6. Collective Learning

Humans are unusual. We walk upright and build cities. We travel between continents in hours and can communicate across the globe. We can build bombs and invent medicines. Why can we do all these things that other creatures can't do? The answer is in our ability to learn collectively.

What makes humans different?

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Deep in the Amazon jungle, a European explorer had a
chance meeting.

On June 5, 1799, the Prussian geographer and naturalist Alexander von Humboldt set sail for South America aboard the Spanish frigate Pizarro. He landed in Cumaná, Venezuela, and then went on to Caracas, in what was then New Granada. In February 1800, the Humboldt expedition set out to map the Orinoco River, collecting plant and animal specimens along the way. Deep inland they encountered a group of indigenous people armed with finely crafted bows and arrows. Humboldt identified them as the Yanomami, a reclusive tribe that he knew was rumored to live in the Orinoco basin.

Humboldt's scientific interests were wide ranging and his work included physical geography, meteorology, and biology. He was among the first to suggest that South America and Africa had once been connected and his work with “isothermal” lines helped develop the modern science of climatology. Charles Darwin credits Humboldt with inspiring him to undertake his own explorations and may have emulated his writings, while Alfred Wegener was surely familiar with his work, which stressed the value of studying the geographical distribution of plants and animals.

Humboldt did not consider himself an anthropologist and though his later work, collected in the multivolumed Kosmos, attempted to explain the “unity of nature” by applying all of the physical sciences collaboratively, it's uncertain to what extent he viewed his encounter with the Yanomami and other indigenous people as a window into the human past. Modern anthropologists use the study of foraging societies as a way to better understand how our hunter-gatherer ancestors lived and to help unravel the mysteries of human evolution.

Scientists believe that the earliest humans diverged from other primates partly in response to a changing climate in what is now East Africa. Forests grew drier and the savanna – large swaths of grassland interspersed with trees – spread, leading these early ancestors of ours to give up tree-dwelling and to instead range the open spaces, hunting and gathering.

Over time, our ancestors slowly became us. They switched to bipedalism, walking exclusively on two feet. Unlike the big toes of great apes, which are separated from other toes to help in gripping tree branches, human big toes evolved to be parallel to the others. Our ancestors developed a wider range of vision more suitable to broad expanses than to the tight, leafy confines of the forest. They made simple tools to procure food, and used fire to cook it. Their brains grew in size and weight, from about 850 grams for Homo erectus or Homo ergaster to about 1,350 grams for
Homo sapiens.

But there are other species that use tools and other species with large brains. It is collective learning, the ability to share, store, and build upon information that truly distinguishes humans.

When did collective learning start?

No one can pinpoint when our ancestors started to learn collectively, but many agree that the ability to communicate with each other symbolically using the voice must have come first. So when and how did humans develop such a precise language? There are dozens of theories. Some say it was the cooing of a mother to an infant that evolved into the first protolanguage. Others believe that sounds were learned from animals. Some point to the development of certain anatomical features in the human skeleton and tissues that are necessary for human speech. Recent genetic research has highlighted the importance of a specific gene, FOXP2, and its likely importance in the human capacity for precision speech and early collective learning.

By whatever means our ancestors learned to communicate with each other, they then began to learn from each other, to teach each other, to share information with their companions, their children, and their grandchildren.

It's clear that our foraging ancestors used collective learning 50,000 years ago and perhaps much earlier. They used it to adapt to life in various climates, to share information about food sources, and to develop tool technology. Generally we don't give nearly enough credit to foraging people. When we think of humans who live as hunter-gatherers, we tend to think of them as “primitive.” We have our caricatures of the “Stone Age” and hairy, unintelligent, club-toting creatures called “cavemen.” How can we see this period more clearly?

The Yanomami still follow the same lifeways they did when Humboldt encountered them. They are one of the largest and most traditional intact tribes of the Amazon, and they have become famous among anthropologists because they can help teach us about how earlier human foraging societies might have lived. Studying them can tell us a lot about our past and also about our present.

You fly to Manaus, the capital city of Amazonas state in Brazil, travel hundreds of miles up the largest river on Earth, drive a jeep on a muddy jungle road for several hours, board a motorized canoe and twist along one of the Amazon's small tributaries for several more, and finally you arrive at a village of thatch-and-mud huts perched on a hill above the dark water.

If you've made arrangements through a friend of the tribe, the chief might welcome you with painted torso and tropical bird feathers in his hair and offer you a place to stay – a place to hang your hammocks from the roof posts of a round hut. If it is January, the village will be celebrating the arrival of the pupungha – a bright red tropical fruit that is a major food source. The young men head off to hunt and the women dance in the central court of the village while the elders, painted and feathered, watch them approvingly from a long bench beneath a thatched roof.

If there is a 12-year-old boy with you, he might be invited to make an arrow. An elder will sit down cross-legged with him under a small thatched roof and teach him how.

It takes a great deal of patience to make an arrow, the elder says. He shows the boy, slowly, carefully, step by step. He starts with a long arrow shaft cut from a special type of straight, hollow reed called pé de fleche.

“This part, the shaft, is like the mother and all the other parts come to her,” he explains.

The arrow-maker carefully carves a tiny but crucial component for the nonpointed end of the arrow from a species of wood called pai kawa. He notches the wooden piece with a hand chisel. This is the part into which one nocks the drawn bowstring and that must transmit a great deal of force to the arrow. He rubs the small component with a special tree sap, then carefully turns and inserts this piece into one end of the hollow shaft, wrapping it around with a thin root fiber, crushing reed and small wooden piece together like an organic weld. He gently applies the arrow's guiding feathers with a vegetable glue, carves a razorlike arrow tip from a thin sliver of bamboo, affixes it to the arrow's other end, and finally paints the arrow with a mixture of forest beeswax and vegetable pigment called urucu. The arrow is so long it looks almost like a spear. Later, the arrow-maker can dab its tip with poison concocted from the sap of a certain tree's inner bark, to paralyze the creature the arrow will impale.

It's finished. The arrow-maker picks up his bow, carved of pupinha wood and as tall as he is, aims the arrow straight into the air, draws it back with powerful arms, and then releases it. The arrow launches high overhead, reaches its apogee, turns over, and plunges to Earth. Such is the arrow-maker's craftsmanship and skill in shooting a bow that the arrow drops straight down and pierces the foot-packed ground a yard from where he stands.

If you were to do it on your own, you could spend much of your life learning to make an arrow but you wouldn't make one nearly as good or effective as this one. That is because this arrow is the culmination of generations of skill and knowledge, a product of human intelligence and collective learning – like learning to live in the Amazonian forest itself, with its thousands of species of plants and animals that have proved useful for survival. Watch a tribal elder make an arrow, and you won't call him “primitive.”

If it had been made 100,000 or 200,000 or half a million years ago, that Yanomami arrow would not have survived in the archaeological record. Its organic materials would have quickly deteriorated. What we are generally left with from the earliest humans is a record of bones, stone tools, and a few fossilized footprints. The picture these give us is only a dim, distant glimpse of their actual life.

Gone from the record too are the interactions of these early humans. Gone are the stories they may have told, their dances, their songs—almost everything of what made them who they were. Gone are the earliest hints of collective learning.

As humans improved their tools, planned journeys, and learned how to forage for resources, language developed along with them. New ways to convey ideas and communicate plans all feed into a community's collective learning, which means that people can work together to find new and better ways to live. But collective learning is affected by factors that can limit or accelerate its impact. Knowledge sharing has its own form of network effects, where the quantity and diversity of ideas exchanged influence the overall network. Over time, the Yanomami mastered the art of the arrow and increased their encyclopedic knowledge of the jungle. But being so reclusive for so long, with environmental and cultural limitations on the ways in which they connected with different ways of thinking, they did not follow the same path that led other groups to agriculture, and the new innovations that came with it.

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