Originally, deme N had a population size of 2538, which grew to 4127 around 1979.1421 generations ago and has not changed since.
time_units: generations
demes:
  - name: N
    start_time: .inf
    epochs:
      - start_size: 2538
        end_time: 1979.1421
      - start_size: 4127
        end_time: 0