The story of human evolution is a truly amazing story. For some helpful (free) interactive sources on human evolution see the great video here (from ASU’s Institute of Human Origins) and this PBS Evolution activity.

To date, the story of evolution has been the story about what happens to a whole organinism. But can evolution happen within a single organism? Today’s Nature news has a truly fascinating News piece on this issue by Philip Ball entitled “Why a person doesn’t evolve in one lifetime“. It is well worth reading, especially if normative theorists are serious about taking people as they really are. Here are a few excerpts from this article:

It’s not easy making a human. Getting from a fertilized egg to a full-grown adult involves a near-miracle of orchestration, with replicating cells acquiring specialized functions in just the right places at the right times. So you’d think that, having done the job once, our bodies would replace cells when required by the simplest means possible.

Oddly, they don’t. Our tissues don’t renew themselves by mere copying, with old skin cells dividing into new skin cells and so forth. Instead, they keep repeating the laborious process of starting each cell from scratch. Now scientists think they know why: it could be nature’s way of making sure that we don’t evolve as we grow older1.

Evolution is usually thought of as something that happens to whole organisms. But there’s no fundamental reason why, for multicelled organisms, it shouldn’t happen within a single organism too.

….To renew themselves, epithelial tissues retain a population of undifferentiated stem cells, like the unformed cells present in embryos, that have the ability to grow into different types of cells. When replacements are needed, some of these stem cells divide to make transient amplifying cells (TACs). The TACs then divide several times, and Pepper and his co-workers think that each division produces cells that are a little more developed into mature tissue cells.

All this costs a lot of metabolic energy, so it is not very efficient. But, the researchers say, it means that the functions of self-replication and proliferation are divided between separate groups of cells. The stem cells replicate, but only a little, and so there’s not much chance for mutations to arise or for selective pressure to fix them in place. The proliferating TACS may mutate, but they aren’t simply copying themselves, so there isn’t any direct competition between the cells to create an evolutionary pressure. As a result, evolution can’t get started.

Pepper and his colleagues have used computer modelling to show that this proposed mechanism can suppress evolution in a long-lived, multicelled organism.

….The researchers think that their hypothesis could provide new insights into cancers more generally. Whereas conventional wisdom has it that cancer is caused by some genetic mutation that leads cells to proliferate uncontrollably, this new picture implies that the problem would lie with TAC mutations that interfere with differentiation — so that a TAC cell ends up just copying itself instead of producing cells on the next rung up on the way to mature tissue cells.

Cheers,
Colin

A friend asked us to look over Joseph Chilton Pearce’s recent The Death of Religion and the Rebirth of Spirit. As usual he expresses a strong dislike of Western Religion, which he would like to think is dying. On one page he described “a university professor I knew”, a former “preacher” who “wrote a brilliantly researched book” in which he denounced monotheism; it caused wars.

His friend, and Pearce himself remind me of several seminary students, disillusioned by lessons from more advanced teachers, who turned their hostility upon “religion”; one of them took up a beatnik role in the French Quarter (of N.O.). We could hope that at least some of those unfortunate young men might in due time have worn out their hostility toward organized religion.

A larger number of men I knew became disillusioned at the parish level; they usually didn’t “throw out the baby with the bath water”, the way it appears to me that Pearce did.

Strange! he’s a habitue of Indian gurus. Apparently he doesn’t consider this ‘religion’, but I do. He has his own religion although he would never own to it.

I’ve known so many people who went that route, and more often than not, the attraction of Indian religion seemed to be primarily a reaction against western religion. (Jung would have found that a matter of great concern.)

There are religions and religions, even western ones. I yield to no one in my criticism of the abuse of the Christian religion. The abuses (and the wars) began when Constantine took possesion of the church, and unfortunately it’s still in that Captivity up to the present, when princes of the church will signal support for just about any cockeyed war the latest Constantine wants to convene.

But that doesn’t impeach the gospel; if they had only stuck to it in 325.