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1.  Memory, transmission and persistence of alternative foraging techniques in wild common marmosets 
Animal Behaviour  2014;91(100):79-91.
Experimental studies on traditions in animals have focused almost entirely on the initial transmission phase in captive populations. We conducted an open diffusion field experiment with 13 groups of wild common marmosets, Callithrix jacchus. Seven groups contained individuals that were already familiar with the task (‘push or pull’ box) and thus served as potential models for naïve individuals. Additionally, in four groups one individual was trained for one of the two possible techniques and in two control groups no skilled individuals were present. First, we investigated whether experienced individuals would remember how to solve the task even after 2 years without exposure and whether they would still prefer their learned technique. Second, we tested whether naïve individuals would learn socially from their skilled family members and, more importantly, whether they would use the same technique. Third, we conducted several test blocks to see whether the individual and/or group behaviour would persist over time. Our results show that wild common marmosets were able to memorize, learn socially and maintain preferences of foraging techniques. This field experiment thus reveals a promising approach to studying social learning in the wild and provides the basis for long-term studies on tradition formation.
•We show all key components of behavioural traditions in free-living primates.•Wild marmosets maintained a foraging technique for over 2 years without exposure.•Naïve individuals adopted the technique from their skilled family members.•They preserved their learned foraging variants for at least 9 months.
PMCID: PMC4045399  PMID: 24910466
common marmoset; field experiment; memory; persistence; social learning; tradition
2.  Giant clival chordoma causing pathological laughter 
Chordomas are rare slowly growing tumors that originate from remnants of the notochord. They have a malignant local behavior, causing symptoms due to bone infiltration and compression of neurovascular structures. Only a few cases of brain tumors associated with pathological laughter have been reported in the literature.
Case Description:
We report a case of a 42-year-old male patient with this atypical clinical presentation treated at our institution, and discuss the concerning literature.
Although being a very rare presentation of chordomas, pathological laughter is usually expected to improve after brain stem decompression.
PMCID: PMC3994695  PMID: 24778906
Chordoma; clivus; pathological laughter
3.  Critically endangered blonde capuchins fish for termites and use new techniques to accomplish the task 
Biology Letters  2011;7(4):532-535.
We report the spontaneous modification and use of sticks to fish for termites, above the ground, in wild blonde capuchins (Cebus flavius). These critically endangered Neotropical primates inhabit remnants of the Atlantic Forest. They used two previously undescribed techniques to enhance their termite capture success: nest tapping and stick rotation. The current ecologically based explanation for tool use in wild capuchins (i.e. terrestrial habits and bipedalism) must be viewed cautiously. Instead, remarkable manual skills linked to a varied diet seem important in promoting tool use in different contexts. The repertoire of tool-using techniques employed by wild capuchins has been expanded, highlighting the behavioural versatility in this genus.
PMCID: PMC3130233  PMID: 21389018
tool use; manual skills; cognition; blonde capuchins; primates
4.  Caatinga Revisited: Ecology and Conservation of an Important Seasonal Dry Forest 
The Scientific World Journal  2012;2012:205182.
Besides its extreme climate conditions, the Caatinga (a type of tropical seasonal forest) hosts an impressive faunal and floristic biodiversity. In the last 50 years there has been a considerable increase in the number of studies in the area. Here we aimed to present a review of these studies, focusing on four main fields: vertebrate ecology, plant ecology, human ecology, and ethnobiology. Furthermore, we identify directions for future research. We hope that the present paper will help defining actions and strategies for the conservation of the biological diversity of the Caatinga.
PMCID: PMC3415163  PMID: 22919296
5.  Brevity is not always a virtue in primate communication 
Biology Letters  2010;7(1):23-25.
Semple et al. (Semple et al. in press, Biol. Lett. (doi:10.1098/rsbl.2009.1062)) argued that the ‘law of brevity’ (an inverse relationship between word length and frequency of use) applies not only to human language but also to vocal signalling in non-human primates, because coding efficiency is paramount in both situations. We analysed the frequency of use of signals of different duration in the vocal repertoires of two Neotropical primate species studied in the wild—the common marmoset (Callithrix jacchus) and the golden-backed uakari (Cacajao melanocephalus). The key prediction of the law of brevity was not supported in either species: although the most frequently emitted calls were relatively brief, they were not the shortest signals in the repertoire. The costs and benefits associated with signals of different duration must be appreciated to understand properly their frequency of use. Although relatively brief vocal signals may be favoured by natural selection in order to minimize energetic costs, the very briefest signals may be ambiguous, contain reduced information or be difficult to detect or locate, and may therefore be selected against. Analogies between human language and vocal communication in animals can be misleading as a basis for understanding frequency of use, because coding efficiency is not the only factor of importance in animal communication, and the costs and benefits associated with different signal durations will vary in a species-specific manner.
PMCID: PMC3030868  PMID: 20573617
law of brevity; Neotropical primates; vocal repertoire; signalling
6.  The Maintenance of Traditions in Marmosets: Individual Habit, Not Social Conformity? A Field Experiment 
PLoS ONE  2009;4(2):e4472.
Social conformity is a cornerstone of human culture because it accelerates and maintains the spread of behaviour within a group. Few empirical studies have investigated the role of social conformity in the maintenance of traditions despite an increasing body of literature on the formation of behavioural patterns in non-human animals. The current report presents a field experiment with free-ranging marmosets (Callithrix jacchus) which investigated whether social conformity is necessary for the maintenance of behavioural patterns within groups or whether individual effects such as habit formation would suffice.
Using a two-action apparatus, we established alternative behavioural patterns in six family groups composed of 36 individuals. These groups experienced only one technique during a training phase and were thereafter tested with two techniques available. The monkeys reliably maintained the trained method over a period of three weeks, despite discovering the alternative technique. Three additional groups were given the same number of sessions, but those 21 individuals could freely choose the method to obtain a reward. In these control groups, an overall bias towards one of the two methods was observed, but animals with a different preference did not adjust towards the group norm. Thirteen of the fifteen animals that discovered both techniques remained with the action with which they were initially successful, independent of the group preference and the type of action (Binomial test: exp. proportion: 0.5, p<0.01).
The results indicate that the maintenance of behavioural patterns within groups 1) could be explained by the first rewarded manipulation and subsequent habit formation and 2) do not require social conformity as a mechanism. After an initial spread of a behaviour throughout a group, this mechanism may lead to a superficial appearance of conformity without the involvement of such a socially and cognitively complex mechanism. This is the first time that such an experiment has been conducted with free-ranging primates.
PMCID: PMC2636861  PMID: 19223965
7.  Sclerosing Cavernous Hemangioma in the Cavernous Sinus: Case Report 
Skull Base  2003;13(2):93-99.
Cavernous hemangiomas of the cavernous sinus belong to a well–distinguished entity of extra–axial cavernous hemangiomas located in the cavernous sinus and have a typical appearance on magnetic resonance imaging (MRI). Severe intraoperative bleeding has been described during the excision of these lesions that is probably associated with their pathological features. An atypical case of a sclerosing lesion with distinct MRI features is described. In these particular cases, especially with giant hemangiomas where en bloc excision would be difficult, safe internal decompression and resection can be achieved.
PMCID: PMC1131836  PMID: 15912165
Cavernous hemangioma; cavernous sinus; magnetic resonance imaging; skull base surgery

Results 1-7 (7)