Lecture Report

Christian deDuve Lectures on the Origins and Evolution of Life at UCSD

by Casey Luskin
Graduate Student, Earth Sciences, Scripps Institute for Oceanography

On Thursday, April 5th, Nobel laureate Christian de Duve gave a free public lecture at UC San Diego, sponsored by the NASA Specialized Center of Research and Training  (NSCORT / Exobiology) at the Scripps Research Institute and Scripps Institution for Oceanography.  De Duve, who won the Nobel Prize for medicine in 1974 for discoveries concerning the structural and functional organization of the cell, titled his lecture, "Reflections on the origins and evolution of life."  This was the 3rd talk sponsored by NSCORT--2 years ago Freeman Dyson spoke on the origins of life.

De Duve's lecture was very interesting, as he started off by saying that most of his life he's been a research biochemist, but only in the last few years has he become an "armchair" theorist with regards to the origins of life.

De Duve is convinced that all of the necessary origins of life prebiotics could have come from outer space.  He very briefly flashed an overhead as evidence for this claiming that the 1968 Murchison meteorite contains amino acids were found in the same proportions as they are produced by Stanley-Miller type experiments.  He thus concluded that Stanley-Miller-experiment type processes were going on in outer space and producing amino acids in meteorites.

That was surprising to me because Stanley-Miller type experiments have been done a thousand different ways, each often producing very very different results.  So many experiments have been done, that to say it is a something like a perfect match could be a meaningless stretch.  Furthermore, if the processes are indeed Stanley-Miller-like, how could they get amino acids into stony meteorites in the first place.  He also failed to discuss the common lack of organics in many meteorites, such as this one reported for the New York Times on April 6th, 2001.  In any case, he used that to justify his claim that pre-biotics came from outerspace.

As far as pre-biotic chemistry goes, de Duve had some pretty radical things to say.  He started off with an interesting statement, stating that "Nowadays, a lot of importance is being put on information".  But he cautioned us to remember that information is carried by molecules.  I was glad that at least he gave information a cameo appearance, but as Phillip Johnson noted in personal communication, "The question isn't how information is carried, but how it is created".  I very much agree, and de Duve never attempted to address that question.

De Duve's question was, "what preceded the appearance of catalytic organic molecules?"--where did enzymes come from?  He said that the first proteins were made by RNA molecules interacting with one another.  Occasionally an RNA molecule would experience a mutation, and perhaps a new protein would be created--one with catalytic capability, which today we might call an enzyme.

Now he noted that more than just catalytic capability is necessary to make a protein special--enzymes only work if they have a substrate, something upon which to act, and an outlet--an end product which is useful!  So, from a non-biochemist's perspective, this has to be a moderately complex, but highly specified molecule which requires a lot of other molecules to be functional.

He went on to say that life as we know it today requires 200 and 300 enzymes to function at the most barebone level.  How did these all come into existence?  He finds it unlikely that enzymes were progressively accumulated in a Darwinian manner in a population of simple organisms, but rather said that in the pre-biotic chemical world there were tons of enzymatic-like reactions going with protein-like molecules which could catalyze reactions between other protein-like molecules.  As far as I could tell, all of this was going on for no apparent reason--there was just this sea of catalytic proteins out there ready for use by these proto-metabolic organisms.

The pre-metabolic RNA strands somehow hijacked all these enzymes for their own personal use, and somehow started making them, so that they could then be better reproducers themselves.  The proteins selected for the RNA, and the RNA selected for the proteins.

His conclusion was that getting the first true metabolism required many re-biotic chemical reacions, involved a large number of steps, and took a long time.  However, he believed that given the right conditions, that one would end up with life over and over again if on kept trying.  Essentially, he saw the origin of life as highly determinstic and "bound-to-happen eventually" as long as the reactions kept trying to get there.  He thinks there's life "out there" even if we never see it.  That's a good thing to say when you're speaking for the NASA Center for Exobiology!!!  However, I was waiting for him to tell us why it was necessary to have this sea catalytic peptides doing nothing but catalyzing reactions among their molecule friends.  Sounds pretty chance-dependent to me.

(He also said at one point that the origins of life require many steps, unless we are going to believe in miracles, but we aren't allowed to use miracles as a working hypothesis in science.  This drew a laugh from the audience.)

De Duve then switched gears and discussed the evolution of life, in somewhat philosophical terms.  He said that all mutations are accidental, and that they do not foresee into the future to know what they might ultimately do.  Mutations also must face the chance of the environment selecting for them.  The best mutations will only make it in the right environments.  He said that essentially, the mutation-selection mechanism is like a "chance squared" scenario, as two levels of chance must be met in order to make it--the mutation must occur, and then it must find itself in an environment which allows it to be useful!

However, despite all this chance, he disagrees with the common "evolutionary dogma" that if we were to "play the tape over again" that it would turn out completely differently.  While he agrees that chance plays an important role, he said that chance does not exclude inevitability.  In other words, if you play the lottery enough times, at some point you're bound to win.  What matters is the number of opportunities you provide, not the odds.  I agree, but I also think the number of opportunities available, especially given time constraints alleged by the fossil record, are still way too low to build the types of complexity de Duve was talking about.

He did a calculation showing that on average one point mutation occurs every 20 billion cellular divisions.  In a bacterial culture, this is one point mutation per day.  For a eukaryotic unicellular organism, this is once per month.  For human red blood cells, this is once every 2 hours.  We're lucky, he said, because we have many systems which can repair these rapidly ocurring mutations in our bodies.  He used the following examples of how point mutations cause evolution:

Finally, he said that given enough time, things such as fish turning into amphibians WILL happen!  He had a great diagram where he showed that it is a lot easier for one fish to turn into many fish species, than for one fish to turn into something with a completely different body plan, like an amphibian.  The diagram was great because it so clearly illustrated the difference in complexity between building variation on a kind, and creating an altogether new body plan.  Nonetheless, although he conceded that building new body plans was less likely to occur than say, creating a new species of fish through a few point mutations, he still maintained that occasionally the conditions are "just right" and you get new structures and great increases in complexity.  He said that "the drive to further complexity is not obligatory, but given the right conditions, it could happen".  He believes that there is a lot more necessity than chance out there.

Basically, all in all, there was so much hand waving in this lecture that I had to duck to avoid getting hit.  But, one of his conclusions was perhaps the best part, because I believe that he gave the whole house away:

He said that today, we need to recognize that there are forces beyond mere chance and necessity.  Human guidance plays a large role in the world today, and will continue to play a role in the future.  So does this legitimize intelligent action as a cause?

I wanted to ask him a question, but never got up the nerve, but here's what it would have been:  "Given the conclusion of your talk was that human guidance is a possible force shaping nature today, is there any reason that intelligent action should be excluded as a cause shaping the past?"  Now I don't believe that natural intelligent action created life in the past, but that doesn't matter--it takes away the "well, where's the designer" excuse from the ID-skeptic.  I realize this issue is much more complex, but the essence I think is on the side of ID!  Intelligence exists today and shapes the world we live in--who are we to say it couldn't have existed and acted in the past?

Another good question came from a physics lecturer I know who is often very skeptical of the naturalistic theories.  He asked how the proto-metabolic cells were able to encapsulate all their necessary enzymes in the first place.  De Duve said that cellular membrane-like structures are easy to make (they've been created in the lab), but to me it still sounds pretty far fetched that somehow all the right beans would end up in the same bag.  And then the beans have to learn how to make the bag themselves. Perhaps, as de Duve said, given enough time, such things are inevitable.

For now, de Duve, and many other scientists, are holding out in faith that blind chance will do the job for the origins and evolution of life.  Perhaps they're right to do so, but perhaps also they're buying tickets for a lottery that simply never took place.

Copyright 2001 Casey Luskin. All rights reserved. International copyright secured.
Filel Date: 4.09.01