Quote:
Originally Posted by Z-man
- Henry Petroski The Evolution of Useful Things 1990.
...it is the generation that is young enough not to have become so familiar with the old, and yet not so young as to be without the financial resources to do so, that usually embraces the newest technology first.
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for the monkeys the "newest technology" was a method of winnowing rice grains from sand.
here is the story, as told by my favorite biology professor (me):
Invention (Role of Age and Behavioral Propagation)
Imo Examples (Innovation and Invention)
Newton said that if he had seen farther than others it was because he had stood on the shoulders of giants
yet, the innovations of Newton and Einstein dramatically changed Western Society
Imo lived in Japan, and changed her society more than any other
Imo is dead now, but she was a greater innovator than either Newton or Einstein
study of Japanese Macaques (Macaca fuscata), Japanese scientists discovered that one troop knew how to dig out plant roots with their hands, other troop did not. (implies different traditions of cultural innovation)
Candy Eating
introduced new food to the monkeys — juveniles, who are more prone to experimentation, first began eating caramel candies
* later, mothers learned candy eating from their kids (juveniles), then passed it along to their own infants
juveniles ® mothers ® infants
* propagation of the behavior was most rapid among the young animals and slowest among the sub-adult males, who were socially distant from the young and their parents
Potato Washing
In 1952, the scientists began scattering sweet potatoes on the beach
* monkeys ventured out of the forest and extended their activities to a completely new habitat
* Within a year the monkeys had learned to wash the sand off the sweet potatoes
— invented by Imo, 2 year old female
* trait was most readily learned by Imo's own age class (1 to 2.5 years old)
* infants and young less than a year old never learned (too complicated?)
* only 18% of older monkeys ever learned it (all females)
* older males never learned it (in human societies too, the older males are the most conservative) Why? (they have a lot to lose if innovation doesn't work)
* monkeys shifted their washing from a brook to the sea and acquired a taste for salt
Wheat Sifting
In 1955, Imo invented another technique (she was 4 years old): scientists were throwing wheat grains onto the beach as food, monkeys were picking the grains out one by one.
somehow, Imo learned to scoop up a handful of sand and wheat, carry it to the edge of the sea and throw it in the water. She then let the sand sink and eat the wheat floating on the surface.
* behavior spread through the troop like the potato washing but with one important difference:
younger ones (< 2 years) had more trouble learning the technique, probably because it was more complex (you have to "throw away" the food, even if only temporarily)
Behavioral Propagation
Slow Fast
candy eating subadult males young
potato washing young, old males 2 year olds
wheat sifting < 2 yrs, old males 4 yr. females
— young animals tend to be innovators
— if too young, they can't learn complex tasks
— older animals, especially males, are conservative
— small shifts in dietary habits can lead to rapid cultural changes and evolutionary breakthroughs
· monkeys learned to enter the water to bathe, especially in hot weather
· acquired a taste for salt
· juveniles learned to swim — some even began to dive and bring up seaweed from the bottom (new food source)
· one monkey swam to another island (range expansion)
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I hope you enjoyed those thrilling episodes from yesteryear.