Until a shift occurred 8481.1 generations ago, deme J's population was consistently 5303. Since then, it changed to 5087, a number that has remained unchanged to the current time.
time_units: generations
demes:
  - name: J
    start_time: .inf
    epochs:
      - start_size: 5303
        end_time: 8481.1
      - start_size: 5087
        end_time: 0