How to build a better airplane

Orville and Wilbur Wright would surely be astonished at the sight of a jumbo jet or SST. The world of human flight has evolved unimaginably since the 1903 flight of their first primitive flying machine, and it will no doubt change even more dramatically over the century ahead. Yet despite all the modifications and improvements that each generation has added, the core concept of the airplane remains remarkably true to the brothers’ original bold idea.

Scientists call this cultural evolution. Every human creation, from aeronautics to knitting to language, is passed down through generation after generation, with each preserving and improving upon ideas and practices and traditions. We take this for granted, but how does it happen? What are the particular cognitive mechanisms that allow us to move ideas forward? Why doesn’t each generation have to reinvent the airplane? In other words, what’s the psychology of progress?

The prevailing theory of cultural evolution focuses on imitation and teaching. This seems plain enough. Orville and Wilbur didn’t do their inventing in a vacuum; they explained what they were doing and why, while younger apprentice inventors listened and observed. They wrote stuff down, and these notes and manuals and such were passed on.

But what if they didn’t do that? What if instead they died and left no scientific jottings, just a working airplane, parked in a Kitty Hawk hangar? Would the discovery of such an artifact lead to progress, even without modeling and imitation? This is just a fanciful way of asking: Is imitation necessary for progress? Or is the human mind capable of working backward from the artifact and recreating the creative process?

Two psychological scientists at the University of Stirling, in the United Kingdom, figured out a clever way to explore this question in a laboratory. Christine Caldwell and Ailsa Millen recruited 700 volunteers, who were grouped into “microsocieties.” Each of these societies was constantly changing, with participants dropping out as others were added. This was intended to simulate the normal succession of generations, only in a highly compressed time frame. Each society was told to invent the best paper airplane possible.

That’s all. Except that each of the societies had different learning traditions. That is, some learned simply by imitating others, while others had strong mentoring traditions, with free exchange of questions and advice. Still others had little or no communication; they had to learn by emulating the achievements of their predecessors. Other societies had various combinations of teaching, imitating and emulating. They did this for five minutes, and afterward each society’s “youngest” member built an airplane. They flew them all to see whose airplane flew the farthest.

The results were unexpected. As reported in the December issue of the journal Psychological Science, each of the learning mechanisms—imitation, teaching, emulation—was enough in itself to guarantee cultural progress through the generations. No matter what learning tradition a society had, there was significant improvement over time in airplane design. In short, there was cultural progress even without any teaching or imitation.

Human traditions take a variety of forms, the scientists say, and teaching and imitation may indeed be necessary for transmitting some kinds of culture. But these results clearly show that the tradition of mentors and protégés cannot fully explain progress or the complexity of human culture.