Blue Collar Scientist

Some interesting research about the evolutionary development of the human skull is being reported by UC Davis. The researchers have concluded that random change - called genetic drift in the parlance - accounts for most of the differences between human and Neandertal skulls.

In their new study, Weaver and his colleagues crunched their fossil data using sophisticated mathematical models — and calculated that Neanderthals and modern humans split about 370,000 years ago. The estimate is very close to estimates derived by other researchers who have dated the split based on clues from ancient Neanderthal and modern-day human DNA sequences.

This is significant, because it tells us that rigorous study of morphological changes in fossils gives us dates in good agreement with that of DNA methods. The picture here is that two separate disciplines offer mutually reinforcing insights into human evolution over this time period.

But then the press release gets a little strange. The principal investigator, Tim Weaver, says:

A take-home message may be that we should reconsider the idea that all morphological (physical) changes are due to natural selection, and instead consider that some of them may be due to genetic drift. This may have interesting implications for our understanding of human evolution.

As a layperson with a pretty solid understanding of evolution, I’ve been suspicious at times of some scientists’ tendency to see natural selection where I felt¹ some things might more simply be explained as neutral features - not selected against, not selected for, just arising randomly without any particular immediately adaptive traits. On the other hand, I’ve always been aware that I’m not the expert, so I’ve been inclined to trust the authorities and quell my own misgivings.

But despite my being predisposed to have sympathy with this conclusion, I have to admit that this is where the press release falls down into a morass of uselessness.

There is, almost certainly, a reason why Weaver thinks that his research indicates genetic drift, rather than selection, has been a major influence on the evolutionary development of the human skull. I’d bet that reason is a really good one, too. But the UC Davis release, as well as the PhysOrg coverage, are completely silent on what that reason might be. The closest they come to giving a reason for their belief is that they used “sophisticated mathematical models.”

I think it is problematic for a press release to pass up an opportunity to explain not only what we know, but how we know it. As has been often repeated, science is not a collection of purported facts. Science is a process for finding things out. A press release that gives such thin treatment of how a discovery was made, in favor of discussing what the discovery was, fails in its fundamental task of informing the general public.

The model behind this press release may be that laypeople are little people who live outside the University and can’t really understand what is being done, but might have a chance at understanding the conclusions. Or it could be that the public relations writer who wrote the press release² couldn’t understand, or didn’t have time to understand, the reasons why the research led to the conclusions it did.

Whatever the reason, this press release crosses the line between “providing an elegant explanation suitable for laypersons,” and “dumbing down science.” This is an extreme example of dumbing down, because the release appears to make the dual assumption that not only will the public not understand the reasons - however well expressed - but they also will find the principles behind the mathematical model too “sophisticated” to understand.

I call this the Moses model - some bearded guy on a mountain conveying the results of his research on tablets of stone to the masses below. What is demanded of all researchers (and their PR collaborators) in this environment of deplorably poor science education is to provide compelling examples of the scientific method in action, and compelling explanations of their research.

Wondering if I could improve upon the press release, I went searching for the paper. I found it here; and for a measly ten bucks, I can purchase the privilege of being able to read the paper for two days. I’m not going to do that, because (a) the subject is outside my field of expertise, so I’m not likely to get as much out of it as someone more familiar with this field of research; and (b) I’m not actually working on an educational program on human-neandertal skull divergence. But I did read the abstract, and noticed the first line was this:

Recent research has shown that genetic drift may have produced many cranial differences between Neandertals and modern humans.

So, it turns out that this paper does not lead to the conclusion that human skull evolution was driven by genetic drift as opposed to natural selection; it’s the other way around: the conclusion led to the paper. The conclusion was raised as a possibility by previous research, and this paper provides a test of the hypothesis. If only I could be cited back to that previous research, perhaps that abstract would further illuminate me. But I don’t know where to look, because (as is largely customary in abstracts), there is no citation.

The abstract again:

Close correspondence between cranial and DNA-sequence results implies that both datasets largely, although not necessarily exclusively, reflect neutral divergence, causing them to track population history or phylogeny rather than the action of diversifying natural selection.

Now this is fine for an abstract - if you want to learn the reasons why this correspondence is evidence for genetic drift, you are supposed to continue on and read the paper.

But this kind of thing is not fine for a press release, which must provide an accessible explanation of why the scientists believe the things they are asserting. Without doing this, the press release is useless as a tool to increase public awareness or education about the subject. It is far more difficult to write a press release than a research paper abstract, and the system that generated this release has had a major malfunction. However obvious the conclusions are to the research team, they are not going to be obvious - nor necessarily even interesting - to a layperson reading the press release.

I have a psychic³ prediction to make: this paper is going to have virtually no penetration into the public awareness. But it could have had widespread penetration, and it could have been an important event in educating the general public about human evolution, if only some kind of explanation of the conclusions had been offered that the average person could not only understand, but embrace as interesting and logical. As it stands, UC Davis gives us only a dry set of assertions.

Fail.

1. For no good reason, admittedly. [↩]
2. Most press releases are not written by anyone on the research team; the research people provide information to the PR department of their university, and then it is largely out of their hands. [↩]
3. Not! [↩]

The Blue Collar Scientist and the Blue Collar Mom were at the Smithsonian Museum of Natural history today. This is my first trip to Washington, DC for pleasure - I was here about fifteen years ago on government work and got to see absolutely nothing in the way of attractions during the brief time I was here. This time, it’s all for fun.

The Museum is an old-style natural history museum - there were a few outdated dioramas (e.g., showing Tyrannosaurus standing upright and balancing on its tail, though the actual mount was done right), lots of stuffed specimens in the Hall of Mammals, most of the megafaunal mounts on display were of actual fossilized bone rather than casts (with accompanying heavy steel supports), some of the descriptions on the interpretive signs are out of date (and are corrected by supplementary signs), and the whole place has the musty, dusty vibe of a natural history museum of the late ’50’s.

It was so cool.

I went immediately to the hall of fossils and dinosaurs, because that’s my thing - I’m as enthusiastic about paleontology as I am for astronomy. Almost immediately, I noticed that there was something that looked roughly like this Devonian starfish labeled as an “asteroid” (Devonaster sp). Made me feel right at home.

I was pleased to see the Museum is unabashed about displaying their specimens with evolution in mind. They exhibit a cladogram for marginocephalian (fringe-headed) dinosaurs, for example, and also have on display an impressive cladogram for proboscidians (elephants, basically) built around miniature sculptures of each species. Cladograms are really cool - they are diagrams showing the ancestry of species, based on evidence from anatomy, biochemistry, genetics, and so forth. A cladogram shows which species gave rise to which others, and what species are in a modern species’ ancestry. The tool is so powerful that there is a movement within biology to classify living things cladistically, rather than with the modernized Linnean taxonomy that is currently widely used.

I had something on my mind during my visit, inspired by comments that people left (but were never published) on my post about the Atlas of Creation - you know, that book that advocates creationism that (presumably mistakenly) used photographs of fishing lures to represent actual insects. A number of creationists, apparently in an attempt to gloss over that widely respected creationist authorities don’t know the difference between insects and fishing lures, tried to post strident, tiresome rants about how there has never been a single transitional fossil found - not one, not even one! Of course this is wrong - tons of transitional fossils have been found, otherwise we wouldn’t have cladograms. But I was wondering about this claim during my visit, and I resolved to keep my eyes open for examples of transitional fossils on exhibit for everyone to see - not buried in some obscure museum archives, but out in the areas of a museum open to the public.

And I was not disappointed:

• Ten transitional horse fossils.
• Six transitional fossils of genus Homo.
• Thirty-four transitional fossils of fishes from primitive ray-finned fishes, to teleosts.
• Over a dozen transitional fossils from fishes to amphibians.

etc. All right out there for everyone to see. And I remember that a bit over a week ago at the Orlando Science Center I noticed two transitional fossils of birds on exhibit.

How could anyone miss all these?

The answer of course is that the creationists lie. It is as simple as that - the people who say this are either lying, or have been lied to by people that they trust and are willing to repeat. Under the traditional definition, transitional fossils are fossils that have some characteristics of older organisms, but have some new features as well. There is no mistaking a transitional fossil. You can’t look at a fossilized toothed bird skull and fail to notice that some characteristics look like dinosaurs (the teeth, for example), and other characteristics look like modern birds (the beak, for example). This kind of thing is incredibly obvious and a mistake in this arena simply cannot be made in good faith.¹

Of course, we recognize today that every single fossil (and every living organism) is by definition transitional - but even under the traditional definition, finding transitional fossils is apparently pretty easy - the hard work is done, and I found over fifty of them in my first hour in a natural history museum that was new to me.

So, people - don’t let them get away with this kind of thing. When you hear a creationist point out that there are no transitional fossils anywhere, please let them know that the Smithsonian Museum of Natural History has over 50 on exhibit that they can find in less than half an hour. If necessary, let them know that they can get to the Smithsonian on the Blue or Orange lines of the DC Metro and see for themselves.

Remember, be nice. You won’t convince them. But you might convince the people around you who are listening in on the conversation.

1. I grant that some of the more obscure characteristics of fossils may be legitimately missed by people who aren’t specialists and argued over by those who are. What I’m saying here is that any ordinary person in possession of a basic sense of honesty will not fail to notice such obvious characteristics as the presence or absence of teeth. [↩]