Sunday, April 13, 2008

Barbour Correction

Reading through Barbour's essay "Ecological Fragmentation in the Fifties," I noticed one statement that seemed strange to me and I was wondering if anyone else noticed or can interpret what he meant.

On page 244, he says "The theory (paradigm) that continuous evolutionary change marks the history of life required many decades to displace an earlier theory of stasis."

To the best of my knowledge it is the other way around. Paleontologists originally explained gaps in the fossil record as a result of incomplete data, a flaw that had to be ignored. They believed that the incomplete data belied the historical fact of continuous, gradual evolution. Then, in 1972, Eldredge and Gould published "Punctuated equilibria: an alternative to phyletic gradualism," which explained that gaps in the fossil record are real and represent long periods of relative stasis, punctuated by relatively rapid bursts of evolutionary change (rapid on a geologic time scale). This theory was met with resistance at first and took time to become more widely accepted.

Perhaps Barbour was simply referring to the rise of the original theory of evolution by natural selection. In any case I think it is important to clarify that many scientists today do NOT believe in continuous, gradual evolutionary change, but instead adhere more closely to the theory of punctuated equilibrium.

1 comment:

Jim Tantillo said...

Not having Barbour handy, from the sounds of it he is talking about the evolutionary change paradigm overtaking the Clementsian climax theory paradigm, which emphasizes a stable climax as the naturally-occurring endpoint of successional change. As opposed to the model ecologists now seem to embrace, i.e., of nature in constant flux.