Chapter 6 – The Human Animal

Based on the accomplishments of Homo sapiens in recent years, it is unquestionably a very remarkable species of social animal, cognitively superior, bipedal, extremely innovative, dominant, and aggressive, arising as the primate elite from a highly evolved group of prehuman predecessors referred to collectively by biologists as hominids. The group includes other human-like forms (all of which are now extinct) and a number of other not-so-human animals we refer to collectively as great apes (as shown in the previous chapter). Included in this privileged great ape group are humans, chimpanzees, bonobos, gorillas, and orangutans. Males are, on average, larger and physically stronger than females in all great apes, although the degree of sexual dimorphism varies greatly among species. Most extant species of apes, like their lower primate predecessors, are predominantly quadrupedal, using their front limbs to walk on their knuckles, and in addition to humans, some species spend at least part of their time in an erect, bipedal position. They are all able to use their highly manipulative, extensively innervated, and oppositional hands for gathering food or nesting materials, extensive tool use, devices of defense, and, in some cases, for highly perceptive sensors. These anatomical features used to characterize humans and other primates are sometimes found in other animals as well. Humans are rather unique primates in certain ways, having a brain that has evolved to a point of being capable of what appears to be endless cognitive thoughts. While opposable thumbs, an erect posture, and bipedalism have been emphasized as important features leading to human superiority on Earth, it has been primarily the power of the human brain that has led to the development of numerous traits, which more adequately distinguish it from all other animals. Most of the evolution of humans and their predecessors occurred in Africa, especially eastern Africa. Before and during the rise of H. sapiens, millions upon millions of other types of organisms had evolved on Earth as well, some of which formed relationships with humans, which we will tentatively and collectively refer to as quasi-coexistences. Human evolution has occurred over the past few million years, stemming from a common ancestor with other apes, such as chimpanzees and bonobos. Over the past 7 million years, becoming human involved moving from a forest habitat into a savanna-like habitat; a significant change in its acquisition of and type of food; a series of anatomical modifications, including some on the skull and teeth, as well as changes in the axial and appendicular skeleton for walking and running upright; a loss of much of its extensive terminal body hair; an increase in brain size and complexity; the accompanying acquisition of ever-increasing technological skills; and an uncanny ability for locating, using, and manipulating planetary resources. While there are a number of features that are distinctly human, they have retained numerous features from their predecessors that are distinctly animalistic. The latter part of the chapter is devoted to what environmental conditions were prevalent when humans arose and the changes that have come about during their rise to dominance. In our presentation of earlier and the following chapters, we must realize that in a biological world, we are nothing more than a biological entity. We are animals, and as animals, we express a variety of animalistic virtues. We have arisen from a common ancestor with another life form (just as all species do), and we must entertain biological thoughts in order to survive, reproduce, and avoid extinction.