Does Evolution Explain Human Nature?

Does evolution explain human nature?

That's the question posed by the John Templeton Foundation to a dozen scholars of biology--Francisco Ayala, Francis Collins, Eva Jablonka, Lynn Margulis, Geoffrey Miller, Simon Conway Morris, Martin Nowak, Joan Roughgarden, Jeffrey Schloss, Frans de Waal, David Sloan Wilson, and Robert Wright. Each wrote a brief essay in response. All of the essays can be found on the Templeton website.

These essays challenge four of the major misconceptions about evolutionary explanations of human nature. It is often said that such evolutionary reasoning (1)promotes atheism, (2) assumes genetic determinism, (3) subverts morality, and (4)denies the wondrous mysteries of life.

All of these authors accept the truth of evolutionary reasoning in explaining--either partly or entirely--the complexity of human nature. Some of them are religious believers, and two of them (Collins and Nowak) write about their Christian beliefs. Some of the others speak about the importance of explaining the evolutionary origins of religiosity.

That genetic determinism is insufficient for explaining human nature is a major theme for nine of the authors (Ayala, Collins, Jablonka, Margulis, Miller, Morris, Nowak, Schloss, and Wilson). Margulis speaks about "symbiogenesis, the evolution of new species from the coming together of members of different species," and this goes beyond random genetic mutations. Many of these authors stress the importance of cultural evolution, particularly through the human capacity for symbolism. An evolutionary explanation of human nature requires an account of the complex interaction of genetic evolution and cultural evolution.

The most interesting essay on the multi-leveled character of human evolution is Jablonka's. She suggests that an evolutionary explanation of human nature would have to reformulate Aristotle's biological psychology in an evolutionary framework. Aristotle explained human nature--particularly in the De Anima--as manifesting three levels: goal-directed living systems, animal mentality, and human thought. She argues that evolutionary explanations must move through these levels. We need to define evolution as "the set of processes that lead to changes in the nature and frequency of heritable types in populations over time." These "heritable types" include "genotypes, types of transmissible epigenetic (that is, developmentally acquired) variations, types of socially learned animal behavior, and types of symbol-based transmitted information." Jablonka's reasoning is elaborated in her book Evolution in Four Dimensions, which supports the same complex view of human evolution that I will develop in my new book.

Against the claim that a Darwinian view of human nature denies the importance of morality, six of the authors (Ayala, Collins, Jablonka, Margulis, de Waal, Wilson, Wright) emphasize the importance of morality for human evolution. Although the capacity for human morality is rooted in human genetic evolution, the development of moral experience depends on human cultural evolution.

Here is where I would say that we need to move through three levels of analysis--natural order, customary order, and deliberate judgment. The evolutionary history of human morality shows the universality of moral sentiments, the variability of moral traditions, and the individuality of moral judgments.

Many people think that evolutionary explanations of human nature gloss over the deep mysteries of the human condition. But some of these authors (especially, Collins, Nowak, and Wright) insist that evolutionary science forces us to confront the inescapable mysteries of human life. Collins writes: "We see science as the way to understand the awesome nature of God's creation and as a powerful method for answering the 'how' questions about the universe. But we also see that science is powerless to answer the fundamental 'why' questions, such as 'Why is there something instead of nothing?,''Why am I here?,' and 'Why should good and evil matter?'" Nowak speaks of "the mystery and purpose of life, which cannot be answered by natural science alone." And Wright points to two "awe-inspiring mysteries"--the mystery of the cosmic First Cause and the mystery of consciousness.

Nowak thinks another kind of mystery is manifested in mathematics: "the great theorems of mathematics are statements of an eternal truth that comes from another world, a world that seems to be entirely independent of the particular trajectory that biological evolution has taken on earth." We must wonder how "evolution has led to a human brain that can gain access to a Platonic world of forms and ideas."

The conclusion I draw from all these essays is that an evolutionary explanation of human nature requires a combination of all the traditional intellectual disciplines--in the natural sciences, the social sciences, and the humanities--as we strive for a Darwinian liberal education in pondering the deepest questions of human existence.