The Clever Badger To add insult to injury, the platypus is leading.

7Aug/106

A Short Evolution Refresher

Geeks are Sexy has a nice post from a bit over a year ago giving a solid, high-level overview of evolution.  It also includes an excellent 10 minute video that I'm including below, because it deserves as wide an audience as possible (I may have posted this before.  If I haven't, I should have).

The article and video hit a number of frequent objections to evolution.  Actually, it would be more correct to say that the article and video address a number of objections to a strawman caricature of evolution.

The distinction is important because more often than not, the vocal evolution deniers out there will start their sales pitch by claiming that "evolution says <something>", and typically that <something> is either something that evolution doesn't "say" at all, or else "says" quite a bit differently than the denier suggests.  Some examples:

  • Have you ever seen a dog give birth to a cat?
  • Evolution says that man came from monkeys, so why are there still monkeys?
  • DNA evidence proves that all humans came from one woman!
  • Most mutations are harmful and would kill an organism!

The first two, of course, are the same concept phrased slightly differently, and reflect at least three misunderstandings - that individual organisms evolve directly into other individual organisms like some sort of Pokémon,  that one species will cease to exist once it gives rise to a new species, and that humans are descended from monkeys.  (There's a part in the video starting at 5:33 that covers these with a nice little graphic.)

The third one is a distortion of the concept of the Most Recent Common Ancestor (MRCA). We commonly see the term applied to the unfortunately named idea of a Mitochondrial Eve - the most recent common female ancestor of all living humans.1

The reason that it's a distortion is that the MRCA depends on what group you're looking at.  The MRCA of all living humans is not required to be the MRCA of all humans that have ever lived:

(From Wikipedia)

The MRCA of everyone alive today could thus have co-existed with a large human population, most of whom either have no living descendants today or else are ancestors of a subset of people alive today. The existence of an MRCA does therefore not imply the existence of a population bottleneck or first couple.

At this point, some alert individual might assert that even if you expand the pool to all humans that have ever lived, you still necessarily end up back at a first couple, but you'd be wrong because there isn't a requirement that the female MRCA and the male MRCA live at the same time.  Think about it.  If our notional female MRCA had children by two different men, and descendants of all of those children survived to the present day, then neither of her partners would be the male MRCA - her father would be.  (There's also the little matter of identifying exactly where you draw the line between human and non-human.  For a very relevant graphical demonstration, see here.)

The last point is simply untrue.  Most mutations aren't fatal.  Most are neutral.  The fatal ones tend to get removed from the population pretty quickly for obvious reasons.  Neutral ones can just sort of drift around in the gene pool without any particular consequences.  Beneficial ones tend to increase in frequency.2

We could go on with this, and we'd see the same thing over and over again.  That suggests to me that the evolution deniers out there aren't at all interested in addressing the subject on the basis of facts and evidence, but rather seek to turn it into an exercise in emotional manipulation.3

The lesson here, as always, is to do some fact checking when you run across references to cats birthing dogs and such.  If nothing else, ask yourself  "if this is such a simple and obvious flaw in evolution, then why on Earth does anyone still accept it?"   Your answer should be "maybe this supposed flaw has already been addressed, or maybe whoever proposed it doesn't understand evolution very well."

-Jay

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1So named because mitochondria within cells come from the mother - sperm lack mitochondria. Similarly, we can talk about a Y-chromosomal Adam.

2But remember that beneficial depends on the environment, and may be a tradeoff.  Conspicuous physical displays may increase the chances of finding a mate, but may also increase the chances of getting eaten.

3Ken Ham is perhaps the current master of this approach. What the man actually knows about evolution is unlikely to fill a thimble, so he takes the fear-mongering approach of linking evolution to everything that is bad in the world. Ham also attracts attention for his horribly distorted theology. James McGrath recently had a post up summarizing some of the criticism Ham has been receiving from within the evangelical community of late.

15Jul/101

TED Talks: Matt Ridley

Matt Ridley, the author of The Red Queen: Sex and the Evolution of Human Nature, gave a recent TED Talk - When Ideas Have Sex. 

The main idea here is that ideas interact with each other to produce new ideas, and those new ideas drive progress. 

Enjoy.

-Jay

18May/108

In Which Ken Ham Unsurprisingly Fails To Address James McGrath’s Key Points

(Note: This post took me a lot longer to write than I expected.  In the interim, other posts have appeared that either directly supplement this one, or add background.  NCSE commented on the video on their Facebook page, and also has a book excerpt up dealing with Ken HamSkippy has a cogent analysis of the matter as well.)

A couple of weeks ago, James McGrath posted an article on his blog, Exploring Our Matrix, containing this video:

This is part of a longer HBO documentary called Friends of God, which can be found here.

Anyway, in his post, James (who, I'll point out, is an associate professor of religion at Butler University)  calling out  people like Ken Ham (who, near as I can tell, isn't an associate professor of anything) for "false teaching".  My take on James' post is that he feels that people like Ham are encouraging Christians to stand up for pseudoscience rather than relevant social issues.1

14Feb/100

Evolution Weekend

A little plug here for The Clergy Letter Project and Evolution Weekend 2010.

My Sunday School class is on hiatus this weekend, else we'd be participating.  As it is, I'll just bring the topic up next week.

At risk of bringing up the topic of accomodationism, I think the CLP and Evolution Weekend are valuable and relevant efforts to help get people to realize that accepting the evidence for evolution doesn't automatically require them to reject their religious convictions.

More later.

-Jay

13Jan/106

Humans, Apes, and Stephen Baldwin

John Loftus posted a video over at Debunking Creationism featuring Stephen Baldwin (the less well-known brother of Alec, Daniel, and William) rattling off the tired old line "if evolution says that man came from apes, then why are there still apes?"1

(I included the video here, just for completeness.)

The video segues into biologist Richard Dawkins giving an eloquent and easy to follow explanation of why Baldwin's question is so far off the mark that it's not even wrong. Briefly:

  1. Evolution doesn't claim that man came from apes.
  2. Evolution does assert that humans share a common ancestor with chimpanzees and bonobos.
  3. Evolution does assert that the group (humans + chimpanzees + bonobos) shares a common ancestor with gorillas.
  4. Evolution does assert that the group (humans + chimpanzees + bonobos + gorillas) shares a common ancestor with orangutans.

Note that none of the assertions requires any population of modern apes to transform into modern humans.  Baldwin's rhetoric proceeds from a misinterpretation of evolution, so it's broken from the very start.  It may be helpful to consider a typical human extended family:

  1. You share common ancestors with your first cousins.2
  2. The group (you + your first cousins) shares common ancestors with your second cousins.
  3. The group (you + your first cousins + your second cousins) shares common ancestors with your third cousins.

None of these relationships require any of your cousins to transform into you, nor do they require your grandparents (or great grandparents, or great great grandparents...) to transform into you.

I'm not going to spend any more time picking on Baldwin - Dawkins3 does it better in the video - but I am going to spend a little time looking more closely at the question itself.

The basic question "if man evolved from apes, then why are there still apes?" can take on numerous derivative forms (one particularly interesting one I've seen goes something like "if evolution says that chimps are the closest relatives of humans, then why is <some gene> in chickens almost identical to a human gene?"), but they all collapse into a fundamental misunderstanding of the concept of common descent.

Absent some background in biology in general and evolution in particular, it isn't really a stupid question at all - it's a very natural one.4

One reason that this is the case, I suspect, is because our practical experience is that organisms don't seem to change from generation to generation - our cats always have kittens, so to speak.  The kittens may have some odd markings in their fur, or an extra toe on each paw, but they're fundamentally still cats, and nobody makes much of it because everyone knows that there is a considerable amount of variation present in cats.  When you look at things like lions and tigers, it's fairly obvious to most people that those animals are essentially much larger versions of housecats, and if you see a reconstruction of a sabre-toothed cat in a museum, it's cat-like enough to pass muster.  There is enough essential cat-ness to these animals that their relatedness is readily apparent.5

What aren't as readily apparent to the average person are the minute differences between individuals - a slightly thicker coat, slightly longer legs, and so forth - that selection pressures can act on over many, many generations.

It can be a bit difficult to accept the idea that minute, almost imperceptible differences can accumulate over time to the extent that one branch of descent could lead to chimpanzees and one branch to humans, but if you really think it through it makes a lot of sense.6

The point here is that questions like Baldwin's aren't intrinsically stupid questions.  If they're asked sincerely by someone who is genuinely curious, they're very useful questions, because they can lead to informative, constructive dialog.7

I think that in the end, that's what works best.

-Jay

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1Baldwin's words were slightly different, but went to the same point.

2Those ancestors are your grandparents, just in case that isn't obvious.

3I may as well throw this in here. There are a lot of folks who dismiss Dawkins out of hand because he is, among other things, a vocal atheist. Big deal. He also happens to be one of the most gifted science writers on the planet.  Dismissing Dawkins qua science writer because of his position on religion makes no more sense than dismissing him because he wears glasses.

4That said, when high-profile creationist personalities continue to toss this question out even after they've been offered repeated explanations and clarifications, one begins to wonder what their motivation really is...

5I do not intend to suggest by this example that domestic cats are descended from tigers. Or smilodons.

6It's a bit like those word puzzles where you start with one word, and with each step you change one letter (subject to the constraint that each step is, itself, a valid word), you end up with a much different word than the one you started with.

7Personally, I'd rather talk through the concept of common descent a hundred times with someone who really wants to understand it than talk through it once with someone who is content simply to parrot arguments that they read in a Ray Comfort book.