There are lots of reasons to reject religion. Here at the Church of the Churchless we've been pointing them out since 2004, proudly deconverting people from blind faith and dogma one non-soul at a time.
One of those reasons is that contrary to what fundamentalists believe, morality, judging what is right and wrong, doesn't come from God or some other supernatural source. It's the result of evolution.
Browsing through an old issue of Scientific American that I found languishing in a drawer of magazines, a special September 2018 issue about The Science of Being Human included an article by Michael Tomasello titled "How We Learned to Put Our Fate in One Another's Hands: The Origins of Morality."
Here's how the article was summarized in the In Brief section.
Seeds of human morality were planted some 400,000 years ago, when individuals began to collaborate in hunting-and-gathering exploits. Cooperative interaction cultivated respect and fairness for other group members. Later, growing population sizes cemented a sense of collective group identity that fostered a set of cultural practices and social norms.
Here's a scan of an illustration in the article that shows how morality evolved. You also can download the PDF file.
Download Evolution of Modern Human Morality PDF
These excerpts from the article provide a good overview of it.
If evolution is about survival of the fittest, how did humans ever become moral creatures? If evolution is each individual maximizing their own fitness, how did humans come to feel that they really ought to help others and be fair to them?
There have traditionally been two answers to such questions.
First, it makes sense for individuals to help their kin, with whom they share genes, a process known as inclusive fitness. Second, situations of reciprocity can arise in which I scratch your back and you scratch mine and we both benefit in the long run.
But morality is not just about being nice to kin in the manner that bees and ants cooperate in acts of inclusive fitness. And reciprocity is a risky proposition because at any point one individual can benefit and go home, leaving the other in the lurch.
Moreover, neither of these traditional explanations gets at what is arguably the essence of human morality -- the sense of obligation that human beings feel toward one another.
Recently a new approach to looking at the problem of morality has come to the fore.
The key insight is a recognition that individuals who live in a social group in which everyone depends on everyone else for their survival and well-being operate with a special kind of logic. In this logic of interdependence, as we may call it, if I depend on you, then it is in my interest to help ensure your well-being.
More generally, if we all depend on one another, then we must all take care of one another.
How did this situation come about? The answer has to do with the particular circumstances that forced humans into ever more cooperative ways of life, especially when they are acquiring food and other basic resources.
...Early humans needed new options. One alternative involved scavenging carcasses killed by other animals. But then, according to an account from anthropologist Mary C. Stiner of the University of Arizona, some early humans -- the best guess is Homo heidelbergensis some 400,000 years ago -- began obtaining most of their food through active collaboration in which individuals formed joint goals to work together in hunting and gathering.
Indeed, the collaboration became obligate (compulsory) in that it was essential to their survival. Individuals became interdependent with one another in immediate and urgent ways to obtain their daily sustenance.
An essential part of the process of obligate collaborative foraging involved partner choice. Individuals who were cognitively or otherwise incompetent at collaboration -- those incapable of forming joint goals or communicating effectively with others -- were not chosen as partners and so went without food.
Likewise, individuals who were socially or morally uncooperative in their interactions with others -- for example, those who tried to hog all the spoils -- were also shunned as partners and so doomed. The upshot: strong and active social selection emerged for competent and motivated individuals who cooperated well with others.
...In choosing a partner for a collaborative effort, early humans wanted to pick an individual who would live up to an expected role and divide the spoils fairly.
....Anyone who deviated from what was expected and wanted to stay in good cooperative standing would willingly engage in an act of self-condemnation -- internalized psychologically as a sense of guilt. A "we is greater than me" morality emerged. During a collaboration, the joint "we" operated beyond the selfish individual level to regulate the actions of the collaborative partners "I" and "you."
...In my 2016 book A Natural History of Human Morality, I proceed from the assumption that a major part of the explanation for human moral psychology comes from processes of evolution by means of natural selection.
More important, though, the selecting is done not by the physical environment but rather by the social environment.
In contrast to evolutionary approaches that base their arguments on reciprocity and the managing of one's reputation in the community, I emphasize that early human individuals understood that moral norms made them both judger and judged.
The immediate concern for any individual was not just for what "they" think of me but rather for what "we," including "I," think of me. The essence of this account is thus a kind of "we is greater than me" psychological orientation, which gives moral notions their special powers of legitimacy in personal decision making.
The challenge in the contemporary world stems from an understanding that humans' biological adaptations for cooperation and morality are geared mainly toward small group life or cultural groups that are internally homogeneous -- with out-groups not being part of the moral community.
Since the rise of agriculture some 10,000 years ago, human societies have consisted of individuals from diverse political, ethnic and religious lines.
As a consequence, it becomes less clear who constitutes a "we" and who is in the out-group. The resulting potential for divisiveness leads to both internal social tensions within a society and, at the level of nations, to outright war -- the ultimate example of in- and out-group conflicts.
But if we are to solve our largest challenges as a species, which threaten all human societies alike, we had best be prepared to think of all humanity as a "we."