Complex sentence: The swelling size of the female reaches a maximum around the time of ovulation suggested that size helps a male predict when he should mate, and this is further corroborated by the fact that male ejaculation peaks at the same time that female sexual swelling peaks.
Split into simpler sentences: The swelling size of the female reaches a maximum around the time of ovulation, suggesting that size helps a male predict when he should mate. This is further supported by the fact that male ejaculation peaks at the same time that female sexual swelling peaks.