The 100th Monkey Effect

Isn’t about an Individual.

3 min readDec 26, 2017

The Hundredth Monkey Effect:

The idea that once a critical number of members copy a behavior or follow an idea, it will be taken on by all en-masse, automatically.

1952 — Koshima Island, Japan.

Japanese scientists started a study on native Macaque monkeys. Providing food in open places, the monkeys began to develop new behaviors in response:

During 1952 and 1953 the primatologists began “provisioning” the troops — providing them with such foods as sweet potatoes and wheat. The food was left in open areas, often on beaches. As a result of this new economy, the monkeys developed several innovative forms of behavior.

One of these was invented in 1953 by an 18-month-old female that the observers named “Imo.” Imo was a member of the troop on Koshima island. She discovered that sand and grit could be removed from the sweet potatoes by washing them in a stream or in the ocean. Imo’s playmates and her mother learned this trick from Imo, and it soon spread to other members of the troop. Unlike most food customs, this innovation was learned by older monkeys from younger ones. In most other matters the children learn from their parents.

The potato-washing habit spread gradually, according to Watson, up until 1958. but in the fall on 1958 a remarkable event occurred on Koshima. This event formed the basis of the “Hundredth Monkey Phenomenon.” — Ron Amundson; Skeptical Inquirer vol. 9, 1985, 348–356.

According to the documentation, once a critical number of monkeys had learned the behavior — and not before — all monkeys copied the same behavior. Suddenly there were monkeys on other islands that, as if by magic, had started washing their sweet potatoes too.

Unfortunately, this story and it’s papers have been refuted and discredited as unreliable evidence.

But the phenomenon lives on.

New Age / Cult Customs

Many cults and new-age groups thrive on the idea that the next recruit might be the ‘100th Monkey’. The person to convert everyone automatically. But when you’re basing that effect on a highly disputed study from 60-something years ago — it’s…well, unlikely.
Unless I missed something from my research (and that is likely).

Ken Keyes Jr

Author of ‘The Hundredth Monkey’, this modern parable about Nuclear War was well received and used the original study as a call to improve our behavior. It also led fans to invest in the idea even more.

If the 100th Monkey Effect is nonsense — and it definitely seems to be — is there anything useful to learn from it?

(Of course there is.)

The Element of Truth

The internet — our information and disinformation highway — has become less a road we travel on when necessary and more some kind of perpetual room we’re stuck in for most of the day.

But we’ve watched as news, fake news, new words, ideas and opinions have spread faster than they ever could before. It has divided us as much as it’s brought us together but we are — all of us — taking in new information at an unbelievable rate these days.

Gone are the days of learning solely from your local community and family. These days, readers some 6000 miles away can tell you you’re wrong instantaneously. Isn’t that wonderful?

Nothing is a greater example of collective consciousness. Nothing outside of myth and legend, that is.

The 100th Monkey Effect isn’t about a being. But maybe it’s about a tool.




Psychology Graduate interested in Personality Disorders / ASD . I love Science and Science Fiction, but I get most excited when they meet.