SARS-CoV-2 is a new human coronavirus (CoV), which emerged in China at the end of 2019 and is responsible for the global COVID-19 pandemic that caused more than 500,000 deaths in five months. Understanding the origin of this virus is an important issue and it is necessary to determine the mechanisms of its dissemination in order to be able to contain new epidemics. Based on phylogenetic inferences, sequence analysis and structure-function relationships of coronavirus proteins, informed by the knowledge currently available, we discuss the different scenarios evoked to account for the origin - natural or synthetic - of the virus. On the basis of currently available data, it is impossible to determine whether SARS-CoV2 is the result of a natural zoonotic emergence or an accidental escape from experimental strains. Regardless of its origin, the study of the evolution of the molecular mechanisms involved in the emergence of this pandemic virus is essential to develop therapeutic and vaccine strategies. The full article (in French) is available at Médecine/Sciences : https://doi.org/10.1051/medsci/2020123. The full English translation available at https://hal.archives-ouvertes.fr/hal-02891455.