September 10 – Happy Birthday, Stephen Jay Gould

Posted on September 10, 2017

Today's famous birthday is the fellow who came up with "punctuated equilibrium." 

You may think, from the term, that this has something to do with commas, periods, exclamation marks, and other punctuation - but it doesn't.

You might think that this has something to do with keeping your balance, or equilibrium...or maybe staying calm - but it doesn't.

Instead, the theory of punctuated equilibrium is all about how living things change, or evolve.

First, we know that living things DO change. We can see from the fossil record that legless whales evolved from four-legged creatures, and that horses evolved from much smaller plant-eating creatures. 

The question that Gould, who was born on this date in 1941, tried to answer was, do creatures and other living things evolve gradually and evenly? Or do they enjoy long periods of time in which there is little change, and then sudden periods of change, of branching off into a bunch of different species?

He theorized the latter. According to Gould, there is some gradual-and-steady drift in evolution, but most evolution occurs because of sudden changes in the environment, and therefore most branching evolution is comparatively swift.

Here is an explanation of punctuated equilibrium vs. gradualism.

Gould studied land snails. He wrote a book comparing the development of individual organisms (plants, animals, etc. from egg/seed/etc. to embryo to mature organism) and the development of species through evolution. He wrote articles and books for the general public. He argued about evolutionary explanations for human behavior and he fought against creationism being included in science classes. 

To learn more about punctuated equilibrium, check out this video. To learn more about land snails and Gould's work, check out this video

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