Recent progress in bioinorganic chemistry studies of rare earth elements (REE) in animal cells was outlined, and the definition of REE′s biological intelligence as well as their mechanism were also explained. The migration of REE from weathering rocks to the environment is accelerated by various anthropogenic activities, which can eventually result in the entrance of REE into animal and human bodies via food chain. REE can be found in body tissues such as brain, blood, muscle as well as bone. Based on their geochemical properties, REE in low dose show their unique biological intelligence by intervening in the process of signal transduction and its regulation, arteriosclerosis and blood clotting prevention, anticancer, and the promotion of cellular defense enzymes′ activities, nucleic acid metabolism enzymes as well as ATPases, etc. The meaning of REE′s biological intelligence refers to physicochemical properties-based capability to choose the targets (e.g., biometals) in biomolecules for the chelation or replacement of REE, and change the structures and functions of biomolecules, and consequently impact or control the biological functions or behaviors in living organisms. The regulation of various cellular processes caused by REE is mainly via antagonism or replacement of essential target biometals like calcium or via chelation of organic molecules, thereby embodying the unparalleled biological intelligence of REE. Additionally, the dosage effect of REE was also discussed from the angles of yin-yang dichotomy, bioavailability, entropy and evolution. In order to make full use of REE′s biological intelligence in the application for medicine, more detailed studies concerning dosage effect of REE and REE bioaccumulation in organisms should be conducted in future research.
