Kalahari Research Articles

Isolation and partial sequence of a Kunitz-type elastase specific inhibitor from marama bean (Tylosema esculentum)

An isolation procedure utilizing ammonium sulfate fractionation and affinity chromatography was used to purify an elastase inhibitor present in large amounts in marama beans (Tylosema esculentum). The protein appeared to be heterogeneous due to carbohydrate differences, demonstrating two bands on SDS gels with molecular weights of 17.8 kDa and 20 kDa. Partial sequence, derived from mass spectrometry, indicated that the protein is a Kunitz-type inhibitor distinct from other known plant serine protease inhibitors. The marama bean inhibitor is specific for elastase, with very low Ki for both pancreatic and neutrophil elastase. The quantity of elastase inhibitor present in marama beans is many times greater than in soybean or any other bean or nut source reported to date. This raises the question of why a bean found in an arid corner of the Kalahari Desert would be so rich in a very potent elastase inhibitor.

Validation of the Atmospheric Infrared Sounder (AIRS) version 5 land surface emissivity product over the Namib and Kalahari deserts

Hyperspectral infrared sounders require accurate knowledge of the land surface emissivity (LSE) to retrieve important climate variables such as surface temperature, air temperature, and total water vapor from space. This study provides a method for validating and assessing the Atmospheric Infrared Sounder (AIRS) version 5 LSE product using high–spatial resolution data (90 m) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) which has five bands in the thermal infrared region (8–12 μm, 1250–833 cm−1) and high–spectral resolution laboratory measurements of sand samples collected over the Namib and Kalahari deserts in southern Africa. Results indicate that the mean, absolute daytime LSE difference between AIRS and the laboratory results for six wavelengths in window regions between 3.9 and 11.4 μm (2564–877 cm−1) was 2.3% over the Namib and 0.70% over the Kalahari, while the mean difference with ASTER was 2.3% over the Namib and 2.26% over the Kalahari for four bands between 8 and 12 μm. Systematic modeling and surface dependent AIRS LSE retrieval errors such as large discrepancies between day and nighttime shortwave LSE (up to 15%), unphysical values (LSE >1), and large daytime temporal variations in the shortwave region (up to 30%) are further discussed.

Dryland hydrology in a warmer world: Lessons from the Last Glacial period

It has long been recognized that the tropics were drier and mid-latitude deserts wetter during the Last Glacial Maximum (LGM). Until now there has not been a single, unifying explanation for this pattern. Recently, Held and Soden [34] suggested that ongoing global warming will cause the Earth’s drylands to become progressively drier and its tropics to become progressively wetter. Because no suitable “warm world” analogue is available in the paleoclimate record, the best available test of Held and Soden’s proposal is to look at records from the last glacial period in which drylands should have been wetter and the tropics drier. Our survey of the recent paleolake literature confirms that closed basin lakes located in the poleward limits (∼40°) of the drylands in both hemispheres were far larger during the Last Glacial Maximum and parts of the tropics appear to have been less wet. While these observations are consistent with Held’s prediction, evidence from the sub-tropical drylands (15 to 25°) is more complex. As with high-latitude drylands, lakes in subtropical drylands of South America and probably the Kalahari Desert were larger than present during the LGM. By contrast, lakes in the sub-tropical Sahara and Arabian Deserts of the northern hemisphere were largest in the early Holocene, but also apparently larger than today in the early LGM. What paleolake records show are that 1) a strong hemispheric symmetry in lake response occurred during the LGM, 2) a difference in response occurred during the latest-glacial, and 3) lake expansions occurred in response to shifts in the thermal equator related to Heinrich Events and insolation variation as well as to colder temperatures.

Genetic structure, relatedness and helping behaviour in the yellow mongoose in a farmland and a natural habitat

AbstractThe yellow mongoose Cynictis penicillata is a facultatively social species and provides an opportunity to study the evolution of social behaviour. We examined genetic structure, relatedness and helping behaviour in the yellow mongoose in natural habitat in the Kalahari Desert, where the species lives in small family groups of up to four individuals and shows no cooperative breeding; and in farmland in the Western Cape Province of South Africa, where they live in larger groups of up to 13 individuals, engage in numerous social interactions and show cooperative breeding. The farmland population showed significant inbreeding, and lower genetic variability than the desert population, but there was no evidence of a recent population bottleneck. The genetic relatedness between individuals within social groups and that between future potential helpers and pups were higher in the farmland population than in the desert population. However, based on a limited sample, helping effort (in the farmland population) was not preferentially directed towards kin. Thus, the origin of helping in the farmland population is consistent with kin selection, but in the absence of kin discrimination, future research should investigate whether long‐term breeding opportunities or group augmentation contribute to maintaining cooperative breeding in this population.

Over-Imitation in the Kalahari Desert and the Origins of Human Cultural Cognition

AbstractChildren grow up in environments saturated with tools and objects which they must learn to use. One of the most efficient ways in which children do this is by imitating. Recent work has shown that, in contrast to non-human primates, when young children learn by imitating they focus more on reproducing the specific actions used than the actual outcomes achieved. From about 18 months of age children will routinely copy arbitrary and unnecessary actions. This puzzling behaviour is called 'over-imitation'. By documenting similarities exhibited by children from a large, industrialised city and children from remote Bushman communities in southern Africa, we provide here the first indication that over-imitation is a universal human trait. We also show that over-imitation is unaffected by the age of the child, testing environment, or familiarity of the demonstrating adult. Furthermore we argue that, although seemingly maladaptive, over-imitation reflects an evolutionary adaptation fundamental to the development and transmission of human culture.

A new approach to the archaeology of livestock herding in the Kalahari, Southern Africa

AbstractThe author notes that livestock herding in the Kalahari Desert would require water during the dry season. By mapping and dating artificially dug or enlarged waterholes, he shows when and where such herding would have been possible. Dating is by radiocarbon, artefact scatters and cartography. Comparison with climatic, documentary and oral evidence shows that the use of the artificial wells correlates with what is known so far about the movement of peoples over the last two millennia. This inspires confidence in the connection between the wells and herding and in the survey methods.

Bushmen Arrows and Their Recent History: Crossed Outlooks of Historical, Ethnological and Archaeological Sources

Bushmen weapons were considered very early by ethnology: the vision of these nomadic hunter-gatherers walking away into the horizon of the Kalahari Desert, with their bows and arrows on their back, is one of the most iconic representations of this disappearing lifestyle.Besides the technical values that were brought into play in the making of this equipment, their role as vector of social values has also been greatly illustrated. It has been shown, in particular, the way in which an arrow creates a link between the hunter and his prey, but also the interactions the arrow conveys between the user of the weapon and the social networks to which he belongs.Nevertheless, most reference systems are based on the equipment of sub-contemporary and current populations, i.e. on those used by groups occupying a limited territory in the Kalahari Desert, straddling Botswana and Namibia. Yet, only a few decades ago, Bushmen occupied much vaster areas, corresponding to a large western half of Southern Africa, involving the exploitation of territories ecologically more contrasted than today. In addition, the socio-economic status of the ancestors of today’s Bushmen was, it seems, more diversified: groups of nomadic hunter-gatherers lived side by side with pastoralists (who also practiced hunting), and it is likely that both sides belonged, to a greater or lesser degree, to societies with close links between them.Research works realised on several collections of bows and arrows kept in South African museums and compared with historical sources (travel accounts from the 16th to the 19th centuries in particular), also bring to light greater diversity: the diversity of the actual armoury (the spear, the club and the throwing stick in addition to the bows and arrows); diversity in the way the arrows are actually made; and the diversity of their supposed functions (from hunting to war). Behind such diversity, we can try to grasp the complexity of the recent history of the Bushmen populations.

Fish, Floods, and Ecosystem Engineers: Aquatic Conservation in the Okavango Delta, Botswana

The Okavango Delta, Botswana, is a major wetland surrounded by the Kalahari Desert. The delta supports a diverse fish fauna that depends on highly seasonal flooding from inflowing rivers, and on the actions of ecosystem engineers (hippopotamuses, elephants, and termites), for creation and maintenance of their habitats. Conflicts in resource use, especially water, are likely to affect fish populations and the Okavango ecosystem in the near future. We present conceptual models of this remarkable aquatic ecosystem in relation to fish and fisheries as the basis for future research and conservation efforts. Developing understanding of the environmental flow requirements of the delta is key to the management of the Okavango Delta as an ecosystem supporting diverse and abundant fish and wildlife. Once developed, this understanding can be used to allocate water within the Okavango watershed.

Pathology of Mycobacterium bovis Infection in Wild Meerkats ( Suricata suricatta)

Pathological lesions associated with Mycobacterium bovis infection (bovine tuberculosis; bTB) in free-living meerkats (Suricata suricatta) in the Kalahari Desert of South Africa are described. The pathology of bTB in meerkats was determined through detailed post-mortem examinations of 57 animals (52 meerkats showing clinical signs of bTB, and five not showing signs of disease). Lymph nodes and tissue lesions thought to be associated with bTB were cultured for mycobacteria. All 52 bTB-infected meerkats showed gross or microscopical granulomatous lesions, but M. bovis was cultured from only 42% (22/52) of these animals. The majority (96%, 50/52) of diseased meerkats had lesions in multiple sites, the pattern of which suggested haematogenous spread of M. bovis infection in this species. The histological characteristics of the tuberculous lesions, together with the gross pathology and the wide range of body systems affected, indicate that infection in meerkats is acquired principally via the respiratory and oral routes, whereas excretion is most likely via the respiratory tract and suppurating skin wounds. Urine and faeces appear to be unlikely sources of infection. The findings of this study provide information on the transmission, pathogenesis and epidemiology of bTB in meerkats that is likely to be relevant to the understanding of M. bovis infection in other social mammal species such as the European badger (Meles meles).

Optically Stimulated Luminescence (OSL) dating and palaeoenvironmental studies of pan (playa) sediment from Witpan, South Africa

Robust, dateable sources of palaeoenvironmental proxy data are scarce in the southwestern Kalahari Desert, and this study investigates the potential of pan (playa) floor sediments as an archive of late Quaternary environmental change. Augering has revealed the presence of up to 3 m of clay- and silt-rich deposits in the base of Witpan, a small pan basin set amongst linear and lunette dunes. The weakly-stratified deposits include aeolian quartz sands and evaporites amongst a clay-rich groundmass, and are believed to have accumulated on a wetter-than-present pan surface. The aeolian quartz fraction has been dated with Optically Stimulated Luminescence (OSL), and reveals accumulation of at least 50 cm of sediment at around 20 ka, and previous accumulation at around 32 ka. The northern and southern sections of the pan are shown to maintain some hydrological independence, attributed to bedrock outcropping, and also show distinct differences in their physical sedimentology. Biogenic proxies are poorly preserved, with neither diatoms nor pollen found in adequate quantities, although phytoliths, found in both the pan-floor sediments and the fringing lunette dune, may offer a more resilient palaeoenvironmental indicator. The possible value of pan floor sediments as dryland archives of physical and chemical, and possibly selected biogenic, palaeoenvironmental proxies, combined with OSL-constrained chronologies, should not be discounted.

Last Glacial Maximum dune activity in the Kalahari Desert of southern Africa: observations and simulations

It has long been understood that as ephemeral landscape features sand dunes are highly sensitive to environmental change, and thus their distribution and the timing of their development may provide clues to past climate dynamics. The relationship between climate and dune activity, however, is neither simple nor straightforward, with a range of controls affecting the balance between erodibility (the availability of sediment for deflation) and erosivity (the potential for sediment transport). To explore such complex systems over large spatial and temporal scales, a number of dune activity indices (DAI) have been created that incorporate wind speed and moisture balances to calculate the potential for, and degree of dune mobilisation. Using modern weather station data, these indices have generally been shown to provide reasonable indications of dune activity potential. Until recently, however, the detailed quantitative data required to inform these equations has not been available for past climate scenarios, and attempts to determine the relative importance of the various controls of dune activity have relied on rough estimations of climatic parameters. This paper combines data from monthly general circulation model (GCM) outputs from the coupled Ocean-Atmosphere GCMs for 21 ka with the most detailed DAI equation presently available to calculate the potential for dune reactivation in southern Africa during the Last Glacial Maximum (LGM, 18–24 ka). Based on these data and calculations it is indicated that there was significantly less potential for dune activity across southern Africa at 21 ka. When compared to the aeolian sediment records from the region, this study poses serious and fundamental questions about: 1) the reliability of the model outputs, 2) the degree to which DAIs are able to account for the complexity and dynamics of aeolian systems, and/or 3) the interpretation of dune records as palaeoclimatic proxies at millennial time scales.

The Relation of Childhood Mortality to Mobility in Contemporary Foragers

In her stimulating paper Waguespack (2002) argued that the initial migration of foraging tribes from North to South America in the Late Paleolithic could not have been impeded or slowed by a disease barrier because infections did not seem likely to have impacted their mobility. Indeed, the data Waguespack used about the mobility and the infant mortality observed in nine contemporary foraging societies appeared to show no relationship between childhood mortality and either number of residential moves per year or total distances of yearly residential moves [incorrectly labeled in Table 4 and Fig. 3 as “Distance per move”]. Waguespack concluded that “based on modern hunter-gather societies the degree of group mobility between residential camps is unlikely to be affected by disease” (p. 238). Even though Waguespack provided data on the habitat occupied by the different groups, this element was not factored in the analysis. There was a single Arctic tribe, the Greenland Inuit, which was different from the others for both its high childhood mortality and mobility. There were otherwise four tropical forest groups, two from the Philippines (Agta, Batak) and two from Central Africa (Aka and Mbuti), and four tropical/subtropical desert groups, one from Australia (Anbarra) and three from the Kalahari desert (Dobe, G/wi and ≠Kade G/wi). With one exception (childhood mortality of the Agta from Philippines), I have been able to find the source of all the data in Tables 4-1 and 6-9 (pp. 112 and 252) of Kelly (1995). Waguespack’s Fig. 3A is reproduced in Fig. 1a, with an added linear regression slope. I have reanalyzed these data. In order to control for habitat (desert vs. forest), I left the Inuit out as they were the only Arctic population. Figure 1b shows that, overall, when mixing forest and desert people, there is no association between childhood mortality and number of residential moves (slope=0.004, p=0.98). However, among tropical desert people, the association is negative (Fig. 1c, slope=−0.175, p=0.49). The same is true for forest people (Fig. 1d, slope=−0.190, p=0.76). The slope for the whole sample after adjustment for habitat is −0.177 (p=0.17, Fig. 1b). None of the slopes is statistically significant, as can be expected given the small sample size. Nevertheless, the consistency of the negative association and its magnitude among desert and forest people suggests that the lack of association between moves and childhood mortality reported by Waguespack is indeed confounded by habitat: forest people move more often than desert people, but in both groups there seems to be one less residential move for every 5% to 6% increase in mortality. The results are equivalent when using the total distance of residential moves in a year (slopes, crude=−1.44, p=0.78; adjusted=−1.78, p= 0.44), but the variable is only available for three tropical forest groups, which makes the demonstration less neat. The appropriate interpretation of these data is therefore that residential moves are inversely proportional to childhood mortality: Populations with greater childhood mortality move less, or vice versa, less mobile populations have greater childhood mortality. These findings are consistent with Bailey’s report that Efe Pygmies of North-Eastern Africa are less mobile when sick than when not (Bailey 1991). This relationship between mobility and childhood mortality does not fully support the interpretation given by Waguespack (Waguespack 2002). Hum Ecol DOI 10.1007/s10745-008-9209-y

Desert Truffles of the African Kalahari: Ecology, Ethnomycology, and Taxonomy

Desert Truffles of the African Kalahari: Ecology, Ethnomycology, and Taxonomy. The Khoisan people of the Kalahari Desert have used truffles for centuries. The extreme conditions in which desert truffles grow means that they fruit only sporadically when adequate and properly distributed rainfall occurs, and then only where suitable soil and mycorrhizal hosts occur. Truffles are hunted in the Kalahari by men and women; they look for cracks in the soil, often humped, caused by expansion of the truffles, which are then extracted with hands or digging sticks. The truffles are eaten raw or cooked (boiled, roasted over fire, or buried in hot ashes). Commercial harvest of Kalahari truffles has increased in the last decade and the quantities harvested have been observed to be declining where livestock have been concentrated.

Probabilistic predictions of climate change for Australia and southern Africa using the reliability ensemble average of IPCC CMIP3 model simulations

“Reliability ensemble averaging” (REA) is applied to a multimodel ensemble of coupled atmosphere‐ocean general circulation models (AOGCMs) from the third phase of the Coupled Model Intercomparison Project (CMIP3) to produce mean and probabilistic climate change projections for Australia and southern Africa. CMIP3 was conducted in preparation for the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC). REA produces a weighted average of the ensemble of climate change results, based on a measure of each model's bias and each model's degree of convergence in the predicted climate change. The methodology allows an assessment of the reliability of the projected climate change, the quantification of model uncertainty range, and the production of climate change projections in probabilistic form. Temperature and precipitation changes for three emission scenarios (B1, A1B, and A2) are analyzed, with a special focus on the A2 scenario. Regional differences in temperature and rainfall changes are identified, and threshold probabilities and probability density functions (PDFs) for key subregions are produced. In summer for temperature the A2 scenario results show a narrow PDF over southwestern Australia, reflecting agreement between models, partially caused by down weighting of outlier models due to their large biases. In contrast, the PDF for southeastern Australia is much broader, and that for tropical Australia has a bimodal character. There are significant decreases in rainfall under the A2 scenario in winter in the southwest (25–30% decrease) (common in sign to all AOGCM simulations) and the southeast (15–25% decrease) of Australia. There are no changes above natural variability in summer, hence no significant changes in the magnitude of Australian monsoon rainfall. Over southern Africa the region of maximum warming is over the Kalahari Desert in summer and winter. Under the A2 scenario in summer, there is a significant increase in rainfall over Kenya and Tanzania and a significant drying (∼10–20%) over parts of Namibia and Botswana. In winter, most of southern Africa south of 15°S shows significant decreases in rainfall.

Potential for domestication and commercialization of Hoodia and Opuntia species in Botswana

The species Hoodia (Apocynaceae) and Opuntia (prickly pear) (Cactaceae) are highly efficient in water use and belong to the Crassulacean Acid Metabolism (CAM) group of plants. These plant species are quite abundant in Botswana especially in the Kalahari Desert, prickly pear being the most dominant even though they have received very little commercial attention in the country. Elsewhere in the world, prickly pear has multiple uses such as their utilisation in the pharmaceutical industry, as a source of food and drink for animals in the rural communities, and are important in the weaving and clothing industry. Other important uses of the species are manufacturing of paper, making of toothpicks, needles, pins and for numerous essential products. Recently the world has been introduced to Hoodia gordonii or curorri that works as a natural appetite suppressant. This paper reviews the potential uses of Opuntia and Hoodia spp, identifies the important species used by communities in Botswana and recommends protocols and instruments for research, cultivation, and commercialization of these species in the country. Key words: Commercialisation, communities, domestication Hoodia, Opuntia.

Potential for domestication and commercialization of Hoodia and Opuntia species in Botswana

The species Hoodia (Apocynaceae) and Opuntia (prickly pear) (Cactaceae) are highly efficient in water use and belong to the Crassulacean Acid Metabolism (CAM) group of plants. These plant species are quite abundant in Botswana especially in the Kalahari Desert, prickly pear being the most dominant even though they have received very little commercial attention in the country. Elsewhere in the world, prickly pear has multiple uses such as their utilisation in the pharmaceutical industry, as a source of food and drink for animals in the rural communities, and are important in the weaving and clothing industry. Other important uses of the species are manufacturing of paper, making of toothpicks, needles, pins and for numerous essential products. Recently the world has been introduced to Hoodia gordonii or curorri that works as a natural appetite suppressant. This paper reviews the potential uses of Opuntia and Hoodia spp, identifies the important species used by communities in Botswana and recommends protocols and instruments for research, cultivation, and commercialization of these species in the country.

Commentary on “Autonomic and behavioural thermoregulation in tennisAutonomic and behavioural thermoregulation in tennis”

Over 100 years ago, biologist Charles Morris proposed the revolutionary idea that humans evolved as hot weather hunters. Today it is increasingly accepted that we Homo sapiens owe our big...

Can lizard richness be driven by termite diversity? Insights from the Brazilian Cerrado

We test predictions of the Morton and James hypothesis, which states that high termite diversity promotes high lizard diversity. We explore consumption of termites by lizards in the Brazilian Cerrado, a system that shares many similarites with arid Australia whose fauna formed the basis for the original hypothesis. We found that Cerrado lizards prey heavily on termites. Several species had >40% of their diet consisting of termites, some species reached up to 80%. However, lizards prey on termites independently of their diversity in the environment and do not show niche segregation in relation to termite resource. Hence, our results in the Cerrado do not support the hypothesis that termite diversity can promote lizard diversity. The diets of Cerrado lizards have a high proportion of termites; however, the diets of desert lizards from the Australian and the Kalahari deserts have a much higher proportion of termites when compared with those from the Cerrado and the Amazon. Differences in termite consumption by lizards across ecosystems do not seem to be related to local termite diversity. We hypothesize that overall prey availability can explain this pattern. Several arthropod groups are abundant in the Cerrado and the Amazon. In deserts, other prey types may be less abundant; therefore, termites may be the best available resource.

SEDIMENTARY HISTORY AND THE INTERPRETATION OF LATE QUATERNARY DUNE RECORDS: EXAMPLES FROM THE TIRARI DESERT, AUSTRALIA AND THE KALAHARI, SOUTH ÁFRICA

Stabilized sand deposits from arid regions are often used as palaeoenvironmental proxies for past periods of enhanced aeolian activity. Although widespread use of optically stimulated luminescence (OSL) dating techniques has opened up the possibility of systematic analyses of dune building chronologies, palaeoenvironmental histories cannot be reconstructed from chronological data alone. The reconstruction of regional palaeoenvironmental histories should consider all available evidence - stratigraphic, sedimentological and micromorphological, and chronological. This paper highlights potential issues with the interpretation of dune records in the context of stratigraphic preservation, using examples from the Tirari Desert in Australia and the Kalahari Desert in southern Africa. Sedimentological characterisation of linear dunes in the Tirari Desert demonstrates that reworking of underlying dune sediments and buried soils is common, thereby calling into question simplistic interpretations of dune formation involving sequential deposition and pedogenesis. This case study highlights the limitation of the augering technique, although useful information can be gained nonetheless. Three OSL age estimates confirm the presence of at least two Holocene dune building episodes, but cannot constrain the timing of the onset of dune building. Higher frequency sampling and micromorphological analyses may further elucidate the palaeoenvironmental history of individual dunes. In the Southwestern Kalahari, interdune sediments have been described as the least sensitive part of the aeolian landscape, thus offering the potential for longer records of aeolian deposition. This is found not to be the case at Witpan, where interdune sands are extensively mixed and probably younger than the linear dune cores. The lunette at Witpan records numerous short-lived and rapid deflationary events from the nearby pan (playa). These are considered to reflect changes in sediment source rather than pedogenesis. These examples highlight the value of combining micromorphological, sedimentological and chronological studies for palaeoenvironmental reconstruction.

Recapturing Space: Production of Intersubjectivity among the Central Kalahari San

The |Gui and ||Gana, two groups of San, have made extensive use of the central part of the Kalahari Desert, though they were recently resettled outside their previous living area. Since relocation, their rich ecological knowledge has not served them well. Even in this situation, they still show a keen perception regarding the ground conditions: for avoiding obstacles as well as for assessing animal signs in the bushveld. This study explores how they deployed these kinds of knowledge by cleverly using various resources in the environment. My analysis shows that the skills required to find a path between hurdles on the land are closely associated with those used to perceive animal signs. I have documented, in detail, interactions among my informants; and shown how they arrive at a mutual understanding about the land and its signs, and that the presence of outsiders within these interactions encourages the |Gui and ||Gana to formulate their knowledge more explicitly. In these ways, folk knowledge becomes “known” to various participants. Their prediction becomes inseparable from their memory; their selves become involved with the land.