SEX EQUALITY MAY HAVE BEEN A MILESTONE IN HUMAN EVOLUTION
Updated: Aug 9, 2019
If there were a meteor about to hit the Earth, people, regardless of their nationalities, would cooperate and try to beat the meteor.
As astronomers continue tracking the meteors, we evolutionary anthropologists ask the question of “how on earth have humans built systems that could track the meteors, but chimps did not”.
Part of the answer may lie in the social structure of hunter-gatherers, in particular the equality between men and women!
We human beings spent 90% of our existence on Earth as hunters and gatherers. What this means is that the features that separate us from our close relatives such as gorillas, chimpanzees and bonobos emerged while we were hunter-gatherers.
In what way, then, are we going to explain why and how have these features emerged and why humans became human? If we had a time machine, our job would have been much easier! But since we don’t, we look to a handful of remaining groups of people on Earth that still live as hunters and gatherers. For this reason, we (a team of researchers at University College London) lived among Agta and BaYaka Pygmy hunter-gatherers from the Philippines and Congo-Brazzaville in 2013 and ‘14.
Pygmy hunter-gatherers obtain the majority of their diet from forest or sea (antelopes, pangolins, and monkeys) and wild plants. BaYaka and Agta live in camps that consist of multi-family groups of around 20 adults. Men and women make decisions mutually, and there is a great deal of autonomy for couples. Therefore, there is no such thing as a big man. In addition, food sharing between families is common. Other than essential utilities such as pots, machetes and baskets, people do not possess material items. Contrary to groups like us, who are sedentary, families often change and move camps according to natural resource availability or visit families and friends in other camps. Therefore, there is a lot of mobility between camps.
Video: BaYaka women and children collecting wild yams in the forest, Congo-Brazzaville
It is exactly this point that separates many other apes like chimps and gorillas from humans. The inter-group interactions in these other apes are not peaceful, often involving territorial fights.
In addition, within camp relatedness in hunter-gatherer groups is lower than that of sedentary populations. This is a puzzle for evolutionary anthropologists, because humans and many social animals prefer to live and cooperate with their relatives with whom they share genes.
If this is the situation, then why do hunter-gatherers live among fewer kin than sedentary people?
In our article published in Science last week, we proposed a model that answers this question. The main theme of the model is: Imagine you are a part of a hunter-gatherer couple; both you and your spouse want to live with your own kin. At the same time, you both have an equal say over which camp and with whom to live. Now consider that, there are many couples thinking and acting like you in your group. This situation leads to people living with fewer kin at the group level.
In contrast, if you are a newly married woman living in a patriarchal society such as those common among farmers and pastoralists, you’re mostly likely to move in with your husband’s family. To consider this situation, we created another model where only one sex (woman or man) had a say in decision-making. This non-egalitarian model led to people living among more kin at the group level.
We compared the results of our models with data from our field sites. Over two years we constructed hundreds of family trees of hunter-gatherers. By examining these family trees we determined the within camp relatedness levels. To make a comparison, we did the same study with a farmer group in Philippines. Result: the results of the model where women and men had equal say in where to live matched our data from the hunter-gatherer groups. Similarly, the results of the non-egalitarian model fit very well with the data from the patriarchal Filipino farmers.
Why then, is it important that hunter-gatherers live in less related groups and have more fluid social structure? This system where men and women have equal say in decision-making results in families having kin in many other camps. In turn, this leads to peaceful interactions, cooperation and cultural exchange among camps. Contrary to fighting chimp groups!
Think about this, in one camp one family knows the trees to get honey very well; in another camp another family knows which plants to use for diseases perfectly. Cooperative interactions between these two families gives way to information transfer, new explorations and technologies.
And after 200 thousand years since the evolution of modern humans, human beings develop systems to control meteors.