EVOLUTION: "LET US MAKE MAN IN OUR IMAGE"

Position of the Church: The Dogma / Doctrine

1. The Church has no position on evolution per se, other than evolution must, ultimately, be directed by God; it is not the result of random effects, blind chance, uncontrolled by God:

Nothing exists that does not owe its existence to God. (CCC 338)

2. Evolution may be a "secondary cause", i.e. a means whereby God directs change:

God is the first cause who operates in and through secondary causes. (CCC 308)

3. The human body may be a product of evolution, but the soul was first instilled by God:

...the teaching authority of the Church does not forbid that, in conformity with the present state of human sciences and sacred theology, research and discussions...take(s) place with regard to the doctrine of evolution, in as far as it inquires into the origin of the human body as coming from pre-existent and living matter[but] the Catholic faith obliges us to hold that souls are immediately created by God. (emphasis added; Pius XII, Humani Generis).

That is to say, the human soul is specially created; it did not evolve, and, unlike our bodies, it is not inherited from our parents.

4. Are humans descended from 1 man + 1 woman (monogenism), or were there many human ancestors (polygenism)? It is not clear whether monogenism is doctrine or dogma (see CCC 360). The question is, can "Original Sin" be said to have occurred without monogenism? If not, then monogenism is dogma.

Evolutionary Models.

1. Distinguish between evolution--descent of species from some common ancestor or organism--and the Darwinian model for evolution:

• Darwinian Model: Evolution proceeds by small, random variations; those changes which occur that give a survival advantage are perpetuated and give rise to new species.

• Punctuated Equilibrium: Stasis and then sudden increase of freaks who survive in crisis conditions (Jay Gould)

• Spontaneous Self Organization: complex structures tend to form from random associations--computer games (Kaufmann, Prigogine)

• Intelligent Design: Complexity can't be explained by random small variations (see below) (Dembski, Behe)

2. Evidence for evolution:

• fossil record from early times to recent shows change and development of species;

• similarities and differences in protein structures parallel similarities and differences in anatomical form;

Graph above shows similarities between myoglobin structure of human (HU), chimpanzee (CH) and gorilla (GO), differences with pig (PG), whale (WHK), alligator (AQ), tuna (TUY), shark

• similarities and differences in Gene sequences of DNA

Mechanism for Evolution: DNA and Heredity.

DNA provides instructions (through the synthesis of RNA in the cell) for synthesis of proteins, which in turn govern metabolism and construction of cells. DNA consists of four organic bases, adenine (A), cytosine (C), thymine (T) and uracil (U) which link to each other across DNA strands in a very specific way. A sequence of 4 bases, e.g. AGCT, or GGAC, forms a "word", i.e. an instruction for protein synthesis from amino acids.

• Three billion base pairs in the human genome; only about 1.5% is actually used for coding proteins; rest is "junk" DNA;

• 20,000-25,000 genes coding for proteins in range of species: flatworm (1000 cells) to human (millions of cells)

Evidence Against the Darwinian Model?

Problems with the Darwinian model for evolution:

• Variation of numbers of species with time does not follow a the kind of change to be expected from a pattern of small random variations:

• The gap of transitional forms in fossils before the "Cambrian Explosion"

• How do small random variations achieve "irreducibly complex" systems, i.e. biochemical systems with many parts, each of which is required to achieve any function that would lend survival advantage? (Behe: "Darwin's Black Box")

• Irreducible Complexity: the mousetrap won't work unless each part is working; a holding bar half the length needed will mean that the whole mousetrap won't work. How then, can the mouse trap be achieved by gradual changes of each of its parts? If it doesn't work, the slight change will not confer a survival advantage and will not be perpetuated.

  The Edge of Evolution:  Behe also argues in his recent book (2007), "The Edge of Evolution" that the Darwinian model, small incremental changes that aid to survival, can operate up to speciation and possibly to genera and order differentiation, but not at a higher level--the probability for many combined random mutations required for complex changes is just too small.   He uses as an example, malaria.  Humans have evolved several small--one or two amino acid changes--to counteract the effects of the malarial parasite:  sickle cell anemia, Hemoglobin C, fetal cell Hemoglobin, and various forms of thalassemia, which offer various degrees of resistance to the malarial parasite but are non-adaptive otherwise (particularly so for persons with two sickle cell genes), giving rise to anemia and other blood diseases.   The malarial parasite has also evolved  resistance to anti-malarial drugs.   Because the population of malarial parasites is so large (one trillion parasites per infected persons, one billion infected people per year) the overall probability of the parasite mutating a one or two-amino acid change that will give resistance to a drug is relatively large.    Behe applies the observed probabilities for one-amino acid changes (1/10 to the 12th power) and for two-amino acid changes (1/10 to the 20th power) and concludes that for much smaller animal population...less than one trillion over the course of evolutionary time..the chances of coordinated random mutations is vanishingly small. Also over the 4000 years or so since the human sickle cell gene evolved, the malarial parasite has not evolved to counter it, nor has it evolved to survive in non-tropical climates.

Evidence For the Darwinian Model?

• Close similarity between mammalian gene sequences; similarity of "ARE" (Ancient Repetitive Elements or "jumping genes"); evidence for common ancestry (taken from the "Language of God")

• Close similarity between primate chromosomes and gene sequences(from "The Language of God")

• Counter-evidence against "irreducible complexity": proteins taken over in blood-clotting mechanisms and in cilia from other functions.

A Path for Human Evolution: Mitochondrial Eve:

CRITIQUE OF INTELLIGENT DESIGN AND THE DARWINIAN MODEL

Is Intelligent Design  science, rather than philosophy?   Can it be falsified?   Can it offer predictions to be verified by observation or experiment (the Anthropic Principle, i.e. a finely tuned universe did offer one such prediction:  that of the excited carbon-12 nuclear level that facilitated the three-alpha process.)   One has to worry about "God of  the Gaps" type arguments, that because science  does not offer an explanation (at a given point in history), no such explanation is possible and therefore direct (as distinguished from "Second Cause") Divine action must be operative.    Moreover, there are some subtle flaws in Behe's mathematical probability arguments (see class lecture).

Although the phylogenetic tree, the similarities in DNA and proteins between closely related species,  behaves like an evolutionary tree, it only shows common descent, i.e. that organisms evolved from a common one-celled form; it does not verify the Darwinian mechanism for that evolution.   No mathematical analysis has, to my knowledge, shown how complicated genetic structures could be changed in a random way to form the code for different phyla.

THE ORIGIN OF LIFE

The biggest question materialism/physicalism has to answer (and has not yet answered) is how life arose in the beginning.   Frances Krick, co-discoverer of DNA's structure, has suggested it might have been planted here by aliens or arrived via cometary debris.   That just begs the question, and one can ask where did the life from the aliens or on the cometary debris come from?