在动物界,性的活动具有明显的时期性和季候性。在未开化的较原始的人类社会中,性活动也有这种明显的时期性。在已开化的人类文明社会中,从外显的性行为来看,这种性活动的时期性就不那么明显了,似乎在一年的任何时候随时随地都可以唤起、接应性的活动。所以对于人类来说,性活动具有着 In the animal world, sexual activity has obvious period and seasonality. In uncivilized primitive human society, sexual activity also has this obvious period. In the civilized civilized society, sexual activities are less explicit in explicit sexual behavior. It seems that anytime, anywhere in the year can arouse and accommodate sexual activities. So for humans, sexual activity is there