Yes, absolutely - that's what all current science indicates. Paleolithic peoples were aware of the issues of in-breeding and we know that they purposely swapped members with neighboring bands in order to avoid that, so they knew enough not to mate with close relatives, but otherwise, there was no way to monitor paternity, and no real need to, since the band all took care of each other. There are very clear new restrictions on women's social and sexual lives that only appear with sedentism, where women are relegated to indoor work where they can be closely monitored. If you're off foraging, who is going to know who you have mated with? And if everyone shares food and all other resources as a survival strategy, who is going to care?
“Small family bands are likely to have interconnected with larger networks, facilitating the exchange of people between groups in order to maintain diversity,” said Professor Martin Sikora, from the Centre for GeoGenetics at the University of Copenhagen. This appears to have been done purposely and with the understanding that genetic diversity was desirable. It was a cooperative strategy undertaken by a highly social species.
"Because these were such a group-oriented societies, the notion of nuclear families doesn’t really make sense. As John Odling-Smee points out in his review of noted sociobiologist Sarah Blaffer Hrdy’s book Mothers and Others, “Homo sapiens could never have evolved if human mothers had been required to raise their offspring on their own. Human infants are too helpless and too expensive in their demands for care and resources. So human females have to line up helpers — sometimes extending beyond their own kin — to raise their young. That requires both males and females to invest heavily in social skills for bargaining with other members of their groups. Hrdy suggests that females in ancestral hunting and gathering groups may have thrived because they were free to be flexible in this way. Female flexibility was reduced when humans established settlements requiring male coalitions to defend them, probably leading to greater control of females by males… The most refreshing aspect of [this] book is the challenge [it] offers to what we thought we already knew.”
In many places in modern-day South America and some parts of Asia, partible paternity and even polyandry are still practiced. Cooperative breeding, with several fathers taking responsibility for the welfare of children, doesn’t mesh with what we’ve been taught about the Standard Model of Human Evolution, which says that “A woman having sex with another man is always a threat to the man’s genetic interests, because it might fool him into working for a competitor’s genes.” It also dispels the notion that all women seek one mate who can take care of her and her offspring, regardless of culture.
This isn’t our actual evolutionary legacy. If it were, there wouldn’t be so many current cultures that do not practice strict monogamy or have family structures or support systems that don’t fit this narrative.
The great anthropologist and comparativist Sarah Hrdy tells us that, across species, including among humans, the best mother for many eons was the one who was, under particular and far-from-rare ecological circumstances, promiscuous. By being so, she could hedge against male infertility, up her odds of a healthy pregnancy and robust offspring, and create a wider network of support by lining up two or three males who figured the offspring might be theirs. (5)
