Until a shift occurred 7158.2 generations ago, deme S's population was consistently 3499. Since then, it increased to 4766, a number that has remained unchanged to the current time.
time_units: generations
demes:
  - name: S
    start_time: .inf
    epochs:
      - start_size: 3499
        end_time: 7158.2
      - start_size: 4766
        end_time: 0