From fake accounts on social media and generative-AI bots such as ChatGPT to high-frequency trading algorithms on financial markets and self-driving vehicles on the streets, robots, bots, and algorithms are proliferating and permeating our communication channels, social interactions, economic transactions, and transportation arteries. Networks of multiple interdependent and interacting humans and autonomous machines constitute complex adaptive social systems where the collective outcomes cannot be simply deduced from either human or machine behavior alone. Under this paradigm, Taha Yasseri, Niccolo Pescetelli, Tobias Werner, and I review recent experimental, theoretical, and observational research from across a range of disciplines – robotics, human-computer interaction, web science, complexity science, computational social science, finance, economics, political science, social psychology, and sociology. We identify general dynamics and patterns in situations of competition, coordination, cooperation, contagion, and collective decision-making, and contextualize them in four prominent existing human-machine communities: high-frequency trading markets, the social media platform formerly known as Twitter, the open-collaboration encyclopedia Wikipedia, and the news aggregation and discussion community Reddit. We conclude with suggestions for the research, design, and governance of human-machine social systems, which are necessary to reduce misinformation, prevent financial crashes, improve road safety, overcome labor market disruptions, and enable a better human future.

The paper is available as a preprint on arXiv.