Of Mice and Frogs

The gene scene today is again interesting. A new paper by Dr. Ward and his colleagues (1) describes some work with mice and the Grb10 gene were the father contribution has been switched off so that the imprinting possibility is solely from the maternal allele. In this case the adult developed a marked dominance, nibbling off some of their fellows fur and whiskers and generally being the Genghis Khan of their mouse world. It is interesting to remember that we too have the Grb10 gene, but I’m stuck with chewing my own whiskers.

Following on with unexpected genetic developments is the news item on Gastrotheca guentheri, a frog that prefers to live in trees (2). It is the only frog that has a full set of teeth. Frogs evolved to loose their lower set about 200 million years ago. Now our tree frog re-evolved the bottom set about 20 million years ago and has been happy with that ever since.

Already I can here the clamor ‘Why is this important unless you’re G guentheri?’ Well, it has provided a loophole in Dollo’s law. Louis Dollo was a Belgian paleontologist, who in 1893 taught us that evolution is irreversible. This has provided a good subject for discussion. The argument for the view is that evolution is the result of many different genetic changes resulting in a survival advantage but the route is not necessarily optimal and reversing that route would give too many options for there being a significant probability of getting back to the same starting point.

The possibility of ongoing genetic development, combined with an evolutionary advantage to have a full set of teeth, if you are a frog living up trees, seems a perfectly reasonable idea to me and that there is no need to reverse the total genetic evolutionary process. However, a rash minute or two following the threads on the blogosphere, rapidly take one down intelligent design rabbit holes insisting on the reversibility of time. A very scary proposition, which again leaves me chewing on my whiskers, and trying not to think about the reversing of my eating lunch.


2. http://news.bbc.co.uk/earth/hi/earth_news/newsid_9365000/9365076.stm

One Response so far.

  1. jazgal says:

    I can see the White Rabbit right now, ready to bolt down the rabbit hole - just thinking about reversible evolution leaves me in a similarly anxious state! But, it does beg the question of what this tree frog is eating that it needed to re-evolve a set of teeth? Curiouser and curiouser...

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