Frequently Asked Questions (FAQs)-
Elephants move like 4x4 vehicles
(this will be updated as we receive pertinent questions)
What is this research useful for?
It is basic science that is about how elephant limbs function, at a fundamental level, and this is interesting and important in itself, for many reasons (probably some of which no one can predict).
But the data we have collected are precisely the kind of data routinely used in human (and other animal) clinical/orthopaedic gait studies to compare normal and abnormal individuals, e.g. with arthritis or foot problems. Because elephants experience similar health problems, our data form a useful (and to date the only) baseline for beginning to understand how, why and when elephants develop musculoskeletal health problems that have an underlying biomechanical basis.
We also reveal some factors influencing metabolic costs in elephants, which ultimately could help understand their migrations and even aid in conservation. This is a long way off, but would depend on analyses like ours.
How does this research relate to our and others’ previous research?
We have published 11 papers on elephant anatomy and biomechanics since 2003, and this paper is a climax of much of that work. We always hoped to measure how elephant limbs actually worked with forceplates but this was our first opportunity to do so, and has shown us aspects of limb compliance, leverage and power in elephants that we did not initially suspect. It has shown that some of our prior assumptions about elephant limbs, especially that they divide braking and propulsion between the fore and hind limbs, were incorrect.
Our findings that elephant limbs have somewhat mediocre leverage are surprising in one sense, but also fit into emerging theory that very large land animals face uniquely stringent constraints imposed by gravity, that cause them to be limited in their speed and gait in ways that smaller animals are not. However, elephants are still capable of remarkable athletic performance despite this, which is fascinating. An example of parallel research is Dr. Hutchinson and others’ work on running in Tyrannosaurus rex.
What research are you doing now, or next?
We are using computer models to “peer inside” elephant limbs and estimate how their muscles, tendons and bones generate the dynamics we have observed experimentally. We are also studying fossil elephants to understand how their bizarre anatomy and gait have evolved, including in fantastic island dwarf (“hobbit elephant”) forms. We are also doing more experiments focused on the feet of elephants and other “hoofed” mammals, with an aim to use biomechanics to better inform the health care of those animals, as often ~50% of mortality (including in elephants) in captivity can be traced back to foot health as a major cause. And finally we are investigating how elephant limbs grow and how that growth influences the mechanics of their tissues (especially bones), because elephants experience drastic changes in size and presumably loading as they mature.
Why do elephants use this unusual mode of moving?
This is a hard question. Elephant anatomy certainly is very different from that of other large mammals’. A good contrast is with rhinoceroses, which have a more “standard” body shape for their size. Elephant limbs, as most mammals go, are unusually long relative to their size; rhino limbs are not. This is an important distinction. The slender limbs of elephants are weak when not loaded in their standard standing/slow-walking “pillar-like” fashion. They also are so slender that the muscles themselves have poor leverage around the joints- you cannot see really big bumps and crests and other muscle attachment sites on elephant limbs, compared with the outrageously robust limbs of rhinoceroses.
The rhino-like evolutionary design seems to be good for remaining athletic at a large size, without forfeiting too much performance from smaller ancestors, but one could speculate it comes at a cost of expensive maintenance (big muscles and bones aren’t cheap) and poorer long-distance walking capacity.
The elephant-like evolutionary design seems to be good for walking, maybe even long distances (which elephants do sometimes), but bad for athletic performance (they can’t gallop, jump, etc., even as babies). So this unusual way of moving in elephants may simply have been something early elephants settled into doing and stuck with it for ~50 million years. Being as huge as they are means that athleticism may not be so critical e.g. for escaping predators, especially in the large social groups that elephants often form (unlike rhinoceroses).
But there is a lot left we could learn about this question, and much of it should relate to the unique behaviour, ecology and evolutionary history of elephants.