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Bio 103, Week 5, Diversity an Evolution

Paul Grobstein's picture

Glad you're here, to share explorations of life. If you're registered in Biology 103, remember to log in before posting here. Others are welcome to contribute without logging in. Such comments though will be checked to avoid spam postings and so be delayed in appearing.

In any case, remember that this isn't a place for polished writing or final words. Its a place for thoughts in progress: questions, ideas you had in class (or afterwords), things you've heard or read or seen that you think others might find interesting. Think of it as a public conversation, a place to put things from your own mind that others might find useful and to find things from others (in our class and elsewhere) that you might find useful. And a place we can always go back to to see what we were thinking before and how our conversations have affected that. Looking forward to seeing where we go, and hoping you are too.

You're free to write about anything that came into your mind this week. But if you need something to get you started, what did you think of our discussion of evolution? Is it a good scientific story, one that summarizes lots of observations and raises questions/possibilities that might not otherwise have occurred to one?
Shanika's picture

Sorry I posted late: "Evolution is dangerous.


Yes Evolution is a process, a changing process that will never stop forming new stories of observations. It is endless. Evolution is kind of scary when i look at it from family point of view. My mom constantly reminds me every night that "God" is good. She made me believe that "God', created the world and everything in it. With the conversation of Evolution, "God" did not create the world. If i ever speak of the idea of evolution with my mother, I will be told off. It is dangerous because it makes me think other than what my mother convinced me to believed. I wonder How she would react if she reads what I am posting now!

Any ways...Humans are distinctive in differen't ways. I feel as though all living things have a purpose on this world. How different are humans from other organisms if we all have unknown purposes to be found?

Shanika Bridges-King
LaKesha's picture

I think that evolution is so

I think that evolution is so interesting. The thought that we, HUMANS, are still evolving is soooo cool. I mean what's next. I want to know. I mean the thought of humans going extinct is scary but I don't think thats going to happen. I meann we hae come so far and there is soooo much technology out there helping humans to live longer lives. I wonder whats going to happen....evolution is a neverending story....or will there be an end?
Sharhea's picture


This week I have to say that the lab was good. Although my partner and myself couldn't quite get our onion membranes to do what the others did and did enjoy learning about osmosis. I have never had osmosis explained to me through an experiment but just a definition. I never quite understood it until this lab.
vcruz's picture

trying to make sense with the story...

Although this whole new concepts on evolution are still battling in myhead, like many have mentioned, I can't imagine this world without humans.I can't agree with the idea that something else will come out, or evolvefrom us. It's easier for me to see the changes and adaptations in animalswith their environment and as mentioned in class the idea that there areinternal changes in species create environmental changes, which then causenew changes in the new species seems logical. Still, I can only apply thatto animals, like Darwin's finches. The whole idea of humans going extinctis not something that will convince me just because of what's happened inthe past with old species - even if it's 99% of them..., if that was thecase, then prokaryotic cells would not exist any more - since that's whatit all started with and created new cells. I can however think ofdifferent ways in which humans have adapted to different things, likelifestyles, different eras, etc. The idea of a physical change is notsomething that I take, even when argued that our brain has evolved,because I see that due to more discoveries leading to more intelligentobservations of things rather than smarter brains...

r.mabe's picture

the story of evolution

the story of evolution is an amazing story. it is astounding that while the change that is constantly occuring is usually very slow, it sometimes is rapid and major. On Friday, I found the discussion of the atmosphere's evolution very interesting-it is amazing that there was a time when most of the organisms on earth were poisened by oxygen since our very existance depends on it. Examining the fossil record puts our position in perspective, we have no right to assume that we will be on top or even in existance forever. What is shocking to me is that the things we take for granted and view as constant are in actuality only semi-constant and that the very things we depend on are going to shift eventually. When considering the end of the human race I usually I think about it in terms of our destructive actions (to each other and the earth) and it is very eye-opening to think about the earth altering changes that have occured in the past as a result of some outside source. I think that it is important to look at evolution to put our existance into perspective and realize how fragile we are. 
kharmon's picture

Friday's discussion was

Friday's discussion was definitely overwhelming! I for one can't imagine a world where humans are not the dominant form of life. Of course, I won't necessarily have to face this issue in my lifetime, however it surely gives you something to thing about. On the other hand, theres that statistic that 99% of all organisms in the fossil record are now extinct. I'm still grappling with the idea that humans could one day be a minority, but it is STILL entirely possible that we could just become extinct. As a matter of fact, it's not just possible, it's likely when considering history and its patterns.

In a way, this statistic contradicts what we agreed to about evolution. We decided that "better" cannot really be used when comparing existing organims because just like we have been successful enough to thrive on Earth, so have bacteria and prokaryotes that exist today. For humans to become extinct like the majority of the fossil record's other organisms, something BETTER would have to come along that would prevent us from thriving. I hate to be arrogant, but can anyone think of anything better than us? Not smarter, not more efficient, not bigger, but better?

OrganizedKhaos's picture

Evolution as it continues

The discussion on evolution was very interestong. The idea that prokaryotic organisms were not better or more advanced than eukaryotic ones was a new concept. It makes sense because they do still exist. What really intrigued was when we began to think about humans and how evoltuion doesnt necessarily stop. As we are now the dominant organism on earth and bacteria was once dominate but as decline will the same happen to humans? will we become outnumbered? it's something to ponder.
asavannah's picture

A World Without Humans?

I thought that Friday’s discussion on evolution was very interesting. I have always found evolution to be a process that was very visible in animals but not much in humans. When the question of, how have humans evolved over the past 60,000 years was asked, it made me think. The class came up with answers like our skin color has changes and we have gotten taller. Then the question of what will happen to humans in the future was asked. This was very interesting because many people said we may be extinct. What would the world be like if there were no humans? What would replace us?

PS2007's picture

Still Evolving?

I was really interested in the idea that humans are still evolving. A lot of other people have already touched on this, but I left the class thinking about what the humans of the future will look like. An idea that is really controversial is designer babies, or the idea that one day we will be able to pick and choose the best genes for our children. This seems to me like a kind of sped up evolutionary process. I don't really know how I feel about the idea of designer genes, but if we are ever able to actually do this it would be interesting to see what traits humans choose for their children and how we evolve when we have more control in the process.
Rachel Tashjian's picture

Designer genes = (un)natural selection?

I was thinking about the same thing. I heard this story about a year ago on NPR about how parents are beginning to select for certain genes in their children-to-be. The story first explained this through a couple that had a child with a rare genetic disease that died within a few weeks of its birth, so when they decided to try to have children again they selected for an embryo that didn't have this disease. (Would that be considered unnatural selection?) This made sense to me, and I thought, "Wow! Here's an example of science being used for great things!" But later in the story, the reporter said that couples might start using this for what I thought were more artificial reasons...I don't remember exactly what they were, but they were things like hair color, height, and speculations about athletic abilities, etc. Then I thought, "This is preposterous!"

Now that I think about it, though, I'm not sure why it is exactly that I have such drastically different reactions to the two. I believe abortion should be available to women, but think it is her personal choice. So shouldn't I feel that "designer genes" should be available but a personal choice?

The "designer genes" idea just seems so unnatural, like it might create an army of robots. But if it's a change inflicted by a species (despite the aid of science) couldn't it still be considered natural selection?

ekoike's picture

This whole discussion about

This whole discussion about designer genes that we had in class was really interesting-! It made me think so much about what constitutes a "designer" selection.

Someone in class was saying that we make our own designer selections through choosing our partners... and perhaps in some sense, we are making our own steps towards "selecting" desirable traits and passing them off to our offsprings.

The whole idea of "designer genes" is a bit unnatural... and probably creates less of a variation (that would occur more in natural selection).

Jen's picture

I think evolution is a

I think evolution is a useful story which helps us make sense of our current observations; however I do not think it is the be all and end all; for instance, evolution does not help describe why organisms conform to the Golden Ratio.

I also do not understand why those who believe in Intelligent Design theory or those who believe that God created the universe must completely dismiss evolution theory as counter to their religious beliefs. For all we know, God could be the author of evolution, or evolution could be one of many tools He used to create the universe.  
andrelle's picture

Usually when people think

Usually when people think of evolution or just about life in general, we always put humans on top as the dominant specie.  It's hard to think that before humans were on this earth, there were species that were the most superior.  When we think about it, it lets us know that eventually there could be the rise of another specie, and that specie could become dominant.  I know that its hard and scary for me to think that there could ever be anything bigger than us. 

eharnett's picture

Humans evolving

Like many of the previous posters I, too, find it hard to believe that humans are still evolving.  Though it does make sense (we can see that there has definitly been recorded changes in humans, such as becoming taller) it's still hard to believe.  Evolution does not have one set "goal"-like we discussed in class, it is not necessarily working to make the "perfect being", so this should explain why humans would still be evolving.  I'm just intrigued and curious as to what some of the changes will be to humans in the future. 
kcough's picture

Again, I thoroughly enjoyed

Again, I thoroughly enjoyed this week’s lab. I really like working with the microscope—it’s so amazing that there is another invisible world moving around, under and through us all the time. It is also amazing that these invisible things change and react just as we do. I loved watching the cells swell and deflate as we removed and added the sodium solution—it was fascinating to see what a calculated impact we were able to have on them.


I also found class this week very interesting, especially on Friday. It is mind boggling to think that 99% of life has gone extinct, and that humans, in all likelihood, will suffer the same fate. What then are the organisms that are still around? Is it just prokaryotes that have survived throughout the ages? If so, why? It seems as though the more complex an organism is, the more difficult a time it has surviving. I suppose that would make sense, seeing as how more complex organisms depend on more things. I wonder what would have happened had that meteorite never hit earth…would humans still have evolved?

Samar Aryani's picture


Like a few have already suggested, the idea of evolution is a very complex story but at the same time a good story.  It is interesting to think that simple organisms have evolved into more complex organisms.  The concept itself is fascinating because it is hard to grasp the idea that we are all different because we are a product of a system that produces with variation but at the same time it makes a great deal of sense!  Also, the idea that humans are only a step in the process of evolution and not the final result is scary but understandable because as history has proven, there are many organisms that have come into existence and then gone extinct.  It is all fascinating but rather mind-boggling at the same time!

cmcgowan's picture

I really enjoyed discussion

I really enjoyed discussion this week because it clarified a topic that I always found out-putting. Before this class, evolution was always described to me as "survival of the fittest." For some reason this phrase has become the universal phrase associated with evolution and it never really made sense to me. I always thought there was something more that needed to be said. I like the idea of describing evolution as a combination of descent with variation and natural selection.  I think it makes a lot more sense than "survival of the fittest." It seems to me that people have always understood survival of the fittest as it relating to individual organisms, but I don't think that is how it supposed to be understood. I think it is more the survival of genes by reproducing successfully and I really don't understand where "the fittest" is supposed to apply. I don't think that there is one characteristic or even a few characteristics that we could use to determine fitness in this sense. 

I have realized this week how humanocentric a lot of science is. I think that we often just assume that we as humans are the most superior forms of life when really we have no concrete evidence to prove that. I like the idea that we are not better in a biologocal sense just because we are more complex than other species, although it is a bit unnerving to realize that humans are not the culmination point of evolution. It is especially unnerving because I will never get to know what comes after us...

In the past whenever I read news articles about scientests discovering new species, I never really realized what that meant about the whole grand scheme of evolution and diversity.  I think my general reaction was "How many more species can they really discover? Can there really be that many left?"  I realize now how ignorant those thoughts were. Scientests will never stop discovering new species because new species will never stop being created. We will never be able to have concrete answers for what life is and we will never be able to reduce our knowledge of species to a single number. Life will never stop changing and diversity will never stop expanding and branching out. I like this. 
ekim's picture

on evolution.

i like the notion that evolution is a consequence of history 'cause that puts a time dimension to the change which doesn't simply equivocate "change" as necessarily being advancement, which is why there are still the simple living organisms like bacteria and complex living organisms like humans.

but what i don't get is how from simple living organisms...other more complex living organisms came about. are we all essentially related in a sense then?


Kendra's picture

Humans still evolving?!?

I found the class discussion on evolution fascinating. I have always had an interest in evolution and how it happens etc. It was very interesting to learn that humans are only at a stage in evolving and although I did not understand why at first, I soon learned that it makes sense. Using prokaryotic cells and other bacteria as an example, the specimens that were found millions of years ago were not the same as the ones that exist today. They evolved. So, it would make sense to realize that humans are still evolving. Though this process takes thousands and thousands of years it really makes me wonder...into what will humans evolve?

I also found it interesting the discovery of a small layer of iridium. I just thought it was cool that it is very rare on Earth yet common in meteors. 

I hope we go into more detail in class about humans still evolving... 
LuisanaT's picture

In case I didn't make myself clear about the photocopy analogy

In the book I am reading for this class, The red Queen, Sex and The Evolution of Human Nature, the author, Matt Ridley helps us understand the idea that asexual reproduction is more vunerable to losing its ability to contribute its specific genes when bad mutations are also apart of the organism.

First, we must understand Herman Muller's the "Muller ratchet", which can be explained like this:

There are ten water fleas in a tank, only one of which is entirely free of mutations; the others all ahve one or several minor defects. On average only five of the water fleas in each generation manage to breed before they are eaten by a fish. The defect-free flea has a one-in-two chance of not breeding. So does the flea with the most defects, of course, but there is a difference: Once the defect-free flea is dead, the only way for it to be re-created is for another mutation to correct the mutation in a flea with a defect- a very unlikely posibility. The one with two defect can be re-created easily by a single mutation in a water flea with one defect anywhere among its genes. In other words, the random loss of certain lines of descent will mean that the average number of defects gradually increases. Just as a ratchet turns easily one way but cannot turn back, so genetic defects inevitably accumulate. the only way to prevent the ratchet from turning is for the perfect flea to have sex and pass its defect-free genes to other fleas before it dies.

Muller's ratchet applies if you use a photocopier to make a copy of acopy of a copy of a document. With each successive copy the quality deteriorates. Only if you gaurd the unblemished original can you regenerate a clean copy. But suppose the original is stored with the copies in a file and more copies are made when there is only one left in the file. You are just as likely to send out the original as to send out a copy. Once the original is lost, the best copy you canmake is less good than it was before. But you can always make a worse copy just by copying the worst copy you have.

( Ridely, Matt 48)

LuisanaT's picture

Gaps between the clusters

Why are there these "empty spaces" between what we call clusters of clumps? One theory is that the organisms that would fit the criteria have not been discovered and therefore not classified as such. Another theory could be that evolution and time have not introduced the appropriate environment and elements necessary for that type of organism to arise. If the natural changes in the environment do not cause enough of an effect to bring about a new clump of organisms, than the effect it must have on atleast one of the clusters of clumps can cause a new enough change to occur and continue the never-ending evolutionary process.

Now if it is true that there are "gaps" under any scale, does that mean that there are "gaps" even at a small scale in humans? For example, there are million upon millions of different combinatiosn in physical appearance alone. Can there really be a gap within that crumb of a clump of a cluster?

One thing that occurs often in classrooms is that people would (and the professor would do so purposely) ask the wrong kind of question. For eaxmple, when the question of why there is diversity was brought up, it made the rest of the class stray away from the right question, and therfore right answer. Becuse its not a matter of why there is diversity but rather why there isn't homogeneity. The combination of reproduction with variance where there is differential contributuion of genes in the next generation with changes in the environment causes distinctions amongst groups where some will thrive in different ways than others.

But this way is of conducting a class is probably the best way to approach any matter of science because its similar to what happens in a laboratory experiment proving your hypothesis wrong; it forces you to really look at whats in front of you for further evaluation. Way to go all Profs out there.

Shanika's picture

Just some thoughts

It was mentioned in class today, that the past is an indictation of the future". If this is true, are humans going to be extent just as the dinasours? Evolution is an evolving process itself, but i can not believe that humans will become extent.I have a problem with the notion that the past is an indictation of the future. It is a bothersome statement when i think of it in the content of "HUMANS". Can one make sense of the past to reflect it to the future?
kgould's picture

ID v. Evo

I've found all of our discussion on Evolution very interesting and I can't wait to move further into the subject. I'm currently taking Anthropology 101 and we're currently tackling the subject of Evolution, specifically that of hominoid apes and humans. We also got to write a paper (lucky us!) on Intelligent Design and Evolution.

I found the comparison of Intelligent Design and Evolution... interesting. It made me wonder what people were thinking when they decided that Intelligent Design was a "science" and should be taught in schools.

Whereas Evolution has mountains of evidence to back it up (literally, mountains), Intelligent Design has, well, nothing.

It is my understanding that mainstream scientists avoid debating over Intelligent Design because they think it might give the scientific "theory" some credibility...

I think people are entitled to believe what ever they so choose. That is what makes life so interesting; that is what allows for change and growth and development. But does that cross the line when state legislators are pushing for the teaching of Intelligent Design in schools? 

ekim's picture

on evolution and movement.

just a thought:

if change over time accounts for clustered diversity and reproduction with variation accounts for individual variation, does random movement (of atoms) account for anything? i mean, after all, everything around us, including us, is made up of atoms.

Kee Hyun Kim's picture

humans are special

First, i was a little bit surprised that Eukaryotic organisms were not necessarily more adept or advanced than their Prokaryote counterpart, the only difference is the level of complexity. In hindsight, its a very obvious idea but for some reason, i always thought that because eukaryotic organisms appeared much later, they were therefore more advanced and fit.

Paul Grobstein's picture

clustered diversity, reproduction with variation and randomness

Next way to think about it but maybe too one to one/parallel? More multi-factorial and loopy? Clustered diversity results from descent with variation AND time (and randomness in the environment?). Descent with variation itself depends on randomness in the atoms/molecules, (ie mutation), as well as at other levels? And perhaps in turn causes additional variation in descent with variation?
ekim's picture

so it's a cycle.

there's clustered diversity 'cause of descent with variation and time, and there's descent with variation and time 'cause of clustered diversity. they're interdependent and "loopy" 'cause of the randomness of all the atoms/molecules that living things are made up of.

just goes around and around.