Sauropod forelimbs -or- why I was wrong -or- why I do research

An in-press, open access paper by Joel Hutson extensively cites my Bonnan (2003) paper while developing a hypothesis that quadrupedal dinosaurs did not evolve fully pronated forearms.  Hutson suggests, correctly, that the hypothesis linking hand morphology and pronation in Bonnan (2003) is falsified.  I agree.  I also agree with Hutson that dinosaur forearms are best understood in the context of other non-mammal tetrapods, and I agree that mammalian-style (and chameleon-style) pronation of the hand was not possible in known quadrupedal dinosaurs.  But I take issue with the tone of Hutson’s paper, and for what I think he misses about the process of science.  To put this in context, first a little history:

As odd as it may seem, the forelimb posture of quadruepdal dinosaurs is anything but settled.  This is due to several reasons, chief among them being that a large amount of articular cartilage encapsulated the ends of the long bones (see here and here, for example).  Since this tissue is rarely preserved, determining how the elbows and shoulders of dinosaurs went together, let alone their possible ranges of movement, is difficult to determine at best.  This makes determining how the bones were oriented in life difficult to resolve.  Regardless of how much cartilage was or was not there, a dinosaur forearm and that of a large, quadrupedal mammal are different.  Without going into a long, drawn-out discussion on the subject, suffice it to say that, like other archosaurs, the radius and ulna of most quadrupedal dinosaurs lie parallel to one another.  If the forearm was held as a relatively vertical support structure, it is difficult to envision how the hand would be pronated so that it moved in synchrony with the foot.  Large mammals accomplish this by significant crossing of the radius over the ulna: this turns the hand palm-side down (pronation) and essentially allows it to work effectively in tandem with the foot to push the animal forwards.  In other words, an elephant hand and foot push in the same direction.

In graduate school (mid-to-late 1990s), I noted what I believed were inconsistencies: 1) sauropod trackways show that the manus is often pronated (although not quite as much as mammals and certainly the palm did not face directly backwards); 2) the forearm bones articulated like they do in other archosaurs, like alligators, that cannot assume an upright, columnar forelimb posture with a pronated hand; 3) quadrupedal dinosaur forelimbs were often restored with the radius crossing the ulna to some degree, which cannot occur when you articulate the bones together.  In essence, there appeared to be a mismatch between trackways and bone morphology.

It had been well-known that the hands of most sauropods were a vertically-oriented, tubular metacarpus (palm) with stubby fingers and sometimes a large thumb claw, whereas the hind feet were more what you might expect in a big animal: a large foot spread across a fat pad.  Why the difference?  I began to notice that when the radius was articulated with the ulna, it was cradled on either side by ulnar processes at the elbow.  One of these processes was not present in “prosauropods,” theropods (including birds), and crocs.  It occurred to me that, perhaps, the radius had shifted internally in the forearm relative to the ulna, and this “new” process (the craniolateral process) evolved to buttress the humerus where the radius once resided ancestrally.  If the radius had shifted medially, this would further “drag” the hand into pronation.  There was also a lot of cool Evo-Devo stuff going on at the time, and I was absolutely enraptured with the concept of the digital arch that forms the hand in embryos.  Since this arch forms from the ulna side and spreads to the radius side, I hypothesized that a shift in radius position internally could bend the hand into a U-shaped structure.

I published on this in the Journal of Vertebrate Paleontology in 2003, and it is one of my most cited papers.  It was, to the best of my knowledge at that time, the simplest “solution” to two “problems” — pronation of sauropod hands and their U-shape.

Needless to say, a lot has happened since 2003.  Many, many more sauropods and “prosauropods” have been discovered, and other well-known species have been re-described.  In my 2003 paper, I predicted that when the earliest sauropods were found, if they had an ulna with a craniolateral process that hugged the radius, they should also have a U-shaped hand.  You know what?  I was wrong.  My first excursion out to South Africa cinched it for me — I got to examine the forelimb of Melanorosaurus, either an almost-sauropod or a basal sauropod.  That one animal blew up my hypothesis — it had a craniolateral process on the ulna, but a flattened hand.  End of story. Done.

Well, sort of.  Adam Yates and I published on the forelimb of Melanorosaurus in 2007, and we drew attention to this issue.  We suggested that the radius might still have shifted proximally at the elbow, but that it did not directly and radically effect the hand.  We suggested that the U-shaped hand seen in most “classic” sauropods evolved after this shift and may have enhanced pronation by assuming a U-shape.  But we definitely stated that the Bonnan (2003) hypothesis linking the possible shift in the radius and the U-shaped hand was falsified.  As we stated in the abstract for that paper:

The forelimb morphology of Melanorosaurus suggests that pronation of the manus occurred early in basal sauropods through a change in antebrachial morphology, but that changes to the morphology of the manus followed later in eusauropods, perhaps related to further manus pronation and improved stress absorption in the metacarpus. Thus, we conclude that changes to antebrachial morphology and manus morphology were not temporally linked in sauropods and constitute separate phylogenetic events.

So, to return to Hutson’s paper, I was surprised that he is apparently unaware of the Bonnan and Yates (2007) paper on Melanorosaurus where we clearly say, yes, there probably was no direct link between pronation and U-shaped hands.  Again — the hypothesis put forward in Bonnan (2003), based on what was available and known at the time, is falsified, so far as the U-shaped hand and radius-shift are concerned.

I was also surprised that Hutson claims, for example, that I formulated my original hypothesis within a restricted phylogenetic context.  At the time, I had dissected and studied bird and reptile forelimbs, and also examined and articulated where possible the forelimbs of “prosauropods” and theropods, and had examined a variety of mammalian forelimbs — keep in mind, this is all before it was feasible to easily digitize and manipulate sauropod dinosaur skeletons.  I reference all of these taxa in additional to numerous sauropods in my study.  To suggest my hypothesis was developed within a restricted phylogenetic context is specious.  Hutson also suggests that I was unaware of the plesiomorphic condition for pronation in tetrapod forelimbs.  I will leave that to my readers and to the scientific community to judge.

Throughout the paper, Hutson uses phrases like “Bonnan reasoned …,” “Bonnan relied upon a suggestion …,” and so forth that imply I did not examine material first-hand.  I did, and spent many many months and years agonizing over what I had examined, articulated, and dissected.

I could go on, but my point is this.  Science proceeds by making hypotheses, testing them, putting that through the process of peer-review, and the allowing the scientific world community to continue to test and modify those hypotheses.  As a scientist, you are going to be wrong, and wrong a lot.  Over time, new data are going to emerge, new approaches will crop up, and new eyes will look at old bones.  You do the best you can with what you have, but you can’t let perfection be the enemy of progress.  No paper and no study is perfect — hypotheses will be overturned.  If we waited to publish when everything was perfect, nothing would be.

When your hypotheses have been falsified, it is okay to admit that.  In 2007, that is precisely what Adam Yates and I did — we said, yep, Bonnan (2003) got some things wrong because we now have better data, and the data don’t agree with that hypothesis anymore.  And you know what?  That is going to keep happening — scientists evolve past their older papers, and science is self-correcting.  If I were still trumpeting from the hills that my Bonnan (2003) article was totally correct and unassailable, the scientific community would be right to castigate me in light of all the new data.

So I think Hutson misses the point.  There are statements in his paper such as, “Unfortunately, pronation research has suffered from a lack of awareness that semi-pronated forearm anatomy is plesiomorphic to Archosauria, and indeed all tetrapods.”  I know many colleagues who spend an inordinate amount of time carefully collecting and examining data from fossils and living animals.  The issue is not one of ignorance or lack of awareness, but one of difficulty — it is damn hard to elucidate evolutionary patterns of forelimb posture because of so many contingencies.  I have grown to appreciate these even more as I’ve ventured into collecting kinematic data on live animals.  It ain’t easy, and it never will be perfect.

I wish nothing but the best for Hutson and his future studies on what is admittedly an intriguing evolutionary history among the archosaurs. I do hope that he remembers, when his hypotheses are ultimately changed or falsified, that this is the process of science — and that that’s okay.

Why science definitions matter: a response to the NCSE’s Misconception Mondays

Dear fellow scientists and science educators: may I suggest the time has come to work together to standardize the major terminology of our field?  I don’t mean the terminology of specific disciplines, I am getting at the fundamentals here: what is science, and how do we effectively and efficiently communicate what a hypothesis, law, and theory are?

I am writing this post because I read with some dismay the recent National Center for Science Education’s blog Misconception Mondays: Hypotheses, Theories, and Laws, Oh My! by Stephanie Keep.  I encourage my readers to read her blog post and form your own opinions.  I want to be clear from the beginning that this is nothing personal about Stephanie Keep — her post simply caught my attention and serves as a spring board for discussing what I read and hear all too often from many of my colleagues.

The take home message from Keep’s post is this: it doesn’t matter what labels we give concepts in science, so long as science is being taught.  In essence, don’t get bogged down in semantics and lose the forest for the trees — it is more important that students understand the science.  At face value, this seems reasonable: don’t be pedantic be practical.

On deeper reflection, however, this attitude (an attitude shared by many in the sciences) is troublesome, because definitions and the meanings we attach to words do matter, especially for students and the public who vote on science issues.  Keep says:

People—especially scientists—like firm definitions. Science is full of technical terms that we learn to master (or learn to quickly look up on the Internet), and thanks to a mixture of precedent and state standards, many teachers keep making kids learn definitions for theory, law, and hypothesis in the introductory weeks of a new class. I’m not suggesting that kids shouldn’t learn what a hypothesis is—of course they should! Forming and testing hypotheses are fundamental parts of any scientific endeavor. But I am suggesting that we be willing to admit that there is often no good reason why something is called a law vs. a theory, or a hypothesis vs. a theory—and that’s okay.

But therein lies the fundamental problem with this approach — not just Keep’s approach, but, I would argue, the approach so many of us have been taught to take.  How can you teach a student how to test a hypothesis if you simultaneously tell them that we can’t tell if it’s a hypothesis or a theory?  These definitions do matter.

Something else is troublesome in Keep’s statement that, “many teachers keep making kids learn definitions for theory, law, and hypothesis in the introductory weeks of a new class.”  In any discipline, you learn what it is and how it works in the beginning so that you have a common language through which to teach and make sense of the core material.

If we are charged with doing science and with educating the public about science, shouldn’t we able to say: here is what science is, here are it’s limits, and here’s how the toolkit works?  Especially at the beginning of a class?  As scientists and science educators, we seem on the whole to be so circumspect about this because, I suspect, we appreciate that science is not about certainty but about probability.  Therefore, we are loathe to say we have a concrete definition because we fear that what we convey is an absolutism rather than messy reality.  Believe me — I understand and appreciate wanting to avoid teaching our students that science = unassailable truth.  But if this is a fear of looking too authoritarian, in my opinion, it has led to much confusion both among ourselves and the public at a time when science is under attack.

Dear scientists and science educators: it is okay to have firm definitions that define and describe what we do, and we need to give ourselves permission to be okay with that.  It is no longer okay for us to say to students, in essence, we can’t really describe or define what it is we do precisely, but you’ll know it when you see it.

It would be arrogant and presumptuous on my part to suggest I have the definitive answer or definitions for what we do, nor do any of us work and teach in a vacuum — much of what I teach my students is cobbled together from what I have found works for me as an instructor (borrowed and morphed from many gifted individuals), particularly the approach of a former graduate mentor, Dr. Ron Toth at Northern Illinois University.

But I would like to start a conversation about fundamentals.  Surely, science as a discipline is not an amorphous thing.  I suspect most of us would define it as a tool for understanding the natural world.  Many of us test hypotheses – these are predictive statements that can be tested and falsified which guide our research.  We often test our hypotheses under an explanatory umbrella we call a theory.  As an example, a paleontologist might test the relationships of various dinosaurs (a hypothesis called a phylogeny) using data collected from fossils, working under the explanation that they are closely or distantly related through common ancestry (a theory called biological evolution).

Laws, I will admit, often stick in many of our craws.  I have come to see scientific laws as testable descriptions of repeatable phenomena or processes.  If we define scientific laws in this way, we are now more clear about what should qualify.  For example, in her essay, Keep says,

Have you ever noticed that most of the “laws” in science tend to be in the physical sciences and astronomy? There aren’t a lot of “laws” in biology—in fact, I can’t think of any aside from Mendel’s Laws. Why is that? Is it because biology is a “soft science” while physics and astronomy are “hard sciences”? Not at all. It’s because people in those fields really liked the term “law.” No, really. That’s pretty much it.

I would argue that we do have laws in all the branches of science, we just don’t always call them that.  If a scientific law is a repeatable phenomenon or process, Genetic Dogma (DNA is transcribed and translated by RNA into proteins) is a law — it happens continuously in all living things, always the same — a repeatable phenomenon or process.  Natural Selection is a Law — all individuals vary, more individuals in a population are born than can survive, and those with variable traits that allow them reproduce viable offspring are “selected.”  Look at any population in the living world, and this process is on-going and repeatable.  How about calling the Cell Theory, the Cell Law?  After all, that living things are made of cells is pretty much a repeatably observable phenomenon.

This works for me and for teaching my students, but I am not suggesting I have the market cornered on this definition.  Rather, my point here is that when we have a clear definition, we can more easily comprehend what we are communicating to one another and to our students.  If I am testing a hypothesis, you and others know I am probably working under an explanation, a theory.  If I am testing a law, you and others know that if I find variation or the phenomenon does not repeat, I may be in a position to reject or modify that law.

We need to have this conversation because definitions do matter in science.  What you call something does matter, especially when you need it to convey a particular set of qualities.  True, there will always be exceptions to the definitions and the natural world is messy, but don’t let perfection be the enemy of progressScience is and should be definable — we don’t just know it when we see it.

I welcome any constructive feedback and ideas from all of my colleagues as to how we can and should move forward.  I want to thank Stephanie Keep for sparking this conversation.

For those who don’t know and who might be interested, I have outlined and explained my own approaching to teaching science and evolution.

Why I Believe Bill Nye Should Not Debate Creationism

If you are not already aware, Bill Nye (the Science Guy) and Ken Ham (founder of the Creation Museum) are scheduled to have a debate at the Creation Museum on February 4, 2014.

This debate was apparently triggered by a video posted by Bill Nye entitled, “Creationism is Not Appropriate For Children” on YouTube.  Not to be undone, Ken Ham posted his own response with embedded links to two other Ph.D.s who amplify his belief that evolution, not Creationism, is damaging to children.

If the goal is science education, then I believe this debate is a poor way to improve the reception of science education in the general public.  Why do I feel this way?

There is a poor or nebulous definition of evolution and science by both parties.

In his video, Bill Nye states, “Evolution is the fundamental idea in all of biology.”  I really like Bill Nye, but I’m sorry, Bill.  Evolution is not an idea.  It is a scientific theory.  If you’re going to have a debate about science, definitions become hugely important.  A scientific theory is a testable, falsifiable, and predictable explanation of natural phenomena.  If you couch evolution as an idea, you open the door to a debate about ideology, not science.

Of course, Ken Ham has science wrong as well. He says, “Science means knowledge – you can divide science into historical science … and observational science.”  No on both fronts.  First, science as it is practiced is not a definition but a method — specifically methodological naturalism.  It is the tool by which we understand the natural world — a narrow discipline, in fact, that seeks to pose answerable questions about nature.  Second, science is science.  All science is based on observations at some level — the dinosaur bones may not “come with labels on them,” but they are observable data that can measured, studied, and so forth.  So, there is not observable versus historical science — it’s all the same thing.

A scientist works under a theory, an explanation for some type of phenomenon in the natural world, to test hypotheses.  If you work on chemistry, you are working under (among other theories) the atomic theory which states that all matter is made of atoms with specific properties.  Until recently, chemists have done a bang up job of testing and predicting chemical reactions and their consequences without seeing directly into atoms.  That’s because the testable explanation (atomic theory) was effective for inferring what should occur.  So, to say that evolution is “historical science” which is “beliefs about the past” is a gross misconstruction of how science works.

When Ken Ham says, “If evolution were true … it would be so obvious to the kids …” he is ignoring the fact that many applicable theories of science are weird and not obvious.  For example, the theories of general and special relativity predict that time is experienced differently by different objects at different speeds and in different gravitational fields.  If you use satellite technology, those satellites whizzing in orbit around the earth have clocks that quickly go out of synch with those on earth (which is explained by the theories of relativity) and thus we have to take special measures to synchronize them with our devices on the earth (GPS comes to mind).  That is good science but not something particularly obvious to kids.

In a nutshell, science is like the honey badger of internet lore — it doesn’t care about your beliefs or opinions.  Data drives what is accepted and rejected.

We are again fighting a metaphysical clash of civilizations.

Based both on what Bill Nye and Ken Ham say, this debate is not about data.  A scientific debate would be about data.  Instead, we have what amounts to, in my mind, another metaphysical clash of civilizations.  Ken Ham and his organization are very clear on this.  He is not concerned about data, but rather showing that “Creationism teaches children that they’re special, that they’re made in the image of God.”  In that one statement, you have what is actually being debated spelled out: whether or not you believe in a particular deity in a particular way.  This is why Ken Ham, his organizations, and others like him make the leap from teaching evolution to teaching kids they’re “just animals” to gay marriage and so forth.

However, Bill Nye is not doing anyone a favor by saying, “In a couple of centuries that world view [creationism] will not exist … there’s no evidence for it.”  Nye has basically indicated that, yes, evolution is a world view, but it is supported by evidence.  And if that is true, then it follows that in this metaphysical clash of civilizations you have to pick a side.  At least, if you follow Ken Ham and his compatriots, that is likely what you are led to believe from such statements.

There is No Clear Distinction About Faith and Creationism

I have said this before, but it bears repeating – there is no conflict between science and faith.  Yet, that is precisely what this debate is already boiling down to.  Science is not faith – it is a tool for understanding the natural world.  Faith is a deeply personal set of beliefs that often cannot be demonstrated scientifically, but that makes them no less valid to the individuals that hold them.  This is not my idea, not by a long shot, but to rephrase the words of many who have come before me, science and faith are after separate goals.  You don’t scientifically test faith, and you don’t apply faith where science works well (the natural world).  This is why they can and should coexist — they serve different purposes, often to the betterment of us all by people with noble intentions.

But the Creationism of Ken Ham and the Creation Museum is not mainstream Christianity.  Many Christians from many faith traditions accept science and evolutionary theory while maintaining their faith.  Ken Ham wants you to conflate his narrow concept of Christianity (a fundamental, literal interpretation of a particular version of the Bible) with Christianity as it actually exists in the world.  But that conflation works to his advantage, because if we are choosing camps, and you identify as a Christian, you cannot “believe” evolution because a humanist (whatever that may mean to you), Bill Nye, is coming after your faith.

A Plea and Some Thoughts

No one person holds all the keys to our problems, so I would never be so bold as to say I have the answer.  Here, then, is my plea and a few thoughts.

I think what many scientists, myself included, are troubled by is hucksterism and charlatanism — snake oil salesmen dressed in religious or authoritarian garb using ignorance to fund their own ambitions and power.  But it is vitally important that we do not conflate that clear and present danger with faith overall.  Given that a majority of Americans identify as people of faith, broadly lumping them in with extremists serves no one and is very damaging.  My plea to my scientific colleagues is, stop doing that.  This is just as damaging as saying that people with no religious beliefs are evil, wrong-headed, and trying to subvert American culture.

As I have said before, fear, not data, is the bottom line here.  People are afraid that their faith is being attacked — once you are afraid, data (the currency of scientists) doesn’t really matter.  What scares people about science?  What scares them about evolution?  How, as scientists, do we work with the majority of people who can see the benefits of science as a tool but are afraid to compromise their spirituality?  That, to me, is the challenge of our time.

You will not convince those with extreme convictions to self-reflect and re-evaluate.  You can bring oceans of data and heaps of observations, but it will do you no good, because the debate is not really about science but about fear and emotion.  So, if Ken Ham and his followers are convinced they are right, having a debate only ever further convinces them that they are.  Do you really think Ken Ham would ever take the results of the debate as anything but a win if not just great publicity?

My last thought or plea: don’t debate Ken Ham and other so-called Creationists.  There are people convinced to their core that the world is flat – no amount of data and debate will sway them, and nothing much will be accomplished.  But they, like Ken Ham, do not represent the majority.  The majority is who we desperately need to reach.  Certainly, when such extremist views threaten to undermine science education, we should and must push back as the National Center for Science Education has admirably done.  That is very different, however, from going out of one’s way to have what will amount mostly to spectacle and the reinforcing of deeply held convictions on both sides.

Again, I like and respect Bill Nye a lot, and I think he has done wonders for science education in the United States. To Bill Nye and any other well-meaning scientists out there who want to improve science education, please do not debate Creationists — this is not the way to accomplish what we all want.

Evolution, climate change, and uncertainty: why understanding the process of science matters

As the National Center For Science Education has been demonstrating for some time now, denying biological evolution and denying climate change are part of a larger phenomenon related to science illiteracy.   But I think we often tend to conflate the knowing of scientific data with knowing the process of science itself.  As a college professor, I can tell you that  smart students who know a lot about the natural world don’t always actually know the process of science.  In one of my first lectures to undergraduates in the introductory biology majors course, when I press them to define science, hypothesis, and so on, very few can.  And I have come to believe that our current societal issue with accepting science is a fundamental misunderstanding of the process, not simply a dearth of facts.

In my undergraduate days, I was a climate change denier.  That’s correct — I felt that the evidence was at best equivocal for global warming.  If you couldn’t prove it directly, how confident could we be?  In fact, I felt a good amount of the environmental “science” out there was nothing more than misplaced hysteria or political propaganda. For those who do know me and my political leanings, you are probably surprised.

So I speak from experience when I say that I understand the reservations among many people when it comes to climate change.  Ask any climate scientist, and they will never tell you with 100% certainty that their predictions will come to pass.  In fact, these scientists rely on models of climate, and those models are a hypothesis of reality, not reality itself.  Remember, I was a science major with aspirations of becoming a paleontologist, so my undergraduate self decided that if we couldn’t be certain, we shouldn’t go around broadcasting that it was the end of the world.  In my undergraduate head, the best science was certain, and that was why paleontology was so difficult — a lot of uncertainty.

So here’s the thing — a climate scientist can show you a lot of data (see below), and can tell you based on their expertise which are the most probable outcomes of current trends, but if you were my undergraduate self, you would not be convinced.

From Wikipedia Commons: “This image is a comparison of 10 different published reconstructions of mean temperature changes during the 2nd millennium.”

Whether or not my younger self (let alone my older self) was stubborn or simply a bit daft (probably both), I again point out a key feature in the thought process: if it isn’t certain, it’s not good science.

So, the assumption or implication that good science is certain is the first part of the puzzle.  The second part of the stubbornness by many of us to accept climate change or perhaps biological evolution is that we want evidence presented in a court room.  We want the TV show Law & Order, and we want the good lawyer to give us an iron-clad argument, or to show that our opponent is a lesser person, or to literally give us a smoking gun.  We are convinced that science works like this, and that the person with the best argument and evidence wins.  And most importantly, that the winner stays the winner.  Nothing can ever overturn the win.  Good science should be certain and win the day’s argument, for now and forever.

But of course, science has little or nothing to do with certainty and court room drama.  There is no certainty in science — there is simply probability.  Because a good scientist recognizes that we are only human, and we can only realistically deal in samples, we can’t measure every aspect of the known universe, and we certainly can’t have all the data on all the clouds, carbon dioxide, and local temperatures.  Therefore, a good scientist will never say they have “proved” something — rather, they will indicate that their data suggest certain scenarios are more probable than others.  The higher the probability, the more confident one can be that the predictions may come to pass.

It took a while for this concept to sink in with me.  It took graduate school and having to do science, and taking an excellent seminar from Professor Emeritus Ronald Toth at Northern Illinois University, that finally made science as a process click.

(As an important aside, much of my thinking as a scientist I owe to Ron — so the “smart” stuff I say about evolution and science are me emulating him.  My evolution podcasts and understanding evolution website are extensions [and I hope a sincere form of flattery] of Ron’s approach.  Thank you, Ron!)

That means, as someone who earned a B.S. in Geology with a Biology major, I had no real concrete idea about science as a process!  I am not surprised nor judgmental that many of our undergraduates, let alone the larger public, don’t understand this either — but this I believe is what needs to be most addressed.

Even if you do succeed in uncovering something new or accurately predicting a trend, there will always be new data. The complaint you often hear about science is how we keep changing our damn minds — we knew Pluto was a planet, or we knew that birds were not dinosaurs, or we knew that cholesterol was bad, and so on. But the process of science requires that one keep testing the hypothesis, and to incorporate new data as it comes in.  So we’re not changing our minds to tick you off — we adapting our models and our understanding of the natural world as more data come rolling in.

What I realized at long last in graduate school was that scientists speak in probabilities.  And when you think about it, we deal in probabilities all the time, and we make decisions based on those probabilities, and we are okay with that.  Every time you get in a car, there is a probability you will be in an accident … but you probably still get in that car.  Imagine if someone told you that unless you could 100% guarantee that no accidents would ever occur, it was pointless to drive.

Okay, but now for something more ominous: what about the probability that you will get sick if you ingest salmonella bacteria.  I have been sickened myself by this nasty “bug,” and many people have died from salmonella poisoning.  But there will always be cases where someone ingests salmonella or another pathogen and doesn’t become sick.  Now imagine a friend tells you that since every time a person has ingested salmonella they haven’t always become ill or died, we don’t have enough data to know whether or not it is truly deadly.  Therefore, wasting money and resources on preventing the spread of salmonella is not advisable because we can’t know with 100% certainty that everyone who ingests it will get sick or die.  This person would probably not remain your friend for long.

Probability in science works along this spectrum — from low to high odds.  Low odds: you will be hit in the head and killed by a rouge meteorite tomorrow.  High odds: the climate will continue to change, with an overall trend toward higher global temperatures.  Can we be certain climate will change in these ways?  Not 100%.  But the probabilities are high … and that’s why we should be concerned: the scientific predictions of increasing global temperatures suggest our world will change in ways that, if we are not prepared, will be devastating.  Of course, we could wait until we’re certain, and we could wait for the ultimate court room battle of the sciences … but if the probabilities are high, why wait?  What are waiting for?  Waiting for all the data to come in (which will never happen) and waiting for 100% certainty (which will never happen) is simply another way of doing nothing in the face of probable danger.

If you understand that the process of science is by its very nature is one based on probability, not certainty, I think we begin to get to the heart of the scientific illiteracy problem.  Giving people more and more data won’t help if they sincerely believe that uncertainty means no one knows anything.  This is, I believe, the core issue with science literacy — and why our politicians, our media, and our public are so often mislead to disregard good science and its important predictions that effect us all.