In Search of a Turtle

It has only been a month, but Nathaniel Jeanson already has an ‘update’ on his Bio-Origins Project (see here for last month) – Bio-Origins Project Update, Hypothesizing Differential Mutation Rates. Here’s how he opens:

You might expect that the same gene in different creatures would have the same sequence. Surprisingly, this is not so.

See, I wouldn’t expect that (I wouldn’t want to just assume the opposite in all cases either, however). I can’t speak for any creationists, however, so perhaps this is a new revelation for them?

As we reported last month, our preliminary protein/DNA comparison data show profound molecular differences across creatures, and these differences fall along traditional Linnaean classification groupings as shown in Figure 1.

Yes, Dr Jeanson has rediscovered evolution’s hierarchies. His data, as it happens, is very scant. In effect what he’s got is the differences in the sequence of the mitochondrial gene ATP-6 from three different animals. According to his figures – I don’t have the ability to check them, so don’t reuse this information – elephants and mice have a 63% similarity, elephants and fruit flies are 36% similar here, and mice and fruit flies are at 32%. He’s been busy.

The evolutionary explanation for this is that, as you would expect, elephants and mice are more similar to each other than to fruit flies is that they are more closely related. But Jeanson can’t fall back on this – all of those species should fall in to their own, separately created “kinds.” They should really be equally (un)related, but they’re not. Why not?

What would you conclude from this result? How did these differences arise? Was this same gene created differently in different creatures? Did these differences arise primarily because of post-creation and post-Flood change? How do we explain these results from a young earth perspective?

One fascinating hypothesis is that these differences arose as a result of different rates of mutation accumulation in different “kinds.” This hypothesis—that the differences stem from different rates of origin—is different from the evolutionary explanation that the differences reflect different times of origin.

I have a problem with the “different times of origin” description, as you might expect – it doesn’t describe evolution at all, and would be more applicable to progressive creationism, a form of old Earth creationism that claims that each ‘kind’ of organism was created when it appears in the fossil record but not descended from anything else. The gene has existed for just as long in each lineage, after all.

That aside, this hypothesis is really quite interesting. What Jeanson is proposing is that each kind started off with identical genes which mutated away in different directions over time:

Consider the basics of molecular biology for how this might play out practically: The genome (complete set of genetic instructions) in each creature is unique, but genes (subsets of DNA sequence that are ultimately translated to protein) involved in common cellular processes are shared across diverse creatures. If we assume, for example, that God created the same ATP6 (one particular gene involved in energy transformation) gene sequence in elephants, mice, and fruit flies, and if we assume that elephants accumulated mutations slowly; mice, slightly faster; and fruit flies, much faster, then after 6,000 years of mutations, mice would appear (molecularly) different from elephants, and fruit flies would appear even more different from both mammals. Hence, a hierarchy of mutation accumulation rates could produce a hierarchy of molecular differences over time.

Except it would not create a hierarchy.

Jeanson’s hypothesis is effectively stating that the situation in the first diagram took place: that there was a single origin point for the gene, which the three organisms migrated randomly away from so that the mouse and elephant would be equal distance from the fruit fly. But it needn’t have been that way – the second diagram would be just as likely, with the mouse being much closer to the fruit fly than the elephant is. If you add more organisms then the picture gets even more complicated (and multidimensional, if you like), and the probability of getting the kind of hierarchical structure we observe in the real world just gets more and more remote.

Of course, we still haven’t got to the part where Jeanson explains why the fruit fly should have evolved, I mean mutated, further from the original gene than the rest:

Preliminary data on species’ rates of mutation accumulation are consistent with the above hypothesis. A key factor in these rates is the speed at which species reproduce.

One measure of species’ reproduction rates is generation time—the time from conception to sexual maturity. Comparison of the generation times in elephants, mice, and fruit flies shows a hierarchy of time as shown in Figure 2—elephants reproduce slowly, mice more quickly, and fruit flies the fastest. Conversely, by calculating the theoretical number of generations that have passed in each of these species since creation, it is apparent that fruit flies have had many more opportunities to accumulate mutations than either of the mammals (Figure 2).

The test of this aspect – which I am frankly positive that he will fail, but would be quite interested in being proved wrong on – would be to strategically add a fourth creature in there. I’m thinking a turtle, or some other non-mammal that will have a longer generation time than a mouse, but a shorter one than an elephant (still needs to be a vertebrate though). It can probably be assumed, based on evolution,* that the turtle ATP-6 gene will be closer to the mammals than the fruit fly, but that the mammals will still be closer to each other than to the turtle. But Jeanson’s hypothesis would not predict that.

If the generation time is the “key factor” in mutation rates, then Jeanson’s model would have the turtle being almost as close to the origin as the elephant, making it most likely more similar to the elephant than the mouse is. In other words, we would predict that the similarity between elephants and turtles would most likely be higher than 63% – something that I would bet my hat against if I actually had one. In other words, not only would this hypothesis not produce a hierarchy, even if it did it wouldn’t produce the right one.

All that being said, he concludes:

This very small dataset is consistent with the differential mutation rate hypothesis. However, we have much more data to analyze before we reach any firm conclusions.

Yes, yes you do. There are other problems with this hypothesis too, not least in that it contradicts other creationist arguments. If genes are free to wander randomly under the influence of mutations to such a huge degree over such a small period of time, then what can we make of the genetic load argument? If such huge gaps are so easily crossed, then what does that mean for the differences between kinds? This is an unfortunate hypothesis.

A much better idea – better because it is harder to falsify, which is the best we’re going to get – is that mice and elephants (being much larger and structured differently) need different ATP genes than fruit flies, and so were designed differently from the fly from the beginning. It’s a slippery argument that I’ve seen before, but it “explains” things better than Jeanson’s idea. Anything would, really.

---

*Why I’m so confident here is that the evolutionary relationships between organisms are largely determined from genetic similarity in the first place, so it would be strange if this gene bucked the trend. Though if it did that might be why it was picked…