Evolution of Evolution — Text-only | Flash Special Report
Interview with Ross MacPhee
What do we know about plant and animal distribution that we didn’t know in Darwin’s time?
Well, in Darwin’s time, we had a pretty good idea of the substantial nature of the distribution of plants and animals in the tropical and temperate regions. We had a much less clear idea of what was going on in the Arctic and virtually no idea of what was going on in the Antarctic. Now, having said that, Darwin labored under several kinds of difficulties that we’ve, if not overcome, at least have a much better understanding of. One is the adequacy of the fossil record. The number of fossils that have been discovered in the last 150 years, as compared to what Darwin or Richard Owen knew about, it’s many multiples and, as a result, we have a much richer understanding of what went on.
But, today we have better tools for understanding plant and animal distribution.
We’ve also had a major breakthrough, and this in itself is now 50 years old in respect to plate tectonics. Darwin laws were contemporaries. These were almost, to a man, fixists, and what fixism means is that you do not accept the idea that the continents, for example, have ever had any other relationship than the relationship that we see today. He, of course, had no understanding of that because the tools that you need to understand what went on in the course of earth history with tectonic movements were largely discerned from sea floor studies and, at the time he was working, the deep sea, in particular, was a complete unknown.
Do you think Darwin would have concluded the prior existence of supercontinents?
No I don’t because if you’re a fixist, you’re a fixist, and you’re not going to suddenly assume that there are all kinds of connections in the tectonic sense. That is, that the continents themselves moved, but Darwin knew that something had gone on. He had a big problem. He had, for example, the fact that, say, lemurs exist in Madagascar today and their ancestors lived in places like Europe and North America. Well, how did that happen? If all the lemurs live on an island today, then was there some kind of connection between Madagascar and these other places? Series of hypotheses about how things might get moved around by natural means, by seeds adhering to dirty birds’ feet, this is the famous example, by material being caught in icebergs and being transported in that manner, by ocean currents, and so on and so forth.
How common is it to find an animal whose closest relatives are a continent away?
Well, it’s very common, and the thing to understand here is that we needn’t always invoke vast tectonic movements occurring over millions of years. We do in that particular case of the devil frog. Very possibly the reason why the devil frog occurs in Madagascar and South America and not elsewhere is because Madagascar, like South America, were originally joined to Antarctica, and presumably the frog or its ancestors were able to walk along what was then probably at least semi-tropical kind of conditions to get from one place to the other.
What will be the next big discovery in Polar Sciences?
Speaking now as a vertebrate paleontologist interested in mammals, for me, the next big discovery, the discovery that they – the discovery that would put the icing on the cake in terms of trying to gather plate tectonics and the evolution of mammalian groups and so forth would be evidence that mammals, including groups that are still with us today, either developed, differentiated from their ancestors in Antarctica or utilized Antarctica as kind of a highway to get from one area to the other.