Supergeek

One of the hallmarks of complex life is the development of creatures with a two-sided body plan. Mammals, reptiles, birds, fish, insects, all fit the description: They are creatures with a left and a right side that are roughly mirror images, or symmetrical. This is as compared to simpler, earlier life forms that had no such symmetry (such as amoebas).

Well,

[b]lob-like fossils dating back about 600 million years may indicate that complex life evolved much earlier on our planet than had been thought, scientists say.

The animals are less than a fifth of a millimetre long and have a two-sided body plan previously thought to have existed much later in Earth's history.

These "bilaterians" have what look like mouths and guts, as well as internal and external layers of body tissue. ...

The animals - their scientific name is given as Vernanimalcula guizhouena - even have what look like pits in their outer surface that might have contained sensory organs.

If the find holds up - and some scientists are openly skeptical, suggesting that what look like fossils might be natural mineral formations - it would push back the development of complex life to at least 50 million years before the so-called "Cambrian explosion" which featured a seeming sudden emergence of a huge variety of shapes and sizes.

It could affect not only the timeline of evolution but our understanding of it. Stephen Jay Gould's terrific book on the Cambrian explosion, Wonderful Life, was what convinced me as an interested layperson of the validity of the "punctuated equilibrium" notion of evolution, which features sudden outbursts of change with little change between. That's as opposed to the more traditional idea of slow but relatively steady accumulation of small genetic changes selected for survival. (I like to imagine punctuated equilibrium as being like a water pressure valve designed to release pressure if it exceeds a certain level. Invisibly to the observer, the pressure is building up - in life terms, DNA changes are accumulating - until it reaches a critical point when there is a sudden, dramatic shift.)

However, if the roots of complexity are much older than thought, that is, as research team leader Jun-Yuan Chen of Nanjing University writes,

the genetic toolkit and pattern formation mechanisms required for bilaterian development had already evolved by Doushantuo times, long before the Cambrian,

the "explosion" may not have been quite the sudden burst scientists had believed, which could affect the reading of "punctuated equilibrium" versus "steady accumulation of change over time."

I should note that Gould was a rather controversial figure among paleontologists, who accused him of all sorts of intellectual crimes, most of which boiled down to he had a flaming big ego (which he most certainly did), he had political convictions (which he also did, and very progressive ones), and he disagreed with the ideas of the paleontologists who were accusing him of having an ego and political convictions.

While the ideal of science is a dispassionate search for truth, of course it rarely works that way in practice, and personalities and egos play a real role. Nowhere is that more true, it seems, in paleontology and archaeology, where disputes over hypotheses can become quite bitter and personal. I suspect it's because unlike, say, physics where you can at least hope to have quantifiable results that will settle things one way or another, paleontology and archaeology will forever have a large measure of interpretation. So it's necessary to constantly filter through personal animosities to get at the actual arguments. (Interestingly, one of Gould's controversial arguments, one for which he received a great deal of flak, is that the science of a time is affected by the cultural atmosphere that surrounds it.)

Ultimately, I believe that much of the criticism directed against Gould was that he wrote for a popular audience rather than focusing on research to be published in scholarly journals. Because of that, he was considered by some to be somehow less of a scientist and therefore less deserving of serious consideration - and therefore those same some tended to be outraged by (and jealous of) his notoriety. This was much the same fate that befell Carl Sagan, whose public popularity was in and of itself sufficient cause for some to malign him as an astronomer.

Yes, we do need the scientists who will do the uncelebrated research and publish in musty, jargon-laden journals that only others in their field will read (or understand). But we also need the popularizers, the scientists who understand what others have discovered and translate it into terms the rest of us can understand, appreciate, and become excited by. Sagan was one such, Gould was another.

Footnote: For a somewhat dated but still fuller discussion of the debate between punctuated equilibrium and gradual change, try here.