Causes and consequences of acidification in the Baltic Sea: implications for monitoring and management.

Increasing atmospheric CO2 drives ocean acidification globally. In coastal seas, acidification trends can however be either counteracted or enhanced by other processes. Ecosystem effects of acidification are so far small in the Baltic Sea, but changes should be anticipated unless CO2 emissions are curbed. Possible future acidification trends in the Baltic Sea, conditional on CO2 emissions, climate change, and changes in productivity, can be assessed by means of model simulations. There are uncertainties regarding potential consequences for marine organisms, partly because of difficulties to assign critical thresholds, but also because of knowledge gaps regarding species' capacity to adapt. Increased temporal and spatial monitoring of inorganic carbon system parameters would allow a better understanding of current acidification trends and also improve the capacity to predict possible future changes. An additional benefit is that such measurements also provide quantitative estimates of productivity. The technology required for precise measurements of the inorganic carbon system is readily available today. Regularly updated status evaluations of acidification, and the inorganic carbon system in general, would support management when assessing climate change effects, eutrophication or characteristics of the pelagic habitats. This would, however, have to be based on a spatially and temporally sufficient monitoring program.

Vocal functional flexibility in the grunts of young chimpanzees.

All living things communicate yet only humans can be said to communicate using language. How this came to be the case is a fundamental mystery unsolved by contemporary science. Within a human lifetime, language emerges from a complex developmental process. As such, understanding chimpanzee vocal development is essential to understanding the evolutionary roots of language. In human development, language is directly built upon the early capacity for "vocal functional flexibility"-the ability to flexibly express the same vocalizations in different ways to achieve different functions. Primate vocalizations, by contrast, have long been believed to be relatively inflexible regarding both production and function. In this paper, we break new ground by providing evidence for vocal functional flexibility in one of the first systematic studies of early chimpanzee vocal production and function. This finding implies the developmental foundations for language are rooted in our primate evolutionary heritage.

Directedness and engagement in chimpanzee vocal ontogeny.

Directedness and engagement during pre-verbal vocal communication play a major role in language development. What was their role in the evolution of language? This question invites us to examine these behaviours in chimpanzee vocal ontogeny. We collected observational data on infant (N = 15) and juvenile (N = 13) chimpanzees at Chimfunshi Wildlife Orphanage, Zambia. We examined the impact of age and vocalization type (grunts, whimpers, laughs and screams) on directed cues (gaze directedness and face directedness) and engagement (mutual face directedness) during vocal communication. We also assessed the impact of directed cues and engagement on social interactions by coding the behaviour of social partners before, during and after a vocalisation, and examining whether they contingently changed their behaviour in response to the vocalisation if it was directed or if engagement occurred. We found that face directed vocalisations showed a general increase during ontogeny and we observed call-type dependent effects of age for mutual face directedness. Only face directed vocalisations were significantly predictive of behavioural responses in social partners. We conclude that like young humans, young chimpanzees routinely exhibit directed behaviours and engagement during vocal communication. This social competency improves during ontogeny and benefits individuals by increasing the chances of eliciting behavioural responses from social partners. Directedness and engagement likely provide a foundation for language phylogenetically, as well as ontogenetically. RESEARCH HIGHLIGHTS: We show that directedness and engagement routinely occur during early chimpanzee vocalisations. Directedness increases throughout chimpanzee vocal ontogeny, similar to human infants. Directedness enhances social partner responsiveness, demonstrating a direct benefit to this style of communication. Directedness and engagement could provide a route towards language phylogenetically as well as ontogenetically.

Visual exploration in adults: Habituation, mere exposure, or optimal level of arousal?

Exploration is one of the most powerful behaviours that drive learning from infancy to adulthood. The aim of the current study was to examine the role of novelty and subjective preference in visual exploration. To do this, we combined a visual exploration task with a subjective evaluation task, presenting novel and familiar pictures. The first goal was to ascertain whether, as demonstrated in babies, short habituation favors visual exploration of familiarity, whereas longer habituation leads to an exploration of novelty. The second goal was to evaluate the influence of familiarization on participants' subjective evaluation of the stimuli. When presented with novel and very familiar stimuli, participants explored the novel stimuli more. In line with the optimal-level of arousal model, participants showed more positive evaluations of the semi-familiar stimuli compared with very familiar or very novel ones.

Alteration of early attentional processing after analogue trauma exposure: evidence from event-related potentials.

The present study aimed to determine whether exposure to an analogue traumatic event affects attentional processing of emotional information. Two groups of non-clinical participants matched on anxiety level, depression symptoms and stressful life events viewed either a trauma or a neutral film. They then performed an emotional Stroop task during which both continuous electroencephalographic activity was recorded and intrusive memories were measured. Results revealed that the valence effect (measured by the difference between emotional and neutral conditions) for the P1 amplitude was significantly greater in participants who viewed the trauma film than in participants who viewed the neutral film. This interaction was specific to words semantically related to the analogue trauma event and did not extend to all negative words. Further analyses revealed a relationship between intrusions frequency, P1 amplitude and emotional Stroop interference, indicating a link between attention and intrusive memories. Our findings suggest that exposure to potentially traumatic events has an important impact on neurocognitive function, even in the absence of psychopathology, and that this impact occurs at an early, possibly automatic stage of processing.

Attachment and joint attention in infants: The role of expectation.

Previous research highlighted the correlation between parent-infant's attachment quality and joint attention skills. However, the underlying mechanisms of this relationship are still unclear. The aim of this study was to assess whether it is by mediating the expectation component in Internal Working Models that the quality of attachment style can affect joint attention. At first, 12- to 20-month-old infants were classified into secure and insecure groups using the Strange Situation Procedure. On a following day, using a violation-of-expectation paradigm, infants were habituated to two joint attention videos. Finally, the mean looking time duration of secure and insecure infants were compared with each other between two "divergent attention" and "joint attention" videos. Infants looked longer for divergent attention videos suggesting they did have expectation regarding the appropriate response in triadic interactions. In line with our main hypothesis, secure infants, but not insecure ones, looked longer in the divergent attention situation when an attachment-related context was present, revealing the possible mediating role of "expectations" in the correlation between attachment and joint attention.

Are there non-verbal signals of guilt?

Guilt is a complex emotion with a potentially important social function of stimulating cooperative behaviours towards and from others, but whether the feeling of guilt is associated with a recognisable pattern of nonverbal behaviour is unknown. We examined the production and perception of guilt in two different studies, with a total of 238 participants with various places of origin. Guilt was induced experimentally, eliciting patterns of movement that were associated with both the participants' self-reported feelings of guilt and judges' impressions of their guilt. Guilt was most closely associated with frowning and neck touching. While there were differences between self-reported guilt and perception of guilt the findings suggest that there are consistent patterns that could be considered a non-verbal signal of guilt in humans.

The meagre future of benthic fauna in a coastal sea-Benthic responses to recovery from eutrophication in a changing climate.

Nutrient loading and climate change affect coastal ecosystems worldwide. Unravelling the combined effects of these pressures on benthic macrofauna is essential for understanding the future functioning of coastal ecosystems, as it is an important component linking the benthic and pelagic realms. In this study, we extended an existing model of benthic macrofauna coupled with a physical-biogeochemical model of the Baltic Sea to study the combined effects of changing nutrient loads and climate on biomass and metabolism of benthic macrofauna historically and in scenarios for the future. Based on a statistical comparison with a large validation dataset of measured biomasses, the model showed good or reasonable performance across the different basins and depth strata in the model area. In scenarios with decreasing nutrient loads according to the Baltic Sea Action Plan but also with continued recent loads (mean loads 2012-2014), overall macrofaunal biomass and carbon processing were projected to decrease significantly by the end of the century despite improved oxygen conditions at the seafloor. Climate change led to intensified pelagic recycling of primary production and reduced export of particulate organic carbon to the seafloor with negative effects on macrofaunal biomass. In the high nutrient load scenario, representing the highest recorded historical loads, climate change counteracted the effects of increased productivity leading to a hyperbolic response: biomass and carbon processing increased up to mid-21st century but then decreased, giving almost no net change by the end of the 21st century compared to present. The study shows that benthic responses to environmental change are nonlinear and partly decoupled from pelagic responses and indicates that benthic-pelagic coupling might be weaker in a warmer and less eutrophic sea.

The social function of the feeling and expression of guilt.

Humans are uniquely cooperative and form crucial short- and long-term social bonds between individuals that ultimately shape human societies. The need for such intense cooperation may have provided a particularly powerful selection pressure on the emotional and communicative behaviours regulating cooperative processes, such as guilt. Guilt is a social, other-oriented moral emotion that promotes relationship repair and pro-sociality. For example, people can be more lenient towards wrongdoers who display guilt than towards those who do not. Here, we examined the social consequences of guilt in a novel experimental setting with pairs of friends differing in relationship quality. Pairs of participants took part in a cooperative game with a mutual goal. We then induced guilt in one of the participants and informed the other participant of their partner's wrongdoing. We examined the outcome using a dictator game to see how they split a joint reward. We found that guilty people were motivated to repair wrongdoing regardless of friendship. Observing guilt in others led to a punishment effect and a victim of wrongdoing punished close friends who appeared guilty more so than acquaintances. We suggest, therefore, that guilt has a stronger function between close friends as the costs of relationship breakdown are greater. Relationship context, therefore, is crucial to the functional relevance of moral emotions.

The pitch of babies' cries predicts their voice pitch at age 5.

Voice pitch (fundamental frequency, F0) is a key dimension of our voice that varies between sexes after puberty, and also among individuals of the same sex both before and after puberty. While a recent longitudinal study indicates that inter-individual differences in voice pitch remain stable in men during adulthood and may even be determined before puberty (Fouquet et al. 2016 R. Soc. open sci.3, 160395. (doi:10.1098/rsos.160395)), whether these differences emerge in infancy remains unknown. Here, using a longitudinal study design, we investigate the hypothesis that inter-individual differences in F0 are already present in the cries of pre-verbal babies. While based on a small sample (n = 15), our results indicate that the F0 of babies' cries at 4 months of age may predict the F0 of their speech utterances at 5 years of age, explaining 41% of the inter-individual variance in voice pitch at that age in our sample. We also found that the right-hand ratio of the length of their index to ring finger (2D : 4D digit ratio), which has been proposed to constitute an index of prenatal testosterone exposure, was positively correlated with F0 at both 4 months and 5 years of age. These findings suggest that a substantial proportion of between-individual differences in voice pitch, which convey important biosocial information about speakers, may partly originate in utero and thus already be present soon after birth.

Eutrophication Increases Phytoplankton Methylmercury Concentrations in a Coastal Sea-A Baltic Sea Case Study.

Eutrophication is expanding worldwide, but its implication for production and bioaccumulation of neurotoxic monomethylmercury (MeHg) is unknown. We developed a mercury (Hg) biogeochemical model for the Baltic Sea and used it to investigate the impact of eutrophication on phytoplankton MeHg concentrations. For model evaluation, we measured total methylated Hg (MeHgT) in the Baltic Sea and found low concentrations (39 ± 16 fM) above the halocline and high concentrations in anoxic waters (1249 ± 369 fM). To close the Baltic Sea MeHgT budget, we inferred an average normoxic water column HgII methylation rate constant of 2 × 10-4 d-1. We used the model to compare Baltic Sea's present-day (2005-2014) eutrophic state to an oligo/mesotrophic scenario. Eutrophication increases primary production and export of organic matter and associated Hg to the sediment effectively removing Hg from the active biogeochemical cycle; this results in a 27% lower present-day water column Hg reservoir. However, increase in organic matter production and remineralization stimulates microbial Hg methylation resulting in a seasonal increase in both water and phytoplankton MeHg reservoirs above the halocline. Previous studies of systems dominated by external MeHg sources or benthic production found eutrophication to decrease MeHg levels in plankton. This Baltic Sea study shows that in systems with MeHg production in the normoxic water column eutrophication can increase phytoplankton MeHg content.

Sex stereotypes influence adults' perception of babies' cries.

BACKGROUND: Despite widespread evidence that gender stereotypes influence human parental behavior, their potential effects on adults' perception of babies' cries have been overlooked. In particular, whether adult listeners overgeneralize the sex dimorphism that characterizes the voice of adult speakers (men are lower-pitched than women) to their perception of babies' cries has not been investigated. METHODS: We used playback experiments combining natural and re-synthesised cries of 3 month-old babies to investigate whether the interindividual variation in the fundamental frequency (pitch) of cries affected adult listeners' identification of the baby's sex, their perception the baby's femininity and masculinity, and whether these biases interacted with their perception of the level of discomfort expressed by the cry. RESULTS: We show that low-pitched cries are more likely to be attributed to boys and high-pitched cries to girls, despite the absence of sex differences in pitch. Moreover, low-pitched boys are perceived as more masculine and high-pitched girls are perceived as more feminine. Finally, adult men rate relatively low-pitched cries as expressing more discomfort when presented as belonging to boys than to girls. CONCLUSION: Such biases in caregivers' responses to babies' cries may have implications on children's immediate welfare and on the development of their gender identity.

How do infants recognize joint attention?

The emergence of joint attention is still a matter of vigorous debate. It involves diverse hypotheses ranging from innate modules dedicated to intention reading to more neuro-constructivist approaches. The aim of this study was to assess whether 12-month-old infants are able to recognize a "joint attention" situation when observing such a social interaction. Using a violation-of-expectation paradigm, we habituated infants to a "joint attention" video and then compared their looking time durations between "divergent attention" videos and "joint attention" ones using a 2 (familiar or novel perceptual component)×2 (familiar or novel conceptual component) factorial design. These results were enriched with measures of pupil dilation, which are considered to be reliable measures of cognitive load. Infants looked longer at test events that involved novel speaker and divergent attention but no changes in infants' pupil dilation were observed in any conditions. Although looking time data suggest that infants may appreciate discrepancies from expectations related to joint attention behavior, in the absence of clear evidence from pupillometry, the results show no demonstration of understanding of joint attention, even at a tacit level. Our results suggest that infants may be sensitive to relevant perceptual variables in joint attention situations, which would help scaffold social cognitive development. This study supports a gradual, learning interpretation of how infants come to recognize, understand, and participate in joint attention.

Fathers are just as good as mothers at recognizing the cries of their baby.

Previous investigations of parents' abilities to recognize the cries of their own babies have identified substantial and significant sex differences, with mothers showing greater correct recognition rates than fathers. Such sex differences in parenting abilities are common in non-human mammals and usually attributed to differential evolutionary pressures on male and female parental investment. However, in humans the traditional concept of 'maternal instinct' has received little empirical support and is incongruous given our evolutionary past as cooperative breeders. Here we use a controlled experimental design to show that both fathers and mothers can reliably and equally recognize their own baby from their cries, and that the only crucial factor affecting this ability is the amount of time spent by the parent with their own baby. These results highlight the importance of exposure and learning in the development of this ability, which may rely on shared auditory and cognitive abilities rather than sex-specific innate predispositions.

Unusual feeding behavior in wild great apes, a window to understand origins of self-medication in humans: role of sociality and physiology on learning process.

Certain toxic plants are beneficial for health if small amounts are ingested infrequently and in a specific context of illness. Among our closest living relatives, chimpanzees are found to consume plants with pharmacological properties. Providing insight on the origins of human self-medication, this study investigates the role social systems and physiology (namely gut specialization) play on learning mechanisms involved in the consumption of unusual and potentially bioactive foods by two great ape species. We collected data from a community of 41-44 wild chimpanzees in Uganda (11 months, 2008), and a group of 11-13 wild western gorillas in Central African Republic (10 months, 2008-2009). During feeding, we recorded food consumed, its availability, and social interactions (including observers watching conspecifics and the observers' subsequent activity). Unusual food consumption in chimpanzees was twice higher than in gorillas. Additionally chimpanzees relied more on social information with vertical knowledge transmission on unusual foods by continually acquiring information during their life through mostly observing the fittest (pre-senescent) adults. In contrast, in gorillas observational learning primarily occurred between related immatures, showing instead the importance of horizontal knowledge transmission. As chimpanzees' guts are physiologically less specialized than gorillas (more capable of detoxifying harmful compounds), unusual-food consumption may be more risky for chimpanzees and linked to reasons other than nutrition (like self-medication). Our results show that differences in sociality and physiology between the two species may influence mechanisms that discriminate between plants for nutrition and plants with potential therapeutic dietary components. We conclude that self-medication may have appeared in our ancestors in association with high social tolerance and lack of herbivorous gut specialization.

Neophobia and learning mechanisms: how captive orangutans discover medicinal plants.

Great apes sometimes feed on items of low nutritional value with bioactive secondary compounds. These molecules may be toxic and neophobia is presumed to be an essential factor in avoiding the ingestion of noxious items. The aim of this study is to investigate, in captive orangutans, individual and social learning involved in the discovery and ingestion of new items. We presented novel aromatic plants - 11 fresh plants and 4 infused plants - to 4 captive weaned Bornean orangutans, both under isolated and group conditions, and recorded their behaviour and interactions between group members. All animals tasted by nibbling or ingested most of the plants presented. Regardless of the experimental condition, individual responses did not vary visibly across the sessions, despite numerous close observations, and food transfers between individuals were observed. Our results suggest that a low level of neophobia and a strong propensity to look to conspecifics for information allow Bornean orangutans to expand their diet after weaning. Our results also provide some evidence that olfaction is a key sense in determining food edibility based on previous experience.

Invasive Staphylococcus aureus strains are highly variable in PFGE patterns, agr group and exoprotein production.

In the present study, we have investigated 37 invasive Staphylococcus aureus strains (collected between 1997 and 2005) from 33 human episodes of septicaemia causing either endocarditis or vertebral osteomyelitis. All S. aureus strains were typed using pulsed field gel electrophoresis (PFGE), and most strains belonged to any of 4 different PFGE clusters. There was no correlation between any of the PFGE clusters with site of infection. All strains showed highly different expression patterns of extracellular proteins, i.e. we found a vast variation in the number of proteins and amount of individual proteins expressed by the different strains. There was no correlation between any cluster of exoprotein patterns with endocarditis or with vertebral osteomyelitis. We did not find any correlation between agr group and endocarditis, as previously reported. On the other hand, a correlation between some of the PFGE clusters with a certain agr group was found. Known risk factors for S. aureus infections were observed in a majority of the patients.

Mathematical modelling of the regulation of spa (protein A) transcription in Staphylococcus aureus.

In the present work a general systems biology approach has been used to study the complex regulatory network controlling the transcription of the spa gene, encoding protein A, a major surface protein and an important virulence factor of Staphylococcus aureus. A valid mathematical model could be formulated using parameter values, which were fitted to quantitative Northern blot data from various S. aureus regulatory mutants using a gradient search method. The model could correctly predict spa expression levels in 4 different regulatory mutants not included in the parameter value search, and in 2 other S. aureus strains, SH1000 and UAMS-1. The mathematical model revealed that sarA and sarS seem to balance each other in a way that when the activating impact of sarS is small, e.g. in the wild-type, the repressive impact of sarA is small, while in an agr-deficient background, when the impact of sarS is maximal, the repressive impact of sarA is close to its maximum. Furthermore, the model revealed that Rot and SarS act synergistically to stimulate spa expression, something that was not obvious from experimental data. We believe that this mathematical model can be used to evaluate the significance of other putative interactions in the regulatory network governing spa transcription.

Maximal transcription of aur (aureolysin) and sspA (serine protease) in Staphylococcus aureus requires staphylococcal accessory regulator R (sarR) activity.

Previous studies have shown that expression of aur (metalloprotease; aureolysin) and sspA (V8 protease; serine protease) in Staphylococcus aureus strain 8325-4 is maximal in the postexponential phase of growth, when the agr (RNAIII) system is activated. Transcription of aur and sspA is mainly regulated through repression by sarA and rot, and RNAIII stimulates protease production by inhibiting translation of rot mRNA. As SarR is a repressor of sarA, inactivation of sarR would result in downregulation of aur and sspA transcription. This was confirmed by mRNA analysis using quantitative real-time PCR. However, we found that sarR acted as a direct stimulator, i.e. its positive effect on aur and sspA transcription did not require sarA (or rot) per se. In addition, aur and sspA were dependent on sarR for maximal transcription. This stimulating role of sarR was not restricted to the rsbU-deficient laboratory strain 8325-4 but was also demonstrated in S. aureus strain SH1000 (rsbU-complemented derivative of 8325-4) and in one clinical isolate.

Modeling the regulation of the competence-evoking quorum sensing network in Streptococcus pneumoniae.

Competence for genetic transformation seems to play a fundamental role in the biology of Streptococcus pneumoniae and is believed to account for serotype switching, evolution of virulence factors, and rapid emergence of antibiotic resistance. The initiation of competence is regulated by the quorum sensing system referred as the ComABCDE pathway. Experimental studies reveal that competence is down-regulated a short time after its induction and several hypotheses about the mechanism(s) responsible for this shut-down have been presented. Possibly, a ComX-dependent gene product, such as a repressor or a phosphatase, is involved. To better understand the down-regulation of the competence-evoking system in S. pneumoniae, a mathematical model was set up. By analyzing the model, we suggest that shut-down of competence possibly occurs at the transcriptional level on the comCDE operon. As a result of introducing a putative comX-dependent repressor, which inhibits expression of comCDE and comX, in the mathematical model, competence is demonstrated to appear in waves. This is supported by experimental studies showing the appearance of successive competence cycles in pneumococcal batch cultures.