Last week the University of Manchester issued a press release with the somewhat sensational title, "St Bernard study casts doubt on creationism." Picked up by several, though not all, science news outlets, such as Wired News and Discovery, the story was based on a study of St Bernard skulls published in the journal Proceedings of the Royal Society B. While the study is interesting and worthwhile, the role it plays in "disproving" creationism is a bit harder to pin down--though I'll do so for you by the end of this post. First, an explanation of the study and a few comments:

Authors Abby Drake and Christian Klingenberg conducted their study of morphological evolution by examining 47 St Bernard skulls dating from 2001 to as far back as 1885. By using computer techniques that compared "landmark" points around the skull, the researchers could statistically analyze the rate and extent of evolution (or "change," more appropriately) over 116 years. St. Bernards were especially useful for the study because they are known to have originated in the mid-17th century (when monks at the Great St. Bernard Pass in the  Swiss Alps began breeding them). Records of the breeding history have been kept since the late 1850's. The pedigree included: A bulky body, large skull, high cheekbones, a short and wide muzzle, and prominent eye ridges. With those characteristics in mind, the monks and other dog breeders began crossing dogs that best matched the desired "St. Bernard" standard. Consider the following two skulls. The first is of a St Bernard from around 1892.

 Compare that with the skull below, from a more recent St Bernard--about 1976. Notice the high brows and the steep transition from the muzzle to the forehead.

 The obvious differences in the skulls highlight the point the authors of the Proceedings B study make, which is that selection (in this case artificial selection) can produce significant morphological change in a relatively short amount of time. The amount of shape-shifting that occurred in the skulls was measured by something called Procrustes distance (0.084 units), and according to the authors is comparable to the rate of evolutionary change that has occurred in "average body shapes among fish populations separated by periods up to 4000 years or between tooth shape divergence of mammal taxa separated by thousands to millions of years." They continue:

Episodes of particularly strong selection can achieve even faster divergence, as suggested by selection experiments on wing shape in Drosophila [fruit flies] or observations on bill size and shape in Darwin’s finches. The results from our study of St Bernard dogs are remarkable in that they indicate that a sustained response to such selection can be maintained for many generations.

Again, the point is clear and well taken--the right circumstances of selection can produce change quite quickly. However, the question creationists and ID theorists have raised is "are there limits to change?" And the study itself would seem to indicate so: 

Interestingly, there appears to be no trend for centroid [overall] size of the skull, even though the breed standard specifies that the head should be ‘massive’ and the size of the head is presumably under selection. Because body size and the sizes of structures such as the head usually are associated with heritable variation that provides the potential for a response to selection, the apparent lack of a response raises the question whether some constraint may have prevented an increase of skull size in St Bernards.

. . . . 

The historical change in St Bernards shows that selection by breeders can produce sustained change of shape in one direction, and thus can produce morphological alterations comparable to the differences between taxa that have been diverging for much longer times. Morphological variation in dogs is comparable to diversification in higher taxa, and dogs can therefore serve as a model system for studying the mechanisms involved in the evolution of morphological disparity.

To swipe a controversial title, is there an edge to the evolution of St. Bernards? Given the right artificial selection, could the breed be grown, say, 75% larger over the next hundred years? And like those "higher taxa," could Bernards be changed into, say, ponies? I'm as interested as any Darwinist in discovering what evolutionary potential--or boundary--exists in organisms, so I think such a simple experiment would be worthwhile. And just imagine the possibilities if St Bernards are truly being morphed by mutation, as the authors hint:

The more or less linear trend in the shape variable that corresponds to historical change indicates a sustained response of skull shape to the selection imposed by breeding. There is no evidence for a slowing down of the trend, as it has been found in many artificial selection experiments. Unfortunately, the available data do not allow us to decide whether a sufficient amount of genetic variation still persists from the initial, heterogeneous breeding stock or whether genetic variation is replenished continuously by new mutation.

 As it turns out, Bernards are particularly susceptible to a unique host of health issues, such as eye disorders, seizures, heart disease, eczema, and bone problems, including hereditary bone cancer. If mutation is doing its work on St. Bernards, evolution obviously has a few kinks to fix.

So what does this study show? It proves that artificial selection, and by analogy natural selection, can produce morphological change over time. Does it challenge creationism? Not in the least, because biblical creationism not only accepts, but promotes the concept of natural selection--except that young earth creationists believe morphological change can happen (or happened in the past) more quickly than most evolutionists suppose. It seems then that St. Bernard study co-author Christian Klingenberg was severely misinformed when said in his university's press release:

"Creationism is the belief that all living organisms were created according to Genesis in six days by 'intelligent design' and rejects the scientific theories of natural selection and evolution.

"But this research once again demonstrates how selection — whether natural or, in this case, artificially influenced by man — is the fundamental driving force behind the evolution of life on the planet."

Yet a simple glance at the website of Answers in Genesis, the major organization behind the creationist movement in America, shows that creationists wholeheartedly accept natural selection. Where Klingenberg heard otherwise is a mystery, and I'd like to hear from him if has a source at hand for his statement.

What creationists disagree with is the claim that the morphological change in St. Bernards is rightly "comparable to diversification in higher taxa." Creationists argue that simply because change is seen to occur on a small scale in a single species, isn't licence for that change to continue indefinitely and without bounds, until a particular species changes into something radically different, forming a new family of animals.

So while natural selection may be a fundamental driving force behind the (micro)evolution of life on planet, it doesn't explain the origin of that same life.

Other news: Homer Jacobson recalls his 1955 paper on the origin of life after it is cited by creationists; some of the best wildlife photos of the year have been selected; and, Vivek Wadhwa claims U.S. shortage of science and engineering grads is nothing but a myth.

St. Bernard photo from Wikipedia, used under creative commons license/St. Bernard skull photos provided, copyright Abby Drake.