It was religion, a psychologist stresses in his new book, that played a very important role in the grim struggles of prehistory. Belief in God provided humans with a way to relate to each other and the world around them.
Matt Rossano, professor and head of the Department of Psychology at Southeastern and author of the book "Supernatural Selection: How Religion Evolved", said religion offered them significant survival and reproductive advantages.
"The roots of religion stretch as far back as half a million years, when our ancestors developed the motor controls to engage in social rituals - that is, to sing and dance together," he said.
"It forced the survivors to create new strategies for survival, and religious rituals were foremost among them," he added.
Rossano's work is, in part, a response to the 2006 best-selling book "The God Delusion" by scientist Richard Dawkins, an atheist manifesto that pitted science against religion.
But, according to Rossano, Dawkins missed the science that revealed how religion made man more human.
Neither an apologist for religion nor a religion-basher, he pulls together the evidence from a wide range of disciplines to show the valuable purpose served by a systematic belief in the supernatural.
According to Rossano, evidence seems to confirm that at its core religion was not about doctrines, creeds, institutions or miracles, but about relationships.
"Religion is a fundamental way for humans to relate to each other and the world around them, and in early prehistory that was a definite advantage," Rossano explained.
"Religion emerged as our ancestors' first health care system, and a critical part of that health care system was social support.
"Religious groups tended to be far more cohesive, which gave them a competitive advantage over non-religious groups and enabled them to conquer the globe," he stated.
Rossano noted that for Dawkins and his supporters, there is nothing quite so wicked as religion and all that trails in its wake: suicide bombers, Taliban-style tyranny, child abusing clergy, etc.
"But if religion was so clearly damaging to the human psyche and so corrosive of human society, how could it have ever evolved?" How is it possible that every culture throughout human history has had religion?" he asked.
"Time and again, studies show that religious people tend to be happier, healthier, more generous and civic-minded than their non-religious counterparts," he continued.
"Religion is also tenacious. Enlightenment thinkers promised that religion would fade as science and reason provided a more accurate picture of the natural world.
"To the bewilderment of Dawkins and his ilk, the world seems to have reneged on that Enlightenment promise," he concluded.
Rossano, who has studied the evolution of religion and other cognitive traits for some time, is the author of "Evolutionary Psychology: The Science of Human Behavior and Evolution," as well as numerous papers on evolution, ritual, religion and moral behavior.