Initially, the population size of deme O stood at 7531, but this changed 6416.764 generations ago when it changed to 3424, and it has been stable at that size up to today.
time_units: generations
demes:
  - name: O
    start_time: .inf
    epochs:
      - start_size: 7531
        end_time: 6416.764
      - start_size: 3424
        end_time: 0