Impairments in social interaction in Autism Spectrum Disorder (ASD) differ greatly across individuals and vary throughout an individual’s lifetime. Yet, an important marker of ASD in infancy is deviations in social-visual engagement, such as the reliably detectable early deviations in attention to the eyes or to biological movement (Klin et al., 2015). Given the critical nature of these early developmental periods, understanding its neurobehavioral underpinnings by means of a nonhuman primate model will be instrumental to understanding the pathophysiology of ASD. Like humans, rhesus macaques 1) develop in rich and complex social behaviors, 2) progressively develop social skills throughout infancy, and 3) have high similarities with humans in brain anatomy and cognitive functions (Machado and Bachevalier, 2003). In this study, male infant rhesus macaques living with their mothers in complex social groups were eye-tracked longitudinally from birth to 6 months while viewing full-faced videos of unfamiliar rhesus monkeys differing in age and sex. The results indicated a critical period for the refinement of social skills around 4–8 weeks of age in rhesus macaques. Specifically, infant monkeys’ fixation to the eyes shows an inflection in developmental trajectory, increasing from birth to 8 weeks, decreasing slowly to a trough between 14–18 weeks, before increasing again. These results parallel the developmental trajectory of social visual engagement published in human infants (Jones & Klin, 2013) and suggest the presence of a switch in the critical networks supporting these early developing social skills that is highly conserved between rhesus macaque and human infant development.

自闭症谱系障碍（ASD）中的社交互动障碍在个体之间差异很大，并且在个体的一生中都会发生变化。然而，婴儿期ASD的重要标志是社交视觉参与度的偏差，例如可以可靠地检测到的注意眼睛或生物运动的早期偏差（Klin等，2015）。鉴于这些早期发育阶段的关键性质，通过非人类灵长类动物模型了解其神经行为基础将有助于理解ASD的病理生理学。像人类一样，猕猴1）在丰富而复杂的社交行为中发展，2）在婴儿期逐步发展社交技能，3）在大脑解剖结构和认知功能方面与人类高度相似（Machado and Bachevalier，2003）。在这个研究中，从出生到六个月，对与母亲一起生活在复杂社会群体中的雄性恒河猴进行了纵向跟踪，同时观看了不同年龄和性别的恒河猴的全脸视频。结果表明，猕猴在4至8周龄时，社交技能的提高至关重要。具体来说，幼猴对眼睛的注视显示发育轨迹发生了变化，从出生到8周增加，在14-18周之间缓慢降低到低谷，然后再次增加。这些结果与人类婴儿社会视觉参与的发展轨迹相类似（Jones＆Klin，