Sunday, July 22, 2007

Listening to the Sky

I went to a public lecture by Geraint Lewis last night on cosmic background radiation and the inflationary model of the universe.

Curiously, I have come away with rather more scepticism about the Big Bang model than I had hitherto. I still think that the weight of the evidence is vastly in its favour. Declaring my biases, I still find it vastly more congenial to my worldview. However, I would no longer put it in the ‘that’s settled, then’ basket with continental drift and the evolution of all terrestrial life from a common ancestor.

(1) Briefly, the basic big bang model predicts background radiation in the universe that fits the blackbody radiation curve and is homogeneous with the same intensity in all directions. The steady-state model doesn’t. We have found background radiation which beautifully, definitely, fits the blackbody radiation curve. However, it is not homogeneous. Is it easier to tweak the big bang theory so that the radiation isn’t homogeneous, or the steady-state theory so that the background is thermal? Probably the former. And there are a lot of other problems with the steady state theory. Still, I can’t help wondering- if for purely historical reasons most theorists had stayed in the steady-state paradigm and devoted their lives to tweaking it, and only a few crackpots had kept beavering away at the big-bang model, would we have an elegant steady-state model today that fit all the data perfectly? Maybe we wouldn’t, but maybe we would. I just am not as sure as I was before that the universe is busily beating us over the head with the right answer.

(2) This is not an objection to the theory at all, but it is something I hadn’t known before, and it would certainly be something that would be shouted to the rooftops if a similar situation were to arise today- e.g., if a researcher affiliated with an oil company came up with a theory for climate change that confirmed the expected biases of their employer, even if it fit the data better than the anthropogenic global warming one. The Catholic church is not just perfectly happy with the Big Bang because it is consistent with Catholic ideas: it was a Catholic priest who came up with the theory.

Friday, July 13, 2007

The Clone Wars

I don’t see anything intrinsically wrong with reproductive cloning.

I think it would be handy for all sorts of people who because of disease, accident, sexual orientation, or vocation, are unable to pass on their genetic material in the regular way. It has two problems, but these are problems shared by other assissted reproductive technologies:
(1) Wastage of ‘surplus’ embryos. I know nature does this, but I still think we should strive to keep it to a minimum.
(2) Health problems in the offspring. These are well documented but relatively minor for children put together by in vitro fertilisation. With cloning on the other hand, in the mammals we have looked at so far there are all sorts of peculiar and unexplained health problems. It would be criminal to experiment on human reproductive cloning at the moment because of these problems.

But there is no reason we should not keep on experimenting on our near relatives. Primates seem to be tricky things to clone. By all means let us try to clone chimpanzees. Once we can reliably clone perfectly healthy chimpanzees with a minimum of embryo wastage, why not apply the same technology to ourselves? I see no rational reason not to.

I do see therapeutic cloning as intrinsically wrong.

I think deliberately creating human embryos in order to destroy them is going too far. I don’t lose a great deal of sleep over it, because I was lucky enough to hear a talk in February 2006 by Graham Parker who is on the board of the journal ‘Stem Cell Research’ and works at a research hospital in Michigan. I learned the following things:

(1) The more differentiated a stem cell is when you start messing around with it, the more effective it is. This is why we still need to donate blood, and don’t just culture haemotopoetic stem cells. Inner-cell-mass-derived (aka embryonic) stem cells are less differentiated than somatic (aka adult) stem cells and appear much more likely to turn into invasive cancers when you inject them into mice.

(2) Nobody has a clue how stem cells really work clinically. It does not look like they just move in and turn into the sort of cells that are around them. They do other weird things that nobody understands yet.

(3) The chaps who first discovered inner-cell-mass-derived stem cells never claimed they had clinical uses. They still don’t. They are of fundamental importance in understanding developmental biology, which is important fundamental research and will eventually lead to all sorts of innovations- but they won’t involve injecting people with stem cells. 97+% of this fundamental research could (and should) be done with stem cells of the other mammals that we share so much of our DNA with.

This suggests to me that we are not likely ever to have a situation where therapeutic cloning would be done on an industrial scale and would be a big moral quandary for anyone with a serious illness. And if someone says, ‘I want to experiment on human embryonic stem cells’, the correct response is, ‘go do your experiments on chimpanzee embryonic stem cells’. There is no justification for playing with human embryonic stem cells. Maybe, once you have demonstrated that you can reliably and safely repair damaged chimpanzee brains, or whatever, then we can sit down and have a debate on extending the technology to humans.