axocanth
Registered Senior Member
Ax, You and Parm are both well read in Phil of Sci, so I may have to sit on the sidelines for a while with this thread and just try to keep up. Occasionally I may ask for clarification. E.g. when one speaks of a challenge to evolutionary theory, it is helpful to ask what part. The bucolic banjo players specifically target speciation (we are divinely created not the great-grandchildren of monkeys, by gum!). IOW they direct their gap-toothed sneers at macroevolution while grudgingly acknowledging well-observed instances of microevolution, like darkening beetles. Punked Eek, otoh, challenged Darwin's (and Wallace's) slow and steady version (phyletic gradualism) with something quite different, rapid and infrequent cladogenesis. Calling the present body of theory Darwinism does seem silly, rather like calling modern physics Galileanism.
I'll quote Gould at some length shortly. Other PE exponents such as Niles Eldredge and Steven Stanley say very similar things. I'd just add first, for what it's worth, that all three are a delight to read, wonderfully clever and sophisticated men, such a breath of fresh air compared to the likes of Dawkins' naivete and simplemindedness (Parmalee's observation about certain scientists not thinking comes to mind). Indeed, I do wonder if Dawkins even understands the force of the PE critique of traditional Darwinism, as it is quite subtle, even philosophical in parts. As you'll see in the quotes below, Gould does too.
All quotes below, unless otherwise attributed, are from Gould's 2007 "Punctuated Equilibrium".
In a nutshell, what is this "profound departure" that Gould speaks of? Essentially this: The traditional view is that macroevolution is nothing but microevolution writ large; the former reduces to the latter. In other words, the forces that drive short-term, small-scale evolution can be extrapolated to explain all evolution, even the dramatic fish-to-TheVat type changes that we all intuitively think of as evolution, rather than the insignificant changes happening within populations of moths or finches that not even Creationists deny.
The PE mob say the opposite: macroevolution does not reduce to microevolution. Clearly, whether they're right or not, this is not being advanced as a "complement" or "extension" of traditional theory; it's a direct contradiction thereof.
First a mental-masturbatory pause . . .
We've recently been looking at the vexed issue of scientific realism vs antirealism, asking questions such as "Is dark matter real?" But what about species?
It's not entirely clear that even Darwin himself believed that species are real, suggesting in some places that they are nothing more than arbitrary sections on a continuum. Scholarly opinion differs on Darwin's view of this, while biologists themselves take different attitudes to the reality of species, at least among those who contemplate the issue at all. The two dozen or so competing "species concepts" vying for attention should also be a warning sign to readers. Even among biologists who affirm the reality of species (and some don't), there exists nothing like a consensus on what a species is.
Now, as everyone knows, one major tenet of PE theory -- the "trade secret" of paleontology -- is that what typically (not always) happens is this: In contrast to traditional Darwinian gradualism, species enter the fossil record abruptly, change little or not at all for a few million years, then disappear just as mysteriously.
But, punctuated equilibrium was never formulated as a hypothesis about great variability in anagenetic rates (which, indeed, everyone has long acknowledged). Punctuated equilibrium presents a specific hypothesis about the location of most evolutionary change in punctuational cladogenesis, followed by pronounced stasis. - p345
This realization allows for a complete reconceptualization of what species are. They are not only real, but they are individuals. This is the more philosophical part of PE doctrine that I alluded to above, and it takes a while to get your head around it.
Species are real insofar as they have a fairly well defined beginning (or birth, if you like), a well defined end (i.e. extinction), and a fairly stable "lifetime" in between, not unlike an individual organism (e.g. Louise the kitten) or a tornado, say.
To say that species are individuals is in contrast with the traditional view that species -- if real at all -- are more like sets constituted by their members. On the traditional view, every individual tiger is a member of the set tiger. On the PE view, in stark contrast, each individual tiger is a part of an individual whole: the species tiger, just as your head is part of your body, or each star is part of a galaxy, or each individual state is a part of an individual whole: the USA.
Traditional Darwinian gradualists would deny individuality to species by arguing that they are mere abstractions, names we give to segments of gradually transforming lineages. But under the punctuated equilibrium model, species are generally stable following their geologically rapid origin, and most evolutionary change occurs in conjunction with events of branching speciation, not by the transformation in toto of existing species. Under this model, therefore, species maintain the essential properties of individuals and may be so designated.
- S J Gould, essay "Challenges to Neo-Darwinism", found in "The Richness of Life", p 226
Now, being real and being an individual has its advantages, not least you can do stuff; you can play a role in the evolutionary drama, exactly analogous to that played by individual organisms in traditional theory. Species, just like individual organisms, have properties that are distinguished from the properties of each individual organism. Some species, for example, might have a wide geographical range, conferring an advantage to them in the survival game in the event of a localized meteor strike, say.
"The theoretically radical features of punctuated equilibrium flow from its proposals for macroevolution, with species treated as higher-level Darwinian individuals analogous to organisms in microevolution"
- S J Gould, essay "The Structure of Evolutionary Theory", found in "The Richness of Life", p 243
Here endeth the navel gazing.
This now leads to what PE exponents frequently speak of as an "uncoupling" or "decoupling" of macroevolution from microevolution, opening up an entirely new realm of research. You won't understand the large, significant, long term changes in the saga of life by applying the same principles as you do to finch beaks and changes in moth color frequencies, let alone characterizing evolution as something that happens to genes (Dawkins).
A new hierarchy now emerges wherein not only individual organisms are actors in this grand play, but individual species, and perhaps even higher taxa, are too.
to be continued . . .