The domes of wisdom

Here's an interesting photo provided by Markus Bühler (of Bestiarium): it shows a bull Asian elephant Elephas maximus at Hagenbeck Zoo, Hamburg.


The picture is neat for a few reasons. For one, it emphasises the agility of elephants: despite their size and 'graviportal' specialisations, they can still do some pretty impressive bending and stooping. They're not bad at climbing slopes, albeit ones much shallower than the zoo trench shown here. Actually, people have reported (and even illustrated) elephants clambering down precipitous slopes. Tennent (1867) showed an Asian elephant clambering down a slope on its elbows, belly and knees, and quoted a report from 1844 that described this behaviour. The 1844 report even states that this 'is done at more than an angle of 45°;' (Carrington 1958). I admit to being slightly sceptical however.

What also interests me is the shape of the bull's head...


You will note that he has large twinned domes on the top of his head, and a large bony convexity at the base of his trunk. These aren't unusual features; they're typical for big, old males, but they're unfamiliar to many people because they're used to seeing females or juveniles of this species. Since 1987, two particularly large bull Asian elephants - Raja Gaj and Kansha - have been observed (and later photographed and filmed) in Bardia National Park, Nepal (Lister & Blashford-Snell 1999). Raja Gaj [shown here] was about 3 m tall at the shoulder. Both animals exhibited particularly massive skull domes and a large nasal convexity, and this unusual appearance led to the speculation that the animals might be living examples of Stegodon. This idea seems to have originated from Clive Coy at the Royal Tyrrell Museum of Palaeontology and was promoted by John Blashford-Snell, who led an expedition to film the Bardia elephants and (with actress Rula Lenska) later wrote a book on them (Blashford-Snell & Lenska 1996). In fact the Bardia elephants don't look like Stegodon at all, and when lecturing on the Bardia elephants the picture that Blashford-Snell would show of a Stegodon was not a Stegodon at all, but in fact a reconstruction of the fossil Asian species E. hysudricus from Osborn's 1942 The Proboscidea* [I was the first person to point this out to him, it seems]. Somewhere, things had gotten confused.

* In keeping with its subject matter, this is a publication of massive proportions. It consists of two volumes, each is huge (but, without a copy in front of me, I dare not guess how huge).


Lister (1995) had noted that the Bardia elephants superficially resembled E. hysudricus [life restoration shown here], and he suggested that bottlenecking had resulted in the emergence of genetic 'throwbacks' in the Bardia region. Later DNA results were to confirm this: the Bardia elephants were genetically bottlenecked and quite distinct compared to other Asian elephant populations, but they were definitely part of E. maximus (though note that I say all this from stuff I've seen on TV: I can't find it reported in the literature). Indeed, as emphasised by the Hagenbeck Zoo example shown above, the skull morphology of the Bardia elephants wasn't that unusual anyway, with the Bardia animals falling within the range of variation already known for Asian elephants - albeit at the extreme end of that range. The late Clinton Keeling was to point out that the twinned skull domes of big, old Asian elephant males were termed 'domes of wisdom' in Indian folklore.

One last thing: E. hysudricus, the fossil species sometimes compared to the Bardia elephants, is - in being Asian - not necessarily typical of fossil members of its genus, as some of the best known fossil Elephas species were African. In fact Elephas probably originated in Africa (during the early Pliocene) and spent more of its evolutionary history in this continent than in Asia.

For previous pachydermal posts see Of dragons, marsupial lions and the sixth digits of elephants: functional anatomy part II, How do you masturbate an elephant?, RIP Yeheskel Shoshani and The tangled mammoths.

Refs - -

Blashford-Snell, J. & Lenska, R. 1996. Mammoth Hunt: In Search of the Giant Elephants of Nepal. Harper Collins, London.

Carrington, R. 1958. Elephants: A Short Review of Their Natural History, Evolution and Influence on Mankind. Chatto & Windus, London.

Lister, A. M. 1995. Living in isolation. Geographical Magazine 1995 (Jan), 35-37.

- . & Blashford-Snell, J. 1999. Exceptional size and form of Asian elephants in western Nepal. Elephant 2, 33-36.

Tennent, J. E. 1867. The Wild Elephant, and the Method of Capturing and Taming it in Ceylon. Longmans, Green and Co., London.


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I read the book when I was younger and really enjoyed it (in spite of being sure throughout that his mammoth dreams would be slightly disappointed).

From memory wasn't Mark O'Shea involved in the expedition also looking for rock pythons or something?

So... why do they have that oddly-shaped head again?

In keeping with its subject matter, this is a publication of massive proportions. It consists of two volumes, each is huge (but, without a copy in front of me, I dare not guess how huge).

Volume I, 802 pages; volume II, 828 pages.

Hmmm...very true what you said about zoo populations of Elephas. I've never actually seen an individual with such pronounced domes. That male looks like some of the drawings I have seen of Elephas recki.

By Adam Pritchard (not verified) on 05 Dec 2008 #permalink

A possibly stupid question. If the Bardia elephants were an isolated population genetically within Elephas maximus but looking like E. hysudricus, how can we be sure - without genetic data - that E. hysudricus wasn't an isolated group within E. maximus as well?

By William Miller (not verified) on 05 Dec 2008 #permalink

The head domes are obviously used for males only...because that's the only thing cranial domes are good for, yes? ;-)

Does anyone know the makeup of this dome? Is this a larger braincase or a thickening of some sort (bone, dermal or fatty tissue)?

I have seen the skull of a female Asian elephant close up. The domes are bone, but either heavily vascularised or possibly penetrated by extensions of the sinuses - at any rate the bone is extremely porous

Does anyone know the makeup of this dome? Is this a larger braincase or a thickening of some sort (bone, dermal or fatty tissue)?

The domes are bone, but either heavily vascularised or possibly penetrated by extensions of the sinuses - at any rate the bone is extremely porous

Allan nailed it. The skulls of big proboscideans are almost completely filled with sinuses. There is a braincase in there, but it's not nearly as big as you'd think from looking at the skull. I've seen 6.5 kg cited for the brains of big bulls, which is about 4 times more massive than the largest human brains but still only a very small fraction of the cranial volume.

From our anthropocentric perspective we expect skull shape to conform to brain shape, but this is actually pretty uncommon in mammals, especially big ones. Goats, pigs, cattle, antelopes, giraffes, tapirs, rhinos, and elephants all have brains roughly the same shape as ours, but they're buried in the head and the shape of the external skull is almost totally decoupled from the shape of the brain. The intermediate spaces are filled with sinuses. I suspect that this is largely because all of those big herbivores have big, heavy teeth, which require a lot of muscle attachment area on the back of the skull, which is economically achieved with pneumatic bone. I doubt if an elephant could lift its head for very long if the skull was filled with marrow rather than air (obviously it could lift it for a while, since elephants can carry heavy logs around with little apparent difficulty).

I would also be interested to know if those big cranial sinuses help thermally insulate the brain. It has been shown experimentally that little birds with pneumatic skulls stay warmer than conspecifics whose skulls are not yet pneumatized, but so far as I know similar experiments have not been done with mammals. Please let me know if I'm wrong about that!

Having once ridden an elephant in difficult terrain in Nepal I can confirm that they are quite amazingly agile and sure-footed. That elephant did go down on its knees/elbows once to negotiate a short, but steep and slippery clay slope. My impression was that it did this mostly to avoid a possible fall, which would be very dangerous for such a heavy animal. Incidentally it lurches quite a lot doing this.

By Tommy Tyrberg (not verified) on 06 Dec 2008 #permalink

"They're not bad at climbing slopes, albeit ones much shallower than the zoo trench shown here. "

Elephants in India climb up and down even steeper slopes, virtually vertical river gorges.

Its very nice experience, when you are on elephant ride, sitting with bins and camera with heavy telephoto lenses, and back of your elephant suddenly turns vertical. They provide small vertical poles to hold to.

Actually, there is quite a lot of variability in Asian elephant, like every species.

I think zoology of 2000's has too simplified paradim as viewing every species (or at best, aubspecies) as uniform homogenized group. Incredible local variability in morphology and ecology is normally overlooked.

I recall seeing Mammoth Hunt in the bookstore many years ago, but never had the chance to sit down and read it.

It's particularly intriguing, how much of the world was crammed full of proboscideans until very recently, especially Asia. When you take into account the fact that Elephas maximus was much more widespread in the past, plus all the other extinct species of Elephas and Stegodon that lived in various parts of Asia during the Pleistocene, it does raise some intriguing questions about overlap in temporal and geographical distribution, and whether these species competed for resources.

Dr Vector
Interesting, thank you. Being prone to sinus infections myself I feel sorry for the big beasties.

Thanks so much Darren, I'd been looking for a resolution to the "Surviving Stegodon" myth for ages!

By Tim Morris (not verified) on 07 Dec 2008 #permalink

Nepotism alert! When I was writing the above comment on the pneumatic skulls of elephants, I felt hampered by my inability to include any pictures. So I wrote a mostly-about-skulls post at SV-POW! and put in a couple pix of elephant sinuses.

(It's a bit incestuous because Darren is 1/3 of SV-POW! Still, it's all for a good cause.)

great post!

For those wanting to learn more on elephant skull structure, check out this site.

In the collection there is a CT scan of a juvenile Asian can view a cross section movie of the skull thus exposing the complex honeycomb structure of it's skull.

The site also includes many other specimens of various species...all with 3D representations of scanned skulls.

Matt: I guess this establishes once and for all that skulls really are modified vertebrae. Otherwise they couldn't appear on SV-POW. Q.E.D.

Andrew: Watching rotating elephant skulls made my morning. A chaotically tumbling elephant skull would make a wonderful screen saver.

By Nathan Myers (not verified) on 09 Dec 2008 #permalink

Darren, is there a more recent, complete treatment of prosboscidea than the 1942 book you refer to? I'm looking for something with a full overdue of mastodon, mammoth and other pleistocene elephanty things.

Dr Vector
Re: skulls post at SV-POW!
Nice, thanks.

Hi Darren:

Interesting article, thanks! I don't have the answers, but a few notes/thoughts:

A. I wouldn't use Osborn's 1942 classification. A much better one is in the "The Proboscidea: Evolution and Palaeoecology of Elephants and Their Relatives". Of 448 genera/species/subspecies in the 1942 listing, only 39 carried forward unchanged (name or definition) in the latter taxonomy.
B. A review of 130 Chinese papers showed the Stegodon to be more common in southern China than the Asian elephant, and showed it to be quite recent -- the most recent radiocarbon date of 4100 BP. (See online reference in Stegodon within Wikipedia.)
C. You probably aren't aware of the still remaining enormous confusion and chaos in Proboscidea, particularly at the species level. By 1939 552 species/subspecies had been named. Some more recent lists have 160, and most Proboscidean experts believe much more consolidation will eventually occur.
D. Hysudricus is obscure and little studied; unlike the Stegodon I've never seen anything listing it as anything but of great antiquity.
E. Keep in mind, the Bardia Proboscidea are way bigger than any Asian elephant ever.
F. Good point about the picture, though I wonder how much of its feature "pronouncement" is due to its unusual crouch.
G. If you have studied this and can articulate in detail the skeletal differences between the Asian, the Bardia mystery, the Hysudricus, and the Stegodon, I'd be interested.
H. Realize the Stegodon is rather close to the "true" elephants within the Proboscidea order.

In summary, I know almost nothing about Hysudricus and know little about the Stegodon -- but the latter is far more common, has been found fossil-wise in Nepal anciently and extensively in China (more than the Asian elephant), and is thought to be of recent timing. And I know quite a bit about the enormous Proboscidea chaos -- as time goes on more and more genera and species get consolidated away -- experience would say Hysudricus has a good chance of being consolidated away (and into a Stegodon?). Thus I would think a bit more caution perhaps should be in store before declaring the Bardia mystery not a Stegodon. If Hysudricus were much more rare and much older, wouldn't that be more of a surprise being alive than something quite common and quite recent?

Around about 1994, there was a TV documentary made about sightings of Mammoths (turned out to be giant elephants) in Nepal. They found an elephant named Raja Gaj, also a smaller one named Kancha. At the time it was compared to the supposedly 100,000 years extinct stegodons found in the fossil record. The expert comment was something like: "...maybe the gene has recurred in a modern elephant" (My words). I remember thinking at the time maybe it just never became extinct.

I've often wondered if we've over classified relations between mammoths and elephants. I see more visual variety within the Canine group, Feline group and even Homo sapiens.

Does anyone know the name of the TV documentry?

By Don Smith (not verified) on 09 Sep 2010 #permalink

I think elephant ancestors were a bit like beavers leaning against wedtland stems...

As so often, you are way too quick to jump to conclusions.

By David MarjanoviÄ (not verified) on 18 Sep 2010 #permalink