An official website of the United States government
Abstract Infancy is a sensitive period of development, during which experiences of parental care are particularly important for shaping the developing brain. In a longitudinal study ofN = 95 mothers and infants, we examined links between caregiving behavior (maternal sensitivity observed during a mother–infant free‐play) and infants’ neural response to emotion (happy, angry, and fearful faces) at 5 and 7 months of age. Neural activity was assessed using functional Near‐Infrared Spectroscopy (fNIRS) in the dorsolateral prefrontal cortex (dlPFC), a region involved in cognitive control and emotion regulation. Maternal sensitivity was positively correlated with infants’ neural responses tohappyfaces in the bilateral dlPFC and was associated with relative increases in such responses from 5 to 7 months. Multilevel analyses revealed caregiving‐related individual differences in infants’ neural responses to happy compared to fearful faces in the bilateral dlPFC, as well as other brain regions. We suggest that variability in dlPFC responses to emotion in the developing brain may be one correlate of early experiences of caregiving, with implications for social‐emotional functioning and self‐regulation. Research HighlightsInfancy is a sensitive period of brain development, during which experiences with caregivers are especially important.This study examined links between sensitive maternal care and infants’ neural responses to emotion at 5–7 months of age, using functional near‐infrared spectroscopy (fNIRS).Experiences of sensitive care were associated with infants’ neural responses to emotion—particularly happy faces—in the dorsolateral prefrontal cortex.
more »
« less
Associations between fecal cortisol and biparental care in a pair‐living primate
Abstract ObjectivesWe quantified variation in fecal cortisol across reproductive periods in Azara's owl monkeys (Aotus azarae) to examine physiological mechanisms that may facilitate biparental care. Specifically, we evaluated evidence for the explanation that owl monkeys have hormonal mechanisms to mobilize energy during periods when each sex is investing heavily in reproduction, that is, the gestation period for females and the infant care period for males. Materials and methodsBetween 2011 and 2015, we monitored 10 groups of Azara's owl monkeys from a wild population in Formosa, Argentina and collected fecal samples from 26 adults (13 males, 13 females). Using enzyme‐linked immunosorbent assays, we quantified fecal cortisol as a proxy for evaluating stress responses, including energetic demands, on both sexes during periods of reproduction and parental care. ResultsMale cortisol was lowest during periods when they were caring for young infants (<3 months) compared with periods with older infants or no infant. Female cortisol was elevated during gestation compared with other periods. Mean fecal cortisol in both males and females was lower when an infant was present compared with when females were gestating. DiscussionOur results do not support the hypothesis that owl monkey males have elevated fecal cortisol during periods when they need to mobilize energy to provide intensive infant care. Our findings are also inconsistent with the Maternal Relief hypothesis. However, results from studies measuring fecal cortisol must be interpreted with care and alternative explanations, such as seasonal fluctuations in diet and thermoenergic demands, should be considered when drawing conclusions.
more »
« less
- Award ID(s):
- 1848954
- PAR ID:
- 10449224
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- American Journal of Physical Anthropology
- Volume:
- 176
- Issue:
- 2
- ISSN:
- 0002-9483
- Page Range / eLocation ID:
- p. 295-307
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Females generally attend more to social information than males; however, little is known about the early development of these sex differences. With eye tracking, 2‐month olds’ (N = 101; 44 females) social orienting to faces was measured within four‐item image arrays. Infants were more likely to detect human faces compared to objects, suggesting a functional face detection system. Unexpectedly, males looked longer at human faces than females, and only males looked faster and longer at human faces compared to objects. Females, in contrast, looked less at human faces relative to animal faces and objects, appearing socially disinterested. Notably, this is the first report of a male face detection advantage at any age. These findings suggest a unique stage in early infant social development.more » « less
-
The socioecological model predicts that food availability and risk of parasite transmission influence sociality in primates. As a semi-solitary ape inhabiting the masting forests of Southeast Asia, orangutans provide a unique opportunity to compare social and non-social periods and highly variable foraging conditions within one population. This study compared two data collection periods when fruit availability differed markedly to determine whether sociality and parasite prevalence decrease as expected during periods of fruit scarcity. Fecal samples were analyzed using direct smear and fecal concentration techniques on-site at Cabang Panti Research Station from 2013-2014 and 2018-2019. From the high fruit period to the low fruit period, sociality decreased from 54% of focal follows containing a social event to 29%, while overall parasite prevalence remained the same at 100%. Interesting differences arose for certain parasite species, however. Enterobius sp. prevalence decreased during the low fruit period for both sexes but even more so for males (50% to 29% for females; 56% to 0 for males). Prevalence of Trichuris sp. increased for females during the low fruit period (5% to 43%) while prevalence among males remained the same. These results lend support to the prediction that social contact influences transmission risk for some parasite species, while other parasites may be more responsive to factors such as changes in reproductive state. These findings suggest that differences in the behavioral strategies of the sexes and the differential energetic demands of life history stages have an influence on parasitic infection patterns.more » « less
-
The Challenge Hypothesis, designed originally to explain the patterning of competitive behavior and androgen levels in seasonally breeding birds, predicts that males will increase their androgen levels in order to become more competitive in reproductive contexts. Here we test predictions derived from the Challenge Hypothesis in white‐faced capuchin monkeys (Cebus capucinus), a species that has somewhat seasonal reproduction. We analyzed demographic and hormonal data collected over a 5.25‐year period, from 18 males in nine social groups living in or near Lomas Barbudal Biological Reserve, Costa Rica. Alpha males had higher androgen levels than subordinates. Contrary to our predictions, neither the number of breeding‐age males nor the number of potentially fertile females was obviously associated with androgen levels. Furthermore, male androgen levels were not significantly linked to social stability, as measured by stability of male group membership or recency of change in the alpha male position. Androgen levels changed seasonally, but not in a manner that had an obvious relationship to predictions from the Challenge Hypothesis: levels were generally at their lowest near the beginning of the conception season, but instead of peaking when reproductive opportunities were greatest, they were at their highest near the end of the conception season or shortly thereafter. This lack of correspondence to the timing of conceptions suggests that there may be ecological factors not yet identified that influence ifA levels. We expected that the presence of offspring who were young enough to be vulnerable to infanticide during an alpha male takeover might influence androgen levels, at least in the alpha male, but this variable did not significantly impact results.more » « less
-
Abstract The costs and benefits of breeding behaviors are influenced by environmental conditions, and habitat variation can shift the degree to which behaviors are expressed. Novel urban habitats have been shown to differ significantly in disturbances such as noise, light at night, and human presence, as well as resource availability, compared to rural habitats. Perhaps because of these environmental differences, urban males of several species are consistently more aggressive than rural males, raising the hypothesis that greater territorial aggression is beneficial in urban habitats. Though often ignored, female songbirds of many species also perform aggressive territorial behaviors toward conspecifics during the breeding season. For socially monogamous songbirds, this aggression functions to ensure partner fidelity and secure resources for reproduction. Studies of the effects of urbanization on songbird behavior have yet to determine if urban females also express greater territorial aggression. Importantly, energetically demanding behaviors such as territoriality and parental care should constrain one another, leading to behavioral trade-offs during the breeding season. Though territorial aggression and parental care are inversely related in males of several species of songbird, this relationship is understudied in female songbirds, particularly those facing environmental change, such as urbanization. In this study, we compared aggressive signaling and a measure of parental care (maternal nest visitation rates) between female song sparrows (Melospiza melodia), living in urban and rural habitats. We hypothesized that female aggressive signaling would be higher in urban environments compared to rural, and negatively correlated with maternal visitation rates. We found that urban females, like males, expressed increased aggressive signaling compared to rural. However, female aggressive signaling was not related to our measure of maternal care, suggesting females aren't facing a trade-off between these two behaviors. Collectively, our results are consistent with the hypothesis that urban habitats promote territorial aggression in female song sparrows. As urbanization continues to spread, understanding the behavioral changes animals employ in urban environments requires studying individuals of different sexes and age classes, and will help us understand how some species are able to cope with human-induced rapid environmental change.more » « less
