The Scientific Method

As many of you know, I was recently in an accident and am on three kinds of medication. I told my doctor that I would like to drop one. I was taking six pills a day and it was initially given to me as a prophylactic and I was unsure if it was doing anything. I’ve never been on medication before and my doctor shares my feeling that’ no meds are good meds.’ So she made a plan for me.

“You’re taking two pills, three times a day. Start out by dropping one of the two with the morning dose first. Try doing five for four days and, if you don’t feel any effects of dropping one, then drop another one. If you ever get to where you are feeling symptoms, then you’ll know that it is doing something and you’ve found your threshold.”

Not only did I think that this was a wonderful plan, I thought it was a wonderful general application of the scientific method. Eighth-grade biology aside, there is nothing sacred about the scientific method. Not everyone agrees on how many steps there are to the method and there is no agreed upon definition. Depending of where you look, you’ll find anywhere from five to eight steps. It is simply consistent a way of looking at a problem and working it out. Wherever you look, the scientific method will incorporate the following:

  1. An observation is made.
  2. A question of some sort is asked based on the observation.
  3. A hypothesis for the question’s answer is made.
  4. The hypothesis is tested to be either true or false.
  5. A conclusion is derived based on the tests and the evidence.

Fool’s Gold

As an example, let’s say that you’re a kid who finds a rock. It’s gold colored and your pals think that you’ve struck gold and spend their time figuring out how to spend your money. Except for one: her Dad is a geologist and she thinks you’ve got a chuck of Fool’s Gold. How to tell the difference?

You you have a problem: is this one pound thing in your hand gold? You hypothesize that it is. To test you your hypotheses, you decide to compare your stone to the characteristics of gold. You won’t know if you have pyrite or not and comparing the characteristics of gold to your sample might not even tell you if you have gold. But it will tell you if you don’t have gold.

You call up Wikipedia and read that gold is a ductile metal (soft and pliable) and is usually found as a nugget or grain. What you are holding is a very solid cubic mineral. You read that gold is easily scratched with a hardness of only 2.5 on the Moh’s Scale. You try to scratch your piece with a nail file and are unable to. Finally you read about streaking. You find an old tile from when your parents re-did the shower and scratch your stone across the back of it. You read that gold should leave a line that is goldish-yellow in color But yours leaves a greenish-black line of dust. You hand it back to your friends. Your conclusion, based on whether of not it meets the criterion for gold, is that it’s not.

This is very akin, but not quite the same, as when your mom decided that your little sister is lactose-intolerant. She noticed that every time your sister has ice-cream for desert, she ends up with a nasty stomach ache. Your Mom has made an observation and asked a question based on the observation – is the girl lactose-intolerant? She decides that the girl will go without ice-cream for two weeks. She does and has no stomach ache. This isn’t proof that she is lactose-tolerant: there are a dozen reasons why she might be sick from eating the ice cream. But she has isolated something that correlates to a high degree. And though ‘correlation does not mean causation’ this is important, too.

One point sometimes made is that, to be scientific, the conclusion must be something falsifiable: it must be such that it can be proved wrong. For example, ‘becoming religious will help overcome a a drug problem’ is not falsifiable. Or provable. But may or may not be true. So the statement is an unproveable assertion. There are certainly religious people who have a drug problem and there are non-religious people who don’t. Is evolution falsifiable? It is. The geneticist J. B.S. Haldane was famously asked the same question and responded that “rabbits in the Precambrian” would disprove evolution. In other words, a gross error in the geologic column of fossils would show that a major tenet of evolution was wrong. Richard Dawkins agreed and argued that fossil mammals in the Precambrian would “completely blow evolution out of the water.” The philosopher Karl Popper initially made waves when he called evolution unfalsifiable. He later complained that this was misinterpreted and argued that evolution was difficult to disprove when compared to sciences like chemistry or physics. The falsibily of the statement that “pouring salt into water turns the water blue” is easily performed: pour salt into water and watch for the color change. That ‘all are animals are related’ is falsifiable but much more difficult to show. This was Popper’s point.

One of the most exciting finds using the scientific method in recent years is the story of Tiktaalik that Neil Shubin outlines in his book Your Inner Fish.

In the opening chapters, he outlines a research program that at first sounds audacious but, in reality, steps right through the scientific method to find an intermediate between fish and land animals.  He knows that the task is daunting. To maximize his effort, he begins with three essentials:

  1. They need to find rocks of the right age.
  2. They need to find the right type of rocks to preserve fossils.
  3. They need to find rocks that are exposed at the surface.

Tiktaalik

Shubin begins his book straightaway with the hunt for fossils. He looks for fish bones. He notes that “Fossils are one of the major lines of evidence that we use to understand ourselves”. He wonders where he can find a fossil fish that is an intermediate in the emergence of land animals. He understands how difficult the task is: it is generally argued that 99% of earth’s species have become extinct and fossilization is rare. He is encouraged, though, by technology that would allow him to “even scan your backyard for fossils from [his] laptop”. With an understanding of the question and of the challenges, Shubin starts making educated guesses. From Chapter One he writes:

“What makes this tricky is that fossil sites are rare. To maximize our odds of success, we look for the convergence of three things. We look for places that have rocks of the right age, rocks of the right type to preserve fossils, and rocks that are exposed at the surface.”

Shubin and his team start filling in the blanks. He knows that all early animal life occurred in water. We have tons of evidence of fish but not of land animals up to around 385 million years ago. Around 365 million years ago we see clear evidence of amphibians and reptiles. Shubin needed to find rock around 375 million years old to find this intermediate. With this information he began thinking about rock. We know that volcanic  and metamorphic rocks aren’t conducive to fossilization. Volcanism melts everything and metamorphosis squeezes and squishes and breaks everything. The great bulk of fossils are found in sedimentary rocks that have been laid down over time by silt in oceans and river beds. Now Shubin knows two things: he is looking for sedimentary rock formations in the range of 375 million years old. Is there anywhere that these rocks exist that are exposed for exploration? In an exciting part of Shubin’s tale, they stumbled unexpectedly upon a map that showed exactly what they were looking for. The map was of North America to the Arctic and delineated three distinct areas where sedimentary rocks of this age are located. One was in Greenland, one in Pennsylvania where Shubin had been exploring for years, and one was in the upper reaches of the Arctic. For reasons outlined in the book, the group chose to travel to the Arctic to search for their land-grabbing fish. They analyzed, studied and gathered information, and now made their prediction: if this thing can be found then this is one of the places we should find it.

You can guess how the story ends. It took several years and several trips, but, one day, just as everyone was settling down in the tent for dinner, one of the team members ran into the tent ‘wild-eyed’ and ‘out of breath’. He had found, on the side of a nearby hill, a ‘carpet of fossil fish bones’. Over the next several days they scoured the site until they found what they were looking for – a broad and flat skull jutting out from the rock face – hopefully with an intact skeleton encased within the rock. Shubin comments that “What we saw gradually emerge from these rocks during the fall of 2004 was a beautiful intermediate between fish and land animals.” They asked the local natives to name the animal. Two names were suggested by the elders and Tiktaalik – meaning ‘large freshwater fish’ and the only one of the two that the team could pronounce – was chosen. And thus we have maybe the most celebrated intermediate known to date. More will be found, maybe even by Shubin, and all will follow the same pattern using this method of using existing and observable knowledge to predict what we should find and where we should find it.

In summary, using our pattern:

Neil Shubin and Tiktaalik

  1. The observation: No fossils of land animals are found that are 385 million years old or older.
  2. The problem:        We know from the fossil record that by 365 million years ago that reptiles and amphibians swarmed over the land. How did animals make the leap from fishes to land animals?
  3. Hypothesis:           There must be an intermediate that existed about halfway though this period.
                                        If there is fossil evidence of this creature it will be found in rock about 375 million years old, likely in sedimentary rock with an exposed face.
  4. Testing:                  Tiktaalik is found exactly where the science says that it should be.
  5. Conclusion:          Tests and assays show that Tiktaalik is, indeed, an intermediary between fish and land animals.

Some people, and I’m inclined to be one of them, believe that the scientific method is mankind’s greatest achievement, offering the greatest power to understand the world that we live in and to harness much of it for our benefit.

Cheers!


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Your Inner Fish on PBS.
Shubin on Wiki.
JBS Haldane on Wikipedia
The Evolution Page on this site.