The most important factor in creating diverse species is individual and separate environments. Species develop based on their unique environment, which "selects" for particular traits.
(Ventromedial) hypothalamus
Among its other functions, the hypothalamus controls a person's feeling of hunger and satiety in two anatomically distinct centers -- the lateral hypothalamus and the ventromedial hypothalamus. When glucose levels in the body are low, the liver signals to the lateral hypothalamus that a person needs to eat to increase his/her glucose levels. This gives the feeling of hunger.
As a person eats, he reaches a point called satiety, which tells him/her that he/she should stop eating. As food begins to move from the stomach to the intestines, a hormone called cholecystokinin (CKK) is produced to signal the ventromedial hypothalamus that a person must stop eating. This gives the feeling of satiety, often characterized by the full or distended feeling of the stomach and intestines.
Yes I believe that is true
According to natural law moral theory, the moral standards that govern human behavior are, in some sense, objectively derived from the nature of human beings and the nature of the world. While being logically independent of natural law legal theory, the two theories intersect.