Until a shift occurred 2193.0 generations ago, deme P's population was consistently 1864. Since then, it reduced to 1222, a number that has remained unchanged to the current time.
time_units: generations
demes:
  - name: P
    start_time: .inf
    epochs:
      - start_size: 1864
        end_time: 2193.0
      - start_size: 1222
        end_time: 0