The development of a diachronic conception of biology has rarely been explored during childhood, except by Maurice-Naville and Montangero (1992). The aim of the present study was to further explore this issue. In the course of an interview, 163 children aged between 6 and 11 expressed their diachronic conceptions of the growth and death of several living things. Results confirmed previous data and extended them to humans and animals, highlighting some diachronic dimensions previously identified by Maurice-Naville and Montangero regarding trees: past and future, seriation and identity appear before 10 years of age, while time span and rhythm, as well as irreversibility, were only mastered at 11 years. Our results confirm that the mastery of biological properties during childhood is partly contingent upon diachronic thinking.