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My latest Mind and Matter column from the Wall
An odd thing about people, compared with
other animals, is that the more of us there are, the more we
thrive. World population has doubled in my lifetime, but the
world's income has octupled. The richest places on Earth are among
the most densely populated.
By contrast, it's a fair bet that if you took
a few million rabbits and let them loose on Manhattan island, they
would starve, fight, sicken and generally peter out. Whether you
like it or not, whether you think it can continue forever or not,
you cannot deny that when people come together in dense swarms,
they often get richer.
In this fact lies a vital clue to the nature
of the human animal, one that has until recently been overlooked:
namely, that what explains the sudden success of the human species
over the past 200,000 years is not some breakthrough in individual
ability, but rather the cumulative effects of collective
enterprise, achieved through trade. A new study of fishing tackle
in the South Pacific provides intriguing support for this
Two anthropologists, Michelle Kline and Rob
Boyd, collected information on the "marine foraging technology"
used by native people in 10 different groups of Pacific islands at
the time of Western contact. They assigned scores not only for the
number of tools but also for their complexity. A stick for prying
clams from the reef, for example, counted as one techno-unit,
whereas a bamboo crab trap with a baited lever counted as 16,
because it comprised 16 working parts, each a technology in its own
What they found was that the bigger the
population, the more varied and more complex the tool kit was.
Hawaii, with 275,000 people at the time of Western contact, had
seven times the number and twice the complexity of fishing tools as
tiny Malekula, with 1,100 people.
But it's not just the size of the population
on the island group that matters, but the size of the population it
was in contact with. Some small populations with lots of
long-distance trading contacts had disproportionately sophisticated
tool kits, whereas some large but isolated populations had simple
tool kits. The well-connected Micronesian island group of Yap had
43 tools, with a mean of five techno-units per tool, while the
remote Santa Cruz group in the Solomon Islands, despite having
almost as large a population, had just 24 tools and four
Mr. Boyd and his colleague Joe Henrich think
that cultural change happens when one person learns a specialized
skill and teaches it to others. But if others are poor learners or
the teacher dies young, there is a tendency for skills to fade,
creating a "treadmill of cultural loss," especially in small and
isolated societies. Tasmania, for example, suffered a progressive
simplification of its technology after its people were isolated by
rising sea levels 10,000 years ago.
This tendency is counteracted by the sporadic
innovation of expert specialists. Their ideas, embodied in
technology, spread by trade and imitation. The greater the
population and the connectedness between populations, the greater
the pool of innovators to draw upon.
Archeologists suggest that the ephemeral
appearances of fancy tool kits in parts of southern Africa as far
back as 80,000 years ago does not indicate sudden outbreaks of
intelligence, forethought, language, imagination or anything else
within the skull, but simply has a demographic cause: more people,
Technology is more than just a barometer of
human collaboration. It is the embodiment of human collective
intelligence. Most of the technologies we use, as the economist
Friedrich Hayek first observed, are things that nobody knows how to
make from scratch. Humans have transcended the limits of their own
brain power by combining their brains into networks.
Thanks to the Internet, the islands of
humanity are now connected as never before, with only a few remote
atolls like North Korea and Burma still holding out. So we can draw
upon the inventiveness of a network of more than six billion