Reply to Stojanowski et al.

In the accompanying Comment1, Stojanowski et al. challenge the evidence for inter-group conflict at Nataruk2. They make two arguments—first, that the lesions in three crania are due to soil compression; second, that there is a correlation between body position and age, reflecting different burial traditions. We believe that their interpretation is incorrect on both counts

Variable cognition in the evolution of Homo: biology and behaviour in the African Middle Stone Age

The emergence of the human mind is a core problem in human evolutionary studies, and many attempts have been made to describe the pattern of emergence, to characterise how it is distinctive from other forms of cognition, and to determine how and why it evolved. It is now evident that the African Middle Stone Age (MSA) is the context in which many key elements developed or came together, for this is the period in which both anatomical and behavioural modernity can first be identified. And yet, there are many unsolved problems. While the MSA is the setting for the first modern human behaviours, many of those behaviours are shared with Eurasian and African archaic hominins, suggesting either convergence or a deep shared ancestry. The MSA is also a period of at least 300 Ky, with both long periods of continuity and the recurrent appearance of novel traits, and the pattern does not match particularly closely with the evidence for the origin of anatomical modernity. In this paper we review the evidence for cognitive and behavioural evolution in the context of the African MSA, and draw the conclusion that a more sophisticated way of measuring human cognition across this period is required. We introduce the variable cognitive state model as a means of achieving this, and consider how it might be applied to the archaeological evidence

Evidence of human occupation in Mexico around the Last Glacial Maximum.

The initial colonization of the Americas remains a highly debated topic1, and the exact timing of the first arrivals is unknown. The earliest archaeological record of Mexico-which holds a key geographical position in the Americas-is poorly known and understudied. Historically, the region has remained on the periphery of research focused on the first American populations2. However, recent investigations provide reliable evidence of a human presence in the northwest region of Mexico3,4, the Chiapas Highlands5, Central Mexico6 and the Caribbean coast7-9 during the Late Pleistocene and Early Holocene epochs. Here we present results of recent excavations at Chiquihuite Cave-a high-altitude site in central-northern Mexico-that corroborate previous findings in the Americas10-17of cultural evidence that dates to the Last Glacial Maximum (26,500-19,000 years ago)18, and which push back dates for human dispersal to the region possibly as early as 33,000-31,000 years ago. The site yielded about 1,900 stone artefacts within a 3-m-deep stratified sequence, revealing a previously unknown lithic industry that underwent only minor changes over millennia. More than 50 radiocarbon and luminescence dates provide chronological control, and genetic, palaeoenvironmental and chemical data document the changing environments in which the occupants lived. Our results provide new evidence for the antiquity of humans in the Americas, illustrate the cultural diversity of the earliest dispersal groups (which predate those of the Clovis culture) and open new directions of research

The Relationship Between Planned and Reported Home Infant Sleep Locations Among Mothers of Late Preterm and Term Infants

OBJECTIVE: To compare maternal report of planned and practiced home sleep locations of infants born late preterm (34 0/7 to 36 6/7 gestational weeks) with those infants born term (≥ 37 0/7 gestational weeks) over the first postpartum month. METHODS: Open-ended semi-structured maternal interviews were conducted in a U.S. hospital following birth and by phone at one month postpartum during 2010–2012. Participants were 56 mother-infant dyads: 26 late preterm and 30 term. RESULTS: Most women planned to room share at home with their infants and reported doing so for some or all of the first postpartum month. More women reported bed sharing during the first postpartum month than had planned to do so in both the late preterm and term groups. The primary reason for unplanned bed sharing was to soothe nighttime infant fussiness. Those participants who avoided bed sharing at home commonly discussed their fear for infant safety. A few parents reported their infants were sleeping propped on pillows and co-sleeping on a recliner. Some women in both the late preterm and term groups reported lack of opportunity to obtain a bassinet prior to childbirth. CONCLUSIONS: The discrepancy between plans for infant sleep location at home and maternally reported practices were similar in late preterm and term groups. Close maternal proximity to their infants at night was derived from the need to assess infant well-being, caring for infants, and women’s preferences. Bed sharing concerns related to infant safety and the establishment of an undesirable habit, and alternative arrangements included shared recliner sleep