Can Elephants Gallop?

ScottS-M — Mon, 10 Mar 2008 15:10:36 +0000

I watched 10,000 BC yesterday and was pretty disappointed in the animal animations (which were the main reason I went). Most of them looked rather cheap and computer generated. The most unnatural looking was when the elephants galloped with their back feet moving together. That seemed completely wrong to me but I’m no elephant expert so I took a look at the literature when I got home.

You can see tiny bits of the offending gallop in this preview at around the 40 second and 2 minute mark:

If you can manage to get a glimpse of the mammoths’ movement in that, then compare it to this example:

Luckily there is a Nature paper addressing this issue pretty directly. I think the title “Are fast-moving elephants really running?” is a pretty good give away. If you’re getting published in Nature for determining if an animal runs, it’s pretty unlikely said animal is galloping around.

So the authors (Hutchinson, Famini, Lair and Kram) went to Thailand, got a bunch of elephants, painted motion capture dots on their joints and had the elephants run a 30 meter dash on video camera. You can see a speedy elephant video in their supplementary material. The elephants reached speeds of 25 km/hr. First to take care of the galloping question:

The fastest gait used by elephants has been variously described as a walk, amble, trot, pace, rack or a running walk… …trotting and galloping are running gaits with footfall patterns that are distinct from walking… Our elephants maintained the same walking footfall pattern…

That’s a lot of …’s but I think it gets the point across. Elephants are certainly not galloping. Since that was a little anticlimactic I thought I’d also cover the more interesting question, are elephants running?

The authors first seek to define “running”. Running can be defined as a gait which includes periods where no foot touches the ground and where each foot touches the ground for less than 50% of the time. The second part is new on me but I’m not a kinematicist. It turns out elephants always have at least one foot on the ground but their feet are on the ground only 37% of the time.

Since that didn’t settle the question, the authors turn to physics. The Froude number is a measure of intertia vs gravity often used in boat physics. Apparently scientists also apply it to animals as velocity²/acceleration of gravity/hip height. The authors explain that most animals begin running at at a Froude number of .5 and start to gallop around 2.5. Elephants had Froude numbers as high as 3.4 which seem too high to be a walk.

As a final shot, Hutchinson and his coauthors decided to look at the movement of the center of mass. They explain that in a run the center of mass is lowest at midstride, while in a walk it is highest. Since they couldn’t directly measure the center of mass, the scientists used the position of the elephant’s shoulder and hip to estimate it. Funnily enough, the shoulder and hip were moving in opposite directions with the shoulder indicating walking and the hips indicating running.

So it looks like fast-moving elephants aren’t walking but they’re not really running either. They certainly were not galloping. Which brings us back to the movie 10,000 BC. I can’t understand why they wouldn’t do even rudimentary research (or watch Lord of the Rings which if I remember right got the gait correct) into the movement of animals filling such a central role in the movie. The galloping mammoths look completely fake even without knowing anything about elephants. But I guess with the general lack of concern for history, it’s not too surprising they wouldn’t worry too much about accurate biology either.

Reference

Hutchinson, J.R., Famini, D., Lair, R., Kram, R. (2003). Biomechanics: Are fast-moving elephants really running?. Nature, 422(6931), 493-494. DOI: 10.1038/422493a

10,000 BC Review

ScottS-M — Mon, 10 Mar 2008 05:29:52 +0000

In another adventure in early morning cinema, we decided to go see 10,000 BC. I can report that there are definitely not large crowds in the theater at 10AM on Daylight’s Savings Time Sunday.

So I went into this expecting it to be pretty horrible (Rotten Tomatoes is giving it a 8%.) but I like the theme and wanted to see the CGI animals. Unfortunately, the whole thing seemed recycled from other movies and forced. They really wasted a good theme by not even bothering to accurately portray the animals or the history. That said it did keep me and the girlfriend mildly entertained (then again we still haven’t bought a TV so our entertainment criteria is pretty low).

The movie starts out with what I would assume is a fairly good guess at what life was like in 10,000 BC; huts, fire and hunter gatherers. After a few adventures, the characters reach another tribe of people who are just starting to grow their own crops. Again pretty accurate. 10,000 BC is right around when people are thought to have discovered agriculture. After a few more adventures, the history goes right out the window as the heroes run into a full fledged Egyptian culture complete with writing, pyramids, maps of the world and sailing ships. The movies takes one sentence to explain this anachronism as either aliens or Atlantis. This seemed pretty silly to me since we would definitely have archaeological records of such an advanced civilization. Why not just call it 2,000 BC? (Probably because they couldn’t have mammoths then.) As a final punch in the historical gut, the movie ends with the hero receiving a gift of seeds including corn. Pretty annoying (and completely unnecessary) since corn is from the Americas and would not reach the Old World for another 11,500 years. That’s about all I have to say about the history and the plot.

The movie had quite a few (I feel) bad movie making decisions. First right at the start of the movie, everyone decides to cover their faces in mud (a la Braveheart). I’m sure mud facial decorations were common in many ancient tribes but I really don’t think it’s the best idea when the audience is just being introduced to the characters. Then throughout the movie it continually flashes over to show an old witch doctor lady from the village. Besides her being pretty uncharismatic, I thought this was pretty unnecessary to the plot. (Yes I realize they were setting up the ending but I think the mammoth had that taken care of already). Also, the tribe talks in an assortment of phony accents. I saw in a preview/advertisement that the director wanted to do the whole thing in subtitles (a la Apocalypto). I like subtitles much more than dubbing in foreign flicks but since no one has any idea how they spoke 12,000 years ago this seemed kind of stupid. I guess funny accents were the next best thing for him. If you do watch the movie, I swear somewhere in the first part at the village someone is doing a Scarface impression. Let me know if you catch it too. Also, there was a huge amount of noisy pixels in some of the dark shots. I’ve never noticed this in a Hollywood movie before. Not sure why they’d let that through into the final copy.

Finally the part that let me down the most was the computer generated animals. We only get three types in this movie; mammoths, some sort of giant bird and a sabertooth tiger. The birds seemed animated well enough but you never get a real good look at them. The tiger seemed pretty good in the dark but in the light it really looked fake and didn’t seem to move quite right. Also contrary to what the poster would have you believe, the tiger gets about 45 seconds of screen time. The mammoths are in a lot of the movie and oddly enough are often shown galloping with two front feet in the air followed by two back feet. I’m no elephant expert but this looked completely phony to me so I decided to look through the literature once I got home and it looks like it is in fact completely phony (I’ll post about this ~~tomorrow~~ Update: here). Overall the CGI seemed about equivalent to a Discovery channel show which is sort of a let down when they’re supposed to be a highlight of a Hollywood movie.

Now after all those negatives, I do have to give it some credit. Despite all the shortcomings, I was entertained for the parts where I wasn’t groaning at the accents, history or biology. It’s not a horrible movie, it’s just not all that good.

Rating: 2 out of 5

Scott Sherrill-Mix, March 10th, 2007

Dammit Jim! » 10000 BC

Can Elephants Gallop?

Reference

10,000 BC Review