LSM1303 Animal Behaviour Student Blog : eating

Inhuman Doctors: Zoopharmacognosy and Self Medicating Animals

Vigneshwaran Shunmugam — Fri, 21 Mar 2008 15:15:00 GMT

Many major cultures around the globe have developed some form of medical science. The Indians have Ayurveda, the Chinese have TCM and of course there is Western medicine. What these fields have in common is that they are derived from the process of observing the effects of certain herbs or foods on the health of the imbiber and thus correlating cause and effect. While medical science and its practitioners have long been held to be at the forefront of human intellectual pursuits, we now realise that this was no great achievement at all. In fact, even monkeys do it.

Observe this Orang Utan for example.

Right. This is just a monkey opening a packet of powder. Nothing fancy. However, monkeys DO develop their own medical techniques to deal with their own health issues. This is known as Zoopharmacognosy which is basically the animal form of Medical Science. Many species of animals use various techniques to deal with their maladies.

If you have seen your dog or cat eating grass you may have been puzzled at their sudden vegetarianism. They do have good reason for doing so. Eating grass "stimulates either retching or the rapid expulsion of worms in diarrhea" (Hart and Hart 1985). Compare this with the Tamil proverb which claims that a Tiger would not eat grass, no matter how hungry.

Medicine is not a purely mammalian pursuit either.Snakes too have herbological knowledge! "According to Chinese folklore, many centuries ago a farmer in the Yunnan district found a snake near his hut. Fearful for his life, he beat it senseless with a hoe and left it for dead. A few days later, the same snake returned. Again he tried to kill it, but again it returned. After he had beaten it a third time, the farmer followed the severely wounded snake as it crawled into a clump of weeds, started feeding on them, and thereby rapidly cured the worst of its injuries. The plant in the story was Panex notoginseng, which now forms the main ingredient in the herbal formulation 'Yunnan bai yao', a white powder that cauterizes cuts and stems external bleeding immediately. It was standard issue in the Vietnam War, for use when soldiers were wounded far from conventional medical treatment. "(Reid 1987).

Our closest cousins, the Great Apes have various methods by which they keep themselves in the pink of health.

Above we see a chimpanzee(Pan troglodytes) chewing on the bitter pith of the Vernonia Amygdalina plant. Chewing on the pith allows the chimp to extract the bitter juice that is within. THe chimpanzees use this method to kill parasites in their intestinal tracts. Interestingly, chimps do not usually eat this leaf due to it being slightly toxic to them. Thus, they only eat this leaf for medicinal purposes! This paper has extensive information on this phenomenon, complete with graphs. The author Michael Huffman is an eminent figure in the field of Zoopharmacognosy.

Chimps sometimes consume the leaves of the Aspilia plant, which they got to great lengths to obtain. The leaves are covered in stiff hairs and are swallowed whole, despite the difficulty of doing so. "Huffman doesn't doubt that there is a medicative function behind leaf swallowing behavior. His theory about how it gets rid of worms revolves around the hairiness of the leaves. Huffman found live worms in chimp *** stuck "like Velcro" to leaf hairs and trapped within the folds. He speculates that worms may become attached to the leaves or somehow enticed into the folds during digestion, taking a "magic carpet ride" through the gastrointestinal tract, eventually to be excreted from the body. Chemicals in the plant may also decrease the ability of the parasites to adhere to the intestine, making it easier for them to be swept out by the leaves."

Perhaps the animal use of medicines to treat themselves is not such a surprising phenomenon. In fact post-Darwinists should have predicted it regardless of evidence. Using medical methods enables an animal to prevent its death,prolong its life, to heal faster and have a survival advantage. This is an advantage that would allow those animals who use it to be more successful than those who dont. In the abscence of a consequent negative selection pressure, animals who self-medicate would definitely outsurvive those who do not. Thus, Zoopharmacognosy is not surprisingly prevalent in the animal kingdom.

Not only do animals consume herbs and plants as medicines, but they also consume certain types of soil(geophagy) and insects for the same purpose.

Even more interesting than the fact that animals employ medical science is the fact that many of the herbs and techniques employed by animals are similarly employed by humans. This highlights the cross pollination of medical knowledge from the animal kingdom to ours.

To learn more on the exciting field of Zoopharmacognosy, this book might help.

"Really Wild Remedies—Medicinal Plant Use by Animals" by Jennifer A. Biser. Zoogoer, January/February 1998

Huffman, M.A. 2001. Self-Medicative Behavior in the African Great Apes: An Evolutionary Perspective into the Origins of Human Traditional Medicine. Bioscience, 51(8):651-661.

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Think you can eat the fastest? Think again!

TAN YAN XIU KIMBERLY — Tue, 18 Mar 2008 09:31:00 GMT

Doesn't this baby mole look cute?

(image source: http://www.dirtdoctor.com/pics/content_img.2118.img.bmp)

Well, it grows up to look like this.

(image source: http://farm2.static.flickr.com/1128/554140889_72473dfcae.jpg)

This is the star-nosed mole, found in wetlands and marshes in the West, and recent studies have found that it is the fastest eating mammal in the world. The most interesting part of this animal is its nose, which consists of 22 extremely touch-senstive 'tentacles'. These are covered by "25,000 sensory receptors and contains 100,000 large nerve fibers - six times as many as an entire human hand". Its sensitive nose aids it in sensing, identifying and eating prey, and is so useful that the mole has gained the title of eating champion.

Here s a video to explain more:

Research has focused on the speed at which the star-nosed mole can handle food, even taking as little as one fifth of a second. The rate at which they can consume prey is very interesting for a number of reasons.

The first is the nature of the appendages themselves. Moles have extremely poor eyesight, but its nose seems to make up for this lack in vision, due to its sensitivity. It also acts as a 'hand' in grasping prey and putting them into its mouth. Its nose also has a very large surface area, with individual 'fingers' that aid it in pushing objects around at a faster rate. This implies that it can find a significantly larger number of small prey than other mammals without this type of nose, in a given period of time. Furthermore, the star-nosed mole’s brain may also have been evolved to become more efficient. This is demonstrated by the fact that "all mammal brains represent the information that comes from touch-sensitive maps of the body”. While other moles have two of these maps of their nose, star-nosed moles have three. This results in its greater overall effectiveness.

Star-nosed moles move "almost at the speed limit set by its brain and nervous system". They practically utilize the maximum potential of its brain, and this enables them to work very swiftly. This gives them a competitive advantage over other animals, by factoring in prey profitability. This is the "ratio between the energy a predator gains from eating a prey animal and its “handling time,” where handling time is defined as the time between detecting an animal and eating it. According to the prey profitability formula, by reducing its handling time to a fraction of a second, the star-nosed mole can gain energy from chowing down on small insect larvae, tiny worms and other small food sources. Predators that take a few seconds to handle each prey animal, on the other hand, actually use more energy in the process of catching and eating such small prey than they gain from eating it". This clearly illustrates the extent of how beneficial its nose can be, by allowing to mole to be very energy-effective, expending less energy than it takes in from eating small prey.

Star-nosed moles live in wetlands and marshes, and this is why only this particular mole has this sort of nose. The soil found in wetlands is damp compared to dry soil, and contain a multitude of small insect larvae. As aforementioned about prey profitability, these collectively provide energy for the star-nosed mole, because it only expends a small amount of energy on locating them. Moreover, wetlands also have damp soil that would not damage their sensitive noses.

The star-nosed mole clearly illustrates how eating behaviours can be adaptive in the grand scheme of evolution. In addition, it shows how selective and specific these behaviours may be, as they particularly cater to the needs of the animal.

If you'd like to learn more, you can go to the star-nosed mole theatre here.

References:

"Photo in the News: A Many-Fingered Nose," by Sean Markey. National Geographic News, 2 February 2005.

"Speediest feeding mammal revealed as a mole," by Kelly Young. New Scientist, 2 February 2005.

"Star-nosed mole has moves that put the best magician to shame," by David F. Salisbury. Exploration, 2 February 2005.

"Underground Gourmet: Mole Sets a Speed Record," by Carl Zimmer. The New York Times, 8 February 2005.