In his debate with Rick Warren, Sam Harris provides us with the conventional perspective on evolution:
HARRIS: I'm doing my Ph.D. in neuroscience; I'm very close to the literature on evolutionary biology. And the basic point is that evolution by natural selection is random genetic mutation over millions of years in the context of environmental pressure that selects for fitness.
WARREN: Who's doing the selecting?
HARRIS: The environment. You don't have to invoke an intelligent designer to explain the complexity we see.
Harris is correct in noting that we don't have to invoke ID to explain "complexity." I, for example, merely tentatively infer ID because of certain data patterns. But that's another topic. Instead, I'd like to focus on the conventional definition "“ "evolution by natural selection is random genetic mutation over millions of years in the context of environmental pressure that selects for fitness." While I agree this is a valid perspective of evolution, I would suggest the problem is that it is incomplete. That is, it is a superficial perspective on evolution. Perhaps this is why it appears to have misled the scientific community and public.
We have just seen how the conventional view of evolution appears to have gotten it severely wrong on something as fundamental as the origin of mammals.
According to conventional views, dinosaurs had ruled the Earth by soaking up all the good niches. As Krauze explains:
Once upon a time, the world was ruled by the dinosaurs, with mammals being confined to cracks and crevices. But the fortuitous impact of an asteroid caused the dinosaurs to go extinct, paving the way for the advance of mammals and, ultimately, us. That, plus some philosophical bon mots about the randomness of evolution, has been the traditional story of mammalian evolution.
It is important to remember two things for historical record. First, this conventional view quickly became deeply embedded in evolutionary science. In other words, this was not some question of scientific minutia, this was an explanation for the origin of mammals and it became an instant hit, finding its way into countless textbooks and museums.
Second, this view of mammalian origin is a direct product of the conventional view as outlined by Sam Harris. It was a story that highlighted the central roles of contingency and the environment. It was the environment that kept mammals from evolving into anything of significance during the Age of the Dinosaurs and it was again the environment that was behind their massive radiation once dinosaurs went extinct. And what unleashed all this massive environmental pressure? The raw contingency of an asteroid impact. This is a story that was both scripted by the conventional view and then was used to support the conventional view. In essence, scientists saw what they expected to see. This was a story that appeared to be strongly supported by "the evidence."
But it now appears it was all wrong.
According to the Bininda-Emonds et al. study (discussed by Krauze), the cornerstones of the conventional theory have been removed, as their study undermines the conventional view from both sides. First, it shows that mammals underwent some rather extensive evolution while the dinosaurs "ruled the Earth"; all of the extant orders of mammals appeared before the dinosaurs went extinct. And as if this isn't bad enough, once the asteroid hit and the dinosaurs went extinct, opening up all sorts of new niches, no massive radiation of new mammalian evolution was triggered; it wasn't until 10 million years later that the mammals began to radiate at the family level. In short, there seems to be a distinct disconnect between mammalian evolution and the environment, clearly indicating that Harris's notion of the environment doing the "selecting" is a superficial perspective on evolution.
We are now left with the following pattern. Egg-laying mammals split off the rest about 166 million years ago. Then, about twenty million years later, marsupials split from placentals. Nothing much happened for about 50 million years, then over the next 20 million years or so, all of the extant orders of mammals had evolved. Ten million years later, the asteroid hits and the dinosaurs go extinct. Ten million years later, the mammals again begin to significantly diversify over a period of 40 million years.
The challenge for the conventional view is to come up with environmental pressures at these key points, while explaining why the environmental changes associated with a global catastrophe and global-wide die-off seemed to have no effect. The alternative is to hypothesize that environmental pressures are secondary evolution forces that are more important in small-scale acts of fine-tuning. That is, the truly interesting evolution may emerge from factors that are intrinsic to life.