Horses discriminate between facial expressions of conspecifics.

In humans, facial expressions are rich sources of social information and have an important role in regulating social interactions. However, the extent to which this is true in non-human animals, and particularly in non-primates, remains largely unknown. Therefore we tested whether domestic horses (Equus caballus) could discriminate between facial expressions of their conspecifics captured in different contexts, and whether viewing these expressions elicited functionally relevant reactions. Horses were more likely to approach photographic stimuli displaying facial expressions associated with positive attention and relaxation, and to avoid stimuli displaying an expression associated with aggression. Moreover, differing patterns of heart rate changes were observed in response to viewing the positive anticipation and agonistic facial expressions. These results indicate that horses spontaneously discriminate between photographs of unknown conspecifics portraying different facial expressions, showing appropriate behavioural and physiological responses. Thus horses, an animal far-removed from the primate lineage, also have the ability to use facial expressions as a means of gaining social information and potentially regulating social interactions.

Discrimination of honey of different floral origins by a combination of various chemical parameters.

Honey is a high value food commodity with recognized nutraceutical properties. A primary driver of the value of honey is its floral origin. The feasibility of applying multivariate data analysis to various chemical parameters for the discrimination of honeys was explored. This approach was applied to four authentic honeys with different floral origins (rata, kamahi, clover and manuka) obtained from producers in New Zealand. Results from elemental profiling, stable isotope analysis, metabolomics (UPLC-QToF MS), and NIR, FT-IR, and Raman spectroscopic fingerprinting were analyzed. Orthogonal partial least square discriminant analysis (OPLS-DA) was used to determine which technique or combination of techniques provided the best classification and prediction abilities. Good prediction values were achieved using metabolite data (for all four honeys, Q(2)=0.52; for manuka and clover, Q(2)=0.76) and the trace element/isotopic data (for manuka and clover, Q(2)=0.65), while the other chemical parameters showed promise when combined (for manuka and clover, Q(2)=0.43).

Matriarchs as repositories of social knowledge in African elephants.

Despite widespread interest in the evolution of social intelligence, little is known about how wild animals acquire and store information about social companions or whether individuals possessing enhanced social knowledge derive biological fitness benefits. Using playback experiments on African elephants (Loxodonta africana), we demonstrated that the possession of enhanced discriminatory abilities by the oldest individual in a group can influence the social knowledge of the group as a whole. These superior abilities for social discrimination may result in higher per capita reproductive success for female groups led by older individuals. Our findings imply that the removal of older, more experienced individuals, which are often targets for hunters because of their large size, could have serious consequences for endangered populations of advanced social mammals such as elephants and whales.

Unusually extensive networks of vocal recognition in African elephants.

Research on acoustic communication has often focused on signalling between territorial individuals or static neighbouring groups. Under these circumstances, receivers have the opportunity to learn to recognize the signals only of the limited number of conspecifics with which they are in auditory contact. In some mammals, however, social units move freely with respect to one another and range widely, providing individuals with opportunities to learn to recognize the signals of a wide range of conspecifics in addition to those of their immediate neighbours. We conducted playback experiments on African elephants, Loxodonta africana, in Amboseli National Park, Kenya, to determine the extent to which adult female elephants, which have a highly fluid social system, can recognize others in the population through infrasonic contact calls. Female elephants could distinguish the calls of female family and bond group members from those of females outside of these categories; moreover, they could also discriminate between the calls of family units further removed than bond group members, on the basis of how frequently they encountered them. We estimated that subjects would have to be familiar with the contact calls of a mean of 14 families in the population (containing around 100 adult females in total), in order to perform these discriminations. Female elephants thus appear to have unusually extensive networks of vocal recognition, which may prove to be typical of long-lived species that have both fluid social systems and the means for long-distance vocal communication. Copyright 2000 The Association for the Study of Animal Behaviour.

Perception of female reproductive state from vocal cues in a mammal species.

While acoustic signalling by males is known to affect male-male competition, mate attraction and the timing of ovulation, the extent to which sexual selection has shaped the evolution of female acoustic signals is poorly understood. Among mammals, experimental evidence indicates that females attract mating partners by using olfactory and visual signals to advertise their reproductive state. Whether or not males ascertain female reproductive state from vocal signals has, however, never been systematically tested. In this study, we use playbacks of recorded vocalizations to demonstrate that male Barbary macaques, Macaca sylvanus, can discriminate between female copulation calls given at different stages of the oestrous cycle, responding more strongly to those given around the time when conception is most likely to occur. Acoustic analysis suggests that the mean dominant frequency of call units and a number of temporal parameters could provide males with the information necessary to discern the proximity of ovulation in this way Our results provide the first experimental evidence that the calls of female mammals may contain information on reproductive state, which males can perceive and use in such a way as to increase their reproductive success.

Behavioural deception.

Theoretical models predict that deception should occur even in stable signalling systems. Assessment of the prevalence of deception and its importance has, however, been hampered by the lack of a rigorous definition of what constitutes deception and by the anecdotal nature of much of the literature. For an interaction to qualify as deception, the receiver of the "deceptive" signal must incur a cost. While this cost is often clear in interspecific interactions, it is more difficult to evaluate in interactions between members of the same species. A systematic approach to the study of deception, including the use of experimental techniques to elicit deceptive behaviour, is now required. Such an approach may enable us to address a crucial question in social evolution - whether animals are capable of manipulating the minds of others, or merely their behaviour.

Is mate choice copying or aggregation responsible for skewed distributions of females on leks?

In several lek-breeding populations of birds and mammals, females arriving on leks tend to join males that already have females in their territories. This might occur either because females have an evolved preference for mating with males that are attractive to other females, or because they join groups of other females to obtain greater safety from predation or dangerous harassment by males. We have previously used controlled experiments to show that oestrous fallow deer females join males with established harems because they are attracted to female groups rather than to the males themselves. Here we demonstrate that the preference for males with females over males without females is specific to oestrous females and weak or absent in anoestrous ones, and that it is not associated with a preference for mating with males that have previously been seen to mate with other females. Furthermore, oestrous females given the choice between males that do not already have females with them show no significant preference for antlered over deantlered males or for older males over younger ones. We conclude that female attraction to other females on the lek is likely to be an adaptation to avoiding harassment in mixed-sex herds. In this situation, a male's ability to maintain the cohesion of his harem may be the principal cause of variation in mating success between males.

Female lions can identify potentially infanticidal males from their roars.

Despite evidence from several bird, fish and mammal species that listeners can discriminate between the vocalizations of familiar and unfamiliar adult conspecifics, direct links between discriminatory abilities and fitness benefits have been difficult to identify. In free-ranging populations of African lions (Panthera leo), females with cubs face a substantial threat from one particular category of unfamiliar individuals: infanticidal males. Here we use playback experiments to demonstrate that females with cubs can distinguish immediately between roars from their own resident males (the fathers of the cubs) and those from unfamiliar, potentially infanticidal males. Although they remain relaxed when played roars from resident males, they immediately become agitated on hearing unfamiliar males and retreat rapidly with their cubs if the latter have reached about 4.5 months of age. These responses are not simply a function of the roarers being unfamiliar, for when played the roars of unfamiliar females, females with cubs consistently approach the loudspeaker. Furthermore, females often move toward the cubs in response to playbacks of unfamiliar males but not in response to playbacks of unfamiliar females or resident males. Our results suggest how females with cubs might, by quickly detecting and categorizing unfamiliar intruders within their territory, protect their cubs from infanticidal males and expel intruding females. Distinguishing between individuals on the basis of their vocal characteristics could therefore confer direct fitness benefits on discriminating lionesses.

Roaring by red deer stags advances the date of oestrus in hinds.

Some male mammals call loudly and repeatedly during the breeding season. Although the song of male birds is known to have effects on male-male competition, mate selection and ovulation, until now the loud calls of male mammals have been shown to affect only competition between males. Although it has been suggested that loud calling could also serve to attract females, the possibility that it has a direct effect on reproduction in females has not previously been investigated for any mammal. Here I report that roaring in red deer (Cervus elaphus) advances ovulation and that harem-holding males can improve their mating success by regular calling.

Normative standards of plasma cholesterol and triglyceride concentrations in Canadians of working age.

Fasting plasma cholesterol and triglyceride concentrations were determined for 6407 working Canadian adults aged 20 to 69 years in Toronto and Hamilton. Means, medians and 5th and 95th percentiles were ascertained from the data for men, women taking oral contraceptives or estrogen preparations, and women not taking such medication. Mean plasma cholesterol values (mg/dL) ranged in men from 168.3 at ages 20 to 24 years to 211.5 at ages 45 to 49 years, and in women using hormone preparations from 180.3 at ages 20 to 24 years to 224.2 at ages 50 to 54 years; corresponding values in women not using these preparations were 164.9 and 220.6. Plasma triglyceride means (mg/dL) ranged in men from 108.7 at ages 20 to 24 years to 166.7 at ages 40 to 44 years, in women using hormone preparations from 115.4 at ages 20 to 24 years to 145.3 at ages 45 to 59 years, and in women not using these preparations from 77.5 at ages 20 to 24 years to 112.4 at ages 50 to 54 years.