Abstract: The ecological degradation triggered by the modern industrial revolution had already drawn the attention of Marx and Engels to the hazards of environmental pollution to life and health. Tracing humanity's ecological niche shift from a weak part of the ecosystem to its so-called "dominator", we can see distinct differences in perceptions of the human-nature relationship across historical stages. From the reflections of Morgan, Marx and Engels on this relationship to the disciplinary consciousness of modern environmental history, the core concept of "care for life" runs through all these thoughts. Therefore, the logical starting point of environmental history research should be based on the historical positioning and existential basis of humans as a biological species in Earth's life system, and the mission of the discipline should respond to the fundamental issues of human existence. Establishing a research path centered on "care for life" as both its logical starting point and disciplinary mission is not only a reflection on the development path of modern civilization, but also an inevitable direction for the evolution of the discipline of environmental history.