The cross-species and cross group comparisons of newborns (and the effect of 30 days of postnatal development) are described here to specify how early rearing environments impact the developing organizational systems of orientation, motor performance, and behavioural state. It is evident that chimpanzee groups differ in mutual gaze – an index of engagement with caregivers ( Bard et al., 2005), differ in object manipulation – an index of engagement with objects ( Bard & Gardner, 1996 Menzel, 1964a, b), and differ in the quality of attachment bonds ( van IZjendoorn et al., 2009), the building blocks of complex social cognition. A Behavioral Intervention project, conducted from 1987-1995 at the Yerkes Research Center ( Bard, 1996: Bard & Gardner, 1996), studied chimpanzees from birth through the first year of life to document how differential experiences impacted social, emotional, and cognitive outcomes. Unfortunately, most of the studies of comparative social cognition disregard the effects of both development and early experiences in apes while demonstrating that human joint attentional skills depend on early developmental experiences of emotional engagements with caregivers and objects, as well as cognitively-based triadic coordination ( Bard & Leavens, 2009 Leavens, Hopkins & Bard, 2005 Tomasello & Carpenter, 2005). These motivations to share emotions and social experiences, it is argued, begin with the joint attentional skills of 9-12 month-old human infants. The currently most popular theory in comparative psychology suggests that humans have unique motivations for cooperation, which is the foundation for complex species-unique cultural learning (e.g., the cultural intelligence hypothesis: Herrmann, Hernandez-Lloreda, Call, Hare, & Tomasello, 2009). Comparative developmental studies are valuable for understanding hominid evolution (e.g., Boesch, 2007 Johnson-Pynn, Fragaszy, & Cummins-Sebree, 2003), and essential for delineating those characteristics that are uniquely human (e.g., Bjorklund, 2006 Leavens, Bard, & Hopkins, in press). The current article presents a detailed study of the neurobehavioural integrity of newborn chimpanzees, which was part of a larger project that documented imitative (e.g., Bard, 2007 Custance, Whiten, & Bard, 1995), cognitive (e.g., Bard & Gardner, 1996 Bard, Fragazsy, & Visalberghi, 1995 Bard, Todd, Bernier, Love & Leavens, 2006), and socio-emotional development (e.g., Bard, 2009, 2005, 2003, 1998a, b Russell, Bard, & Adamson, 1996 van IJzendoorn, Bard, Bakermans-Kranenberg, & Ivan, 2009) in a comparative perspective. What are the inborn capacities of chimpanzees? How do chimpanzees compare to humans? These questions typify the long-standing scientific interest in ‘what makes us human’ (e.g., Burghardt, 2009 de Waal, 1982 Fouts & Mills, 1997 Goodall, 1986 Hayes, 1951 Kellogg & Kellogg, 1933 Wrangham, 2009 Wrangham, McGrew, de Waal, & Heltne, 1994 Zlatev, Racine, Sinha, & Itkonen, 2008). The results of this study support the conclusion that the interplay between genes and environment, rather than genes alone or environment alone, accounts for phenotypic expressions of newborn neurobehavioral integrity in hominids. The human group was indistinguishable from at least one of the chimpanzee groups in the remaining 24 of 25 NBAS scores. Surprisingly, the cross-species comparisons revealed that the human group was distinct in only 1 of 25 NBAS scores (the human group had significantly less muscle tone than all the chimpanzee groups). Among the 4 chimpanzee groups, significant differences were found in 23 of 24 NBAS scores. The cross-group and cross-species comparisons were conducted at 2 and 30 days of age. Thirty-eight chimpanzees were tested every other day from birth, and analyses revealed significant developmental changes in 19 of 27 NBAS scores. Neurobehavioral integrity related to orientation, motor performance, arousal, and state regulation of 55 chimpanzee (raised in four different settings) and 42 human newborns was measured with the Neonatal Behavioral Assessment Scale (NBAS) a semi-structured 25-minute interactive assessment. The aims of this article are to describe the neurobehavioral integrity of chimpanzee newborns, to investigate how early experiences affect the neurobehavioral organization of chimpanzees, and to explore species differences by comparing chimpanzee newborns to a group of typically developing human newborns.
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