Pashu Sandesh, 21st July 2018.
Dr Rajesh Kumar Singh
Animal behavior is intimately connected with chemical signaling, often through glandular secretions. This is very significant and obvious in Asian male elephants during their musth period when their temporal glands secrete a fluid with a characteristic odor. Musth gland activity greatly influences the elephant society as well as man-elephant interaction.
Elephants have had a checkered association with humans. In spite of its long association with man, we have not been able to domesticate elephants fully as we have domesticated other animals like dogs. This is arguably due to the 'musth' condition that occurs periodically in males when they become temperamental and very often aggressive. Instances are many when musth elephants have killed their mahouts. The musth period lasts a few months and is characterized by a secretion from the temporal glands that has a significant odor (recognizable even by humans).
A deeper understanding of musth gland activity can help us not only to fathom elephant behavior and evolution but also to find possible ways to control abnormal aggression.
The Musth Gland
Also called the temporal gland, it is located about midway between the eye and ear on either side of the face. The size of the gland may be that of a human fist but this gets enlarged more than double in the active state and the swelling is noticeable. When it is not active, the duct end is seen as a hole only. When activity starts in the male, a patch of fluid can be seen. The musth gland is considered to be a modification of an apocrine sweat gland.
Stages of Musth
Musth occurs in male elephants, both Asian (Elephas maximus) and African (Loxodonta africana). There is pronounced testosterone secretion during musth in only adult males. In the Asian male elephant, both tuskers and tuskless males (mukhnas) come into musth. The temporal gland secretion starts in the subadult stage but becomes typical musth only after reaching maturity. In the adult male, five stages of musth have been described viz pre-musth, early musth, mid-musth, post-musth and non-musth, the musth activity being typically over a 16 week period. In pre-musth, only volatile compounds are given out from the temporal gland and may not be noticed by humans. In early musth, the secretion begins; Continuous secretion is seen in mid-musth (Figure 4) and is characterized not only by the oily secretion and pungent smell, but also frequent urine-dribbling from an extended penis and marked aggression. There is a tendency to spread musth fluid on objects like tree trunks leaving it as a message of the animal's condition (Figure 5). The body temperature is higher than normal. The elephant shows decreased appetite and thirst as compared to a non-musth tusker. Activity decreases in late musth when secretion and aggression tapers off into the non-musth condition. At the end of musth, the elephant might have lost almost a tenth of its body weight.
Chemical Composition of Musth
Hundreds of organic substances have been identified at various stages of the musth condition. The most significant compound is testosterone and its derivative dihydrotestosterone. Apart from testosterone and dihydrotestosterone, the other predominant compounds are several ketones, proteins, mucopolysaccharides, lipid metabolites, etc., whose relative concentrations vary with the time course of musth. Another significant compound is frontalin, a pheromone described first in insects that is used by the female insect to attract males. Many of these compounds are present not only in the musth secretion, but also in the blood serum and urine as well. The urine dribbling has significance in this connection since other elephants smelling it will know the condition of the musth elephant - males avoid it while females in receptive condition may be attracted. Males in musth are attracted to females whose urine contains the female pheromone Z-7 dodecenyl acetate. The whole gamut of chemicals may together transmit an 'honest' message to the receiver on the state of the giver.
Musth and Elephant Behavior
The most important aspect of musth is the behavior associated with it. Musth has been conserved through evolution in spite of the loss in body condition suffered during the period. Elephants in musth are very aggressive and dominate other males, which may be stronger physically but not in musth. Possibly, as a result of their aggressive behavior, musth males are able to get more mating opportunities with receptive females and their genes get transmitted through generations. It is not that all elephants are aggressive in musth; many as they reach the latter years of fifty or thereabouts, though quite reproductively active, are less aggressive and are safely handled, as observed in captive Asian animals.
Since elephants have exceptional olfactory perception (as good or better than a bloodhound), they can smell the musth components even when the condition is just starting in one male during pre-musth and this may inhibit the initiation of musth in the receiver males. This phenomenon has been noted among the camp elephants of the Tamil Nadu Forest Department where records show that only one adult male is in musth at a time. This is perhaps nature's way of preventing conflicts within a group. A musth elephant is also smelt from far away by conspecifics and may be attracted by receptive females who also advertise their condition. Other non-musth males take care to avoid the musth male.
Physiology of Musth
The chemicals found in musth and other body fluids have to be produced by body metabolism. Starvation noticed during musth can itself change the metabolism and many of the compounds secreted may reflect this effect. This is possibly the cause for increase in ketones in the breath, urine and musth secretion. The source for testosterone in males and estrogen in females is cholesterol (produced by lipid metabolism). Hormones initiate the changes in the sexes leading to sperm production in males and ovulation in females at the appropriate time. The testosterone levels in the temporal gland secretion during musth reach 0.5 mg/mL and in the serum it is about one tenth of this. Other degradation products connected with lipid metabolism are also generated. For the production of high quantity of androgens, the cellular activity gets increased manifold. In a typical musth gland cell, the organelles connected with lipid metabolism like smooth endoplasmic reticulum, golgi bodies and mitochondria exhibit hypertrophy and ultimately, the cells rupture exiting the numerous cellular components in the musth fluid. The androgen testosterone is also considered as a pro hormone since dihydrotestosterone, a more potent androgen, is derived from it as also estradiol which in the brain, increases sexual desire, a noticeable condition in musth.
Is Musth Controllable??
Musth in elephants is a normal process. It becomes a problem only in the case of man-elephant interactions. Guidelines have been issued in Kerala, on care of elephants in musth to avoid harm to humans. The mahouts know that animals in musth misbehave but laxity on their part can lead to tragedy. Very often the animal becomes quite docile subsequent to the aberrant behavior almost as if it regrets its misconduct and the mahouts consider this normal and a factor not to be held against the elephant. A drug, Leuprolide acetate has been tried to suppress the condition in captive elephants by reducing testosterone production. The same drug is injected to treat prostate cancer in humans, where also it acts by reducing testosterone in circulation (one may end up with slightly female characteristics as the general androgen balance is upset). Obviously, long-term use of the drug can change behavior in elephants.
More studies are called for in all aspects of musth; the ultra-structural pathology, the signals involved in transforming dormant cells to musth secreting cells, detailed physiology as also the behavioral responses and of course possible ways to control the aggression to the extent of preventing fatalities but not normal sexual behavior.
Dr Rajesh kumar singh, jamshedpur, jharkhand, India,