Question

What is need of replacement of oestrous cycle by menstrual cycle in the course of primate evolution

Answer 1

Answer:

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Explanation:

The menstrual cycle has evolved relatively recently and is quite rare even among primates. Instead, most mammalian females have cycles of estrus. Distinguishing characteristics of the menstrual cycle have traditionally included: copious menses, concealed ovulation and extended sexual receptivity. The menstrual cycle consists of several days of menses, which is followed by the follicular phase, ovulation and then the luteal phase. The luteal phase, which is not present in many estrous cycles, is energetically more demanding than the follicular phase. Indeed, it has been suggested that a benefit of menses is that it helps the female conserve energy, by stopping the energetically costly build-up of an endometrium which cannot be fully re-absorbed. Bleeding is associated with reproductive cycles other than the menstrual cycle, but copious bleeding as a result of the sloughing off of the endometrium is unique to the menstrual cycle. In addition to the luteal phase and menses, humans and a few other species have extended sexual receptivity. Females with estrous cycles typically have a narrow window of sexual receptivity and in several species, the act of mating reduces that window. This is unlike the extended sexual receptivity present during the entire menstrual cycle. Along with extended sexual receptivity, "concealed ovulation" has traditionally been thought to be a defining characteristic of a true menstrual cycle.