One of the most spectacular failures of creationism—indeed, of theistic evolution, or any kind of religious explanation of the world—is the inability to explain human nature and human instincts.
The monotheistic religions, which trace human nature back to the Garden of Eden, present the following explanation for what human nature is like. God created Adam and Eve as almost perfect people. They were adapted, physically and mentally, to living in a garden where all their physical needs were met. I say almost perfect because, according to the most conservative literalists, there were two problems. One was that Eve was gullible, and the other was that Adam had this tendency to do what his wife told him to do. So when the serpent told Eve to eat the apple, she just couldn’t resist. Sort of the primordial version of the irresistible expensive handbag, I suppose. It was therefore really her fault that Adam ate the apple; he trusted his wife too much. And from that point forward, human nature has been primarily evil. Sometimes more evil, as with Cain, and sometimes less, as with Abel.Sometimes more, as with Nimrod, and sometimes less, as with Noah. But even the good people had flaws, such as Noah getting drunk. And even evil people have a deep yearning to go back to the garden. Therefore, from a conservative religious viewpoint, human nature is a complex mixture of good and evil.But what kinds of good and what kinds of evil? Religion gives us no way to understand this.
But evolution presents a different picture. Science reveals humans as an evolutionary product of cave-man days. Our bodies and minds are adapted to prehistory, to a time before agriculture, to a time when the availability of food was unpredictable; when we had to run a lot to catch prey or to keep from becoming prey; when we had to be constantly aware of danger; when the only way to survive was to fight our enemies and form intimate alliances with our friends; when the way to evolutionary success was to stop at nothing to leave as many offspring as possible.
We have numerous adaptations to these particular prehistoric conditions. We have strong appetites, which make us eat as much food as we can when it is available, and to store what we do not use as fat; we crave salt so that we can sweat a lot when we get hot; we have a strong sense of awareness of the world around us, which makes us suspicious of every little movement; we are both honest and deceitful; and we have an overwhelming craving for sex. We hate and we lust and we love more strongly than logic could possibly dictate. That is, human instinct is a complex mixture of gluttony, craving, suspicion, lust, hatred, and love. And there is an evolutionary reason for each of these instincts.
Many of the problems that we have today result from the fact that our bodies and minds still work in prehistoric ways, even though these adaptations are now dangerous. Gluttony, with its attendant medical problems, results from our bodies preparing themselves for a famine that never comes, and makes us fat and diabetic; craving for salt so that we can sweat while we run away from non-existent predators now gives us high blood pressure. Anxiety and worry result from focusing on dangers that modern society has largely eliminated, and finding new things to worry about, giving us mental problems that cavemen probably did not have. Today we could get by on altruism and honesty alone, but we still have the habit of violence and deceit. And the things that cavemen had to do to get a mate would land us in jail today.
According to religion, sin is just random bad stuff that happens to be against the will of God. And righteousness is random good stuff that happens to meet God’s approval. We pursue sin because the devil makes us do it. But according to evolutionary science, both what we call sin and what we call righteousness evolved during cave man days.
Both conservative religion and evolution explain human nature as a complex mixture of good and evil. But only evolution gives specific explanations. Evolution gives specific explanations of why humans have gluttony, cravings, anxieties, and violence. If you ask a religious person why we are tempted by gluttony, he or she can give no explanation. Why do our brains make us crave rich food and sugar and salt? Are these just arbitrary temptations that God has imposed on us as punishment for Eve sweet-talking Adam into eating the apple? And why are we almost crazy with sexual desires? Religious people can only tell us that the devil makes us do it.
According to traditional religion, the cave man days never existed. When Adam and Eve were in the Garden, they did not have to stuff their faces with food, because the Garden had no food shortages; they did not have to crave salt, or be paranoid, because there were no wild beasts to run away from; they certainly did not need a sex drive strong enough to fight off competitors, because they were literally the only people in the world. Then, when Adam and Eve were expelled from the Garden, almost immediately there was agriculture and herding (Cain and Abel, respectively). Humans went straight from sinlessness into civilization. In Biblical chronology, there is no period during which gluttony, cravings, paranoia, and sex drive would have been adaptive. These instincts went straight from being nonexistent to being unnecessary.
Jeremiah 17:9 says that the human heart is evil and desperately corrupt, and that only God can understand it. So there. Just give up and don’t try to understand it.
There can be no religious basis for explaining why we get sick and why we have mental problems. But there are detailed evolutionary reasons for these things. And that explanation is that ninety percent of the time Homo sapiens has existed has been in a cave-man environment, the existence of which religion denies.