Description of five new species of the Madagascan flagship plant genus Ravenala (Strelitziaceae).

Madagascar's emblematic traveller's tree is a monospecific genus within Strelitziaceae, the family of the South African bird of paradise. Until now, this endemic genus consisted of a single species: Ravenala madagascariensis Sonn., which is grown everywhere in the tropics as an ornamental plant. The plant is immediately recognizable for its huge fan-forming banana-like leaves and is locally referred to in Magagascar by several vernacular names. "Variants" have been mentioned in the literature, but without any attempt to recognize formal taxa based on diagnostic features. In this paper, we formally describe five new species and fix the application of the name R. madagascariensis to the populations growing on the eastern coast of Madagascar, with the epitype growing in the marshy Fort-Dauphin area in the south. This paper has numerous implications for conservation biology and other domains of life sciences, due to the importance of this genus for the conservation of Madagascan ecosystems, the ornamental plant trade, as well as for its invasive status in several tropical areas.

Primate energy input and the evolutionary transition to energy-dense diets in humans.

Humans and other large-brained hominins have been proposed to increase energy turnover during their evolutionary history. Such increased energy turnover is plausible, given the evolution of energy-rich diets, but requires empirical confirmation. Framing human energetics in a phylogenetic context, our meta-analysis of 17 wild non-human primate species shows that daily metabolizable energy input follows an allometric relationship with body mass where the allometric exponent for mass is 0.75 ± 0.04, close to that reported for daily energy expenditure measured with doubly labelled water in primates. Human populations at subsistence level (n = 6) largely fall within the variation of primate species in the scaling of energy intake and therefore do not consume significantly more energy than predicted for a non-human primate of equivalent mass. By contrast, humans ingest a conspicuously lower mass of food (-64 ± 6%) compared with primates and maintain their energy intake relatively more constantly across the year. We conclude that our hominin hunter-gatherer ancestors did not increase their energy turnover beyond the allometric relationship characterizing all primate species. The reduction in digestive costs due to consumption of a lower mass of high-quality food, as well as stabilization of energy supply, may have been important evolutionary steps enabling encephalization in the absence of significantly raised energy intakes.

Scaling of free-ranging primate energetics with body mass predicts low energy expenditure in humans.

Studies of how a mammal's daily energy expenditure scales with its body mass suggest that humans, whether Westerners, agro-pastoralists, or hunter-gatherers, all have much lower energy expenditures for their body mass than other mammals. However, non-human primates also differ from other mammals in several life history traits suggestive of low energy use. Judging by field metabolic rates of free-ranging strepsirhine and haplorhine primates with different lifestyle and body mass, estimated using doubly labeled water, primates have lower energy expenditure than other similar-sized eutherian mammals. Daily energy expenditure in humans fell along the regression line of non-human primates. The results suggest that thrifty energy use could be an ancient strategy of primates. Although physical activity is a major component of energy balance, our results suggest a need to revise the basis for establishing norms of energy expenditure in modern humans.

[Great apes: who are they? Are they able to self-medicate?]. / Les grands singes: qui sont-ils? Sont-ils capables d'automédication?

Six great ape species (chimpanzees, bonobos, Western gorillas, Eastern gorillas, Sumatran orangutans and Bornean orangutans) live in tropical forests of Africa and South-East Asia. Their habitat, severely threatened by deforestation, contains a vast chemical and biological diversity. During the last decade, we have isolated and identified novel pharmacologically active compounds from plants used by wild chimpanzees in Kibale National Park, Uganda. Our continuous observations over the last 12 years confirm that chimpanzees, when sick, may ingest plant material that are not generally eaten, supporting the existence of self-medication among great apes. Knowledge of great-ape diseases, and the medicinal resources of tropical forests, may be improved by preserving and studying our closest relatives in their natural habitat.

Taste acuity of obese adolescents and changes in food neophobia and food preferences during a weight reduction session.

The relationship between taste acuity and food neophobia, food familiarity and liking has been studied in the context of a residential weight reduction session (WRS; mean duration: 10 months) in 39 obese adolescents. Taste acuity was assessed using recognition thresholds for sucrose, citric acid, sodium chloride and 6-n propylthiouracil (PROP) and supra-threshold perceived intensities for sucrose, sodium chloride and PROP. Food neophobia was assessed by using the food neophobia scale at the beginning and at the end of the WRS. At these time points we used also a food familiarity and liking questionnaire to assess changes in food familiarity and likes or dislikes for different food categories. Taste acuity appeared to mediate behavioural food-related changes during the WRS. High taste acuity was associated with limited reductions in food neophobia; less sensitive subjects showed greater increases in the acceptability of healthy foods, especially fruits and vegetables. Therefore, taste perception (and particularly PROP perception) appears to be a predictor of the magnitude of food-related behavioural change achieved during a WRS.

Taste perception in massively obese and in non-obese adolescents.

OBJECTIVE: The purpose is to determine whether taste functions are different in massively obese adolescents as compared with non-obese adolescents, and to what extent metabolic disorders may interfere with taste perception, as suggested by the results of recent animal studies. RESEARCH METHOD AND PROCEDURES: We compared taste sensitivity and hedonic responses of 39 adolescents with severe early onset obesity (mean BMI: 39.5; min-max: 30.9-51.6) and 48 non-obese adolescents (mean BMI: 21.0; min-max: 16.5-27.9) of both sexes. We measured recognition thresholds for fructose, sucrose, citric acid and sodium chloride. Supra-threshold perceived intensity and hedonic responses were assessed for solutions of sucrose and sodium chloride. In obese subjects, the occurrence of the metabolic syndrome was assessed by measuring blood pressure and, in blood samples, fasting glycemia and insulinemia, the concentration of triglycerides and HDL cholesterol. HOMA modelling was used to assess insulin resistance. RESULTS: Massively obese adolescents present a higher sensitivity to sucrose and sodium chloride than non-obese adolescents, with significantly lower recognition thresholds, and higher perceived intensities at supra-threshold levels for sucrose and salt. Hedonic responses are significantly lower for sodium chloride in the obese subjects. Among obese subjects, a significant positive correlation between taste responsiveness and the number of obesity-related metabolic disturbances is observed only in girls. CONCLUSION: Massively obese subjects have higher taste sensitivity than control subjects, especially for sucrose and salt. This can be explained, to some extent, by the influence of obesity-related metabolic disorders, which appears to be gender-specific.

Food neophobia in the context of a varied diet induced by a weight reduction program in massively obese adolescents.

Previous studies in humans have shown that short to middle-term pre-exposure to multiple foods can reduce the negative response to novel foods (neophobia). In order to explore the effects of a long-term exposure to varied foods on food neophobia, we studied a population of obese adolescents observed in a longitudinal protocol in which the multiple food experiences are induced by a residential weight reduction program (WRP) that encourages the consumption of a wide variety of foods. Seventy-two massively obese adolescents (22 boys) filled the food neophobia scale (FNS, [Pliner, P., & Hobden, K. (1992). Development of a scale to measure the trait of food neophobia in humans. Appetite 19, 105-120]) and an ad hoc food familiarity and liking questionnaire at the beginning and at the end of the program (mean duration: 8.9 months). Their scores were compared to those of a control group of 51 adolescents (14 boys) tested within a similar period. FNS results show a decrease of food neophobia, without significant difference between the control group and the WRP subjects, although only WRP have encountered new foods experiences as attested by the familiarity and liking results. Methodological considerations, concerning the characteristics of the participants, the nature of the multiple food exposure and the food neophobia measurements, will be proposed to explain differences among studies.

Bioactive properties of plant species ingested by chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park, Uganda.

We measured the biological activities of a selected sample (84 crude extracts) of 24 species eaten by wild chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park, western Uganda, to assess their potential chemotherapeutic values. Antibacterial, antimalarial, and/or antileishmania activities were observed in some crude extracts, and five of these extracts showed a significant cytotoxicity against human tumor cells. Active compounds isolated from three plant parts occasionally ingested by chimpanzees (Diospyros abyssinica (Ebenaceae) bark, Uvariopsis congensis (Annonaceae) leaves, and Trichilia rubescens (Meliaceae) leaves) showed highly significant medicinal properties. Two novel antiparasitic limonoids were isolated from Trichilia rubescens and their molecular structures were determined. In addition to elucidating the natural equilibrium maintained between hosts and pathogens, our investigation of the diet of wild chimpanzees may serve as a guideline to discovering plants with bioactive properties that should be preserved from destruction because of their health maintenance value for great ape populations.

Relationship between taste thresholds and hunger under debate.

We determined taste recognition thresholds for six compounds (sucrose, fructose, sodium chloride, quinine sulphate, PROP and liquorice) in fasting students and, in the same subjects, after a meal. The testing procedure was the staircase-method in blind conditions. Although taste sensitivity may vary with hormonal status, our results did not show any significant difference in taste recognition thresholds between hunger and satiety. Our Bayesian analysis did not corroborate the hypothesis of increased sensitivity to nutrition-related tastants in the fasting state that was recently supported by data obtained with the two-alternative forced-choice method.

Ethnomedicinal and bioactive properties of plants ingested by wild chimpanzees in Uganda.

Wild chimpanzees eat several plant species claimed by traditional healers to cure diseases. However, the behaviour leading apes to ingest these peculiar species is not clearly understood. Some of the items consumed by chimpanzees have low nutritional value, and there is a growing body of evidence suggesting that health might be improved or regulated by such ingestion. Observations concerning the diet and the health condition of wild chimpanzees (Pan troglodytes schweinfurthii) in the Kibale National Park (Uganda) are discussed in relation to the ethnomedicinal utilization of plant species reviewed in literature. Among the 163 plant parts known to be eaten by these chimpanzees, at least 35 (21.4%) are used in traditional medicine as treatments for intestinal parasites, skin infections, reproduction and respiratory diseases. Relationships with pharmacological properties are presented, taking into account the difficulties of interpreting ethnomedicinal data. In conclusion, a greater knowledge of ape's behaviour and health may provide a new complementary method to select plants for biomedical research.

On the possible adaptive value of coprophagy in free-ranging chimpanzees.

Coprophagy occurred during major periods of feeding on fruits of Dialium spp. (Caesalpiniaceae) in a group of orphaned chimpanzees released in Conkouati Douli National Park, Republic of Congo. Since stress, boredom or food scarcity could not explain coprophagy according to our daily behavioral and veterinary control observations, we suggest that Dialium seeds were the item of interest in the feces. Two types of Dialium seeds were commonly found in the feces after chimpanzees swallowed the mesocarp and whole seeds together. These seeds were either whole and hard or whole/broken and soft imbibed. A mechanical and/or chemical effect of the gut passage may enable the chimpanzees to chew and ingest the seeds, thus providing nutritional intake.

New perspectives on taste and primate evolution: the dichotomy in gustatory coding for perception of beneficent versus noxious substances as supported by correlations among human thresholds.

In various environments where primates are presently observed, as well as in forests and savannas which have been inhabited by australopithecines and early hominids, there are (or there have been presumably) categories of substances eliciting taste signals associated with stereotyped responses. Such is the case for various soluble sugars of fruits and nectars, attracting consumers, and for several plant compounds in which bitter or strongly astringent properties have a repulsive effect. The occurrence of such classes of tasty substances among natural products appears to be related to the evolutionary trends that shaped primate sensory perception (for detecting either beneficent or potentially noxious substances) in the context of a long history of coevolution between animals and plants. Here, we present original psychophysical data on humans (412 individuals aged 17-59 years) as an analogy with which to test recent evidence from electrophysiology in nonhuman primates (Hellekant et al. [1997] J. Neurophysiol. 77:978-993; Danilova et al. [1998] Ann. N.Y. Acad. Sci. 855:160-164) that taste fibers can be grouped into clusters of "best-responding fibers" with two more specific clusters, one for sugars and one for quinine and tannins. The collinearity found between human taste responses (recognition thresholds) for fructose and sucrose, as well as for quinine and tannins, is presented and discussed as another evidence of the two-direction evolutionary trend determining taste sensitivity. Salt perception appears to be totally independent of these trends. Accordingly, the appreciation of a salty taste seems to be a recent culturally learned response, and not a primary taste perception. The very existence of primary tastes is discussed in the context of evolutionary trends, past and present.