
I need to figure out if my counter is looking at total hits or unique visitors (I assumed the latter; does anyone know?).
The image is from Gregory's recent book which, unfortunately, I have not yet read. It's been on my list for a while...
"...we favor the idea that the host that acquired the mitochondrial endosymbiont was a unicellular eukaryote predator, a raptor. The emergence of unicellular raptors would have had a major ecological impact on the evolution of the gentler descendants of the common ancestor. These may have responded with several adaptive strategies: They might outproduce the raptors by rapid growth or hide from raptors by adapting to extreme environments. Thus, the hypothetical eukaryote raptors may have driven the evolution of their autotrophic, heterotrophic, and saprotrophic cousins in a reductive mode that put a premium on the relatively fast-growing, streamlined cell types we call prokaryotes."In essence, complex eukaryotes came first, followed by prokaryotes which evolved by reduction. In today's letter, Martin et al. point out that this is a re-clothed view of eukaryotic evolution that was popular in the early 1980s. At the time, this idea was mostly centered on the origin and evolution of introns, which were assumed by some to be responsible for building the ancestral set of protein-coding genes by exon shuffling (the introns-early view); to be true, massive intron loss must have characterized the (reductive) evolution of prokaryotes. This scenario has since been thoroughly debunked. Although Kurland et al.'s hypothesis includes more than introns, it suffers from the same problems that led to the demise of introns-early.
"...cellular and molecular biology, especially genomics, reveals signs of an ancient complexity of the eukaryotic cell. This new information was not available to older hypotheses for eukaryote origins..."I don't find Kurland et al.'s arguments any more compelling than when I first encountered them almost twenty years ago. However, it's great to see these important questions being discussed on the pages on Science.
"DO WE need another popular book on evolution? That 54 per cent of adults in the US believe we did not evolve from earlier species is reason enough, but David Sloan Wilson's book also has much to teach those of us who are already convinced. His aim is to show that evolution can transform our basic understanding of everyday life. We have no problem believing in the physical sciences, he says, because we are so used to them in our lives - when we drive cars or build bridges, for example. Evolution is different, yet without it we can't understand medicine, politics, economics, art and, yes, religion. With a clear passion for the subject, Wilson shows that understanding evolution is easy, even intuitive - it really is for everyone. If only everyone would read his book."I'm only three chapters into the book so far, but I'm already really enjoying it; I'll report more later. In the meantime, if anyone has comments on the book (or article), please leave them.