Science in Christian Perspective

 

 

Origin of Life *
WALTER R. HEARN**

From: JASA 13 (June 1961): 38-42.

Some of you may feel that I have a lot of gall to say some of the things I'm going to say this afternoon, so I may as well begin by rendering unto Caesar that emulation which is due him and divide my gall, like his, into three parts. (Now, Dr. Kraakevik told me this talk should be semitechnical, and I assumed that the "semi-" part would cover puns as well as misinformation, but maybe I was mistaken.)

In the first part of my talk I want to discuss some recent technical developments pertaining to the origin of life; in the second part, a little about the attitude of scientists toward this kind of investigation-the "climate" in which this work is being done, as it were; and finally, I want to comment on the reactions of Christians to these matters. All of my remarks will he rather sketchy, a few of them will be impertinent (to stir up more lively response from you during the discussion later on), and what I say will of course bear the marks of my own personal orientation both as a biochemist and as an evangelical Christian.

You may be aware that some reviewers of Evolution and Christian Thought Today in the conservative Christian press have felt obliged to put that word, "evangelical," in quotation marks when referring to authors of some of the chapters, or to prefix it with the adjective, "so-called." I shall have an opportunity at the banquet tonight to speak more fully of my Christian experience, so may I suggest that you leave those quotation marks only tentative until after this evening, anyway? Now then, since none of the reviewers felt obliged to call me a "so-called biochemist," I shall proceed now to the technical discussion and you can all relax, knowing it is safe to follow me that far at least. (As a matter of fact, I hope most of you can stand the suspense of leaving me inadequately classified for a while-you're likely to get a lot more out of the talk that way. I've noticed that when a speaker addresses a Christian audience and they don't follow him at all, if they think he's a good guy they'll say "Boy, that guy is profound!"-and if they think he is one of the bad guys they'll say, "Well, he sounded sorta liberal to me!" In either case, if they've got him pegged, they don't have to bother to try to understand what he says. Well, this

*Presented at the Wheaton College Science Symposium on "Origins and Christian Thought Today," February 17, 1961.

**Dr. Hearn is Associate Professor of Biochemistry at Iowa State University, Ames, Iowa.


will be an adult-western-type talk, so hold on to your seats: it'll be hard to tell the good guys from the bad guys. I'll try not to spoil the plot by giving myself away).

 Part I. (Technical)

The goal of all basic biochemical and biophysical research is increased understanding of the mechanisms of life processes: i.e., the translation of biology into the language of chemistry and physics. In a sense then, any advance in biochemistry is likely to shed some light on the scientific problem of the origin of life. If one concedes that the origin of at least some of what we think of as "life processes" may have preceded, or been concomitant with, the origin of life itself on earth, then learning the chemical details of life processes shows us what to look for in the nonliving realm so we can extrapolate intelligently back to the pre-living realm. Now, many exciting things are going on in fields such as intermediary metabolism, the study of viruses, and biochemical gentics particularly, which have a bearing on our ideas of the origin of life. Some of these have been spotlighted in the news, as when Severo Ochoa and Arthur Kornberg won the Nobel Prize for their work on the enzymatic synthesis of nucleic acids-work which should certainly make us ponder a bit before saying dogmatically that no possibility exists for the synthesis of new genetic material (which was said in a letter to the editor of Christianity Today a few weeks ago). In fact, I understand that in the discussion at the Darwin Centennial at the University of Chicago, H. J. Muller said that if the artificial "creation of life" could be defined as putting together a strictly chemical system that can synthesize new genetic material-well, then Kornberg has already done it! (I think this was regarded as a radical opinion, even in that environment.)

Another recent news story dealt with the complete determination of the sequence of amino acids in the protein of the tobacco mosaic virus work which may be of particular interest to this audience because at least two of the men who did it are devout evangelical Christians, C. A. Knight of the Virus Lab at Berkeley and Duane Gish, now at Upjohn and Co. One of the most fascinating and still most frustrating problems of current biochemistry is learning how the genetic information, encoded in the sequence of four repeating bases in the nucleic acid structure, is "translated" into the particular sequence of twenty repeating amino acids which gives each protein its specific biological characteristics. The TMV work is important because in this case a single protein is presumably associated with a single nucleic acid molecule, and now we know the "code" on the protein part. We still cannot read the code on the nucleic acid part, which will require a tremendous amount of chemical work to unravel-and we mav still be frustrated even then if it turns out that & nucleic acid code gets translated in the infected plant, not into virus protein, but into a different, still unknown protein, specifically the enzyme or enzymes which put together the virus protein. I emphasize this difficulty for the benefit of students in the audience who may get the impression that the really interesting problems in biochemistry are just about all solved, so you might as well go into some other field. STOPI DON'T JUMPI We are looking for new students sharp enough to come up with a way of cracking this nucleic acid code, of studying what goes on in an infected cell when virus particles are being synthesized, and of attacking a "host" of other challenging problems- In particular, I'm looking for some sharp graduate students, and I'll be happy to give you some literature to lure you into our department for your graduate training if you're qualified. If I should happen to miss contact with you, by all means write to me if you are the least bit interested.

I think the work you really want me to discuss, however, is the work aimed directly at the problem of the origin of life, and there is a considerable amount of this. I shall discuss some research not unrelated to the subjects I have just mentioned; as you can see we now have protein molecules which can catalyze the synthesis of nucleic acids, and there is plenty of evidence that the pattern for synthesizing specific proteins can be built into the structure of a nucleic acid molecule. There is still a huge gap in our understanding of the origin of metabolizing systems, i.e., complex enzyme systems in which endergonic (energy-requiring) reactions are coupled to exergonic (energy-yielding) reactions to give us a steady state not at thermodynamic e,quilibrium. However, I think you can see that if we can show that under conditions likely to have existed on the pre-biological earth, proteins and nucleic acids are formed chemically, then we have taken a big step in our understanding of the origin of life.

The significant work of Harold Urey and his student, Stanley Miller, in actually trying out some postulated primitive atmospheres to see what might happen, has been cited in my chapter in Evolution and Christian Thought Today. You will recall that a number of amino acids, the building blocks of protein, were found in the reaction mixture after those experiments. Since that time, a number of other investigators have continued along that line, and have shown that at least the simplest amino acids can be produced under a wide variety of relatively mild conditions. One effect of these findings has been to remove some of the restrictions, from the biochemist's point of view, on possibilities for pre-biological environments, still an area of some disagreement among geologists and geochemists. In a sense, whatever the environment, the origin of the building blocks of protein molecules has been settled.

With regard to the polymerization of these amino acids into proteins, there have also been some interesting developments. After many years of feeling that thermodynamic considerations would make this step essentially impossible, there is a rather sudden shift to thinking of it as highly probable. In fact, it has been shown that with HCN as an intermediate in the formation of amino acids (as in Miller's 1957 experiments), the amides of the amino acids are also intermediates, and we know that the energy barrier for polymerizing amino acid amides should be much lower than that for polymerizing the amino acids themselves. One investi, gator I know personally, John Oro of the U. of Houston, has shown that the amides can be polymerized readily under quite reasonable "primitive earth conditions." This might even make the amino acids products of protein-like materials via subsequent hydrolysis rather than their precursors under some conditions. (To put it crudely, you get to the chicken first, and then the chicken lays the egg instead of growing the chicken from the egg. That's about as crude as it can be putl)

Another investigator, Sidney Fox of the Oceanographic Institute of Florida State, has, however, also made a "breakthrough" in the polymerization of amino acids themselves into what he calls "proteinoids." (Incidentally, Urey and Miller are now attached to the Oceanographic Institute of the U. of California, so you can imagine what sort of rivalry goes on in this field between Tallahassee and La Jolla-but a public lecture is no place for gossip.) Fox tried thermal polymerization-i.e., just heating up a mixture of amino acids. Now generally, as all of us know who've ever left something on the steam bath too long by mistake, such a mixture is liable to give you a mess-"intractable tars" is the way you describe it in the literature (if you have to admit a reaction of yours went wrong somewhere). I'm not sure whether Fox actually looked this up before he planned the experiment, or whether one experiment worked and then he looked it up (and I was polite enough not to ask him when I talked to him about it this fall), but at any rate he noted that many proteins from widely varying biological sources contain relatively large amounts of the two acidic amino acids, aspartic and glutamic acids, so he loaded his amino acid mixture with these two and fired away. Whether to his surprise or not, this time he came out with a nice clean product, not crystallizable because it represents a heterogeneous mixture of polymeric molecules, but certainly much more pleasant to behold than the red-brown gunks he and everybody else had always obtained before. Recently he has been trying variations on this theme, tossing in phosphoric acid as a catalyst, etc., and has also been analyzing the polymers which he can make in this way. They deserve the term "protein-like" in almost every sense of the word, having molecular weights of around 10,000, containing all the amino acids, being hydrolyzed by proteases, etc. One feature of Fox's work, or rather of his description of it, that annoys some people in the field is his claim for "morphogenicity" of his proteinoids. In his paper in Science last July, Fox showed a photograph of "microspherules" which were formed by his proteinoid products and described these as models of primitive cells; you don't have to be from California to think that might be stretching the point a bit for effect. However, I think Fox's experimental work is important in spite of some annoyance at the way he writes: he has essentially proved the point that protein structures do form at temperatures under 100'C from mixtures of amino acids. There is even some indication in his work that the sequence of amino acids in these thermal co-polymers is not entirely random i.e., preferred sequence patterns may show up even this early in the game.

With regard to the pre-biological synthesis of nucleic acid precursors, there is also some interesting work by the same investigators. While heating up things, Fox put together some malic acid and urea, both reasonable components of "pre-biological soup," and found he had synthesized ureidosuccinic acid with unexpected ease; this compound. is a known biological precursor of the pyrimidine bases of nucleic acids. More significantly, Oro actually has produced adenine, one of the two purine bases, merely by heating ammonium cyanide at 70' C for half a day. Furthermore, from the same mixture he also isolated 4-aminoimidazole-5-carboxamide, and imidazole groups are now generally conceded to do a lot of the business in biochemical catalysis. The carbohydrate components of nucleic acids can be obtained, everybody agrees, if you have a little formaldehyde in the soup. So ... we are on our way, and more and more biochemists are getting into the soup-I mean, into the act.

Part II. (Less technical-wake up!)

The kind of psychological atmosphere in which this work is going on is pretty obvious, even if the nature of the ancient earth's atmosphere is still being haggled over. There is an air of exhilaration from the results of the few experiments already done that is bound to lead to new theoretical thought and subsequently to accelerated experimentation. This is the excitement of a "new frontier" (if I may use such a Democratic phrase on a protestant campus)-and the assurance that "thar's gold in that thar soup!" This enthusiasm over "prebiological evolution" is getting more biochemists interested in taking a closer look at mechanisms for biological evolution-and biology is liable to perk up considerably as a result. If you were under the impression that evolution was about to blow over, I think you've misread the weather signs!

The extent to which these ideas permeate the thinking of biochemists not actually working in the field was brought home to me only a few weeks ago when a manuscript I had submitted to a journal was returned to me with a referee's comment. The paper was on a laboratory synthesis of delta-aminolevulinic acid, a known biological precursor of the porphyrins (such as the heme of hemoglobin), and we mentioned that even though the yield was poor our method had some interesting analogies to the known biosynthetic pathway. The referee commented that our method did throw some light on a possible pre-biological pathway to porphyrins, but why didn't we use succinic anhydride instead of the acyl chloride? The anhydride was much more likely to occur in a pre-biological soup! Well, we wrote back to the editor that we hadn't had pre-biological evolution in mind at all when doing the work; and besides, we had tried the anhydride first and it didn't work-gave us only "intractable tars"!

Part III. (Danger-this is philosophical!)

Well, I've used up my time, so maybe we just won't have a third part and you'll never know whether the speaker was a bad-good guy or a goodbad guy-whether he belongs in quotation marks or not. I would like to say a few words about some of the people I've mentioned who are working in this field, in case you have them pegged as bad guys, a snarling bunch of vicious anti-Christian types plotting to do away with the necessity for God, or something. Well, they are certainly not vicious, and hardly plotting anything except how to do tomorrow's experiment. They know some interesting questions, they've found out how to get some good answers, and they're having fun. If you think of this as the Lord's universe then you should realize that these are the men wKo are having the fun of exploring it for you. You ought to get acquainted, you know? Last year at the Federation meetings I met Stanley Miller through John Oro and spent a marvelous afternoon talking about these things; he is a delightful chap. I don't know whether he has any strong feelings about Christianity or not; he may not even be aware of it yet as a live option, although I did get a chance to identify myself as a Christian in our conversation. John Oro has at least come in contact with evangelical ChristiansI was on his graduate committee. I have given copies of Evolution and Christian Thought Today to both John Oro and Sidney Fox. Fox is probably a thoroughgoing logical positivist with no concept of the supernatural at all, but as far as I could tell from a long discussion with him he has little interest in philosophical argument and none at all in undermining anyone else's position. He did say he would like to get 'people to think, but you can hardly blame him for that.

I know that Dr. Fox continually comes in contact with Christians, however-at least by correspondence. His work has been widely,publicized in the popular press, and he told me he has a huge scrapbook full of letters, some highly emotional, some denouncing him for monkeying around with God's Word (he receives Bibles in the mail regularly), and some calling him a fool for denying God by trying to do something anybody knows only God can do.

Now I ask you, if you are an evangelical Christian, is that the way you would go about trying to witness to Sid Fox?

I hope not. That's not the way I'm trying to go about it, anyway. Thank you.

REFERENCES

Hearn, W. R., and Hendry, R. A., The Origin of Life, Chapter 3 of Evolution and Christian Thought Today, Edited by Russell L. Mixter; Eerdmans, Grand Rapids, 1959.

Fox, S. W., The Chemical Problem of Spontaneous Generation. J. Chem. Ed. 34, 472-9 (October, 1957).

Harada, K., and Fox, S. W., The Thermal Copolymerization of Aspartic Acid and Glutamic Acid. Arch. Biochem. -Biophys. 86, 274-80 (February, 1960)

Fox, S. W., and Harada, K., Thermal ~opolyrnerization of Amino Acids in the Presence of Phosphoric Acid. Arch. Biochem. Biophys. 86, 281-5 (February, 1960).

Fox, S. W., and Harada, K., The Thermal Copolymerization of Amino Acids Common to Protein. J. Am. Chem. Soc. 82, 3745-51 (20 July, 1960).

Fox, S. W., How Did Life Begin? Science 132, 200-208 (22 July, 1960).

Oro', J., Kimball, A., Fritz, R., and Master, F., Amino Acid Synthesis from Formaldehyde and Hydroxylamine. Arch. Biochem. Biophys. 85, 115-30 (November, 1959).

Oro', J., and Guidry, C. L., A Novel Synthesis of Polypeptides. Nature 186, 156-7 (9 April, 1960).

Oro', J., and Guidry, C. L., Direct Synthesis of Polypeptides. 1. Polycondensation of Glycine in Aqueous Ammonia. Arch. Biochem. Biophys. (In press).

Oro', J., Synthesis of Adenine from Ammonium Cyanide. Biochem. Biophys. Research Commun. 2, 407-12 (June, 1960).

Oro', J., Synthesis of Purines under Possible Primitive Earth Conditions. 1. Hydrogen Cyanide Condensation in Aqueous Ammonia. Determination of Adenine after Acid Treatment of the Reaction Product. Arch. Biochem. Biophys. (In press).

Summary of Comments by Walter R. Hearn,

Wheaton Science

Symposium Panel Discussion 

February 18, 1961


In my talk on the "Origin of Life" I tried to point out that the success of recent chemical experimentation in this field has had a profound effect on scientific thinking: events interpretable as filling in the gap between nonliving and living systems are now regarded as being highly probable. At both the pre-biological and biological levels, there is great interest in The Molecular Basis of Evolution (see book with this title by C. B. Anfinsen, published by John Wiley & Sons, 1959).

Christians have sometimes taken refuge in the Second Law of Thermodynamics to argue against the evolution of complex living systems from simpler systems (R.E.D. Clark, for example). 1 consider this type of argument entirely invalid, and generally based on a misunderstanding of the Second Law. There is abundant evidence that local order can be produced in a system in which the general trend is toward disorder, as required by the Second Law. (For entertaining discussions of the "order from disorder" principle, see H. von Foerster, in Self-Organizing Systems, edited by M. C. Yovits and S. Cameron; Pergamon, New York, 1960.) Christians need not be upset by this idea if they are willing to focus their attention on God's universe as a whole, instead of only on minute parts of it, such as themselves. There is no less majesty in the view that the marvelous complexity of our bodies and minds was actually structured into the original creation, than in the view that there are limits to what God's matter can accomplish under His steady direction. I think there is also no reason in this view to think that God is any less personally interested in us, or that the Bible is any less His Word revealed to us.

However, many Christians have gotten into the habit of thinking of God's direct action in nature as always of a sudden, instantaneous type-never a steady type involving processes which could be studied by the scientific method. "Processes" are considered "natural" and instantaneous events "supernatural." This sort of thinking inevitably leads one to a "God of the gaps" philosophy, no matter how sophisticated he may be about the nature of the present gaps. I am for a "Science of the gaps"-that's exactly what science is for, to fill in gaps. I am also for a "God of Creation," who is involved directly in all natural processes (See W. B. Pollard, Chance and Providence, Scribners). I am baffled by the idea that God is "in" some events more than in others. An illustration in the spiritual realm: In what way was God involved in our becoming a Christian-in our own "New Birth"? Only at the "instant" of that birth? What a strange viewl  Surely He guided us to Himself through the
influence of others, the testimony of His Word, etc. And if so, then surely in the chain of events that
led to our physical birth (and what a chain of events, stretching back centuries while God pro tected our germ plasm in the bodies of our ancestors-and even beyond that), in the preservation of the Bible, and in all the other events that eventual ly brought us together in Christ. Why pick out only the event that is particularly dramatic to us personally and say "This was God's doing!" Why not get in the habit of seeing God's creative handi work in everything that happens? Only then can we honestly call ourselves His creatures, and Him
our Creator, for surely we know that processes have been involved in bringing us into existence.


Why shudder, then, at the idea that processes were involved in bringing Adam into existence? Granted
that we do not yet know details of the processes, why may we not assume that God did use processes?
This outlook probably makes me a "General Creationist" rather than a "Special Creationist" (see my letter to Christianity Today, "Evolution Revisited," September 29, 1958), but gives me no less reverence for Genesis as the revealed Word of God. I cannot understand why people are disturbed at my statement that "The expressions in Scripture regarding the creation of life are sufficiently figurative to imply little or no limitation on possible mechanisms" (Chapter 3 of Evolution and Christian Thought Today). Genesis says that God breathed into Adam the breath of life, and he became a living soul; surely no one would question that "God breathed" is highly figurative, anthropomorphic, symbolic language (and I hope no one would be so immodest as to say he knows exactly what the figure of speech means!). To say that I don't take this passage literally-i.e., that I don't think the Creator exhaled through mouth or nostrils-does not imply that I don't take the passage seriously; I regard it as true, as God's Word, as intended to reveal something about God to me. In addition, I think it is a beautifully poetic expression and I value it for this reason as well. Biochemical descriptions of God's creative activity are almost invariably more complicated and less beautiful.