The modest Vetiver

Bountiful Nature certainly holds the antidote to many anthropogenic and natural problems. One such is Vetiver (Chrysopogon zizanioides), formerly known as Vetiveria zizanioides, a xerophytic and hydrophytic perennial clump grass of the Poaceae family with fast-growing tough root system and the ability to grow very tall with rigid stems and leaves. Since it is native to India, we tend to be quite familiar with its myriads of uses as listed below.

Vetiver roots’ aromatic and cooling properties
Vetiver’s roots are highly aromatic, with a pleasant, cool, refreshing, and earthy smell.
1. The roots are added to water in earthen pots in order to impart a distinctive flavour as well as a cooling effect.
2. The roots are kept in cupboards so that the clothes have a ‘fresh’ smell (similar to how we use sachets of lavender).
3. The fragrant essential oil from the roots is widely used in perfumery.
4. Mats and fans made of woven Vetiver roots are used to cool rooms during summer.
5. Other handicrafts made of Vetiver roots are popular due to the subtle aroma.

Medicinal property
Vetiver is often used in Ayurveda, the traditional (and viable) Indian system of medicine.
1. Water is purified by adding the roots.
2. Infusion of the roots can help in allaying fever, inflammation, and tummy problems.
3. It is effective in normalising, moisturising, and rejuvenating the skin. Apparently, it is also effective in removing acne and can be applied on irritated, wounded, and inflamed skin for speedier healing.
4. When applied regularly, the oil can prevent stretch marks (especially during pregnancy).
5. Due to its beneficial effects on the central nervous system, applying the oil also helps in psychological and emotional balance- i.e. helps in overcoming depression, stress, tension, anxiety, nervousness, and even insomnia.
6. When applied locally, it is effective in countering rheumatism, back pain, headaches, and sprains.
7. And apparently, the oil is also an aphrodisiac.

Vetiver roots’ decontaminating property
1. Vetiver decontaminates the polluted/contaminated soil.
2. As mentioned before, the roots have the property of purifying water. Being a hydrophyte, the plant can be used in treating wastewater.

For addressing environmental problems
Vetiver’s roots are unique- these grow very deep downwards and are thick with high tensile strength. As a result, it has the following uses:
1. For controlling erosion: Vetiver is very effective in preventing soil erosion when planted on the boundaries of agricultural lands, dikes, bunds, embankments, slopes, or on stream and river banks.
2. Runoffs are mostly blocked and spread in the surrounding areas. As a result, not only are the soil, sediments, and agricultural fertilisers trapped (thus enriching the land), but the soil moisture is also conserved (which the plants use during times of water scarcity).
3. Groundwater recharge- apparently, groundwater levels have increased in areas where vetiver is widely used.
4. Since Vetiver grows in clumps, weed invasion is prevented.

Vetiver requires minimal maintenance and has very sturdy characteristics. It is highly tolerant of adverse climatic conditions and variations (including droughts, floods, submergence, and extreme temperatures from -14ºC to +55ºC), pH (from 3.3 to 12.5), salinity, frosts, herbicides, pesticides, and pollutants. Its sturdy stems can withstand deep and heavy water flows. It is also noninvasive, propagating by small offsets instead of stolons or rhizomes. Should there be any fires or heavy grazing (or any other hazard), the new shoots easily develop from the underground crown. Interestingly, Vetiver is intolerant to shade which may result in a reduction of growth or even its elimination.

Vetiver is thus a low-cost effective solution to myriads of problems, including soil erosion which otherwise results in great expenses. For the farmers, this is a very beneficial tool which evidently results in increased crop yields, irrespective of adverse weather conditions. Furthermore, flooding risks are greatly reduced and runoffs of agricultural chemicals (into streams/rivers) are restricted. Even the rest of us are blessed by this modest grass!

Photo: by treesftf

Man-eating lions and their decision-making

Should one dismiss the past as something of no significant relevance? Well, Justin Yeakel, of the University of California Santa Cruz, and collaborators (from Field Museum of Natural History in Chicago, University of Puget Sound, University of Cambridge, and University of Utah) seems to think otherwise as exemplified by their paper, ‘Cooperation and individuality among man-eating lions’, in the Proceedings of the National Academy of Sciences.

Historical Background
Let’s go back to March 1898 when the British were building a railway bridge across the Tsavo River in southern Kenya. Unfortunately, their progress was hampered by a partnership of two adult male lions, which launched nightly attacks on the rail workers’ camps. This killing spree lasted for nine months, until they were killed by Colonel John Patterson.

The final death toll has always been ambiguous. The first estimate was 28 victims, i.e. the 28 Indian workers who were killed by the lions. But in 1920, Patterson himself revised the death toll to 135, supposedly after factoring in the natives (estimates of which range from zero to 107).

Yeakel’s methodology
To confirm the final death toll, Yeakel used the premise that the Tsavo lions’ diet can be deciphered by analysing the isotopic ratios of nitrogen and carbon in their hair and bone samples (obtained from the Field Museum in Chicago), for it would reflect the isotopic ratios of their prey (i.e. grazing and browsing animals and humans, such as the Taita people who lived in the Tsavo area). More specifically, dietary inputs of the last 2-3 months of the Tsavo lions could be deduced by analysing the hair keratin from the rapidly regenerating tuft hairs of the tail, whilst the lifetime average could be deciphered by analysing the bone collagen. Once this was accomplished, Yeakel modelled the prey combinations which were most likely to produce these distinct isotope ratios.

So, how many?
The final modest estimate was that the lions ate around 35 people. It is likely that the number of humans killed might be greater than the number of humans eaten, for there might have been cases when the lions couldn’t escape with their prey or when the bodies were recovered before the lions could properly sink in its teeth. Perhaps some may have even succumbed to their injuries later.

The Lions’ platter
The results also revealed that, for most of their lives, these lions ate grazing animals- until March 1898. Although they hunted cooperatively (despite hunting humans not really requiring cooperative hunting for they are significantly less hassle than the larger ungulates), there was a disparity in their diets. One lion ate more grazers and some occasional humans (around 11, i.e. approximately 13% of its food intake), whilst the other ate both grazers and humans (around 24, i.e. approximately 30% of its diet). It is quite likely that the latter’s substantial preference for humans had to do with its severe dental problems and jaw injury which may have impeded its ability to hunt.

Why humans?
So why did these lions widen their dietary preferences to include humans?
One possibility was the existing scarcity of the habitual prey, which may have been the result of
i. the Tsavo region experiencing drought in 1898,
ii. unhindered hunting of the lions’ usual prey,
iii. the rinderpest virus (from Europe) which had killed most of the lions’ conventional prey.

Baldus (2006) reports a similar (and fairly recent) case from Tanzania. His previous study (2004) estimated that lions are responsible for one third of the 200-odd humans killed in Tanzania each year by animals (Packer et al states that, between 1990 and 2004, 563 humans were killed and 308 injured by man-eating lions). Nonetheless, from August 2002 to April 2004, a young adult male lion single-handedly killed 35 humans and injured at least 10 in Mkongo Ward, south west of Dar es Salaam. These took place on a thin stretch of agricultural land, along the southern bank of the Rufiji river and enclosed on its western and southern sides by the Selous Game Reserve. Significantly, a human population of approximately 13,000 was residing near the game reserve. But more importantly, the Mkongo lion shared a striking similarity with the dominant Tsavo man-eater: he had a broken upper left molar with a serious abscess. It is likely that, because of the permanent pain, he would have preferred the humans.

Yet, Baldus stresses that most man-eating lions in Tanzania are healthy, with no signs of infirmities. So what transforms the grazer and browser-preferring lion into a human-preferring lion? Fall in the habitual prey densities.

Carnivore-human conflict
Carnivores are forced into conflict with humans when their habitats and habitual prey densities decline (usually due to human related activities such as the creation/expansion/encroachment of agricultural and/or settlement lands, virulent ungulate poaching/hunting) (Hackel 1999; Schiess-Meier et al, 2007). This carnivore-human conflict has resulted in a decline in carnivore population. In 2005, there were only approximately 5,750 Lycaon pictus a.k.a African wild dogs (Swarner, 2004; Lindsey et al, 2005). Cheetah (Acinonyx jubatus) population has fallen from an estimated 30,000 in 1975, to less than 15,000 in the 1990s, the famed Serengeti National Park in Tanzania having just around 200-250 cheetahs (Kelly 2001).

Thus, very likely, it was the change in environmental conditions which changed the dietary specialisations of these lions. What does this bode for the rapidly expanding human civilisation in Africa and Asia? And more importantly, what does this bode for the wildlife population and their natural habitats?

Yeakel, J., Patterson, B., Fox-Dobbs, K., Okumura, M., Cerling, T., Moore, J., Koch, P., & Dominy, N. (2009). From the Cover: Cooperation and individuality among man-eating lions Proceedings of the National Academy of Sciences, 106 (45), 19040-19043 DOI: 10.1073/pnas.0905309106

Baldus, R. (2005). A man-eating lion (Panthera leo) from Tanzania with a toothache European Journal of Wildlife Research, 52 (1), 59-62 DOI: 10.1007/s10344-005-0008-0

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Hackel, J. (1999). Community Conservation and the Future of Africa's Wildlife Conservation Biology, 13 (4), 726-734 DOI: 10.1046/j.1523-1739.1999.98210.x

Kelly, M. (2001). Lineage Loss in Serengeti Cheetahs: Consequences of High Reproductive Variance and Heritability of Fitness on Effective Population Size Conservation Biology, 15 (1), 137-147 DOI: 10.1111/j.1523-1739.2001.99033.x

Baldus, R. 2004. Lion Conservation in Tanzania Leads to Serious Human-Lion Conflicts. With a Case Study of a Man-Eating Lion killing 35 People. Tanzania Wildlife Discussions Paper No. 41, GTZ Wildlife Programme in Tanzania, Wildlife Division, Dar Es Salaam.

LINDSEY, P., DUTOIT, J., & MILLS, M. (2005). Attitudes of ranchers towards African wild dogs : Conservation implications on private land Biological Conservation, 125 (1), 113-121 DOI: 10.1016/j.biocon.2005.03.015

Packer, C., Ikanda, D., Kissui, B., & Kushnir, H. (2005). Conservation biology: Lion attacks on humans in Tanzania Nature, 436 (7053), 927-928 DOI: 10.1038/436927a

SCHIESS-MEIER, M., RAMSAUER, S., GABANAPELO, T., & KÖNIG, B. (2007). Livestock Predation—Insights From Problem Animal Control Registers in Botswana Journal of Wildlife Management, 71 (4), 1267-1274 DOI: 10.2193/2006-177