The Scope of Evolution Includes the Psychology of Religion
In 2015, I visited the historic Rhea County Courthouse in Dayton, Tennessee—the site of the famous Scopes “Monkey” Trial. That year marked the 90th anniversary of the proceedings, which began on July 10 and concluded on July 21, 1925. At the heart of the trial was science teacher John Scopes, charged with violating Tennessee law by teaching evolution in a public school. Now, in 2025, I revisit the story in its centennial year, reflecting on how far we've come—and how the debate endures.
The arguments presented during the 1925 Scopes Trial may seem like quaint historical disputes—until one considers that a significant minority of Christians in the United States continue to reject scientific explanations for the origins of life in favor of a literal or near-literal interpretation of creation. In 2014, a Gallup poll revealed that 42% of Americans believed God created humans in their present form approximately 10,000 years ago. A decade later, Pew Research (2025) reported that 80% of U.S. adults accept the idea of human evolution. While 77% of Christians now say they believe in evolution, most attribute the process to divine guidance. Among Evangelicals, only 6% believe that God played no role in evolutionary development.
Given the relatively low acceptance of human evolution as a natural process among some Christian groups, the likelihood of embracing an evolutionary framework for psychological functioning appears even more tenuous. Psychological science as a whole—and psychological interventions in particular—often face skepticism from Christian fundamentalists. Introducing evolutionary psychology into this context may further compound resistance. For more on the gap between Christian faith and science, see Irreconcilable Differences? Apes, Adam and an Ark: Relating Christianity and Psychology (Sutton, 2024).
In this post I will summarize recent thinking on
evolutionary psychology.
In the next post I’ll summarize an evolutionary perspective
on the psychology of religion.
An Overview of
Evolutionary Psychology
As one might expect, evolutionary psychology presupposes a foundational understanding of biological evolution. Early life emerged on Earth approximately 3.5 billion years ago, around a half-billion years after the planet formed. The gradual process of human evolution began roughly 6 million years ago, when our lineage diverged from that of other primates. Back in 2015, scientists had identified evidence for around 15 distinct human species; today, that number stands at 21.
Likewise, the timeline for complex behavior—including tool-making and symbolic culture—has extended far beyond the earlier estimate of 100,000 years. For instance, stone tools discovered in Kenya date back 3.3 million years, predating the genus Homo. Evidence for controlled use of fire appears by 1 million years ago, while intentional burials with grave goods remain situated around 100,000 years ago. These findings reveal deep roots of cultural complexity long before anatomically modern humans appeared. (Smithsonian Institution)
Human evolution unfolds through the transmission of adaptive genetic changes across generations. Individuals who survived long enough to reproduce passed on the genes that shaped the structure and behavior of future populations. While it’s self-evident that humans required food to survive and sex to reproduce, the behavioral routines tied to foraging, mating, predator defense, and coping with natural disasters were also subject to evolutionary pressure. Many psychological mechanisms observed today are rooted in these survival challenges.
Natural vs. Sexual vs. Artificial Selection
Natural Selection: This process is not random. While genetic mutations and variation (such as eye color) occur randomly, the traits that persist do so because they enhance survival and reproduction. Evolution operates through differential reproductive success.
Sexual Selection: A subset of natural selection, sexual selection involves traits that improve mating success rather than direct survival. Examples include peacock plumage or ritualized combat behaviors. It typically follows two patterns:
Male-male competition for access to females
Female choice of preferred mates (Note: Role reversals exist in species where males invest heavily in offspring.)
Artificial Selection: Unlike natural processes, this form involves human-directed breeding of plants and animals for desired traits, such as sweeter fruit or docile behavior.
The Role of Sexual Reproduction in Genetic Variation
Sexual reproduction promotes genetic diversity by combining genes from two parents. During this process, genetic recombination (often called "shuffling") occurs, ensuring each offspring inherits a unique set of traits. This variability is crucial to evolution, supplying the raw material on which natural and sexual selection can act.
You can think of a psychological mechanism as a complex pattern of cognition, emotion, and behavior—akin to an app running on a digital device.
Just as our devices rely on specialized software to execute tasks, humans operate through adaptive “programs” that activate in response to specific needs or challenges. Mechanisms such as parent–child attachment, mating behaviors, social group formation, dominance routines, and tool-making strategies evolved in tandem with anatomical, biological, and biochemical changes. As psychologist David Myers aptly notes, “everything psychological is simultaneously biological” (p. 114).
Evolutionary psychology provides psychological science with a metatheoretical framework grounded in the principles of biological evolution. While debates persist over the specific mechanisms of evolution, the overarching theory enjoys near-universal acceptance in the scientific community. However, psychology has yet to arrive at a unified explanation for the origins of complex behaviors and mental processes. That landscape, however, is shifting.
During the 20th century, psychological scientists distanced themselves from instinct-based, quasi-biological accounts of behavior, favoring environmental and social explanations. The rise of computing ushered in new models of the mind as an information-processing system, prompting research into problem solving, concept formation, reasoning, and memory. These studies often emphasized conscious, deliberate cognition.
In more recent decades, researchers have acknowledged that automatic, unconscious processes drive much of our daily behavior. Disrupting these ingrained routines—much like closing an app—requires intentional and effortful thought. But where do these automated behaviors originate? As you might suspect, evolutionary psychologists argue that they reflect inherited solutions to ancestral challenges. These mechanisms—once critical for survival and reproduction—continue to shape contemporary human functioning.
Kirkpatrick’s View on Evolutionary Psychology
In his update titled Evolutionary Psychology as a Foundation for the Psychology of Evolution, Lee Kirkpatrick (2013) outlined three major ways in which evolutionary psychology informs psychological science.
1. Psychological Processes Evolved to Support Selection Mechanisms
According to Kirkpatrick, many psychological functions developed specifically to aid natural and sexual selection. For example, the widely studied attachment process enhances the survival of infants by promoting proximity and caregiving—thus supporting natural selection. Likewise, mating behaviors serve sexual selection by increasing reproductive success. In this view, psychological mechanisms exist because they subserve selection pressures that shaped our evolutionary past.
2. Human Behavior Reflects By-products and Exaptations of Adaptation
Not all behavioral traits are direct adaptations. Kirkpatrick emphasizes that many aspects of human psychology are by-products of evolutionary adaptations. For example, while language itself may be an adaptation crucial for survival, advanced forms of expression—such as literature, music, or abstract art—may be better understood as by-products. Another class of by-product is the exaptation: traits that evolved for one purpose but have since been co-opted for another. Glass lenses perched on noses, which extend the function of our evolved vision, serve as a common example.
3. Understanding human nature requires careful delineation between core adaptations and the by-products or exaptations they give rise to.
The term spandrels, popularized by Stephen Jay Gould and Richard Lewontin, refers to evolutionary by-products that may have little or no adaptive value yet persist in populations due to their association with other selected traits.
Adaptations Reflect Ancestral, Not Modern, Environments
Adaptations emerge slowly over evolutionary timescales, shaped by the conditions faced by distant ancestors. Thus, many psychological adaptations are better suited to ancient environments than to modern ones. For example, the ancestral drive to seek sweet and fatty foods—once adaptive in calorie-scarce environments—now contributes to widespread obesity, given the ease of access to high-calorie foods in contemporary society.
Post Author
Geoffrey W. Sutton, Professor Emeritus of Psychology at Evangel University, holds a master’s degree in counseling and a PhD in psychology from the University of Missouri-Columbia. His postdoctoral work encompassed education and supervision in forensic and neuropsychology. As a licensed psychologist, he conducted clinical and neuropsychological evaluations and provided psychotherapy for patients in various settings, including schools, hospitals, and private offices. During his tenure as a professor, Dr. Sutton taught courses on psychotherapy, assessment, and research. He has authored over one hundred publications, including books, book chapters, and articles in peer-reviewed psychology journals. His website is https://suttong.com
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References
Kirkpatrick, L.A. (2013). Evolutionary psychology as a
foundation for the psychology of evolution. In R. F. Paloutzian and C.L. Park
(eds.) 118-137. Handbook of the
psychology of religion and spirituality, 2nd ed. Guilford.
Myers, D. (2012) Psychology in Everyday Life, 2nd ed. Worth.
Neuman, S. & Greenfieldboyce, N. (2025, June 8). 100 years after evolution went on trial, the Scopes case still reverberates. npr. https://www.npr.org/2025/07/08/nx-s1-5430760/evolution-scopes-creationism-monkey-trial
Pew Research Center. (2025, February 26). Decline of Christianity in the U.S. has slowed, may have leveled off: Findings from the 2023–24 Religious Landscape Study. https://www.pewresearch.org/wp-content/uploads/sites/20/2025/02/PR_2025.02.26_religious-landscape-study_report.pdf
Sutton, G. W. (2024). Irreconcilable differences? Apes, Adam and an ark: Relating Christianity and psychology. Sunflower. ISBN = 979-8323386581 (ON AMAZON)
Related Posts
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Darwin Matters? Book Review
How Can Christians Integrate Faith and Evolution?
Is Religion a By-product of Evolution?
Is the Jury Still Out on the Scopes Trial after 90 Years?
Did the Pope Evolve? Evolution, Psychology, and Christianity
Additional resources
Sutton, G. W. (2015). [Review of the book Handbook of The psychology of religion and spirituality (Second Edition) by Raymond F. Paloutzian and Crystal L. Park (Editors]. Encounter, 12. Academia Link ResearchGate Link
Sutton, G. W. (2008). [Review of the book Why Darwin matters: The case against intelligent design by M. Shermer]. Journal of Psychology and Christianity, 27, 181. ResearchGate Link Academia Link
Sutton, G. W. (2025). Worldviews apart: Christianity and psychology | An exploration of possibilities for bridging the divide between faith and science. Sunflower Press. AMAZON GOOGLE
Web sites
Creationist viewpoint can be found at https://answersingenesis.org/answers/
Darwin online http://darwin-online.org.uk/
Intelligent Design viewpoint can be found at http://www.intelligentdesign.org/
Why Evolution is True by Jerry Coyne http://jerrycoyne.uchicago.edu/index.html
Ted Talks videos on evolution https://www.ted.com/topics/evolution
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