Until 9385.08 generations ago, the population of deme J was 1347. At that point, it changed to 987, where it has stayed up to now.
time_units: generations
demes:
  - name: J
    start_time: .inf
    epochs:
      - start_size: 1347
        end_time: 9385.08
      - start_size: 987
        end_time: 0