Roger Short: Here in Melbourne, in the department of zoology, I had a very good PhD student, Ann Gaeth. I said, ‘Ann, I’ve got these amazing early elephant embryos. Your PhD project is to serially section them. No one’s ever serially sectioned an elephant embryo ever, and goodness knows what you’ll find.’ Ann goes away and sections them and comes up to my office and said,’Roger, can you come and have a look? The kidneys look most peculiar.’ I said, ‘I don’t know anything about the embryology of the kidney. I’ll get my wife Marilyn to come and have a look.’
We looked down the microscope and there we saw these amazing structures in the kidney, which are called nephrostomes, which are little tubules penetrating the whole surface of the kidney and ending up in little glomeruli, so that it was a way of bailing out the peritoneal cavity and siphoning that fluid directly into the kidney, and elephants had got them, and no other mammal has nephrostomes in its kidney. Marilyn said, ‘Those structures are nephrostomes. They are a way of bailing out fluid from the peritoneal cavity and they’re only found in aquatic animals. The elephant must be aquatic.’ I thought, ‘God! Hey, the trunk is a snorkel! Wouldn’t that be fantastic?’
We then thought, well, let’s have a look at the trunk. I had dissected one or two young elephant foetuses and I had noticed something strange, that the lungs were stuck to the chest wall. And I hadn’t paid too much attention to it. Then I looked up an American veterinary review and it said that it’s amazing that every single elephant that has died in captivity has had pleurisy because the lungs are stuck to the chest wall. So I thought, ‘Oh, probably that’s normal.’ We looked at these early embryos and foetuses and, yes, very, very early on the lungs stick to the chest wall and there is no pleural cavity at all.
We did some work with a very good respiratory physiologist in San Diego who had spent his life looking at respiration and he said, ‘If you’re a snorkeler, you know that you’re not allowed to have a snorkel tube that’s much longer than that because, if you do, you will actually rupture the blood vessels in your chest cavity, and so it’s illegal to have a longer snorkel tube.’ And here is an elephant with a snorkel tube that is about eight-foot long, so they couldn’t possibly snorkel were it not for the fact that they have managed to glue their lungs to the chest wall so that they can’t get a pneumothorax, which is what you or I would get.
Robyn Williams: Yes. Would the elephants have been living presumably in rivers or lakes rather than anything out to sea?
Roger Short: Yes, I don’t think they were in the deep ocean, although they crossed large expanses of sea to get to remote islands off the coast of California. Santa Catalina Island has got these elephant remains on it and it had never been part of mainland California, so how had elephants got there? They had swum. David Attenborough has lovely shots of elephants swimming under water in the Indian Ocean.
Now that most fish have disappeared from the North Sea, the trawlers are trawling up the sand banks across the North Sea and coming up with all these amazing elephant remains, of which I have quite a selection here, from tusks to vertebrae to teeth. Mammoths, as they were then, were swimming across the North Sea between England and Scotland and Europe, and they have really been great aquatic animals, and of course they are herbivores. We have been able to do their mitochondrial DNA recently, and guess what their closest relative is? The dugong.
Roger Short: And elephants and dugongs arose from a common ancestor, called Anthrobacune, which I saw the first complete skeleton of in northern Hokkaido just recently.
Does anyone have access to an image of the Anthrobacune skeleton? Not even Google could find me one.
