"It seems to me that for Darwin the pulsing of evolutionary rates was a strictly vertical phenomenon"

Ernst Mayr's quote suggests that Charles Darwin viewed the rate of advancement as a procedure that takes place in a linear fashion, without any variance from the course. This implies that the rate of advancement is continuous and does not change. Darwin believed that the rate of evolution was figured out by the environment and the organisms' capability to adjust to it. He likewise believed that the rate of evolution was figured out by the amount of time available for the procedure to happen. Mayr's quote suggests that Darwin viewed the rate of evolution as a vertical phenomenon, implying that it was a procedure that took place in a straight line, with no discrepancy from the path. This recommends that Darwin believed that the rate of advancement was predetermined and might not be changed. This idea is still accepted today, as the rate of development is determined by the environment and the organisms' capability to adjust to it.