Modern humans belong to a group or “genus” of animals known as Homo. The oldest known Homo fossil, found in Ethiopia, is 2.8 million years old. The first species was probably Homo habilis, although this has been disputed. Compared to their ancestors, these new hominins had much larger brains.
Macrocosm and microcosm is an ancient Greek Neo-Platonic schema of seeing the same patterns reproduced in all levels of the cosmos, from the largest scale; the macrocosm or universe-level all the way down to the smallest scale; the microcosm or sub-sub-atomic or even metaphysical-level. According to this philosophy the mid-point is Man, who summarizes the cosmos.
These philosophers were concerned with a rational explanation of everything and saw the repetition of the golden mean throughout the world and all levels of reality as a step towards this unifying theory. In short, it is the recognition that the same traits and patterns appear in entities of many different sizes, from one man to the entire human population.
Today, the concept of microcosm is used in sociology to denote a small group of individuals whose behaviour is typical of a larger social body encompassing it. A microcosm can be seen as a special kind of epitome. Conversely, a macrocosm is a social body made of smaller compounds.
‘Human earlobes may be free or detached (hanging free from the head) or attached (joined to the head). Whether the earlobe is free or attached is a classic example of a simple genetic dominance relationship; freely hanging earlobes are the dominant allele and attached earlobes are recessive. Therefore, a person whose genes contain one allele for free earlobes and one for attached lobes will display the freely hanging lobe trait. It is a common misconception that this implies a precise 3-to-1 ratio between free and attached lobes in the human population. Such a ratio would require that the allele frequency for free lobes were precisely 50%, which there is no reason to assume.’
– Lai L.Y. 1946. Observations on Ear Lobe Types (Acta Genetica et Statistica Medica) Basel, Switzerland: Karger (1966) p. ?