Up until 1024.0 generations ago, the count of X deme was 8039. Following that period, it reduced to 4877, where it has persisted until now.
time_units: generations
demes:
  - name: X
    start_time: .inf
    epochs:
      - start_size: 8039
        end_time: 1024.0
      - start_size: 4877
        end_time: 0