“False Pearls before Real Swine”

A falsehood is an incorrect or muddled belief widely enough held to be notable, and possibly dangerous. A falsehood is also a potentially powerful teaching tool. Evolution generally, and human evolution in particular, is loaded with them.

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“False Pearls before Real Swine” … I won’t tell you who said that, but when he did say it it was in front of a classroom of several hundred Harvard freshmen, and he was referring to the idea of telling little white lies to the unwashed masses in order to achieve the dissemination of greater truth. No one in the room but the wizened teaching assistants, clustered off to the side furtively consuming their lunch in the “no food allowed” lecture hall, got the reference. There were spit takes.

Teaching Evolutionary Biology is hard. It is not easy, like teaching astrophysics would be. Nobody really knows anything about astrophysics, so all the instructor has to do is find the empty space in the student’s brain and put some astrophysics in there. Simple

The problem with Evolutionary Biology is that everybody already knows lots of stuff about it. Everybody already knows all about animal behavior because they have a cat. Everybody already knows all about human behavior because they are a human. Everybody already knows all about mating systems because they have a mate. Or wish they did. On top of this, we have the venerable science press and the Discovery Channel. Evolutionary biology, especially the part about human evolution, is very cool. Therefore, new findings by evolutionary biologists always get press. Even old findings get press on a slow news day. But reporters are often not really reporting the science. They are writing for an audience; an audience that they have created over time with their particular way of reporting, and to which they must now attend with … well, references to and use of falsehoods, often falsehoods that started out as little white lies.

A very clear example of this is the concept of a Missing Link. Scientists seem to generally agree that there are no missing links in science. Evolutionary biologists reject the concept of a missing link. We don’t use that word. We think it is incorrect and misleading. Yet, it is as difficult to find a news story about a fossil that does NOT use the phrase “Missing Link” as it is to swing a dead cat and not get in trouble with the SPCA. (Not that I’ve not actually tried that…) By the way, reporters know all about this missing link problem. Or at least, science reporters know about it. They always apologize just before they write the story about the missing link. Having said that, it is interesting to note that the term “missing link” (as well as the term “ape-man” by the by) are routinely used by South African Palaeoanthropologists. And, I don’t think they are using “missing link” in correctly. I think, rather, that they have a different idea of what it refers to, perhaps a different idea of what a “link” is, or maybe, what a “chain” is, which makes the term work.

In other words, the term “missing link” sucks, but skepticism about the word “missing link” … if it is simply a knee-jerk reaction, as it almost always is, does no better. Indeed, there actually are “links” in an evolutionary sense and some of them are missing. The problem is not that such a thing does not exist. The problem is that looking for the missing link is rarely the main objective of the science, and many things are called “missing links” because they are newly discovered and for no other reason.

To me, there are two kinds of actual “links” in the fossil record. One is the simple phylogenetic link. For instance, we know that humans and chimps have a common ancestor that existed several million years ago in Africa, and that was pretty much chimp-like in morphology, behavior, and ecology. However, we don’t have any fossils of this population or anything close to it. As you may or may not know, depending on what kinds of falsehoods you labor under, it is rare to actually find members of any given hypothetical or desired population. Usually, we find what we call “representative forms.” These are species that are close in time and space to the population we would like to see, and close in overall morphology and ecology, so they stand in for the focal fossil creature. One difficulty is, of course, that it might be very difficult to be sure that you’ve got the original population (say, a last common ancestor of two living forms) or a “representative” BUt we assume that finding the focal population … the actual Last Common Ancestor … is difficult and unlikely, so we make the guess that we are mainly looking at representative forms.

Having said that, if we found the fossils of the human-chimp LCA, or a representative of it, I think that would be a “link” (or a representative of the link) and since it is now missing, one could say “Missing Link Found!… (or at least a representative).

The second kind of link is sometimes known as a “transitional form.” Now, the current rhetoric from palaeontologists and other evolutionary biologists is that the whole concept of a “transitional form” is bogus, that in a way everything is a transitional form, and that yes, the creationists are always saying there are “no transitional forms” but every time we find one, that does not shut them up … it just creates two new spaces in which there are no transitional forms, on either side of the newly discovered fossil!

Well, this is a case of reacting to the critiques in a way that damaged our own discourse. There are transitional forms, some are unknown (theorized) and others are well documented. Not every species is a transitional form. Rather, it works like this: For many animals (and I’d prefer to stick with animals here) there are categories that make sense. For instance, there is a group of mammals that are today represented by land mammals as well as sea mammals (the seals and their land-mammal relatives). Those are two dramatically different categories … terrestrial vs. marine. Something happened there in an evolutionary sense. To go from terrestrial to aquatic is a big deal, and … transitions must have happened. The difference between the terrestrial and aquatic species is nothing like trivial, and even though the differences among, say, the different species of seals are important, those differences pale in comparison to the terrestrial vs. aquatic differences.

From an evolutionary point of view, understanding this transition is very interesting and very important. The species that straddle this transition are transitional forms. There may be many, as there may be many steps in the transition. And the actual species we find may be “representatives” (see above). But they are all links, and those that are not found yet are … missing links.

I think that people who claim to find the missing link but who are just using the word and have not really found a phylogentically important Last Common Ancestor or a truly interesting transitional form that was not previously known should be flogged. Reporters and science writers who throw the term “missing link” and “transitional form” around like salt on an icy Minnesota driveway should be flogged as well. Flog them all, I say! Preserve these terms for what they mean, not what sells copy.

Of course, it is almost certainly too late. The misusers of these terms have ruined it for everybody. In two ways. One way is just ruining the terms themselves, so we can’t use them. The other is more insidious. By creating the backlash to the misuse of the term, you have otherwise perfectly intelligent paleoanthropologists and other evolutionary biologists, teachers, speakers, textbook writers, and science journalists running around talking about how there are no “missing links” and there are no “transitional forms.”

More Falsehoods !!!

This post is one of a series on the topic of falsehoods. The following is a list of falsehoods posts in order:

Comments

  1. #1 abb3w
    August 18, 2009

    Well, there is a third sense of “link” in biology: the chemical bond links between DNA codons. Which means you can have fun by “misunderstanding” the question of a “missing link”, and point out the very clear correspondence of human chromosome 2 to a fusion of the assorted ape 2p/2q chromosomes. “See, there’s the link: big block of telomeres in the middle of the chromosome, where what was once two chromosomes linked together.”

    This cheap shot usually gets the creationist sputtering in an entertaining manner, and as a bonus sometimes puts another datum into the head of an interesting bystander.

  2. #2 Nathan Myers
    August 18, 2009

    Reporters use “missing link” to mean something very close to what biologists mean by “ghost lineage”. An important difference, of course, is that the discreteness implied by “link” is rot. But the real difference is that it’s them saying their word, not our word.

    It’s similar to stories that get paleontologists in an absolute lather, calling paleontologists “archaeologists” and pterosaurs “dinosaurs”. Most people probably think of the former, in each case, as a special case of the latter. This is engendered, in part, because no commonly known term has been offered for that role — what is a generic term for somebody who discerns the past by digging stuff up?

    Ultimately it’s probably a lost cause to try to get control of the term “dinosaur”, and the graceful thing would be to get used to it. There’s not that much difference, anyway, between ornithodiran and dinosaur, phylogenetically, by which I mean that the terminology could easily have been decided the other way. I’ve heard of “archosaur” and “hellasaur” offered as a substitute to include ornithodirans, plesiosaurs, and crurotarsans, but have seen no evidence that either has any traction.

    There’s a real opportunity to introduce two new terms “last common ancestor” and “ghost lineage”, by contrasting each to “missing link”. Most people are terminally impatient with word games exemplified by attempts to reclaim “dinosaur”, but new concepts are like candy.

  3. #3 Monado
    August 18, 2009

    I use both “missing link” and “transitional form” because I want my articles to show up in the searches typed by people with very little knowledge of evolution and even by creationists. If I use them, it’s harder for them to say, “I searched and there aren’t any.” Once they get to the article, I can say, “Has features of both in a mosaic, as expected” or “Similar to what we expect to find in the common ancestor of…” But unless they find the article, they won’t ever hear the nuance.s

  4. #4 Joshua Zelinsky
    August 18, 2009

    Biology is not the only area where people do have prior knowledge that is mixed in with incorrect facts. While astrophysics may not have much of that problem, astronomy as a whole has many problems related to this. For example, a disturbingly large fraction of people (even people who have had good educations at decent colleges) seem to think that the phases of the moon are caused by the Earth’s shadow.

    Another common misconception is something like “black holes are nasty vacuum cleaner like things.” In fact, if the moon shrunk down while keeping all its mass so that it became a black hole, life on Earth would be almost identical aside from slight changes in tides. A similar remark applies to if you replaced any other local body with a black hole (although if you did this to the sun it would get very cold).

    Almost every area of science has these problems.

  5. #5 Jared
    August 18, 2009

    Joshua, you mean the phases of the moon AREN’T caused by the Earth’s shadow *gasp*
    /sarcasm

  6. #6 Greg Laden
    August 18, 2009

    How would the tides be different?

  7. #7 Nathan Myers
    August 19, 2009

    Not much different. Tidal forces aren’t linear, so a sphere and a point aren’t equivalent. In practice it would mean infinitesimally lower tides. On the upside, it would mean really cool slingshot-effect trajectories. Just don’t get too close or your toes might end up on a different trajectory than your ears.

  8. #8 Jeremy
    August 19, 2009

    Hey a slightly random question about this.

    How many fossils do we have that are probably direct ancestors to humans? I just want to estimate how many actual links we do have, compared to those that are missing :P

  9. #9 Greg Laden
    August 19, 2009

    African Homo ergaster (erectus) is a fossil population that certainly gave rise to African “heidelbergensis” or whatever you want to call “kabwe” and relatives, which in turn is a second population/species. That gave rise to modern humans.

    Before that, some Australopith is ancestral to ergaster maybe or maybe not via a known early homo. The problem there is that there is a big jump from australopiths to homo, and it is quite possible that there was a lot of messy stuff going on during that period, so frankly I expect it to be possible some day to pick an asutralopith and say “this is the one” but not an early homo population with the same level of certainty (becasue we may well not even find it).

    Which australopith is the one that, perhaps via an intermediate population, is truly ancestral to Homo? Starting with this question and working backwards through time, I think we are going to be stuck with “representative” mode but there will be a strong argument for one known australopith being the one. I predict it will be a robust (paranthropus) form from southern Africa that may or may not be known yet, but that’s just a … gut feeling, as it were.

    But that will probably be the best we can do, and prior forms will all be more vague until we discover, if it is true, a single widespread species that can really be the only one because it IS the only one. That is unlikely to happen, but if we settle for a single widepread genus, then we may have a shot of identifying the lineage at that level. Something like Anemensis.