Think about taking a walk: where you need to go, how fast you need to go to get there, and whether you need to take anything with you to carry the results of your errand.
Are you going to take this walk with someone else? Does walking with a friend change your preparation? If you go for a walk with a child, don’t forget to take an extra sweater or a snack? You probably have – because people intuitively vary their plan depending on their current needs and situations.
In my research as an anthropologist, I have focused on the evolution of human walking and running, because I like the flexibility that humans bring to this behavior. People in all kinds of environments across space and time vary how far they go, when they go, and what they go for—whether food, water, or friends—based on a host of factors, including season, daylight, rituals, and family.
Anthropologists divide their research into human activities into two broad categories: what people need to do – including eating, keeping their children alive, and so on – and what solutions they come up with to meet these needs.
How people keep their children alive is a key issue in my research, because it has a direct impact on whether a population survives. It turns out that children stay alive when they are with adults. Therefore, it is universal for humans that women carry heavy burdens every day, including children and their food. This need-based behavior appears to have been an important part of our evolutionary history and explains quite a few aspects of human physiology and female morphology, such as women’s lower center of mass.
The solutions to other important problems, such as exactly what foods women will carry, vary across time and space. I suggest that these variations are as important in explaining human biology and culture as the needs themselves.
Consequences of unusual activities
Evolutionary scientists often focus on how beneficial hereditary traits are passed on to offspring when they confer a survival advantage. Ultimately, a trait can become more common in a population if it provides a useful solution.
For example, researchers have made big claims about the impact that persistence hunting through endurance running has had on the way the human body has evolved. This theory suggests that taking down prey by making them run to exhaustion led to humans’ ability to travel long distances – by increasing humans’ ability to sweat, strengthening our head support, and ensuring ensure that our lower limbs are light and elastic.
But persistence hunting occurs in less than 2% of recorded hunting cases in one large ethnographic database, making it an extremely rare solution to the need to find food. Would such a rare and unusual form of locomotion have had a strong enough impact to select for the set of adaptive traits that make humans such excellent endurance athletes today?
Perhaps persistence hunting is actually a fallback strategy, providing a solution only at key moments when survival is on the brink. Or maybe these possibilities are just side effects of daily walking. I think a better argument is that the ability to predict how to switch between common and uncommon strategies has been the driving force behind human endurance.
The influence of everyday life on evolution
Hunting itself, especially of large mammals, is hardly ubiquitous, despite how often it is talked about. For example, anthropologists tend to generalize that people living in the Arctic even up to a hundred years ago consumed exclusively animal flesh hunted by humans. But actually the original ethnographic work reveals a much more nuanced picture.
Women and children were actively involved in hunting, and it was a highly seasonal activity. Coastal fishing, berry picking and the use of plant materials were all vital to the daily livelihood of the Arctic people. Small family groups used canoes for part of the year to forage along the coast.
During other seasons, the entire community took part in hunting large mammals by putting them in dangerous situations where they could be killed more easily. Sometimes family groups were together, and sometimes large communities were together. Sometimes women hunted with guns, and sometimes children ran after caribou.
The dynamic nature of everyday life means that the relatively unusual activity of hunting large terrestrial vertebrates is unlikely to be the key behavior that helps humans solve the key problems of food, water and keeping children alive .
Anthropologist Rebecca Bliege Bird has investigated how predictable food is throughout the day and throughout the year. She has noted that in most communities, big game is rarely taken, especially if someone hunts alone. Even among the Hadza of Tanzania, who are generally considered a big game hunting community, a hunter acquires an average of 0.03 prey per day – essentially eleven animals per year for that individual.
Bird and others clearly argue that the planning and flexible coordination carried out by women is the crucial aspect of how people survive on a daily basis. It is the daily efforts of women that allow people to spontaneously undertake high-risk activities such as hunting – perseverance or otherwise – a few times a year. Therefore, it is feminine flexibility that allows communities to survive among the rare great opportunities.
Changing roles and contributions
Some anthropologists argue that behavior in some parts of the world varies more for cultural reasons, such as which tools you make, than for ecological reasons, such as how much daylight there is in winter. The importance of culture means that solutions vary more than needs.
One of the aspects of culture that varies is the roles assigned to specific genders. Varying gender roles are related to the division of labor and when people take on certain solution-oriented tasks. In most cultures, these roles change throughout a woman’s lifespan. In American culture, this would be like a grandparent going back to college to hone a childhood passion and then taking a new job to send their grandchildren to college.
In many places, females move from childhood where they could carry their siblings and firewood, to early parenthood where they might go hunting with a baby on their back, to older parenthood where they could carry water on their heads, a baby on their backs and tools in their hands, until postmenopausal periods when they could carry huge loads of mangoes and firewood to and from camp.
Although we always carry burdens, our ability to plan and change our behavior for diverse environments is part of what drives us Homo sapiens‘ success, meaning that women’s behavior at different stages of life has been a major driving force behind this ability.
This article is republished from The Conversation, an independent nonprofit organization providing facts and analysis to help you understand our complex world.
It was written by: Cara Wall-Scheffler, University of Washington.
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Cara Wall-Scheffler does not work for, consult with, own shares in, or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.