Harumi

For the record, I'll just have everyone know that I'm a supporter of science, and therefore a supporter of the theory of evolution.

It started in school one day, when I was talking to several of my Christian friends about evolution. This certain friend of mine is a Creationist, and he brought up an interesting point.

He understood the idea of genetic mutation. For instance, someone's eyes could turn white because of a genetic mutation of some sort, albinism is what it's called isn't it? That makes sense to him, since the gene for eye color is already there. But some creatures that supposedly evolved bothered him. For example, feathers. He couldn't accept the arguement that birds were the descendent of dinosaurs. The gene for feathers was never in dinosaurs in the first place. How did that come about?

I'd appreciate it if someone could explain to me how what seems to be "spontaneous" evolution could happen.

Another one of my Christian friends pointed out to me that the probability of a single celled organism to suddenly turn multicellular has about the same probability of all of our molecules aligning to enable us to pass through a wall. How does evolution explain that?

And there's a fine line betweent adaptation and evolution. Could someone explain the terms to me as well?

I'd appreciate it if someone could explain it to me. The next time we have a discussion like this, I want to be fairly knowledgable of my subject. It'd be rather embarrassing for a theist to win an arguement against an atheist wouldn't it?

Harumi

Kevin Dorner

This objection I don't understand at all... all that it takes for a single-celled organism to turn multicellular is a mutation whereby when a cell divides, the daughter cells stick together instead of becoming independent. Then you have a simple multicellular organism with no differentiation (all the cells are roughly the same, no organs, the organism is just a lump.) I think that the slime molds are very much like this. Over time and many generations, differentiation can occur with future mutations and the organism becomes more complex.

I suggest <a href="http://www.talkorigins.org/origins/faqs.html" target="_blank">the Talk.Origins archives</a> especially their must-read documents, for anyone just starting out who wishes to learn more. It's well-written and covers all of the essentials.

{Edit: spelling}

[ February 12, 2002: Message edited by: Kevin Dorner ]</p>

Corey Hammer

Tell him that current theories suggest that dinosaurs did indeed have feathers but for heat regulation not flight. Feathers themselves evolved out of scales in such a fashion to regulate heat (longer length and more surface area to dissipate the energy would be selected for). Flight came about as some dinosaurs may have attempted to flee predators be climbing trees (as in one hypothesis).

Your friend does not understand probability. Ask him to flip a coin 64 times. The probability of the outcome achieved is 2 to the power of 64. Ask if he doubts that he just got that outcome. Additionally, inform him that those arguments are for one and only one unicellular animal. There would have been trillions of them together and so even improbable events have a high likelihood of occurring once or twice.

If he then attempts to bring up the second law of thermodynamics, then counter with that the 2nd law only about heat transfer in closed systems. Earth is an open system since we have the enormous energy input from the Sun.

mac_philo

I am not sure what the problem is with the feathers. There is no "gene" for feathers; most phenotypic traits involve many genes. What is unique about feathers? One can imagine an incremental transition from, say, scales to feathers. I think that your friend's objection is not coherent, since he needs to specify what is unique about feathers.

As for the probability mentioned by your friend: I don't know how that could be a meaningful probability, but indeed, the odds against each of us being alive are Astronomical with a capital A. Think about it: your ancestors, going back to the dawn of life on this planet, *all* survived long enough to reproduce.

That would be true even if creationism were the explanation. Anyway you slice it, each living creature can be described as an absurd longshot to ever have been born.

Remember, evolutionary explanations work on a geological, not human, time scale. Genetic variation over that timescale is guaranteed to create features that, from the unilluminating perspective your friend likes to employ, are incredibly improbable.

[ February 12, 2002: Message edited by: mac_philo ]</p>

Kosh

I remember watching the launch of Apollo 11.
I couldn't comprehend how a vehicle that large
and complex could be designed, let alone work.
I still can't. Everytime the shuttle goes up,
I am amazed at the complexity and level of
effort that must be needed to make it work. Even
as a software engineer, I find it difficult
to believe that the thing works.

And still, the launches continue to work fine,
regardless of whether my intellect can
understand it.

Happy Wonderer

The next time that somebody complains about how low the probability any event in Earth's history seems to be, consider this. Not only is the earth ~4.5 Billion years old, there are ~200 billion stars in our galaxy alone. I don't know if we have any solid estimates of how many of them would have earth-like planets (we are presently unable to detect such small, dark objects) but there is recent evidence of (large) planets in other "solar systems". Given this, there is no reason to believe that there is anything unique about the processes that led to the development of our solar system. If the odds were 1000-1 against the formation of an earth-like planet, there would still be 200 million (if my math is right this late at night) "earths" -- just in our piddly little galaxy.

There is no reason to believe that life couldn't have come about on any earth-like planet. In addition to present "earths" you have to consider past "earths". The universe itself has been estimated to be over 11 billion years of age.

My point is that for any unlikely event the creationist wants to bring up, the probability of it having happened somewhere in the universe is the (low base probability) multiplied by (11 billion) multiplied by (how many earth-like planets exist or have existed in the last 11 billion years.) The fact that it happened here doesn't make it outside of the rules of probability -- just like winning the lottery. Somebody is going to win, doesn't mean that person should consider themselves annointed by G*D.

We don't know how many earth-like planets exist, just as we don't really know the probability of any "unlikely" evolutionary scenario a creationist presents. Probability assumes independence of possible outcomes, and nothing in an ecosystem is independent. The actual probability of a uni-celled creature spawning a multi-celled one is related to how many of those critters you have, the environment they are in (is there an advantage to having more than one cell), and the amount of error in their replication mechanism -- in that environment.

(Of course the other thing to consider when thinking about unlikely events that happen to little critters is just how the heck many little critters have been on Earth. I heard a guesstimate on the radio yesterday that there are a couple of trillion ants. Any guesses how many bacteria exist today? How many have existed in the last 500 million years?)

&lt;SOAPBOX&gt;
My personal belief is that life is a rare and precious event. There are probably many planets similar to ours that don't have it and will never get it. I'm distressed at how we treat the earth -- almost as if we think there is a "Big Daddy" up there who will give us a new, better one when we have finished trashing this one. The doomsday cults that seem to think that provoking a war in the Middle East will give them a chance to shake Christ's hand in this lifetime scare the weevils out of me. &lt;/SOAPBOX&gt;

I'll admit this isn't a very 'scientific' approach; there are just to darn many unknowns. It is kind of a sketch for a layman's response, though. (If I have made huge errors you will hear about it soon, I'll wager :-) )

HW


<a href="http://www.space.com/scienceastronomy/astronomy/new_planets_000804.html" target="_blank">50 large ex-solar planets found so far</a>

<a href="http://www.astro.ucla.edu/~wright/age.html" target="_blank">Age of the Universe</a>

[ February 12, 2002: Message edited by: Happy Wonderer ]</p>

tronvillain

Well, life seems to have appeared almost as soon as anything resembling liveable conditions existed, so it seems to me there's a chance it's not all that hard. What actually looks hard is complex life.

alek0

I would also like to point out that with single cell organisms you are dealing with huge numbers in addition of large time scale. So when creationists just give you some off the wall probability figure, you can easily counter that not only with time scale but also with parallel processing.

Corey Hammer

Addendum to Feathers:

Here is talkorigins webpage about it:

<a href="http://www.talkorigins.org/faqs/feathers.html" target="_blank">http://www.talkorigins.org/faqs/feathers.html</a>

butswana

The probability thing is a load of shit.
Probability does not equal possiblilty.
Given enough time, almost any thing is probable and possible.
Dawkins is really good at explaining probabilities in "The Blind Watchmaker."