What makes it an irony is the unexpected fact that the issue [Darwin] chose not to tackle (abiogenesis v biogenesis) — is itself raised by his own presupposition, that life begets life. The irony does not change the fact that Darwin did not posit a theory to address abiogenesis v. biogenesis.
Hello Alamo-Girl! It seems the only way I can understand what the fuss is all about regarding this “life only from life business” — which is implicit in Darwinist evolutionary theory as you point out — is that there are people here who would be crushed by the idea that life cannot arise spontaneously from physics and chemistry. Even though Darwin didn’t have a “dog in that fight” respecting biogenesis vs. abiogenesis, it seems many people today do. I get the distinct impression that not only do some people want life to be the spontaneous product of physics and chemistry exclusively, but they absolutely insist on it.
Pasteur’s name has come up before on this thread. I think it is js1138’s view that all Pasteur really showed was that maggots are not spontaneously generated by rotting meat. (I could be misquoting here, and if I am, I’m sure I’ll hear about it.)
Yet regarding the immense contribution of Pasteur to biology, Hubert P. Yockey writes (in Information Theory, Evolution, and the Origin of Life, 2005):
One of Louis Pasteur’s (1822–95) more important discoveries, relevant to the nature and origin of life, is that ammonium tartrate tetrahydrate when made from grapes has only the left-handed molecules…. When examined in a polarimeter, they are found to rotate the plane of polarization of light to the left. Ammonium tartrate tetrahydrate made synthetically is racemic, that is, composed of equal numbers of right-handed and left-handed molecules. The human hand is chiral. Each hand is the mirror image of the other. Neither can be superimposed on the other. [Emphasis added.]From life comes life.Pasteur carefully selected the two kinds of crystals, called optical isomers, and found that each rotated the plane of polarization in opposite directions, one left and the other right. He prepared a synthetic ammonium tartrate tetrahydrate solution and contaminated it with a mold. The solution became more optically active with time. It followed that the mold was using only the left-handed ammonium tartrate molecules [i.e., the kind you get from grapes]. What a delicate appetite that mold had! This achievement of Pasteur is the first demonstration of chiral molecules as an essential and unique element in biology. It can serve as a definition of life, as any substance composed of only one optical isomer must have come from life. [p. 2]
Yockey further observes that the existence of the genome and the genetic code divides living organisms from living nonmatter. He says “there is nothing in the physico-chemical world that remotely resembles reactions being determined by a sequence and codes between sequences.” For one thing, as Chaitin has shown, the information content of biological organisms vastly exceeds the information content of the physical laws. Chaitin actually programmed the latter, and found the information content amazingly small, less than a couple of typescript pages in length. This suggests that there is nothing in matter as governed by the physico-chemical laws that alone can account for life, let alone the origin of life.
Which Darwin didn’t concern himself with. He was concerned with what happens to life once it’s already gotten going. He wrote:
As all the living forms of life are the lineal descendants of those which lived long before the Cambrian epoch, we may feel certain that the ordinary progression by generation has never once been broken and no cataclysm has devastated the world. …from so simple a beginning [i.e., pre-Cambrian life forms] endless forms most beautiful and most wonderful have been, and are being evolved. [Origin of Species, Chapter XV.]This “unbroken” lineal descent is your “tree of life,” Alamo-Girl, in Darwin-speak.
The chemistry of life is controlled by digital sequences recorded in DNA, as George Gamow, according to Yockey, “was the first to realize”:
…J. D. Watson and F. H. C. Crick showed that the molecule of deoxyribosneucleic acid, which can be considered as a chromosome fiber, consists of two parallel chains formed by four different kinds of nucleotides. These are either (1) adenine, or (2) thymine, or (3) guanine, or (4) cytosine with sugar and phosphate molecules attached to them. Thus the hereditary properties of any given organism could be characterized by a long number written in a four-digital system. On the other hand, the enzymes (proteins), the composition of which must be completely determined by the deoxyribosneucleic acid molecule, are long peptide chains formed by about twenty different kinds of amino-acids, and can be considered as long “words” based on a 20-letter alphabet. Thus the question arises about the way in which four-digital numbers can be translated into such “words.”Watson and Crick wrote in 1953 that “the phosphate-sugar backbone of our model is completely regular, but any sequence of the pairs of bases can fit into the structure. It follows that in a long molecule many different permutations are possible, and it therefore seems likely that the precise sequence of the bases is the code which carries the genetic information.” [emphasis added.]
Gamow was very excited by the findings of Watson and Crick, which he considered “brings biology over into the group of ‘exact’ sciences” by placing biology on an exact mathematical foundation. He realized that “different properties (single genes?) of any particular organism are not ‘located’ in definite spots of chromosome, but are rather determined by different mathematical characters of the entire number.” This code Gamow jokingly referred to as “the number of the beast.” Life is not in the chemicals, it’s in the code being successfully communicated within the organism (see Shannon information theory). When the organism stops communicating, it reverts to its chemical basis; i.e., it dies.
In 1958 Francis Crick published The Central Dogma, stating his view of how DNA, mRNA and protein interact. “The Central Dogma states that information can be transferred from DNA to DNA, DNA to mRNA and mRNA to protein. Three transfers that the Central Dogma states never occur are protein to protein, protein to DNA, protein to mRNA.” [Yockey p. 20].
I understand that experimental attempts to develop life from the twenty or so amino acids are bound to fail if the Central Dogma is correct. The hypothesis of abiogenesis is that you can get from amino acids to proteins, and from thence, to RNA and DNA. But this involves transfers that the Central Dogma states do not occur in nature. Life is not fundamentally about material transfers, but about information transfers.
Life is more than “complicated chemistry,” as Gamow put it. It consists of the digital information in DNA sequences sent to the digital information in the proteome by means of a code. The origin of the code cannot be accounted for on the basis of a 20- or 22-letter “alphabet,” which is all that amino acids can provide.
The Watson-Crick theory is not a chemical explanation of inheritance. Rather, it is a genetic information system based on mathematics that involves the recognition that “it is mathematically impossible, not just unlikely, for information to be transferred from the protein alphabet to the mRNA alphabet. That is because no codes exist to transfer information from the twenty-letter protein alphabet to the sixty-four-letter alphabet of mRNA.” [Yockey, p. 24.]What is not at all clear is the origin of the genetic code itself. Crick, along with Darwin, Bohr, and Yockey, regarded it as either unknowable or undecideable.
Yet Crick was evidently interested in biogenesis nonetheless. His speculation about the origin of life involved what has become known as panspermia theory, that life on earth was “seeded” by unknown extraterrestrial agents. I gather that, to an atheist, this utterly untestable seeming “long-shot” is preferable to having to acknowledge a living God Who implemented the genetic code (or Logos) “in the beginning.”
Regardless of the code’s provenance, however, the successful communication of the code seems to answer the question, “What is life/death in nature?”
Well enuf for now. Just some thoughts….
Thank you so very much, Alamo-Girl, for your outstanding essay/posts on these issues!
Wrong. Why do people say these things?! Current thought is that RNA preceeded both protein and DNA.
Chirality additionally has been shown not to be problematic. Inorganic processes can produce organic molecules with enantiomeric excess, and enantiomeric excess can then be amplified in further reactions.
Indeed, what comes first "the chicken or the egg".. Some say/imply here that neither comes first.. They both came from a chemical soup.. Really, quite a simple argument when broken down.. Trumping the old, very old, argument about the chicken or the egg.. with profound implications.. And the SoupNazis are quite proud of their way of doing business(science)..
"Evos" = SoupNazis.. cooking up delicious tales/yarns..
Funny. I get the distinct impression that not only do some people not want life to be the spontaneous product of physics and chemistry exclusively, but they absolutely insist that it not be.
I can only speak for myself, but I really don't care one way or t'other. And what difference would it make if I did?
You say, The hypothesis of abiogenesis is that you can get from amino acids to proteins, and from thence, to RNA and DNA.
If you get a chance to read my reply to LibertarianSchmoe (#1553), please do. I suggested that abiogenesis is theoretically possible in two ways. Does that make sense to you?
No, actually there aren't. The problem is with your terminology. "Spontaneous," as in "spontaneous generation," has historically been used in biology to describe living things arising from non-life as a regular and reoccurring phenomena of nature as opposed to anything like a specific process of chemical evolution which presumably only happened once, presumably of some significant span of time, and under particular conditions.
IOW you need to avoid the word "spontaneous" if you're intending to refer to modern ideas about abiogenesis or biopoesis else you'll invariably cause confusion because of the term's historical connotations.
What is not at all clear is the origin of the genetic code itself.
Good points and exposition all, dear betty boop, as always; these I've copied above were my favorites!
You deserve an award for one of the most interesting and engaging posts ever, a captivating and interesting read.