Lydiane Aubé

Can Population-Level Laterality Stem from Social Pressures? Evidence from Cheek Kissing in Humans

Despite extensive research, the origins and functions of behavioural laterality remain largely unclear. One of the most striking unresolved issues is the fact that laterality generally occurs at the population-level. Why would the majority of the individuals of a population exhibit the same laterality, while individual-level laterality would yet provide the advantages in terms of improving behavioural efficiency? Are social pressures the key factor? Can social pressures induce alignment of laterality between the individuals of a population? Can the effect of social pressures overpass the effect of other possible determining factors (e.g. genes)? We tested this important new hypothesis in humans, for the first time. We asked whether population-level laterality could stem from social pressures. Namely, we assessed social pressures on laterality in an interactive social behaviour: kissing on the cheek as a greeting. We performed observations in 10 cities of France. The observations took place in spots where people of the city meet and greet each other. We showed that: a) there is a population-level laterality for cheek kissing, with the majority of individuals being aligned in each city, and b) there is a variation between populations, with a laterality that depends on the city. These results were confirmed by our complementary data from questionnaires and internet surveys. These findings show that social pressures are involved in determining laterality. They demonstrate that population-level laterality can stem from social pressures.

Could dromedary camels develop stereotypy? The first description of stereotypical behaviour in housed male dromedary camels and how it is affected by different management systems.

Dromedary camel husbandry has recently been evolving towards a semi-intensive system, due to the changes in use of the animal and the settlement of nomadic populations. Captivity could restrict its social activities, limiting the expression of various behavioural needs and causing the manifestation of stereotypy. The aims of this trial were, firstly, to identify and describe some stereotypical behaviours in captive male dromedary camels used for artificial insemination and, secondly, to study the effects on them of the following husbandry management systems: i) housing in single boxes for 24 hours (H24), ii) housing in single boxes for 23 hours with one hour free in the paddock (H23), and iii) housing in single boxes for 22 hours 30 min with 1 h of paddock time and 30 min exposure to a female camel herd (ExF). Every day, the camels were filmed in their single box in the morning for 30 minutes to record their behavioural activities and a focal animal sampling ethogram was filled in. In this study, male camels showed both oral and locomotor stereotypy most frequently when the bulls were reared in H24. Overall, this preliminary study is a starting point in the identification of stereotypies in male camels, reporting the positive effects of spending one hour outdoor and of social interaction with females.

Right-nostril use during sniffing at arousing stimuli produces higher cardiac activity in jumper horses

Lateralization in horses, Equus caballus, has been reported at both motor and sensory levels. Here we investigated left- and right-nostril use in 12 jumper horses freely sniffing different emotive stimuli. Results revealed that during sniffing at adrenaline and oestrus mare urine stimuli, horses showed a clear right-nostril bias while just a tendency in the use of the right nostril was observed during sniffing of other odours (food, cotton swab and repellent). Sniffing at adrenaline and urine odours was also accompanied by increasing cardiac activity and behavioural reactivity strengthening the role of the right hemisphere in the analysis of intense emotion and sexual behaviour.

Effects of a GnRH administration on testosterone profile, libido and semen parameters of dromedary camel bulls.

GnRH treatment has been suggested to increase testosterone levels temporarily and to stimulate libido in stallions, but its use has not fully ascertained in dromedary camels. The aim of this work was to study the effects of administering 100 μg of GnRH on testosterone profile, libido and semen parameters in dromedary camels. The same bulls were used as self-controls and experimental group. Blood samples were collected every 20 min (T0-T12) for 4h, and semen collections were performed over a 2-hour period after T12. GnRH was administered immediately after T0. In GnRH-treated bulls, testosterone levels showed an upward trend, peaking after 140 min, and then slowly decreasing. GnRH administration also led to a decrease in mating time and an increase in spermatozoa concentration. Overall, it seems that administration of 100 μg GnRH might increase testosterone levels temporarily and enhance camel reproduction performance.

Correction: Can Population-Level Laterality Stem from Social Pressures? Evidence from Cheek Kissing in Humans

[This corrects the article DOI: 10.1371/journal.pone.0124477.].