you figure out where you went right and where you went wrong.  That’s good for test-taking skill development.  Remember, many of my quiz questions come right out of my test bank.  Also, as I’ve said in class, words really are important, and the way words are put together into sentences determines the meaning of that sentence.  Read carefully.

5.      A study guide for the tests would be nice.  These are linked on our website.  If you have not already bookmarked our website, do it now!  Also, be sure to look at all the study tips that I have linked on our website.  You should study all the topics we have covered in lecture, using the text and the other materials to supplement, expand and cement your understanding.

6.      Can you talk more slowly……  I know, I know…..  I keep trying.  I’ve numbered the PowerPoints and that should help a bit.

7.      Several of you are struggling to take notes “in your own words”.  I suggest attending some of the study skills seminars aimed at improved note-taking.  Also, you might find it useful to look at the outlines and PowerPoint slides BEFORE lecture, so that you already have some idea where we are going.  Then try to summarize concepts, details and examples.

8.      …your slides should somewhat go over the outlines.  This is what I try to do.  Start by pairing the key concepts with the points on the outline.  Use the PowerPoint text, the text book, and your notes to expand the outlines.  Use your own words when you are expanding the outlines!  If you can re-phrase a concept in your own words, then that means you understand it!

9.      If I use a word you don’t understand, ASK ME!!

10.  Traffic is crazy (8am section).  Yes, I know.  You just have to plan for gridlock on I-26 and in parts of Mt Pleasant.  Leave home early and spend any extra time reviewing in the library – they open at 7:30am on weekdays.

11.  Feeling a bit lost….Don’t know how to prepare….Not sure what I should be doing outside of class…I like to write notes in class….  Don’t delay!!!  Get help now from either me or Alison.  Go to the Study Skills Seminars.  Review the syllabus and the website for more ideas on how to study.  If you can’t make my office hours, email or call for an appointment.  If you struggle to stay focused while you are reading, try to relate what you are reading to a real-world example from your own life.  Or, read in small units and then summarize the concepts….in your own words!  Also, keep in mind that just because the PowerPoints are available, that does not mean you MUST use them.  If you learn better by taking notes in class, do that!

12.  Some of you are still without a text, or are having trouble with internet access.  Please come see me!!!  You should certainly have a text by now.  You should be able to print some stuff at the library.  I can give you copies of some things also. 

13.  Some of you had this material in AP biology in high school.  Don’t let your guard down!!!  You still need to study the material and you need to think about it conceptually and in terms of application.  You should have a head start – use that to your advantage but don’t rely solely on your AP background.

14.  Ask for our opinions more!  I will, as time goes on.  Plus, you can always share your opinions either in class or by email.  I hope you will!!