Wednesday, February 01, 2006

Dembski steps in

The post I referenced earlier, in which someone at Dembski's blog insisted that common descent is the only scientifically justified statement about biology, is gone. Down the memory hole it went, only remembered across the entire blogosphere. Billy Dembski has stepped in to explain that common descent is not obligatory:
intelligent design neither rules out the common descent of life on Earth (Darwin’s single Tree of Life) nor restricts the implementation of design to common descent, … the truth or falsity of common descent is an open question worthy of informed discussion.

To open up Uncommon Descent in this way reflects not just the ID community’s diversity of views on this topic but also the growing doubts about common descent outside that community. For instance, W. Ford Doolittle rejects a single “Tree of Life” and argues instead for an intricate network of gene sharing events. Likewise, Carl Woese, a leader in molecular phylogenetics, argues that the data support multiple, independent origins of organisms.
Common descent in mainstream biological circles has always included the possibility of a small number of ancestors, a number which might be 1, but might be a larger small number. The dispute is whether there were a small number of origins roughly 3 billion years ago, or God/the Designer created all the "kinds," and let things unfold from there.

The people Dembski cites are not denying a single ancestor necessarily, but are arguing that instances of gene transfer between lineages make it impossible to identify a single common ancestor, that the early history of life may reduce to a highly interconnected trunk, unresolvable to the precise ancestor(s).

Darwin famously wrote:

There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
My emphasis. Darwinian biology clearly encompasses an origin of life with "a few forms."

What it does not encompass is the possibility that humans are a result of an act of special creation, a position many of the "witnesses" in the Kansas hearings espoused. The lack of resolution is among bacterial lines close to the origin of life. There is no scientific basis for saying, as Stephen Meyer did of human common ancestry with other mammals:

I'm not sure. I'm skeptical of it because I think the evidence for the proposition is weak, but it would not affect my conviction that life is designed if it turns out that there was a genealogical continuity.
(All references are local to those in the previous document, refer there for links).

Angus Menuge when asked: "Do you accept that human beings are related by common descent to prehominid ancestors?" replied "I doubt it."

Mustafa Akyol responded "I'm skeptical about it because I don't see any compelling evidence that there's a lineage between prehominids and humans."

Russell Carlson said: "I don't accept that as a fact."

Ed Peltzer: "No."

Nancy Bryson: "No."

Charles Thaxton: "Personally I don't, no."

Bruce Simat: "From the data that I've been following it's probably not true."

Jonathan Wells: "I think it's extremely unlikely based on the evidence."

The human genome is remarkably similar to the chimpanzee genome. All humans have remarkably similar genomes, and it's possible to trace the genetic ancestry of humans back to Africa, conveniently close to where chimpanzees live. Humans and chimpanzees share a chunks of viruses that got messed up and stuck in the genome, called endogenous retroviruses. There's no reasonable explanation for shared ERVs other than common descent. Humans and chimps share an ancestor. DaveScot was (and it pains me to say this) entirely right, "nothing but religion argues against descent with modification from a common ancestor."

And, ta-da! there Billy Dembski is doing something that is only justified by religious belief, not by biological data.