Introduction to Evolution

I went to UNC Chapel Hill yesterday and gave a presentation to an honors seminar about evolutionary biology. (You can download handouts of the presentation here.) The seminar was organized by an undergrad and is covering the culture wars of evolution and intelligent design creationism.

My job was to, in a short amount of time, explain the basics of evolutionary biology (mostly popgen) to this group of mostly humanities students. The goal was to give them some foundation in evolutionary science to prepare them to evaluate the claims of intelligent design activists. Luckily they were honors students at UNC and were quick on the uptake. It was a pleasure to go through my slides and answer their questions about the mechanisms of evolution.

In the end I felt that a majority of the seminar “got it”. I hope it sticks.

Last night I got an email from the student organizer thanking me for sharing my knowledge with the seminar. He told me that the students learned a lot about evolution from my presentation and the discussion. I’ve also been invited back for another time, and I may take him up on his offer.

Update

Feel free to borrow any of my slides for Evolution Sunday or Darwin Day presentations. However, the presentation is actually much longer than 30 minutes.

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Yesterday, I introduced a seminar of honors students at UNC to the science of evolution. If you go to my blog, you can read how it went and download handouts of my presentation. De Rerum Natura: Introduction to Evolution... [Read More]

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Posted by minusRusty on February 7, 2007 6:29 PM

No fair!

In your presentation, you ask:

o Why do we vomit? How is it adaptive?
o Why do we vomit when we get dizzy?
o Why do we vomit after other people vomit?

But….….. what are the answers?!?!?!?

I’m half way across the continent, so naturally, I couldn’t attend. Drat!

Posted by Reed A. Cartwright on February 7, 2007 6:56 PM

Think about it and give me some answers. I’ll tell you if you got it right.

Posted by bgplayer on February 7, 2007 9:52 PM

Can you explain slide 20? I’m not sure what it’s supposed to show. Thanks.

Posted by Ron Bear on February 8, 2007 9:33 AM

I want to take a stab at the vomit questions.

Seems like it is an advantage to be able to get rid of bad food. Also if you overeat and/or get really gassy it is better to upchuck than to burst your stomach.

I don’t know about the dizzy part.

Could it be that vomitting when others vomit could be helpful if we all ate the same bad food?
Just guessing,
Ron

Posted by Reed A. Cartwright on February 8, 2007 11:15 AM

bgplayer wrote:

Can you explain slide 20? I’m not sure what it’s supposed to show. Thanks.

(Comment # 35122)

20 is an example of viability selection. The white balls with a red ‘x’ denote that that ball has died. The selection in this case is to blend in to the background.

Posted by Reed A. Cartwright on February 8, 2007 11:17 AM

You got it, Ron. You can answer the second point by connecting it with the first one and asking how the body detects that it has eaten bad food.

Posted by Ichthyic on February 8, 2007 8:20 PM

My only complaint would be your usage of the creationist definition of macro vs micro evolution (slide 5).

Unless the definition changed in the last year or so, AFAIK macro applies to the study of system-level processes affecting evolution, and micro to the study of evolution in populations themselves.

Or were you specifically using the definition you used to address the creationist “kind” issue, without actually addressing it by name (implied by the “same process” comment)?

Just curious as to why this specific approach and definition was used.

Posted by Reed A. Cartwright on February 8, 2007 10:21 PM

Ichthyic wrote:

My only complaint would be your usage of the creationist definition of macro vs micro evolution (slide 5).

Nope, Ichthyic, I used evolutionary biology’s definition.

macro applies to the study of system-level processes affecting evolution, and micro to the study of evolution in populations themselves.

What are you referring to when you say “system-level processes”?

Or were you specifically using the definition you used to address the creationist “kind” issue, without actually addressing it by name (implied by the “same process” comment)?

Nope, making sure that the students understood that “micro-“ versus “macro-“ is in fact an artificial distinction. The same types of differences that distinguish individuals in the same species also distinguish individuals in different species.

See this post of mine for more information.

Posted by Ichthyic on February 8, 2007 10:34 PM

What are you referring to when you say “system-level processes?

I’ve seen paleontologists refer to macroevolution in terms of things like bottlenecks and large scale events that actually affect evolution on multi-species levels. Punc-eek would be considered a “macroevolutionary theory” for example.

this is not an invention of mine, check the big argument we had about this on PZ’s blog along with Larry Moran a while back (I’m sure a search on the term “macroevolution” will likely turn it up).

It was always my understanding (based on the zoo guys I studied with when a grad student at Berkeley), that macroevolution was an entirely manufactered term. However, Larry made an excellent argument showing how the term is used by paleos, and had lots of documentation to back it up.

so, yeah, there IS a distinction in how the terms are used that has nothing to do with cladistics.

I can dig up the references Larry and PZ pointed to, if you like.

Posted by Reed A. Cartwright on February 8, 2007 11:06 PM

I am aware that paleontologists use “macroevolution” slightly differently than population biologists, often talking only about causes of patterns well above the species level. However, this is only a subset of what “macroevolution” refers to when used by biologists.

“Micro” versus “macro” is an artificial distinction, which leads to it being used non-uniformly by scientists. But for teaching purposes among other things, we have to draw a line somewhere between them. “Species” is the best place for it.

In truth I try not to refer to “macroevolution” and “microevolution”, instead I prefer to talk about “macroevolutionary differences” and “microevolutionary differences”.

And finally, punk-eq is not actually a theory about macroevolution, in the sense that you are using it. Punk-eek was developed by Gould and Eldredge to explain the pattern of speciation seen in fossilized lineages using standard population biology ideas of how speciation occurs in nature. They relied nearly exclusively on Mayr.

Posted by Ichthyic on February 8, 2007 11:56 PM

I am aware that paleontologists use “macroevolution” slightly differently than population biologists, often talking only about causes of patterns well above the species level. However, this is only a subset of what “macroevolution” refers to when used by biologists.

well, I’d consider the usage to be quite different, actually. the typical cladistics usage of the definition is rather meaningless, as you rightly point out; rather the paleos feel the level of distinction to have value when discussing different levels of theory.

as a biologist, it wasn’t really relevant to me at the time, but I can see their point now.

“Micro” versus “macro” is an artificial distinction, which leads to it being used non-uniformly by scientists. But for teaching purposes among other things, we have to draw a line somewhere between them. “Species” is the best place for it.

you’re kinda going backwards from where you started out here. Your first paragraph was touching on the correct level of distinction between how paleos and zoologists typically use the terms. You don’t need to explain to me how a zoologist views the definition within that field as being artificial at the level of cladistics. I certainly have no disagreement with you there.

In truth I try not to refer to “macroevolution” and “microevolution”, instead I prefer to talk about “macroevolutionary differences” and “microevolutionary differences”.

that works well when limited to discussion of evolution at the level you are discussing it, and that’s typically how I teach it at the biological level as well. However, again, this ignores the larger level of view the paleos are addressing. I see two distinctly different issues here:

species level evolution vs. large scale effects on evolutionary patterns, usually applied when examining trends in the fossil record. Not a slight difference, really.

And finally, punk-eq is not actually a theory about macroevolution, in the sense that you are using it.

actually, agree or not, it is often given as a prime example of how paleos use the term, even in wiki, for example. check it for yourself if you don’t believe me.

Punk-eek was developed by Gould and Eldredge to explain the pattern of speciation seen in fossilized lineages using standard population biology ideas of how speciation occurs in nature.

EXACTLY. and this is the reason they refer to the patterns as “macroevolutionary” IOW “above evolution”, literally.

again, as a biologist, the distinction has little relevance to my work, but as a categorical delineation, I can understand why the paleos have made the distinction.

bottom line, I agree entirely with you that evolutionary BIOLOGISTS find the distinction not all that useful, but I think you might be (as I did, coming from a zoologist background) ignoring the relevance of the distinction to paleos. I also understand at this point why you chose not to explore it in a 30 minute presentation.

It might be fun to discuss whether the distinction, as the paleos have drawn it, has usefullness to the overall study of the ToE in general.

Hmm, perhaps we could resurrect the thread where we had this discussion a while back on Pharyngula?

I’m sure Larry Moran would be interested, and it would be a good topic for your blog, I think (it generated quite a few thoughtful posts on the matter, that’s for sure).

Larry and PZ threw a whole bunch of references on the issue at me I still have yet to completely read, but I can probably dig up the list if you are interested.

cheers

Posted by Sam on February 9, 2007 4:18 AM

Nice presentation, Reed.

Re: division into micro and macroevolution is an artificial division - don’t see a thing wrong with it. There are plenty of artificial divisions in science that are used simply for convenience.

It’d probably be a much more useful distinction if it wasn’t misused by creationists and IDers.

Posted by fnxtr on February 9, 2007 1:55 PM

Reed: Thanks for this resource.

I get the impression that paleontologists use ‘macro’ to describe an environmental event that leads to major changes, or to describe the fossil evidence of the changes; while biologists see the actual changes in the populations as no different than those that take place on a more regular basis, thus needing no distinction. Is that close?