Bystanders affect the outcome of mother–infant interactions in rhesus macaques

Animal communication involves the transfer of information between a sender and one or more receivers. However, such interactions do not happen in a social vacuum; third parties are typically present, who can potentially eavesdrop upon or intervene in the interaction. The importance of such bystanders in shaping the outcome of communicative interactions has been widely studied in humans, but has only recently received attention in other animal species. Here, we studied bouts of infant crying among rhesus macaques (Macaca mulatta) in order to investigate how the presence of bystanders may affect the outcome of this signalling interaction between infants and mothers. It was hypothesized that, as crying is acoustically aversive, bystanders may be aggressive to the mother or the infant in order to bring the crying bout to a close. Consequently, it was predicted that mothers should acquiesce more often to crying if in the presence of potentially aggressive animals. In line with this prediction, it was found that mothers gave infants access to the nipple significantly more often when crying occurred in the presence of animals that posed a high risk of aggression towards them. Both mothers and infants tended to receive more aggression from bystanders during crying bouts than outside of this time, although such aggression was extremely rare and was received by less than half of the mothers and infants in the study. Mothers were also found to be significantly more aggressive to their infants while the latter were crying than outside of crying bouts. These results provide new insight into the complex dynamics of mother–offspring conflict, and indicate that bystanders may play an important role in shaping the outcome of signalling interactions between infants and their mothers.     

Physiological reactivity to infant crying: a behavioral genetic study

In this study, we examined adults' cardiac reactivity to repeated infant cry sounds in a genetically informative design. Three episodes of cry stimuli were presented to a sample of 184 adult twin pairs. Cardiac reactivity increased with each cry episode, indicating that subjects were increasingly sensitized to repeated infant distress signals. Non‐parents showed more cardiac reactivity than parents, and males displayed a larger increase in heart rate (HR) in response to repeated cry sounds than females. Multivariate genetic modeling showed that the genetic component of adults' HR while listening to infant crying was substantial. Genetic factors explained 37–51% of the variance in HR and similar genes influenced HR at baseline and HR reactivity to infant crying. The remaining variance in HR across the cry paradigm was accounted for by unique environmental influences (including measurement error). These results point to genetic and experiential effects on HR reactivity to infant crying that may contribute to the explanation of variance in sensitive and harsh parenting.     

小儿推拿疗法联合中药热奄包治疗小儿夜啼的疗效及对睡眠质量和生长发育的影响

摘要 目的：探讨小儿推拿疗法联合中药热奄包治疗小儿夜啼的疗效及对睡眠质量和生长发育的影响。方法：选取2019年4月~到2021年8月期间石家庄市中医院收治的120例夜啼患儿作为研究对象。根据双色球法将患儿分为对照组（常规药物治疗）和观察组（对照组的基础上接受小儿推拿疗法联合中药热奄包治疗）,各为60例。对比两组疗效、中医证候评分、睡眠质量、生长发育相关指标和不良反应发生情况。结果：与对照组相比,观察组的临床总有效率明显升高（P<0.05）。与对照组相比,观察组治疗1周后啼哭、腹喜按摩、睡喜蜷曲、四肢欠温、大便稀溏、小便色清评分更低（P<0.05）。与对照组相比,观察组治疗1周后白天睡眠时间、夜间睡眠时间更长,夜间清醒时间更短,夜醒次数更少（P<0.05）。与对照组相比,观察组治疗6个月后年龄别体质量Z值（WAZ）、年龄别身长Z值（LAZ）、身长别体质量Z值（WLZ）和头围Z值（HCZ）更大（P<0.05）。治疗期间两组均未出现不良反应。结论：小儿推拿疗法联合中药热奄包治疗小儿夜啼,可有效改善患儿临床症状,提高睡眠质量,促进生长发育。     

Sex hormone influence on human infants' sound characteristics: melody in spontaneous crying

The specific impact of sex hormones on brain development and acoustic communication is known from animal models. Sex steroid hormones secreted during early development play an essential role in hemispheric organization and the functional lateralization of the brain, e.g. language. In animals, these hormones are well-known regulators of vocal motor behaviour. Here, the association between melody properties of infants'' sounds and serum concentrations of sex steroids was investigated. Spontaneous crying was sampled in 18 healthy infants, averaging two samples taken at four and eight weeks, respectively. Blood samples were taken within a day of the crying samples. The fundamental frequency contour (melody) was analysed quantitatively and the infants'' frequency modulation skills expressed by a melody complexity index (MCI). These skills provide prosodic primitives for later language. A hierarchical, multiple regression approach revealed a significant, robust relationship between the individual MCIs and the unbound, bioactive fraction of oestradiol at four weeks as well as with the four-to-eight-week difference in androstenedione. No robust relationship was found between the MCI and testosterone. Our findings suggest that oestradiol may have effects on the development and function of the auditory–vocal system in human infants that are as powerful as those in vocal-learning animals.