The transition to eukaryote-rich marine ecosystems and the rise of land plans fundamentally altered global biogeochemical cycles. Yet there are poor constraints on when the transition to eukaryote-dominated marine ecosystems occurred and the roles that land plants played in shaping modern-style biogeochemical cycling. Based on an extensive new sedimentary zinc (Zn) isotope record across Earth’s history, I provide evidence for the onset of eukaryotic regulation of the marine Zn cycle at ~800 Ma. A joint evaluation of the microfossil and Zn isotope records suggests that eukaryotes evolved relatively early in the history of life (~1700 to 1600 Ma) but did not rise to ecological prominence until much later in Earth’s history. Lithium (Li) isotopes are an emerging proxy with the potential to track how the magnitude and style of continental weathering have changed through time. There has been extensive work on Li cycling in modern systems and this work has fostered the development of sound constraints upon the modern Li isotope budget. This work has provided a platform and impetus for the generation of a Li isotope record through Earth's history, which I will take a first attempt at providing. My initial results provide evidence for inhibited clay formation during weathering prior to the rise of land plants in the early Paleozoic. Therefore, the long-term Li isotope record provides support for the view that land plants dramatically changed the process of weathering. Interestingly, this transition appears to occur with the earliest (i.e., non-arborescent) land plants.