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! [↩]