4.27.2007

Moi, defender of science? [UPDATED]

There is what I think is an interesting discussion going on in the comments of Passionate Life's blog, over here. He asked questions about evolution and I tried to answer them.

However, I have not learned squat about evolution since, um, 10th grade honors biology with Mrs. Schwartz. (It wasn't even AP. We didn't have AP Science classes.) I never took an evolutionary biology class in college at all. Seriously. Everything I wrote here I gleaned from 10th grade (I did do very well in that class) and, I guess, from reading the newspaper since then.

Are any of you biologists? Don't have BA's in History and Women's Studies? Smarter than me? Help a girl out here! Thanks.

I am going to copy just my comments here, since, well, I wrote them and I figured that I didn't need to ask permission to do that. (I did not ask permission to copy his words, so I didn't. Anyway, you can just go to his blog to read them.) I corrected a few typos in my comments in an attempt to save face, but otherwise, it's exactly as it appears on his blog, mistakes and all. Oh, I also added a few Wikipedia links for the heck of it. In my comments, I quoted his questions, so it should be fairly understandable even without P-Life's side of the debate.

The sane thing to do, of course, would just have been to recommend Natan Slifkin's books and to leave it at that. (He is only four years older than I! I had no idea until I looked at the Wikipedia article.) I have a feeling, though, that P-Life will never be convinced of the viability of science, no matter how many of Natan Slifkin's books he reads.

Without further ado...

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ALG said...

This is probably a waste of my time, but I feel that if you're going to attack evolution, at least attack it properly, not based on your own misunderstandings of the theory.

1. If we evolved from apes, why in the world are there still apes around? Why haven’t they evolved into humans like us?

We didn't evolve from modern apes. Modern evolutionary theory says that we and modern apes both evolved from a common primate species farther up the family tree. We're most closely related to chimpanzees, which are the species mentioned in the NY Times article. We both split off from a common ancestor about 5 million years ago. We're less related to gorillas, even less related to orangutans, and least related to other kinds of monkeys. We didn't descend from any of them.

2. If you are going to tell me that maybe only some apes evolved and not all, then how come ALL Neanderthals, Homo erectus, Homo sapiens, and Cro-Magnon species evolved and there are NONE left outside of Geico commercials?

Neanderthals evolved to some degree, but then became extinct. Homo erectus is less clear. They were an earlier kind of bipedal primate than homo sapiens, and they also became extinct. I'm not sure if there is consensus about whether homo sapiens descended from them or not. Cro-Magnons are an early kind of homo sapien, so they evolved into us, or, rather, we evolved from them. (See (in no particular order) http://www.sciencemag.org/cgi/content/summary/299/5612/1525, http://www.mnh.si.edu/anthro/humanorigins/ha/cromagnon.html, http://www.mnh.si.edu/anthro/humanorigins/faq/Encarta/encarta.htm, http://www.bio.miami.edu/dana/106/106F06_18.html, and you might find this exhibit interesting.

Finally, I apologize for any errors in the above explanations. I think I have it right, but I am not a scientist of any sort, just an educated laywoman. Corrections are most welcome.

Wed Apr 18, 06:11:00 PM EDT


ALG said...

You can go to the New York Public Library (or any other public or academic library) and find the Science article there, or, if you have a NYPL card, you can get the full text online through the EBSCO database. Go to http://www.nypl.org/databases/index.cfm?act=2⊂=24, click on the "General Science Collection from EBSCO" and, after entering in your library card number, check off the science databases within that. I got it by checking off Academic Search Premier, Applied Science & Technology Abstracts, and General Science Collection. I'm not sure which one of those it came from.

There is no excuse for being ignorant in today's day and age, at least not if you're lucky enough to own a computer and live where with public libraries. (Your tax dollars at work!)

I didn't read the whole article--I just linked to it because it was from a reputable source and it said that the Neanderthals were extinct. That was my only point with that source. I'm not sure it's the best thing out there. If you go to the library, a reference librarian can help you find the best information on this topic.

Wed Apr 18, 08:51:00 PM EDT

ALG said...

Clearly, we have very different attitudes towards science and the pursuit of knowledge. I responded in a possibly nit-picky manner because I didn't want to respond to sweeping assertions that were full of errors without providing some guidance as to the actual scientific theory that is being debated. Does that make sense? I'm sorry if my frustration sounded like disrespect.

Also, the questions you asked in your original post indicated that you didn't understand the mechanism behind the theory of evolution, which is natural selection, and I thought you might learn it from reading the links that I provided. I hope I will do a better job explaining that this time.

You wrote:
It [the website I cited] then goes on to list the hypothesis and the challenges to the hypothesis. Conclusion - there is no universal understanding of what the heck happened back then to turn apes into humans other then some targeted "probably this or probably that" guessing....

The point is that its all hypothesis and theories that are not based on FACT rather EXTRAPOLATION and very inventive theories....They stretch and bend to try and come up with theories that fits.


Scientific hypotheses are not guessing. A hypothesis is a suggested explanation based on observations, which you can call "facts" if you want. You are correct that a hypothesis is an extrapolation from a fact, but so is much of what we do in this world. If we based every action we took on observed facts, we would be paralyzed. Also, I would have gotten very wet on the way to work this morning, since I could have sworn that it had stopped raining when I looked out the window. However, I extrapolated, based on recent and older experiences on rainy days, that as long as the sky is overcast I ought to carry an umbrella and wear boots. (That was probably a shoddy example. Providing examples aren't my strong point.)

If or when the hypothesis becomes verified through additional observations (fossils, DNA evidence, etc.), it turns into a theory, such as the theory of evolution.

Evolution, i.e., a broad term which includes that bit about modern human beings descended from an ape-like ancestor is the best--the only--way for science to explain how we came to be, based on existing scientific principles. (Note that these scientific principles do not say anything about an ultimate power behind the machinery. Evolution is NOT incompatible with the idea of an Ultimate Creator.)

So we have the theory of evolution, and several hypotheses about why some descendants of our common ape-like ancestor developed into Cro-magnon and why some developed into the modern modern kinds of chimpanzees. As evidence is uncovered, for example, about when savannas first developed in Africa and as more fossil evidence is uncovered, various hypotheses are strengthened and weakened. As the field progresses, one hypothesis might eventually take precedence over the others and become the accepted viewpoint, or there might always be several possibilities and we might never know the best answer. Such is the study of our past, which we can never fully replicate in a controlled lab environment. Science is okay with leaving some things as questions. I don't understand why you aren't.

Okay, on to your specific questions, which I now see that I did not answer directly in my previous response.

Why did the apes who were less intelligent then the various forms of humans survive while the various forms of humans didn't?

First of all, who knows how intelligent the earliest forms of human beings were? Maybe they walked on two legs but some of them (Neanderthals) weren't intelligent enough to survive, whereas chimpanzees had other advantages that allowed for their survival. Perhaps they were less intelligent, but better at swinging through trees, i.e., better-suited to the jungly forests where they lived.

It is clear that the "most intelligent" creatures don't win out over all others in the game of evolution, or everything would have evolved into human beings, or some other very smart creatures, and we wouldn't have bacteria and other stupid things like that around today. All kinds of creatures are important to this world--everything from the very, very stupid plankton to the more intelligent whale to the even more intelligent human being. (After all, God created and gave us stewardship over them all to care for them and ensure their survival.) There are benefits to being small and stupid (you can reproduce very quickly and don't need to eat a lot), large and stupid (it is physically difficult for other things to eat you), etc.

If there were a hundred thousand cro-magnan people did all their children start turning into full humans? Why didn't 25,000 continue to be cro-magnan the same way apes continue to be apes?

Here's a better example, because the Cro-magnons children didn't "turn into" humans. They were basically humans already, and their children who were born with characteristics suitable to life had more and more children. They did continue to be Cro-magnon, i.e., us, only with clothing and language and other nice things like that.

A better example is homo erectus, if we go according to one theory, which is that homo sapiens (us), descended from homo erectus, but the ones who didn't evolve into us died out.

The reason why some forms of human beings survived while others didn't is that the ones that had the best random mutations to survive in the time and place in which they existed survived and reproduced, and the others didn't. I don't know the specifics, and this is obviously a very, very simplified example, but say it is helpful to have a very strong jaw for eating raw meat. If your cousins all have small jaws, they will die. Why do your cousins have small jaws? Because they were smaller overall and could easily hide from predators. But if they can't eat enough food to stay strong and quick, they won't reproduce as much or as quickly, and your big jaw will ultimately win out over their small size. That is my understanding of natural selection. The homo erectus who had the best mutations for reproducing became us, and the ones who didn't--i.e., the ones who stayed homo erectus and didn't become homo sapiens--died.

I don't know if all apes evolved into modern apes (perhaps they also have dead ends in their family tree as we humans do). If they did, it was because being an ape worked for them, in their environment, and any random mutations were to their disadvantage, and the mutated apes died out before they became a separate sub-group. Or, the changes didn't make much difference in their survival rate so they didn't have more children and those mutations are now evenly distributed throughout the population. I'm not really sure. It also could be that they stayed in more-or-less the same general environment, whereas human beings migrated all over the place, which made their random mutations more relevant. Someone who knows more about evolution than I do can explain how all of these factors come into play.

Gotta' run. It is Friday afternoon, after all.

Fri Apr 27, 04:17:00 PM EDT

UPDATED
on May 10 to add that P-Life responded to some of my points here.

4 comments:

smoo said...

While I always knew the theory of evolution since junior high, I never really UNDERSTOOD it to the point of it being the absolute best way to describe how life ‘evolved’ over time, that is until I read The Blind Watchmaker by Richard Dawkins. His style is extremely clear and convincing, Even if you want to overlook the agenda of proving there is no need for God to be involved, the scientific lessons he presents are fascinating. I think all you questions would be answered there (although you might need to read some of his other works, like The Selfish Gene to better understand why some qualities are more successfully selected).

smoo said...

“If He [God] did set up this program of evolution, I would say that He did not have humans, per se, in mind. He may have designed evolution towards increasing complexity and even the development of cognition and intelligence that would eventually be capable of understanding the universe. The point is that I don’t think he had specifically humans as the goal. Perhaps in the next run it would be winged aardvarks that would reach that level and possibly come up with the idea of God. But the emergence of complexity would ensue nonetheless.”

Above is an excerpt from my post http://shmuzings.blogspot.com/2007/03/progress-notes-on-my-evolving-thoughts.html

Just another later thought I didn’t include on the post was if there is a personal God perhaps his role in the midst of true evolution would be- He’s the one who has the rock fall on the a certain creature and this gives another specials the upper hand in the natural selection process. Maybe He is the one who sends the UV ray that causes the mutation that gives one species a detrimental effect while another gets the mutation that will benefit its species.

So maybe there is some hope for R. Slifkin, that there can be evolution and yet there still be a God beyond an ultimate cause who is still part of the real world (He is certainly part of our mental world!)

ALG's dad said...

First of all, I think you did a good job explaining evolution, and you didn't say anything that was very wrong, though I suspect you won't convince P-Life, any more than Natan Slifkin would. I do think that you could reasonably suggest to him that he read Natan Slifkin's "The Challenge of Creation" before continuing the debate further. He, in turn, might suggest that you read some anti-evolution book, like the one by Michael Behe, I think that's his name, which I guess you would then have to do, if you wanted to pursue this.

A few details in your post that weren't quite right--Cro-Magnons did have clothing, and almost surely had language as well, given their level of culture, and the fact their brains (judging from the shape of their skulls) seem to have been anatomically identical to modern humans' brains. Neanderthals had brains as big as Cro-Magnons/modern humans, even slightly bigger on average, but their cultural level was lower, and their culture didn't develop as fast, relative to the size of their population, so there was probably something different about their brains. Quite possibly they didn't have language, or their linguistic abilities were inferior. I think I have seen arguments that that was the case, based on the shape of the surface of their brains, which matched the shape of the interior of their skulls. I think they did have clothing, though.

The division between the lines that led to humans and to chimpanzees was not between larger and smaller brains, and there is no evidence that the ancestors of humans were more intelligent than the ancestors of chimpanzees, right after that division took place, or for some time afterward. Rather, the division was between walking fully upright all the time, and walking sometimes on all fours as chimpanzees do. Richard Dawkins (who P-Life probably wouldn't like reading, because he constantly throws in gratuitous attacks on religion, although he does explain evolution and natural selection very well) lists 14 different theories as to why it was advantageous for the human line to walk upright, in his book "The Ancestor's Tale." One possibility is that it freed up their hands to carry food, so the males could forage further and bring food back to the females who were stuck at home with the children. Another possibility is sexual selection, which doesn't require any objective advantage to walking upright initially, but only requires a temporary fad that was initiated by someone and caught on. (Read the book to understand for why it then continues to spread. Or I can explain it to you if you want.) In any case, once humans were walking upright, large brains might then have been more of an advantage than they were to chimpanzees, because, for example, they could then invent baskets and carry even more food from even further away. Large brains also have a big disadvantage, viz. more complications in giving birth, and babies necessarily being born in a less developed state (before their heads are too big to fit through the birth canal) and less able to survive infancy. (Carl Sagan points out, in one of his books, that difficulty in giving birth is one of the punishments given to Adam and Chava as a result of their eating the pri etz ha-daat.) So unless there were an advantage that outweighed these disadvantages, larger brains would not have evolved. That could explain why chimpanzees, which didn't walk upright, didn't evolve larger brains than they already had. The environment they were in (jungle, vs. savannah for humans) could also play a role, of course, as you pointed out.

ALG's dad said...

One other thing I thought of, though you basically said this already. P-Life might think that the fact that there are 14 theories for why humans started walking upright means that the whole thing is nonsense. It is true that we really don't know why humans started walking upright, according to evolutionary theory. But that is not a defect in the theory. It simply means we don't have enough data, and might never have enough data, to know what happened. It would be a defect in the theory only if we couldn't think of ANY explanation, consistent with evolutionary theory, for why humans started walking upright. Of course, in order for the theory to be accepted, there have to be other cases where the theory does make testable predictions, and there are.

A theory isn't required to make testable predictions about everything, any more than a purported Navi is required to make testable predictions about everything. But where it/he does make testable predictions, the predictions had better come true, or the theory is wrong. (Maybe not completely wrong, but it has to be modified, and if there is no core of reliable predictions that it makes consistently, no one will take it seriously.)