Saturday, April 14, 2012

Evolution: Prove it to Yourself

One of the methods I use in my biology class when we are on the topic of evolution is to teach it in a way that allows students to prove to themselves that evolution is the only method that makes sense when it comes to explaining the diversity of life on Earth. Whatever evidence I am talking about at the time can be turned into a how-would-you-do-it puzzle for the students.

For example, take the fossil record. Everybody knows about fossils, the remains and traces of ancient forms of life. But to creationists, fossils simply represent a part of God's creation that no longer exists. If you look at how fossils are sorted in the rock layers, however, there can be only one explanation: evolution.

With regard to the layering of sedimentary rock, I start by making an analogy to bed covers. If you make your bed with a top sheet, a couple of blankets, a comforter, and a bedspread, it is easy to see why the sheet is on the bottom and the bedspread is on top. You built them up from the bottom in chronological order. The same is true of rock layers. In an area of undisturbed rock, the oldest layers will be on the bottom. Therefore any fossils contained in the rock layers will be sorted with the most ancient fossils on the bottom, the deepest layers. More modern fossils will be toward the top.

So here's the question I pose to students: If all living creatures on Earth were created as is and at the same time, what would the fossils in each layer of rock look like compared to the fossils in other layers? Sometimes it takes them a second or two, but the answer is always the same: "They would all look alike." And, of course, that is correct. The fact that there are different fossils in different rock layers means that the animals and plants that made them changed over time. Couple that with the observable fact that fossils in more ancient rock layers are always representative of more primitive creatures and the conclusion is simple: Creatures changed over time from simple to more advanced. In other words, they evolved.

I know that, in their desperation, Christian apologists have devised their own answer to the sorting problem. Apparently, they were sorted in the Genesis Flood. But even if we allow that floods tend to sort out different types of sediments (and presumably, fossils), they were sorted in the wrong direction. More advanced animals tend to be larger than the very simple forms of life, and flowing water always sorts with the largest sediment on the bottom. Actual sorting is the exact opposite of the way it would be if fossils were sorted by a flood. Gradual change over time is the only cogent theory that explains the observation.

I also tell students that evolution could easily be proved wrong if someone could show a fossil of a modern mammal in the same layer as a fossil of a dinosaur. But in more than 150 years of searching, nothing like this has ever been found.

Going on to comparative anatomy, I can pose a small thought experiment: Suppose you were asked to construct a working replica of a bird wing, a human arm, and a whale flipper so that each replica would perform as the real ones do. You are not at all restricted in the amount or type of materials you can use. The question is, would you build the three replicas using the exact same structure for its frame or would you, instead, choose a structure that makes sense for the needed function? Obviously, the more thoughtful students suggest using a framing structure that is specific to the function, so that the arm and hand would need to be made of more parts than, say, the whale flipper. For economy, you could conceivably construct a flipper using perhaps six rigid pieces of metal connected with hinges. But with a human arm and hand, you would need to use significantly more parts to get the intricate movements you needed.

In nature, however, a human arm, a bird wing, a bat wing, a dog leg, and a whale flipper are all constructed using the same number of bones connected together in the same way. From an engineering standpoint it makes no sense, and my students understand that, because from the puzzle I presented, they figure it out for themselves. Nature's way makes no sense if you assume that each form of life was created separately and did not evolve. But if you assume that all living creatures evolved from a common ancestor, then it makes perfect sense. The only plausible explanation for what is observed in nature is that creatures evolved from a common ancestor, and my students are taught to figure that out for themselves using their own critical thinking skills and logic.

Then I ask them this hypothetical query: Suppose you are an engineer and you are given the task of building a robot. The robot has to be able to do these chores: "taste" food, detect sounds, detect light and identify objects from it, and make sounds. In that case, you would give your robot all the following mechanism: a microphone, a speaker, a camera, a liquid chemical sensor. But now I tell them that, after a time, the robot would no longer need to detect dissolved food substances so they will no longer need the chemical sensor. Assuming their robot has a unified design, which method would be more efficient to accommodate the change in desired functionality: 1) to just leave the sensor in place but turn it off, or 2) to redesign the robot from scratch so that the chemical sensor is left out, then re-build the robot? Obviously, most students just say leave its tongue in place and turn it off.

In nature, humans and other animals have organs that they should not have. Humans have wisdom teeth and body hair. We also have a coccyx (tail bone) and an appendix that we would be better off without. Horses have tiny vestigial toe bones. Whales and snakes have hip bones. Ostriches have wings. These are all organs we have but don't need, much like the robot with a chemical sensor that has been deactivated. So why do we have them? Well, why does the robot have the chemical sensor? It's because at one point it needed one and it would have been an inefficient process to remove it when it's usefulness was over. With vestigial organs, animals have them because they were useful to our ancestors, and our living animal cousins may still use them. Some herbivorous mammals, for example, have a cecum, the homologous structure of the human appendix. It is used to aid in the digestion of certain plant material. The ancestor of horses had toes instead of hooves; the fossil record bears this out. The fossil record also indicates that the ancestors of snakes and whales walked on land. And the ancestors of ostriches could fly.

When the question of why these animals have organs they don't need, after being given the robot challenge, students could answer the question. They have the organs because they once needed the organs. But we evolved.

I go on, over the course of the lesson, to ask similar questions about why the human embryo needs to grow gill slits and a tail and why at one point it has a 3-chambered heart. Why must the human embryo go through the stages of a fish and a reptile, only to have those structures turn into something else as the embryo grows? The only plausible answer again is evolution. Ontogeny recapitulates phylogeny. I don't say it in class but the only reason a god would have to make us in this fashion is if he were a deceptive god who wanted to deceive us.

Of course, the clincher when it comes to evidence for evolution is DNA. Fossils were once the primary evidence supporting evolution, and they're still important. But we could prove evolution even without fossils based solely on DNA analysis. Fossils simply corroborate the DNA evidence. In the same way that DNA can be used to positively identify a criminal suspect (or a parent in a paternity suit), it can also be used to show exact relationships among different species, living or extinct. Today, using genetics, "family" trees known as cladograms can be used to show the relationships among living organisms and their ancestors. For those who have allowed themselves to learn about this amazing field of research, it truly is the final death knell for creationism or intelligent design. Again, I obviously do not say this to my students because everybody is allowed to believe what they want, but any creationist who wants to persist in his delusion of creation, he should never allow himself to learn the details of archaeological genetics, because if he does, he will no longer be a creationist.

Monday, April 02, 2012

How Religion Quashes Scientific Discovery

Using God to Fuel Discovery

Child: Mom, what is a rainbow?

Mother: A rainbow was placed in the sky by God after the Great Flood as a promise to Noah and all his descendants that He would never destroy the earth by water again. Now, every time you look at a cloud and see a rainbow, you can be reminded of God's promise.

Child: Oh, that's nice. So God is never going to destroy us again?

Mother: I didn't say that. God promised never to destroy the earth by water again. Next time he's going to use fire.

Child: Oh, I see. Mom, isn't God supposed to be perfect in every way?

Mother: Why yes, dear, He is.

Child: Then why does He have to keep destroying His creation and starting over? Why couldn't he have gotten it right the first time?

Mother: Eat your peas!

Child: Mom, what are the stars made of?

Mother: I don't know. I've never been to one. God put them there to rule over the night sky.

Child: I hate the dark. Couldn't God have made them brighter?

Mother: Just eat your damn peas and hush!

Using Science to Fuel Discovery

Child: Mom, what is a rainbow?

Mother: A rainbow is caused when sunlight shines through the tiny water droplets inside a cloud. The droplets bend the light, because light bends when it strikes certain objects. But different colors of light bend different amounts, so when white light from the sun, which is a mixture of all the colors, gets bent, the colors spread out and makes a rainbow.

Child: Cool! What else causes light to bend?

Mother: Light bends when it goes from one clear substance, like air, into another substance, like water. That is called refraction. It also bends when it goes around sharp corners of objects. That's called diffraction.

Child: Silly Mom, light can't go around corners. It goes straight, right?

Mother: Normally it goes straight. But when it strikes a very sharp corner the different colors can bend a little. Hold two fingers up to that light and squint your eye to look between the slit made by your two fingers. See those dark lines?

Child: Yes, what is that?

Mother: That's called a diffraction pattern and its caused by the light bending around the corners of your fingers.

Child: What if I get a piece of clear film and draw tiny lines real close together and let light shine through. Would light bend around those lines and make a rainbow?

Mother: Try it and see!

So the child made a diffraction grating and spent hours experimenting with different ways that light could be diffracted through his homemade kaleidoscope. But he noticed that when he held it up to fluorescent light, it didn't make a complete rainbow. Some colors were missing. So he asked his mom about it.

Child: Mom, why do I get a strange-looking rainbow when I look at fluoescent light through my grating?

Mother: Flurescent light does not produce a continuous spectrum. The coating on the inside of the bulb glows only in certain wavelengths of light.

Child: So do other things also only allow certain wavelengths of light to pass through them?

Mother: I think you're probably right. Why don't you do an experiment to find out?

So the child, with his mother's supervision, vaporized various elements and compounds and shined white light through them after capturing the vapors in a flask. Sure enough, different gases produced rainbows with certain colors missing. The child made a chart showing which colors were missing from different elements and compounds. He then mounted a better diffraction grating to his telescope, connected it to a camera, and let it capture starlight. He could see dark lines in his rainbow as captured from the stars. He concluded it was because the star must be made of certain elements that glow with that particular pattern of light, so when he compared the starlight to his list of elements, he found that what stars are mostly made of was the element hydrogen, with a little helium too.

Child: Mom, I know what the stars are made of! It's hydrogen and helium!

Mother: That's what other scientists have discovered too, dear. Good work!

And that is how religious belief quashes scientific inquiry. Why bother seeking real answers if the only answer you care about is that "God did it"?

Sunday, April 01, 2012

In Praise of My Smart Phone

When I was in my teens, I was interested in science, specifically weather. I even toyed with the notion of becoming a meteorologist. I eventually chose to be a science teacher. But back when my hobby was weather observing, one of the instruments I dreamed of having was a weather radar. Of course, nobody had their own weather radar, except NOAA. Nobody has their own radar even today, but nobody really needs one. They have the next best thing: The Internet.

Around 1990 I discovered that there was a piece of software I could buy for my computer that would allow me to display weather radar images on my screen. I just had to dial up the service and wait several seconds for the image to load. It was a highly-pixelated, 30-minute-old map image of radar echos, but it was better than nothing.

Today, of course, anyone with a smart phone can access up-to-the-minute radar images in high resolution from anywhere they happen to be at the time. It just takes the right app.

During the same period of time that I was pining for my own weather radar, I was listening to my favorite music mixes on a newfangled medium called 8-track tape. Dad was a musician and he liked to record his music in his home studio, so he actually had an 8-track recorder, so I could easily create personalized song mixes. I listened to 8-track in my car, but while at home, I played vinyl albums. But in my fantasies, what I dreamed about was a sort of home jukebox where I could just push a number of buttons to schedule playback of my albums in whatever order I wanted without having to get up and change the disc.

In the mid-'80s, along came CDs to replace vinyl. The 8-track had long been gone, having been replaced by cassette tape. But that forced me to always listen to the songs in the same order. So the CD was a vast improvement because most players allowed me to shuffle the playback. It was closer to my jukebox wish, but I still had to get up and change CDs every once in awhile, even with my 10-disc changer.

One of the other music-related fantasies I had right after I got my first CD player was to have a player that didn't have any moving parts at all. I figured the only thing holding that up was that computer memory was incredibly expensive back in the late '80s. Not anymore. Today, of course, I can take my entire music library with me on my smart phone and listen to it anywhere in high-fidelity. It's a far cry from my old 8-track player that was installed under the dash of my green pick-up truck.

Back in the late '60s I had a portable transistor radio. It would pick up only AM stations and you had to hold it in a certain position for best reception. It came with an earphone, a single plastic speaker-like device that fit in one ear and sounded awful. But that's what we had to work with. Today, on my smart phone, I have an app that lets me listen to any of thousands of terrestrial radio stations from all over the world, and the reception is always perfect, as long as I'm within the 3G reception range or within reach of Wi-Fi. And with a pair of modern ear buds the sound is quite awesome.

I once played the game of Pong on my black-and-white TV with a Coleco game machine whose only sound effect was a beep. Today, I can play Angry Birds on my Smart Phone with MIDI music and in color. I once thought that having a cordless telephone in my house was pretty cool. I could almost walk around the block without losing reception. Today, with my cell phone, I can start a conversation in the living room and continue talking while I get in my car and drive for miles, even across the country. When I was a sophomore in college, I thought our electronic calculator in the science office was fascinating. My smart phone has a calculator that will perform even better tricks of mathematics. When I was in high school I loved to take pictures with my new Polaroid camera I had gotten for Christmas. The film was expensive so I had to be careful what I took pictures of. These days, I can take high-resolution pictures on my smart phone, even video in HD. When I first started driving I liked collecting road maps. I would go to the filling station and get one of their free ones every time I would visit another state. Today, I can call up a map of anywhere in the country and get driving directions. I can also view 3-D map images of almost any place on earth, all with my smart phone.

None of this is news, especially to anybody who owns a smart phone. I haven't commented on any of my phone apps other than to just list and describe them, because smart-phone technology is awesome enough on its own. But I compare them to the things I could only dream about having in my youth because the comparison is striking. The smart phone has fulfilled almost all of my youthful technology fantasies plus it has things I couldn't have imagined back then.

I don't think most people think much about the capabilities of their smart phones. I use mine to pay my bills, transfer money to my bank account, read the news, watch video, play games, check movie listings, listen to music, communicate using text, communicate with face-to-face video, keep track of appointments, surf the Internet, pay my parking meter, look up word definitions, listen to pronunciation of words I've looked up, look up things in the encyclopedia, take pictures, record video, read books with my Kindle app, find movies at Redbox locations, record memos, get map directions, and even talk on the telephone. All this can be done with a piece of electronics that can easily fit in my hand and is no thicker than a slice of Spam. While I'm busy doing all that with my cell phone, I also typically just take it for granted. But as a real geek when it comes to technology, when I think about it, it never ceases to fascinate me that I can carry that much power in the palm of my hand. I think back to the pre-computer age that I grew up in and I can appreciate what science has wrought when it turns into technology. It amazes me so much, sometimes I just have to write about it.