As this paper speaks of ‘human diversity’ it refers not to nuances of sexual orientation, but to all the characteristics that may distinguish each and every human being, that is, to genetic diversity. This paper sheds light on the power or ability of two different chart models to explain the human experience. Because as many as a dozen individuals or more can be born in a 2-hour period at a given place and on a given date, it is necessary for our method of measurement or calculating the birthchart to be able to reflect astrographic differences every 4 min on average, as opposed to every 2 hr on average. Because a sign-house chart (also known as a chart of whole-sign houses) changes only every two hours (less or even more, depending on the latitude), such a system cannot hold explanatory power with regard to the human species, even if one were to take into account both the ascending and culminating degrees, unlike a quadrant-chart model (Placidus, in this case). Whereas whole-sign charts produce one distinction only every two hours on average, quadrant houses no less than 30 (or than 12 under the employment of the micro Zodiac, that is, twelfth parts). As others have also pointed out (e.g. Ralph W. Holden), the Earth’s rotation is the only variable rapid enough to individualise a horoscope.