Chapter 2 of Joel B. Green’s book Body, Soul, and Human Life: The Nature of Humanity in the Bible is entitled “What does it mean to be human?” In this chapter he addresses the title question from two directions. First he discusses the scientific evidence for the connection of human life with the rest of animal life. This includes a consideration of the material features that may, or may not, make us distinctly human. After laying this foundation, Dr. Green then moves on to consider the nature of human uniqueness from a biblical perspective. In the post today I would like to put forth the scientific data and ask how this influences our understanding of what it means for our understanding of the human soul. In the next post I will consider the biblical perspective.
In asking what makes us distinctly human Dr. Green considers three categories or phenomena relating to the material nature of humans: the human genome, consciousness, and mind reading (a fourth category, moral agency, is left for a later chapter).
The development of genome sequencing has led to the discovery that the human genome is smaller than that of many less complex forms of life (common rice has ca. 50,000 genes, a primitive worm, c. elegans, has ca. 20,000 genes, while humans have only ca. 25,000 genes. Clearly the complexity of human life is not reflected by a mere counting of the number of genes coding for proteins. Rather, there is a more intricate, and not fully understood, process of activation effecting the connection between the simple genes and the end result. It is not the number of genes, but when, where, why, and how, the genes are expressed.
Dr. Green also notes that the chimpanzee and human genomes differ in rather small ways (a good summary table can be found in this post). Ignoring insertion and deletion segments the homology is ~98.8%, looking at protein encoding genes the homology is >99% and over all the homology is ca. 95%. The differences between humans and chimpanzees are subtle on this level.
These numbers – either the number of genes or the gene homology between humans and chimpanzees – prove little in terms of human distinctiveness, except to eliminate some possible sources. We are created from “the dust of the earth” as are plants and animals. The features that make us distinctively human arise from something else.
What aspects of our nature make us distinctively human?
Is “humanness” connected to the physical and material form of our bodies? If so, How?
Does “humanness” result from the possession of a soul?
More significant than gene counts and gene homology are considerations of consciousness and the theory of mind.
In discussion of Christian anthropology generally, appeal is often made to baseline human experience that I am more than my body – that is, to my experience of a subjective inner life, the perceptions, thoughts, feelings, and awareness of my experiences, including what it is like to be a cognitive agent. This subjective, first-hand quality of experience goes by the shorthand “consciousness,” and for most of us it is difficult to believe that our first-person experiences of embarrassment or fulfillment, love or hate, smells or color are nothing more than brain states. (p.39)
The theory of mind is another characteristic sometimes thought to be uniquely human and nonmaterial. The theory of mind refers to “the cognitive ability to understand others as intentional agents with their own beliefs and desires.” This may seem to be a purely human, abstract concept. Recent research however, has suggested that there are nerve cells that fire when others are observed engaging in an activity. These mirror neurons are not unique to humans, they were first discovered in monkeys, and play a role in language acquisition, music, and more. Again the difference between humans and other animals appears to be a difference of degree rather than kind.
Embodied mind and consciousness. Not only is it difficult to draw a line separating distinctively human traits and characteristics from those of animals, it is also increasingly clear that all of these human characteristics are rooted in our physical, material, bodies. Everything, including thoughts, perceptions, decision making ability, empathy and more, is traceable to biological responses characterized by physics and chemistry. Dr. Green summarizes this embodiment, and asks what it means for the concept of the soul.
If the capacities traditionally allocated to the “soul” – for example, consistency of memory, consciousness, spiritual experience, the capacity to make decisions on the basis of self-deliberation, planning and action on the basis of that decision, and taking responsibility for these decisions and actions – have neural basis, then the concept of “soul,” as traditionally understood in theology as a person’s “authentic self,” seems redundant. (p. 45)
The realization of the material embodiedness of human existence does not mean that humans are nothing but chemistry and physics; a carefully balanced set of reactions. Nor does it mean that scientists are forming a united front intent on reducing human existence to nothing but materialism. Dr. Green summarizes:
This does not mean that neuroscientists ans neurophilosophers are unanimous in their reducing humanity to their brains or bodies; rather, many, in urging that humans are more than their physicality, simply refuse to identify that “something more” with an ontologically distinctive entity such as a “soul” or “spirit.” (p. 46)
In the next post we will look at the biblical material that touches on the nature of what it means to be human and how this relates to the concept of the soul.
If everything we think and do can be traced to physical and chemical processes in biology – the electrical signals of neurons in response to sight, sound, taste, smell, touch – what is the role for, or essence of, the human soul?
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