The document summarizes research on the evolution of beta amyloid cleaving enzyme 1 (BACE1), which is a drug target for Alzheimer's disease. BACE1 plays a role in the formation of amyloid plaques in Alzheimer's. The research found evidence that BACE1 emerged from a single ancestral enzyme in early chordates and later duplicated, with one copy becoming BACE2. BACE1 has been under stronger purifying selection compared to BACE2, suggesting it maintains the original neuronal function while BACE2 may have taken on new roles. Comparing BACE1 and BACE2 across species could provide insights into their functions and the effects of inhibiting BACE1.