Differences between Neandertal and modern human infant and child growth models

Studying the emergence of distinctive human growth patterns is essential to understanding the evolution of our species. The large number of Neandertal fossils makes this species the best candidate for a comparative study of growth patterns in archaic and modern humans. Here, Neandertal height growth during infancy and early childhood is described using a mathematical model. Height growth velocities for individuals five years old or younger are modelled as age functions based on different estimates of height and age for a set of ten Neandertal infants and children. The estimated heights of each Neandertal individual are compared with those of two modern human populations based on longitudinal and cross-sectional data. The model highlights differences in growth velocity during infancy (from the age of five months onward). We find that statural growth in Neandertal infants is much slower than that seen in modern humans, Neandertal growth is similar to modern humans at birth, but decreases around the third or fourth month. The markedly slower growth rates of Neandertal infants may be attributable to ontogenetic constraints or to metabolic stress, and contribute to short achieved adult stature relative to modern humans.     

Elevated urinary testosterone excretion and decreased maternal caregiving effort in marmosets when conception occurs during the period of infant dependence

The proximate mechanisms that regulate transitions in mammalian female reproductive effort have not been widely studied. However, variation in circulating levels of the androgenic steroid hormone testosterone (T) appears to mediate a trade-off between investment in current and future offspring in males [Ketterson, E.D., Nolan, V., Jr., 1992. Hormones and life histories: an integrative approach. Am. Nat. 140, S33-S62; Ketterson, E.D., Nolan, V., Jr., 1994. Hormones and life histories: an integrative approach. In: L.A. Real (Ed.), Behavioral Mechanisms in Evolutionary Ecology, University of Chicago Press, Chicago, pp. 327-353; Ketterson, E. D., Nolan, V., Jr., 1999. Adaptation, exaptation, and constraint: A hormonal perspective. Am. Nat. 154S, S4-S25]. The purpose of this study was to investigate the possibility that T is also associated with transitions in the reproductive effort of females, by examining the relationship between urinary T excretion, maternal caregiving behavior, and the timing of the postpartum conception in female Wied's black tufted-ear marmosets (Callithrix kuhlii). We examined the maternal carrying effort and peripartum T profiles of six females across two conditions: (1) when they conceived during the period of infant dependence (DPID), such that gestation was coupled with lactation; and (2) when the same females conceived after the period of infant dependence (APID). We also assessed the relationship between postpartum T levels and caregiving effort. When female marmosets conceived DPID, they dramatically reduced their caregiving effort, and had higher levels of urinary T, relative to when they conceived APID. Further, the litter-to-litter changes in maternal caregiving effort that we observed were related to variation in urinary T excretion; as weekly levels of urinary T excretion increased, concurrent caregiving effort declined. Our results suggest that variation in T secretion may regulate transitions in female reproductive behavior, and that the regulation of male and female parental behavior may be mediated by homologous neuroendocrine mechanisms.     

Serotonin transporter gene variation, infant abuse, and responsiveness to stress in rhesus macaque mothers and infants

A functional polymorphism in the promoter region of the serotonin transporter (5-HTTLPR) gene has been associated with variation in anxiety and hypothalamus-pituitary-adrenal (HPA) axis function in humans and rhesus macaques. Individuals carrying the short allele are at a higher risk for developmental psychopathology, and this risk is magnified in short allele carriers who have experienced early life stress. This study investigated the relationship between 5-HTTLPR allelic variation, infant abuse, and behavioral and hormonal responses to stress in rhesus macaques. Subjects were 10 abusive mothers and their infants, and 10 nonabusive mother-infant pairs. Mothers and infants were genotyped for the rh5-HTTLPR, and studied in the first 6 months of infant life. For mothers and infants, we measured social group behavior, behavioral responses to handling procedures, and plasma concentrations of ACTH and cortisol under basal conditions and in response to stress tests. The proportion of individuals carrying the short rh5-HTTLPR allele was significantly higher among abusive mothers than controls. Among mothers and infants, the short allele was associated with higher basal cortisol levels and greater hormonal stress responses in the infants. In addition, infants who carried the short rh5-HTTLPR allele had higher anxiety scores than infants homozygous for the long allele. The rh5-HTTLPR genotype also interacted with early adverse experience to impact HPA axis function in the infants. These results are consistent with those of previous studies which demonstrate associations between serotonergic activity and anxiety and stress reactivity, and add additional evidence suggesting that genetic variation in serotonergic function may contribute to the occurrence of abusive parenting in rhesus macaques and modulate emotional behavior and HPA axis function.     

Sudden infant death syndrome: links with infant care practices.

OBJECTIVES--To investigate infant care practices in a small ethnic minority population within Britain that might suggest possible factors contributing to the low incidence of the sudden infant death syndrome in Asian populations. DESIGN--Ethnographic interviewing, a qualitative comparative method drawn from social anthropology. SETTING--Central Cardiff. SUBJECTS--Non-random sample of 60 mothers of Bangladeshi or Welsh ethnic origin and working or middle class occupational status, who had infants under one year old. None of the families interviewed had experienced a sudden infant death. RESULTS--Broad cultural contrasts emerged as a series of themes from the interview data: living patterns, family networks, sleeping patterns, and concepts of time and dependence. CONCLUSION--Bangladeshi infants were cared for in a consistently rich sensory environment; Welsh infants, in contrast, were more likely to experience alternating periods of high and low sensory input. Long periods of lone quiet sleep may be one factor that contributes to a higher rate of sudden deaths in white than in Asian infants.     

Hand-rearing infant stumptailed macaques

Fifty-four infant macaques (Macaca arctoides) were separated from their mothers between 1 and 10 days of age. Simple training led to them learning to self-feed by about 30 hours, in some cases much earlier. Supplementary feeding of the infant before separation facilitated the establishment of self-feeding. The greater weight of adult stumptailed macaques compared to rhesus may begin during the first months of life.     

A convenient infant tourniquet

A simple, readily available blood pressure cuff designed specifically for neonates, infants, and small children is recommended for use in hand surgery as a tourniquet. Most institutions that have pediatric medicine or surgical departments have these as stock, and thus the problem of illfitting standard cuffs can be avoided where a tourniquet is needed.     

AIDS in the infant

Recently, we and others have encountered a group of infants who developed AIDS. They were born from parents who belonged to identified risk factors for AIDS. The clinical and immunologic features were described. The existence of a pediatric form of AIDS transmitted other than by transfusion suggests the possibility of transplacental perinatal or postnatal transmission.