March 30, 2007
We have Diana Hsieh to thank for bringing this to my attention.
I'm actually a little scared that someone somewhere actually believes this, though. It tempts me to write a letter to them to explain evolution, but at the same time... I just don't have time to write a letter that long.
March 06, 2007
This claim is false.
Of late I've been reading about DNA and evolution and I've come to realize that in pretty much every animal that you might consider from ugly, grubby worms to roaches to mice to alligators to baby seals to people are "missing links." Except, well, they aren't missing unless you've misplaced your baby seal or whatever.
Over the course of history and continuing on today (that's right, evolution continues today) the animal genome has been changing through mutations and the mechanism of natural selection. Variations in genes and chromosomes have been attempted with varying degrees of success. The very successful among genes are ones that we see today repeated across many species.
For example, the genes that produce heads, necks, backs and tails all appear in animals as diverse as fruit flies, sea urchins, mice, and people. In fact, the genes that wind up expressing themselves as wings in fruit flies are the same genes that express themselves as legs in mice with only the most minor of variations.
The mere fact that all animals on earth use DNA is in itself such an obvious testimony to the commonality of our origins that I'm not surprised that many miss it.
To the point of the missing link, though, in my reading of the book Genome by Matt Ridley, I came across this passage:
The story starts with the discovery in Greenland in 1988 of a fossil called Acanthostega. Half fish and half tetrapod, and dating from 360 million years ago, it surprised everybody by having typical tetrapod limbs with eight-digit hands on the end of them. It was one of several experimental limb designs tried out by early tetrapods as they crawled through shallow water. Gradually, from other such fossils, it became clear that the hand we all possess developed in a curious way from the fish's fin: by the development of a forward-curving arch of bones in the wrist from which digits were flung off towards the rear (little-finger) side. You can still just see this pattern in an X-ray of your own hand.
Heavens to Betsy! A missing link! Right there in a regular, old, every day Acanthostega. I looked those up on Wikipedia and they're kind of cute in a slimy, salamandary way.
Acanthostega is an extinct tetrapod genus, among the first vertebrate animals to have recognizable limbs. It appeared in the Upper Devonian (Famennian) about 360 million years ago, and was anatomically intermediate between lobe-finned fishes and the first tetrapods fully capable of coming onto land.
Of course, the Creationists will say, "Well, where is the thing that is half way between half way between a tetrapod and a fish?"
And you might say, "You mean like the tiktaalik?"
Tiktaalik lived approximately 375 million years ago. Paleontologists suggest that it was an intermediate form between fish such as Panderichthys, which lived about 385 million years ago, and early tetrapods such as Acanthostega and Ichthyostega, which lived about 365 million years ago. Its mixture of fish and tetrapod characteristics led one of its discoverers, Neil Shubin, to characterize Tiktaalik as a "fishapod"
And then they'll say something like, "Ok, but where's the thing that is hald way between half way between half way between the tetrapod and a fish?"
And, truly, you would have my permission to simply slap them at this point because they're just being stupid.
(Actually, in thinking about this, really you would bring up the tiktaalik first and then cite the Acanthostega if you wanted to follow the "half of, half of" progression properly.)
Creationists and the like apparently expect there to be herds of half-things just roaming about, but such an expectation reveals a certain, significant level of ignorance about how the mechanism of natural selection works and what information the fossil record provides.
First of all, let's talk fossils. I have bad news. Not everything that has ever lived made it into the fossil record. In fact, gazillions of individual creatures lived and died and no evidence of their existence remains. I will take this one step further, there is such a paucity of fossil evidence that it is not only possible, but likely that entire species of creatures lived and died and left not a single trace of their struggle except, perhaps in the DNA code that they passed down through their progeny which may have survived.
Second, let's talk natural selection. Because the process of natural selection is apparently very, very slow, I can understand why you might expect there to be herds of half-this and half-thats just gallumphing about the prairie or whatever, but I think you're not looking closely enough.
Look at the variations within a given species such a humans. We have black humans, yellow humans, red humans, pale ghostly white humans, sort of mocha-y humans and humans who might be considered to belong to any of several of these groups. Skin color in itself represents a fairly dramatic phenotypic variation within a species that is the result of natural selection and as various pressures continue, we see which is more or less successful for any of various reasons.
Look at how many different kinds of dogs and cats (or any domesticated animal) that have resulted from man's highly selective breeding pressures.
Consider the widespread, rapid variation in viral and bacterial populations. Every season there's a new flu. Genetically, it's a little different every fall. And why don't you do a google for antibiotic resistant bacteria.
There are, in fact, lots of sort of half-critters out there and they're doing all sorts of things on the prairie.
More importantly, natural selection in all the ways that are important is also a very, very subtle process. Even significant genotypic changes take a long time, but along with huge genotypic similarites between species like chimpanzees and humans, we can also observe all sorts of minute genetic variations within a species.
Creationists who say that there aren't half-things out there are doing two things. 1) They're either denying or ignoring the facts and 2) they're moving the goal posts on you.
I say they're moving the goal posts because they won't ever be satisfied with the evidence you offer. Do they care that chimps are 98% genetically identical to human beings? No, because as soon as you tell them about this, they want to see something that is 99% similar. If you find two species that are one percent genetically distinct, they will ask to see one that is .5% distinct. They will continue to change what they mean by "missing link."
My advice to you is this: don't debate with Creationists or Intelligent Design-ists. They don't even agree with you on what constitutes evidence, let alone whether or not the evidence at hand is sufficient to support your case.
New York Times: Darwin's God
Which is the better biological explanation for a belief in God — evolutionary adaptation or neurological accident? Is there something about the cognitive functioning of humans that makes us receptive to belief in a supernatural deity? And if scientists are able to explain God, what then? Is explaining religion the same thing as explaining it away? Are the nonbelievers right, and is religion at its core an empty undertaking, a misdirection, a vestigial artifact of a primitive mind? Or are the believers right, and does the fact that we have the mental capacities for discerning God suggest that it was God who put them there?
In short, are we hard-wired to believe in God? And if we are, how and why did that happen?
As you can see from the excerpt I selected, the article is dedicated to exploring the corner of the scientific community that concerns itself with trying to find an evolutionary explanation for faith in the supernatural.
The idea that people may be genetically disposed to belief actually gained a fair amount of press when Richard Dawkins' last book, The God Delusion, was published in September of last year. I bought the book, but I haven't read it yet.
The idea held by Dawkins and other is that there is a genetic basis for the predominant human belief in the supernatural, but it is a function of genes that do other things.
For example, there is a tendency to assume that some thing is doing whatever happens. If you see something moving in the corner of your eye you "instinctively" assume that it is a person or animal making it happen. It may just be the wind, but the claim is that we're genetically wired to think it's a person or animal. Although a snap judgment, an assumption even, it increases the attentive, although jumpy, human is more likely to survive than the one who waits for the velociraptor to pounce.
The article gives two other such examples.
And, of course, there is another camp of scientists who also argue that there is a genetic foundation for faith, but they argue that the benefits conferred serve to strengthen the individual within a group and also strengthen the group as well.
The example given is of a group of birds where some of the birds are genetically inclined to be sentries who watch for predators. Among a group of non-sentries, the sentry birds run a huge risk because they don't spend as much energy getting food or mates and they're also likely to get eaten because they squawk every time they see something they think there's a predator. Basically, among a group of non-sentry birds, they die off pretty quickly. But among a group of other sentry birds, they might seem pretty attractive, plus, the group as a whole would likely survive longer than the group who let its sentries get killed off.
It's all very... long, but interesting.
Assuming a genetic disposition toward being social rather than solitary, jumpy at a hint of danger rather than complacent, and other such conditions, I guess I could understand why people might be inclined to believe in God. My understanding of the genetic influence on personality, thought, and behavior in humans (if there is any) is such that genes are very, very weak players in this game. So weak that in light of all the evidence, arguments, and discussion, the only excuse I can come up with for people still believing in supernatural foolishness is peer pressure alone.
I may end up with a very low opinion of my fellow man if I conclude that so many people are committing themselves to idiocy based on a desire to be popular alone, but I suppose it would not be the first time people have done that or that I've reached conclusions that should make me think ill of folks.
It's an interesting article. Check it out.
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