Originally, deme Y had a population size of 5881, which changed to 5713 around 3462.405 generations ago and has not changed since.
time_units: generations
demes:
  - name: Y
    start_time: .inf
    epochs:
      - start_size: 5881
        end_time: 3462.405
      - start_size: 5713
        end_time: 0