Elephant (family Elephantidae)

Now I ask you one…What is it has a trunk but no key, weighs two thousand pounds, and lives in a circus?

That’s irrelevant!

Damn right it’s a relephant. Today: elephants!

So, I’m Jeremy, and I’m filling in for Laura today while she’s out of town. Unfortunately, I don’t really know much about animals in general, so today’s episode may be a little scatter-brained, but I thought I should talk about a pretty common and well-known animal that has some surprising depth. Elephants are of course famous for their size, their wacky shape, and their intelligence and social behaviour, all of which are pretty interesting; but there’s more! Elephants also have a pretty surprising evolutionary history, are a perfect illustration of the way mathematical law governs animal growth, and, to top it all off, one of their closest relatives on the evolutionary tree is now the subject of one of the most interesting ecological projects ever thought up. So, even if you already think elephants are cool as the Dickens, hopefully this post will help reinforce that opinion.

Let’s get going. Elephants are comprised of two genera: Loxodonta, the African elephants (Loxodonta africana), and Elephas, the Indian elephant (Elephas maximus). Both species have the traditional elephant shape: large body size, large floppy ears, a long proboscis (trunk) , and tusks. African elephants are larger (they are in fact the largest living land animals), have larger ears, and concave backs. African elephants can reach heights of about 13 ft tall, and weigh up to 15,000 pounds(!)

So, let’s start with the evolutionary history. Elephants are the only surviving member of their order, the Proboscidea, but of course there are many famous extinct elephant relatives, the most famous being Mastodons and Mammoths. What is less well-known is that the closest group of mammals by evolutionary descent to the trunked-and-tusked Proboscidea are the Sirenia—the order comprising manatees and dugongs. Yes, that’s right, the closest living relatives of elephants are aquatic sea cows. Both orders are part of the Tethytheria, which is itself a sub-clade of Paenungulata, a hodge-podge of African mammals that also includes Hyraxes. Basically, because Africa was an island 60-million-ish years ago, ungulates, rabbits, and other animals from North America couldn’t get over to Africa, so a radiation (possibly from an aquatic ancestor) managed to spread out and colonize all the unfilled niches in the African ecosystem. So elephants, despite looking much (MUCH!) more like hippos and rhinos, are more closely related to aquatic animals and tiny shrew-like creatures. Evolution is awesome.

Many species of elephant that are now extinct survived into human times. Mammoths are the famous example, but also a number of elephant species trapped on islands lived until only a few thousand years ago. Many of these elephants, due to being on islands, became dwarf or pygmy elephants. Dwarf elephants lived in California, Malta, Sicily, and a whole bunch of places you don’t really associate with elephants. There were also dwarf mammoths: a group survived on Wrangel island until only about 4000 years ago. Interestingly, this means that while the Pyramids were being built, there were still pygmy mammoths in the world! This is interesting because there is some (fun but not really meaningful) speculation that an ancient Egyptian tomb from about 14oo BC shows a depiction of a pygmy elephant.

Elephants don’t just have an interesting history, they illustrate an important point regarding animal biodiversity. Although elephants are the largest living land animals, they don’t remotely compare to the largest living animals: whales are much bigger. It is obvious to most people that this is because living in water reduces the physical stresses on a large animal’s body. Interestingly, this phenomenon plays a role in land animals as well. It was first recognized by D’Arcy Wentworth Thompson, a Scottish biomathematician, who noticed that, since physical quantities scale differently (lengths scale linearly, volumes cubicly), it requires exponentially more support to keep a large animal up and walking than a small animal. What this means is that the skeleton of a large animal looks like a large animal’s skeleton: the bones are bulkier and thicker, because they must be so in order to support proportionally more weight.

Compare pictures of an elephant skeleton:

Elephant skeleton

Elephant skeleton

to the skeleton of a mouse:

Mouse skeleton

Mouse skeleton

You can see how much more slender the bones of the mouse are; the elephant is not just a resized mouse; the bones have to grow out of proportion to the rest of the animal.

Okay, so diversions into math aside (sorry, it’s what I do!), it’s now time to talk about elephant intelligence. Of course, the idea that elephants are clever, and form societies, is not new, but in the last few years we’ve really realized how remarkable elephants are. For example, other than humans, elephants are the only animals known to have rituals surrounding death. Elephants have been observed to cover the bodies of other elephants with leaves and grass, and will stand by dead or dying elephants for hours. Apparently, they will even sometimes bury human dead(!) They also act in a way that it is hard not to describe as “respectful” and “solemn” when around elephant bones; they will often touch bones even of unrelated elephants with their trunks.

Elephants can also use tools; this took longer for us to realize because elephants of course must use their trunks to manipulate items, but grabbing with the trunk can blunt an elephant’s sense of smell, so they do not go to tools as quickly as chimpanzees or other primates. But, elephants can indeed use items from their environment to solve problems, such as in this video: https://www.youtube.com/watch?v=TkkkXsg8RMk

Elephants can recognize music, and even play music. There is even a band all of whose members are elephants: The Thai Elephant Orchestra. They have three CDs out. I will leave it to the reader to judge whether the music is evidence of genuine musical ability: https://www.youtube.com/watch?v=lSLVgrNJ-HU

All of which above makes it even sadder that elephants are today an endangered species. They are of course hunted for their ivory, but they also have to contend with habitat loss, as the Asian elephant in particular lives in a part of the world that is very highly human-habited. Luckily, steps have been taken to combat the ivory trade, but elephants in both Africa and Asia are still threatened species.

I want to end on a possibly uplifting note re: extinction though. Ever since the advent of cloning techniques, people have discussed the possibility of “de-extincting” certain species; and one of the prime candidate species is the closely-related mammoth! So, even though we should be doing what we can to protect the elephants we currently have, it would certainly be interesting to re-populate the world with a currently extinct elephant species. Obviously there are scientific and moral considerations here, which I am not remotely competent to discuss, but it’s certainly an interesting thing to ponder.

Anyway, that’s what I got. Thanks for reading to the end (if you did).

For the unbearably nitpicky, most of the information here was fact-checked from Wikipedia, or the fantastic blog Tetrapod Zoology (especially the point about the possible dwarf elephant in the Rekhmire tomb). Videos and pictures are all sourced directly.

You can check out D’Arcy Wentworth Thompson’s book On Growth and Form if mathematical biology is interesting to you (it should be!)

For further reading on elephants, Jeheskel Shoshani is apparently the go-to guy; he has tons of books.

Lastly, elephant intelligence has made the news a bunch of times in the last few years: Nat Geo and Scientific American in particular are the popular sources where I heard about a lot of this stuff.

Thanks again!

Cover image source: Shutterstock.com

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