Understanding how co-authors distribute credit is critical for accurately assessing scholarly collaboration. In this study, we uncover the implicit structures within scientific teamwork by systematically analyzing author contributions across a large corpus of research publications. We introduce a computational framework designed to convert free-text contribution statements into 14 standardized CRediT categories, identifying clear and consistent positional patterns in task assignments. By analyzing over 400,000 scientific articles from prominent sources such as PLOS One and Nature, we extracted and standardized more than 5.6 million author-task assignments corresponding to 1.58 million author mentions. Our analysis reveals substantial disparities in workload distribution. Notably, in small teams with three co-authors, the most engaged contributor performs over three times more tasks than the least engaged, a disparity that grows linearly with team size. This demonstrates a consistent pattern of central and peripheral roles within modern collaborative teams. Moreover, our analysis shows distinct positional biases in task allocation: technical responsibilities, such as software development and formal analysis, broadly fall to authors positioned earlier in the author list, whereas managerial tasks, including supervision and funding acquisition, increasingly concentrate among authors positioned toward the end. This gradient underscores a significant division of labor, where early-listed authors mainly undertake most hands-on activities. In contrast, senior authors mostly assume roles involving leadership and oversight. Our findings highlight the structured and hierarchical organization within scholarly collaborations, providing deeper insights into the specific roles and dynamics that govern academic teamwork

翻译：理解合著者如何分配贡献对于准确评估学术合作至关重要。本研究通过系统分析大规模研究出版物中的作者贡献，揭示了科学团队合作中的隐性结构。我们引入一个计算框架，旨在将自由文本形式的贡献声明转换为14个标准化的CRediT类别，从而识别任务分配中清晰且一致的位置模式。通过分析来自PLOS One和Nature等知名来源的超过40万篇科学文章，我们提取并标准化了超过560万项作者-任务分配，对应158万次作者提及。我们的分析揭示了工作量分配的显著差异。值得注意的是，在拥有三位合著者的小型团队中，参与度最高的贡献者执行的任务量是最低参与度贡献者的三倍以上，且这种差异随团队规模线性增长。这证明了现代合作团队中存在核心与边缘角色的一致模式。此外，我们的分析显示了任务分配中明显的位置偏向：技术职责（如软件开发和形式分析）普遍由作者列表中位置靠前的作者承担，而管理任务（包括监督和资金获取）则越来越多地集中在列表末尾的作者身上。这种梯度凸显了显著的劳动分工，即列表靠前的作者主要承担大部分实际操作活动，而资深作者则主要承担涉及领导和监督的角色。我们的研究结果强调了学术合作中结构化与层级化的组织方式，为理解学术团队合作的具体角色与动态提供了更深入的见解。