Postpartum developmental delay has been proposed as an important phenotype of human evolution which contributes to many human-specific features including the increase in brain size and the advanced human-specific cognitive traits. However, the biological processes and molecular functions underlying early brain development still remain poorly understood, especially in human and primates. In this paper, we comparatively and extensively studied dorsolarteral prefrontal cortex expression data in human and chimpanzee to investigate the critical processes or biological events during early brain development at a molecular level. By using the dynamic network biomarker (DNB) model, we found that there are tipping points around 3 months and 1 month, which are crucial periods in infant human and chimpanzee brain development, respectively. In particular, we shown that the human postnatal development and the corresponding expression changes are delayed 3 times relative to chimpanzee, and we also revealed that many common biological processes are highly involved in those critical periods for both human and chimpanzee, e.g., physiological system development functions, nervous system development, organismal development and tissue morphology. These findings support that the maximal rates of brain growth will be in those two critical periods for respective human and primates. In addition, different from chimpanzee, our analytic results also showed that human can further develop a number of advanced behavior functions around this tipping point (around 3 months), such as the ability of learning and memory. This work not only provides biological insights into primate brain development at a molecular level but also opens a new way to study the criticality of nonlinear biological processes based on the observed omics data.

中文翻译：

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基因表达分析揭示了人类和黑猩猩婴儿大脑发育的临界点

产后发育迟缓已被认为是人类进化的一个重要表型，它有助于许多人类特有的特征，包括大脑尺寸的增加和先进的人类特有的认知特征。然而，人们对早期大脑发育的生物过程和分子功能仍然知之甚少，特别是在人类和灵长类动物中。在本文中，我们比较广泛地研究了人类和黑猩猩的背侧前额叶皮层表达数据，以在分子水平上研究早期大脑发育过程中的关键过程或生物事件。通过使用动态网络生物标记（DNB）模型，我们发现3个月和1个月左右存在临界点，这分别是人类婴儿和黑猩猩大脑发育的关键时期。特别是，我们发现人类出生后的发育和相应的表达变化相对于黑猩猩延迟了3倍，并且我们还发现许多常见的生物过程高度参与人类和黑猩猩的这些关键时期，例如生理系统发育功能、神经系统发育、有机体发育和组织形态。这些发现表明，对于人类和灵长类动物来说，大脑生长的最大速率将出现在这两个关键时期。此外，与黑猩猩不同的是，我们的分析结果还表明，人类可以围绕这个临界点（3个月左右）进一步发展出一些高级的行为功能，例如学习和记忆的能力。这项工作不仅在分子水平上提供了对灵长类动物大脑发育的生物学见解，而且还开辟了一种基于观察到的组学数据来研究非线性生物过程的关键性的新方法。