Pascal once said : "Ce que les hommes par leurs plus grandes lumieres
avaient pu connaitre, cease religion l'enseignait a ses enfants." ("Religion
teaches children what the human race has been able to learn only by the
greatest intellectual effort.")
Faith and science express the truth, but their voices are very
different. Faith, bestowed by grace, uses a poetic language the heart receives
with joy. Science, laboriously earned, offers an abstract discourse the reason
masters with pain. It is no wonder that these two paths to knowledge seem at
one time mutually reinforcing, at another time in tension, according to the
state of our understanding.
When clear divergences came to the fore with the explosive development
of physical and biological theories, eminent minds tried to establish a
precarious truce through resort to concordism. But, attempting to soften the
hard outlines of science or to belittle the heights of revelation led only to
repeated failure. In the great days of Laplacian determinism, for example, it
was embarrassing to see the sun and the moon appearing on the fourth day. Some
concordists argued that an earthbound observer could not see the lights of
heaven until the clouds cleared. This is overingenious, to say the least. The
state of knowledge in those days did not permit the idea that light could have
existed before the sun came to be!
Another example. In the glory days of triumphant neo-Darwinism some
ten to twenty years ago, the interpretation of Genesis was changed. Adam could
no longer be thought of as an individual. The name, rather, was a generic term
referring to a developing race of would-be humans. At this time, biologists
believed that whole populations insensibly evolved by gradual steps into a new
species over eons of time!
Concordism was progressively replaced by discordism. It became
fashionable to see man as an anomaly fortuitously issued from an impassive
universe. Our destiny, our duty are nowhere written; we remain forever
This assertion is the "nul" hypothesis, a useful starting point that
makes no assumptions not tied to observation. Observation will tell if the
hypothesis must be rejected because it fails to fit available data. Only then
can we construct more elaborate theories about humanity.
In the hands of some theorists, however, the hypothesis becomes a
proscription. In the name of the postulate of objectivity so dear to Jacques
Monod, they decree that no explanation in teleological terms will ever be
acceptable. The universe, by definition, has no purpose and is leading nowhere.
In a word, they want that God should not exist. It is the discordism of
A strong reaction to so extreme a view is emerging, especially in the
United States. Science knows almost nothing, say the creationists. (This, alas,
is almost true, but not quite.) Therefore, Scripure must be taken literally;
the creationists even add a bit to it. To avoid contradictions, they challenge
all the inconvenient facts in advance. They do not want to grant science its
legitimate rights. This attitude I call the discordism of despair.
Third and most dangerous, believers tend to withdraw. Fearing open
discussion, they steer into "safe" waters. They conceal some revealed truth,
hoping to preserve acceptance of what remains. Some catechisms start with
Abraham, for example, in order to avoid dealing with Adam. This is the
discordism of cleverness. It is not very charitable because it deprives us of
parts of the message of life.
It is urgent that we examine the tension between religion and science
with our cards on the table. Is there or is there not an irreducible
contradiction between revealed teaching and the observed facts?
The beginning of time
Let us glance at the first day of Genesis. God said, "Fiat lux"- and
the light was. Many years ago, Fr. Georges Lemaitre, illustrious president of
the Pontifical Academy of Sciences, very aptly drew the conclusion to which the
recession of the galaxies led. Hubble had shown that the faster a galaxy is
receding, the farther away it is. The universe is a puff of dust blooming in
the infinit; that is the meaning of the red shift. Fr. Lemaitre realized that,
if this expansion had occurred over a long span of time, the universe was once
contained in a smaller volume. At the beginning of time, there was only the
primeval hyperdense speck, the source of all matter and energy.
The discordism of pride revolted against this nation of origin. It was
too close to the notion of creation. (Recall that in the ancient world the
universe was considered eternal. Only Jews and Christians supposed that it had
begun.) The tumult died away over the years, since no other hypothesis can
account for the facts. In the 1960s, radio astronomers discovered the
three-Kelvin backgound radiation, the "echo" of the tremendous event marking
the start of space and time. Scientists now generally concede that the universe
had a definite beginning some twelve to fifteen billion years ago.
The primeval energy appeared as light; "Fiat lux" is the foundation of
modern cosmology. Modestly, we now speak of the "big bang," not the "creation."
It is good that physicists do not use the language of theology when they can
express the same idea with a noncommittal phrase. Neither concordism nor
discordism are relevant any longer; both are obsolete.
As Leibniz foresaw, the models of possible universes are infinite in
number, and theorists continue to refine their concepts of the results of such
a great and sudden surge of energy as the big bang. It is dangerous, though, to
play fast and loose with the basic laws of nature in creating such models,
whether the subject is interstellar gravity or the quantum mechanical behavior
of atoms. If one assumes much divergence from the observed value of basic
parameters, suddenly stars and planets become impossible. The physicochemical
laws that allow living beings to utilize energy in order to live no longer
apply. And, finally, one arrives at the conclusion that very few models allow
for the existence of those who construct the models!
This does not imply, as Engels supposed, that matter is pregnant with
spirit so that spirit will inevitably appear in some corner of the universe. It
simply means that the laws of nature must be such as not to preclude our
existence. This anthropic principle, defined by Brandon Carter, was expressed
centuries ago by the sculptor of the portal of Chartres Cathedral, whose scene
shows God creating the universe with Adam in mind. Once again, however,
physicists are modest . They simply may that we must take human existence into
account in examining the laws of the universe. Their logic is irrefutable.
The forms of life
Let us consider evolution. Two creative acts frame the Genesis
account: the creation of the universe at the beginning and the creation of
humanity at the end. In between, God says, "Let the earth bring forth
vegetation…" (Gn 1:11) and here are the plants; "Let the water teem with an
abundance of living creatures, and on the earth let birds fly…" (Gn 1:20) and
here are fish and later birds; "Let the earth bring forth all kinds of living
creatures…" (Gn 1:24) and here are the animals; and man appears at the end.
This dazzling summary tells us the same story, and in the same order, as is
registered in those immense cemeteries of geological strata laid down over the
ages. How the biblical authors got access to such knowledge science does not
Here, the discordism of despair is of no value. No explanatory
hypothesis can contradict the biblical text, which does not tell us how the
various species appeared. Creationism makes the error of adding an element to
the biblical account, that is, the fixity of species. Each species must have
been created as such, they say. Therefore, evolution is wrong.
There is a difficulty here, but it does not arise from the Bible,
which outlines the steps of evolution. It arises from genetics and
paleontology, which show species remaining unchanged for millions (insects) or
even billions (bacteria) of years. Hence, the harshness of the controversies
raging among theoreticians; reconciling the remarkable stability of species
with the successive appearance of various forms of life is far from easy.
Since species stagnate and life evolves, as Bergson said, there must
be a way to pass from one species to another. Darwin supposed that the most
convenient way to do so would be through the progressive accumulation of
extremely small changes. If small variations occur by random change, the
environment will sort them out. Climate, food supply, predators , and other
factors will ensure that favorable mutations are transmitted to progeny, while
the unfavorable are not. In a very stable environment, species will tend to
remain stable, while rapid environmental change will promote the appearance of
new forms. Thus, both the stability of species and evolution find an
explanation. (Kimura notes that some neutral mutations are not selected either
for or against. This adds some fancy to the picture, but the basic argument is
To put it succinctly, neo-Darwinian theory states that mutations are
the motor and natural selection guide of biological evolution. Because
mutations are random, and their effects are not determined by the environment
to which creatures have to adapt, we are led to the blunt proposition that
Monod borrowed from Democritus: "Everything in nature is the fruit of chance
and of necessity." Such a system requires enormous trial and error, but
geological periods are very long indeed. Neo--Darwinists have to believe that,
given a long enough stretch of time, blind chance will produce the eye.
An experiment in detroit
Aside from a few holdovers from Lysenkoism, no one today pretends to
have witnessed a new species emerging from a parent one. While we may lack
experimental evidence on living systems, however, a very interesting equivalent
can be fruitfully studied, thanks to human ingenuity: the neo--Darwinian theory
of automobile evolution!
From a biological point of view, an auto factory is very similar to a
reproductive organ. All the cars from a given production lineperhaps we should
call them a species-are quite identical but for some minor characteristics such
as paint color (skin color for human beings). Every part is precisely made in
conformity with detailed instructions stored on the magnetic tapes of the
factory's computers, tike the genetic information encoded in the DNA in our
All the human genetic machinery has a more or less close parallel in
the car-manufacturing process. The parallel to natural selection is obvious.
Every novelty introduced into the car will be judged by the consumer. If the
"mutation" is superior to the older model, if it performs better, if is is
better adapted to the marketplace environment, it becomes a hot-selling item.
The factory will reproduce the selected mutation at an accelerated rate, and
soon it will replace the old model entirely. It does not matter whether the
selective advantage derives from a morphological change--the shape of the
fenders-or a metabolic one-miles per gallon. What makes and measures success in
the automobile business is the fitness of machine to environment, which
determines the number of exemplars produced.
Given this set of facts, a neo-Darwinian bookkeeper at a car company
might very logically say: "The whole of automobile evolution can be explained
by sudden variations, appearing by chance and selected for and against by
market conditions." He would be partly right if technological considerations
are overlooked. The president of the company, however, would not be so naive.
Suppose we offer a winning formula: "From time to time you just make a random
change in your model. If the new model sells well, promote it; if not, junk it.
Play this blind game long enough, and you will some day produce everyone's
dream car. You may be absolutely certain of success. Nature herself has
followed this path since it produced the first amoeba and took, here we
The carmaker, thinking over our proposition, would realize that the
more highly elaborated a system, the less likely that a random change will
improve it. (Try randomly interchanging two connections on your personal
computer and judge the results.) It follows that after each improvement the
time required to achieve the next increases exponentially. No banker would
underwrite such a random mutation/natural selection system. The time required
to produce the dream car would be immeasurably greater than geological time. In
real life, "money is time."
The carmaker would no doubt reject our system and instead consult an
engineer regarding model changes. The car's previous evolution, after all, was
guided by the engineer's discoveries. But we, alas, when faced with biological
evolution, have no such option. The mutations we know are random and no one
knows of an engineer.
The ingenuity of life
Perhaps, the engineer is life itself? A few years ago, such a
statement would have been considered absurd. Today, we know that complex
organisms do not read their genetic message as bacteria do, stumbling letter by
letter one step at a time. Complex organisms act tike a film editor. After the
cameramen produce miles of film, someone takes scissors to it, removing the
useless passages and bringing together sequences that throw light on one
another by complementarity or contrast.
While we have begun to recognize this work of recomposition, we do not
understand why it is characteristic of complex organisms and not of bacteria.
An extraordinary evolutionary jump remains unexplained. It is possible that an
enormous gap exists in our knowledge.
The neo-Darwinian story has it that one day a fish with reinforced
fins hauled itself painfully ashore and conquered the continents. With the slow
improvement of legs over the millenia, this fish's descendents became
The summary seems plausible, but what about the mechanism involved?
Let's consider a frog egg. A tadpole hatches from it. With its gills, its fins,
its lateral sensitive line, this tadpole is in every respect physiologically
and anatomically a fish. And, yet, one day, without mutation or selection, it
loses his tail, grows legs, invents lungs, and becomes a tetrapod. This happens
not over millions of years but before our eyes in a fish bowl! Apparently, our
tadpole first found in its genes the code for a fish. Then, after a twist that
thyroid hormone can trigger, it feverishly reread its genetic blueprint and
executed the instructions to make a tetrapod. This tadpole knows more than we
And what about cellular differentiation, building bones, muscle,
blood, and even brain-the most sophisticated computer ever conceived on
earth-all coming out of the single fertilized egg? We are still completely
ignorant of the mechanism that drives differentiation, as basic as it is to
building up the organism, just as we are ignorant of the mechanism of
metamorphosis. How futile it is to pretend we know how an elephant evolved from
a primitive mouse, when we still do not understand how a tadpole becomes a
Species and chromosomes
The order in which instructions are carried out is obviously very
important. The DNA molecules that carry genetic instructions do not float in
the juice of the cell like noodles in a bowl of soup. Not only are they located
on the chromosome in a certain order typical of the species, but the
chromosomes themselves have a length, number, and banding pattern absolutely
characteristic of a given species.
The horse and donkey will serve to illustrate this reality. They are
two different species because their hybrid, the mule, is sterile. Although
better endowed for endurance and agility than its parents, the mule cannot
procreate. The structural differences between the chromosomes of mare and ass
are so great that no equilibrated repartition can be achieved during the
maturation of the reproductive cells.
This genetic barrier, due to chromosomes and not mutation, is the very
definition of the frontier between species. The sterility of hybrids means that
a chromosomal novelty is inevitably selected against. Only when the novelty is
received from both parents will fertility reappear, hence, the need for any
chromosomal evolution to reach this homozygous stage as quickly as possible if
speciation is to occur.
This need is best filled if the first creature homozygous for the
novelty reproduces with itself by autofecundation. Such reproduction is quite
feasible with plants; all the new species we have developed have been
manufactured this way. In higher animals, the separation of the sexes forbids
autofecundation. At this level, then, the need is best filled by generating the
required couple all at once. Pathology offers an indication of how this might
Extremely rarely, a male zygote, carrier of forty-six chromosomes,
including one X and one Y, splits into twins. One of the twins continues its
male identity. The other, not having received the Y chromosome, becomes an
imperfect female with forty-five chromosomes, including only one X. (Normal
females have two X chromosomes.) In my experience, a young girl thus affected
complained that she could not look at herself in a mirror because she was
afraid of seeing her brother. She was feeling a biological truth of which she
was consciously unaware: she was really a fragment of the brother from whom she
In our species, "45,X" females are generally sterile (though some have
produced children) but, in mice, they are perfectly fertile. The experiment
remains to be done, but if a zygote of the type I have described was homozygous
for a chromosomal novelty, the couple that developed from it, if mated, would
originate a new species of mice.
I apologize for this long excursion into genetic engineering. The
hypothesis I set forth would look very revolutionary and very modem and would
be considered the solution to rapid evolutionary change if the story of Adam
and Eve had not already been so much advertised! Science is very reluctant to
discover truths already known for thousands of years.
Primates and the man like us
Two or three million years ago, an extraordinary flowering occurred in
a vast zone ranging from Kenya through Palestine to Asia. New forms appeared
rapidly: homo habilis and then homo erectus, whose brain case is larger than
that of the modem apes. The causes of these developments are mysterious, but
they give the impression of preparations for an important happening.
Some time between one hundred thousand and forty thousand years ago,
the man like us, our own kind, suddenly appears. We are really newcomers. As
far as is presently known, both Cro-Magnon and Neanderthal belong to our
species. As I noted above, Genesis uses the word create when speaking of our
origin. Yahweh modeled a woman as companion to the man from the latter's own
flesh. "[T]he man said: This one, at last, is bone of my bones and flesh of my
flesh; This one shall be called 'woman,' for out of'her man' this one has been
taken" (Gn 2:23).
Here is a deep mystery. Genetics can demonstrate that the most narrow
consanguinity is necessary for the emergence of a new species, even that a
couple born of the same zygote is the optimal way to begin. But, the fact that
a special intervention, a creative act absolutely apart from the rest of
evolution, was necessary for the emergence of our species is pure
revelation-but not a real surprise.
A curious phenomenon
Man is a curious phenomenon, He stands erect; manufactures took, and
speaks. To some extent, one can even rely on what he says. Anterior forms,
however, were bipedal one or two million years ago. The first chips of stone
may date from the same era. Some endocranian impressions suggest that Broca and
Wernicke zones were sufficiently developed to allow a primitive communication
system even in homo habilis.
The full novelty, the absolute superiority, consists in the fact that
man is the only creature able to experience a kind of connivance between the
laws of nature and his feeling of existence. The faculty of admiration is
solely human. No dog ever tasted the fragrance of a rose. No chimp ever
contemplated the sunset or the splendor of the starry sky. The one who was the
first to know he would die and built tombs; the one who helped wounded fellows
and protected their weakness; the one who discovered art and pursued it far
beyond mere technique; this one who is us-and not a hundred thousand years
old-possesses something like a spark of the intelligent love.
Besides the difficulties it presents at delivery, man's large brain is
an enigma of natural selection, as Alfred Russel Wallace was the first to
recognize. Before we could develop our ability to decipher the laws of nature,
leading to such achievements as unleashing the power of the atom and visiting
the planets, generation after generation had to accumulate a fantastic store of
knowledge. How could natural selection anticipate the need for this knowledge?
That the world is intelligible, even partially, is perfectly unintelligible,
unless the Spirit who enacted its laws also created us in his own image.
The rib, the trees, and the garden
Let us glance again at the Genesis account. It refers to Adam's rib
or, more precisely, pair of ribs. Why associate the birth of our species with
the loss of these small bones? Modern exegetes embarrassed by this anatomical
precision might be interested to know that our nearest cousins, the gorilla and
the chimpanzee, have thirteen ribs to our twelve. There is no need to attempt
building a new concordism on this circumstance. On the other hand, it is wise
to transmit the whole message untouched for the sake of science's continued
evolution. Theories fade away, but the truth is everlasting.
During discussion following a talk I recently gave on the origin of
the human species, after I had described the "one-couple expedient" as
suggested by genetics, a knowledgeable member of the audience called out: "Let
us suppose you attained your bipedal being, naked, without fangs, without
claws… and capable of admiration. How will you protect it from the first
predator that comes along?"
"With your permission, sir," I replied, "I will place him in a
carefully preserved park, an agreeable garden."
"And, will you take care that it does not pick up some toxic food that
could unbalance its mind?"
I did not answer. A poison paralysing the connections between the
affective network and the intellective one and capable, at the same time, of
modifying the primitive genetic instructions that dictate the makeup of these
parts of the brain… I cannot describe such a poison in scientific terms. Yet,
philosophers down through the ages have noted the existence of a primeval fault
in our makeup. It consists of an inability to integrate the emotional and the
logical. Most of the time, the heart and the head are not on speaking
With this consideration, we are back to our starting point. Revelation
speaks to the heart, experiment to reason. Can we ever integrate them? It has
A sign in the heavens
Some two thousand years ago, a delegation of astronomers came to
Jerusalem from the East. They had observed a moving, sign in the sky that,
according to their calculations, announced some sort of good news. They had
derived the direction in which to search, but not the precise location.
The astronomers had an audience with the king, who immediately
summoned his counselors. They did not understand the situation but sensed that
there was something to fear; good news is not necessarily good to the
establishment. To leave no stone unturned, the king interrogated theologians.
They revealed that a minor prophet had once written: "But you,
Bethlehem-Ephrathah, too small to be among the clans of Judah, From you shall
come forth for me one who is to be ruler in Israel; Whose origin is from of
old, from ancient times" (Mi 5:1).
So, the Magi were to go to Bethlehem. They felt great joy when the
sign in the sky stood still, confirming this advice. Thus, they made the most
admirable discovery: the creature conceived in perfection, having, by the
action of the Spirit, given birth to the new Adam. They saw the Virgin and the
This story is marvelous not only because it is true but also because
it points the way to a healthy relationship between science and faith. The Magi
did not doubt the competence of the theologians. They decided to go and
For their part, the theologians did not raise their noses from the
text. Perhaps, I am reading in here. Matthew is a charming storyteller,
however, and he would not have missed the chance to portray Herod, his court,
and his experts craning their necks to catch a glimpse of what the Magi were
admiring. I am sure they did no such thing. And, even had they gone, they would
not have seen what the wise men saw. Great patience is needed to decipher
Thus, teamwork led people of good will to the highest truth. Everyone
conscientiously listened to the other without scanting his own hard-won
knowledge. As for the political power, duly enlightened by faith and informed
by science, it behaved as usual. Invoking reasons of state, it massacred the
The children of men
Our own time is witnessing the same thing. All molecular biology
teaches us that human nature is given at conception. The most recent
technology, in vitro fertilization, demonstrates that a new being comes into
existence at conception. The most sophisticated ultrasonic scanning shows us
the two-month-old baby performing, in the mother's womb, a kind of dance, full
of grace and youth. The Church teaches the same unchanging truth. Nevertheless,
the political power has reversed by vote what doctors have sworn to for more
than two thousand years: "I will not give poison; I will not procure
Then, one receives in the heart this terrible revelation transmitted
by our Lord himself, this decree incomprehensible yet absolutely obvious. "I
offer you praise, O Father, Lord of heaven and earth, because whit you have
hidden from the learned and the clever you have revealed to the merest
children" (Lk 10:21).
Dr. Dennis doherty :
With regard to Dr. Lejeune's comments on the use of noncommittal
language, our group feels that scientists should explain things in terms proper
to science. Let them speak their own language. We feel, too, that people of
religious faith have a responsibility to interpret, in religious terms, what
science talks about.
We have two questions for Dr. Lejeune. First, How do you view the
recent works of Eldridge and Gould regarding the long-term stability of
species? Second, What ought to be the goal of dialogue between religion and
science? We found benefit in Fr. Ashley's response. Granted the stance of the
believer, science can paint in the details.
Dr. Lejeune :
I would say that Eldridge and Gould improved upon previous knowledge
that sometimes new species emerge very rapidly in geological terms. It is a
very interesting discovery, but it does not change my views because I have
never been a believer in strict neo-Darwinism. Gould's intervention is most
agreeable to me because it seems to be true.
What should the goal of the dialogue be? I said at the beginning
that religion speaks to the heart and science to the reason. Interest in the
dialogue reflects the human dignity of putting together the feeling of the
heart and the deductions of reason. That is what is called a state of
Dr. Frederick Lawrence:
Our group was most impressed by Dr. Lejeune's genial reincarnation
of the spirit of Pascal. When one is a serious scientist and, at the same time,
a serious believer and allows the two things to illuminate each other, it is an
impressive and wonderful thing, no matter how many difficulties emerge.
We also wonder about what you might call "the dynamics of high
vulgarization," when scientists and religious leaders talk about their
differences. I have heard scientists use Scripture in a way that could be
labeled unprofessional. On the other hand, how scientists must squirm when
theologians make pronouncements on matters where they are less than expert. How
do we deal with this?
We made some observations on what happens when the two cultures of
religion and science are Combined in the ame person. In most of our experience,
the younger the person the greater schizophrenia there is between the religious
and scientific aspects. Older people, on other hand, tend to be more
"myth-loving," to try to bring everything together. We wondered how
priest-scientists resolve these tensions.
More attention should be paid, we feel, to the discordances between
religion and science, to the different character of the truth claims that each
makes. Science operates on the presumption that its conclusions are merely
probable, that they are open to revision. Catholic theology, in fact most
Christian theology, claims that at least some of its statements are not open to
revision. What happens to theology when it moves too far in science's
direction? Doesn't it have to remain faithful to its foundations in religious
belief? But, can it maintain intellectual probity without gravitating toward
Science has a responsibility to accommodate itself as well.
Foundational issues arise in all the sciences. It belongs to the integrity of
science to face these foundational issues, and this means interchange with
philosophy, theology, and religion. What are the criteria of truth in these
different universes of discourse? We need to define what we mean by religion,
faith, and science.
Dr. Avrom Blumberg:
The question arose in our discussion as to whether scientists need
to invoke creation to make sense of the world. Scientists are very frugal with
models; we hate to go out on limbs. Also, whenever an explanation is given, it
always leads to another question. So, we prefer to describe rather than to
explain. The big-bang theory is an adequate model, but it doesn't at all
explain what brought all that matter or energy together in the primeval
Dr. Lejeune makes a point that also fascinated Einstein, namely,
that there is no particular reason why the world should make sense. He puts it
this way: "That the world is intelligible, even partially, is perfectly
unintelligible, unless the Spirit who enacted its laws also created us in his
own image." There may be an opening to fruitful discussion here. Scientists
have faith that there is order and design in the universe. Historically, this
notion came from the concept that there is a God, so, in a sense, belief in God
gave rise both to religion and science.
Our group discussed, at length, the fact that theologians rarely
have scientific backgrounds. A number of theologians have remarked that their
seminary training did not include any course in science. It was also pointed
out, however, that one year of science usually does no good because science is
presented as a finished product; the student doesn't get a clear idea of how
science shapes its models.
Finally, we wanted to ask Dr. Lejeune whether he is suggesting that
the Genesis account of human creation is a fact.
You want to know if I consider the creation a report of a historical
phenomenon? I have no information on that score. I am interested in trying to
discover, from what we know about cytogenetics (the mechanics of the
chromosomes), the best model for building new species with the highest
probability of getting a correct result. It appears, from the equations of
population genetics, that a very tiny population is necessary as regards
evolution at the human level. The closer the consanguinity, brother and sister
mating perhaps, the greater the probability that a change will reach the
homozygous stage and that a new species will be built from there. So, one is
led to propose the couple born from a single egg as the starting point for the
human race. Thus, I constructed my theory.
I did not attempt to prove this theory in my talk; I was merely
discussing a possibility. Now, let's suppose that we have done the experiment I
proposed, that we have done some genetic engineering and succeeded in building
a new species of mice, recognizable as such and entirely sterile with respect
to the original population. Let's suppose this is possible. Even this
experiment would not prove that Adam and Eve are a historical fact. It would
only demonstrate an interesting system for building a new species: taking the
female out of the male. Did it happen that way in the particular case of
humanity? God knows.
Fr. Mcmullin :
I want to make an observation first and then ask a question. I was
charmed by the Gallic eloquence of our speaker. He is in the great tradition
not only of Pascal but of Teilhard de Chardin. I heard echoes of a long
tradition of poetry and rhetoric as well as of great science.
I was a student of Fr. Lemaitre when Pope Pius XII gave his
allocution to the Pontifical Academy of Sciences in 1951. I had Lemaitre in a
seminar shortly after he came back from the Academy meeting, and he was upset
at the way the pope had used his big-bang theory as almost a proof for the
existence of God. I still remember one of his comments, which has turned out to
be scientifically prophetic: "How does His Holiness know that the big bang
wasn't preceded by a big squeeze?" As we all know, the cyclical universe is now
considered a possibility.
Lemaitre would have been perfectly happy to acknowledge a broad
resonance between religious and scientific opinion in this matter. He would
have agreed that, if God created the universe at a moment in time, that moment
must have looked something like a big bang. But, that was as far as he would be
willing to go in the way of argument.
Fred Hoyle, by the way, was also upset by that allocution and
deliberately used the term creation for his own opposing theory, the
"continuous creation" view. (His coworkers called it the "steady state
theory.") That particular view went down in the 1960s, of course, because of
the discovery of the three-Kelvin radiation.
I have a question regarding something I find troubling in your talk,
Dr. Lejeune. I want to press you a little on this, just as I would have pressed
Bergson or Teilhard, because I catch echoes in your thought of theirs. The
question is prompted, in part, by your choice of the "Detroit analogy." As you
pointed out, engineers are in charge of these automotive "mutations". So, they
aren't random mutations.
Most people in evolutionary biology today, I think, would agree that
the neo-Darwinian synthesis is not a final account, that it doesn't explain
everything. Most would say neo-Darwinism has correctly outlined the process and
identified the proper explanatory resources, though some additions may be
needed. You proposed an extremely interesting conjecture regarding the origin
of species. Should we take your suggestion as yet another in a long line of
amendments to the neo-Darwinian synthesis? Or, are you suggesting, since you
criticize the notion of chance, chat somehow evolutionary events are not
chance-that there is an elan vital or psychic energy moving through the
process? How are we to construe the notion of chance in the light of your
Dr. Lejeune :
That is not easy to answer. First, let me say that, while I like the
writings of Fred Hoyle, he was wrong to use the term creation in describing his
steady state cosmology. If his model is true, nothing is created.
Fr. Mcmullin :
According to him, one atom of hydrogen was created every million
years or so per cubic yard of space.
Dr. Lejeune :
But, it was not created out of nothing. It was created out of a
"special property of the void".
You asked about my criticisms of neo-Darwinism. First, what I
propose about chromosomal mechanics does not come out of the blue. We know that
each species has its own chromosomal makeup. That must mean something; we
cannot ignore the fact. Yet, it has been entirely ignored in books about
evolution. Second, you will never find an entry for metamorphosis in the index
of a neo-Darwinian book. This suggests to me that those who write these
scholarly books about evolution, about neo-Darwinian theory, have deliberately
overlooked the fact that there are many ways of looking at the same genetic
makeup. A tadpole does a fantastic job of climbing the taxonomic tree in
fifteen days' time.
I suspect that behind the chromosomal mechanism there lie special
phenomena of living systems that will entirely change our view of evolution. If
you want to press me to the limit, I can tell you what I feel. It is just a
feeling, an imagination, an opinion, not a scientific demonstration. I believe
that the genes in the chromosomes are disposed in such a way that the genetic
message, during the life of the cell, is expressed three-dimensionally.
Generally, we think of this message as written on a linear molecule so that it
is a linear system, like a magnetic tape. But, I suspect it is not like that in
the living cell.
My hypothesis is that, with the specialization of the cell-whether
it becomes a brain cell, an epidermic cell, or an hepatic cell-a particular way
of reading this message develops. For example, segment A of a given chromosome
is placed in proximity to gene B of another chromosome so that A and B can be
read in order or so that A can act on B, turning it on or off.
Step by step, these chromosomes will constitute a three-dimensional
design, very comparable to the logical network of a computer-the wiring being
specific to a given tissue or organ at a given moment of the development of the
individual from the egg state to the completed adult. Time, so to speak, is
progressively incorporated in this progressive network.
So much for specialization of cells. Let's look at evolution. Let's
suppose that an accident, a chromosomal mutation, occurs so that genes A and B,
which only came in contact after quite an elaborate process of cell
differentiation, are now definitely joined in a rearranged chromosome. If this
accident happens in a reproductive cell, it will give to the next generation
logical information built in the linear order of the new chromosome; a
fantastic acceleration of the developmental process!
This chromosomal novelty should not be considered purely random;
first, because it happened between two points that had already been placed in
proximity by a physiological process; and, second, because it encodes in the
linear message an information that was previously expressed in the
three-dimensional construction. If such a novelty establishes itself in the
homozygous state, it will modify the resulting network, hence the
One can then suppose that the next chromosomal change to occur in
this lineage will have some causal relationship with the previous one. In other
words, a given line will obstinately move in its own particular direction. The
ancestors of horses try to become more and more horse-like, not cow-like.
Certainly, these very simple and rough ideas do not pretend to
represent a new theory of evolutionary forces. But, my strong feeling-you asked
for it-is that some day we will better understand these processes and discover
some logic underlying apparently random accidents. The neo-Darwinian model does
not provide this logic. Nevertheless, it must exist.
To illustrate: a chromosomal rearrangement in a cancer cell may
place gene A (an oncogene) into proximity with gene B. The behavior of the cell
changes as a result and, depending upon the chromosome involved, a leukemia of
such and such a type, perfectly recognizable, is produced. Hence, the
hypothesis that chromosomal changes can modify the makeup of an organism (and,
if established, produce a new species) is not pure fancy. It is just an
extrapolation of what we have learned in the last five years about the
evolution of cancer cells.
It is futile to pretend to the public that we understand how an
amoeba evolved into a man, when we cannot tell our students how a human egg
produces a skin cell or a brain cell! The very broad field of research I have
outlined may give us some hints about both phenomena. It is hoped that it will
give us new and better ideas.
Fr. Ashley :
You mentioned than species can be recognized on the cellular level
by chromosomal number and shape. We also know that the human species includes
poeple with forty seven chromo somes-for example, those with trisomy 21. If you
tried to define the human species in terms of forty-six chromosomes-the
"normal" number-you would have trouble with the person who has forty-seven.
Somehow, the definition has to take this reality into account. My first
question is this: Would the definition of species be more complete if it
included chromosomal banding?
My second question also has to do with species. In zoology, an
individual is said to belong to a certain species when it can only breed with
members of that species. Is fertility the only external test we have to
determine species? What constitutes a really new species in the sense in which
you are using the term?
I accept the Aristotelian notion of species: the members of one
species can crossbreed and their progeny is fertile. Also, it can be said that
individuals who crossbreed are more similar than others who cannot. That is
true and is the taxonomic definition, but the species identity is related to
its karyotype, the shape of its chromosomes. Indeed, banding pattern helps
greatly in recognizing the fact that each species has its own peculiar
You ask me whether I should say that a Down's syndrome baby is not a
member of our species because he has forty-seven chromosomes instead of
forty-six. Well, he has one chromosome too many-three exemplars of pair 21-but,
the other forty-six chromosomes are typically human, not chimpanzee-like or
orangutanlike or gorilla-like. Hence, I see him first as a man, second as a
patient with a disease-trisomy 21. If this patient later procreates, fertility
will be observed.
On the contrary, if two individuals differ by their specific
karyotype rather than by a simple error as in Down's Syndrome, we can safely
predict that hybrids, if possible at all, will be sterile, as in the case of
horse and ass. This explains why I use a chromosomal and genealogical
definition of the term species. I realize that some people are using species
more loosely, in ways that seem to me scientifically unuseful. I will go a
little further and say that I have a deep respect for Darwin, but not his use
of English. If he had called his book The Origin of Races, I would be a
Darwinian. Unfortunately, he called it The Origin of Species, and I cannot
Dr. Wilson :
This is fun because it is beginning to turn into a lively scientific
debate. I don's want to take too much time, but I felt I must say that I
recognize very little of modern biology in what Dr. Lejeune is saying. I find
the model that he is presenting, insofar as I understand it, singularly
unconvincing and without a shred of evidence. It seems an attempt to revive
orthogenesis at the molecular level. It should also be noted that his view is
surely shared by less than one percent of the biologists of the world or, at
least, the Western world. I myself know of no active evolutionary biologist in
the United States or Great Britain who shares such a view.
I realize discovery lies in recognizing that all great oaks from
small acorns grow. Today's heresy may well be tomorrow's orthodoxy.
Nevertheless, Dr. Lejeune, the definition of species you have given is shared
by scarcely any modern evolutionary biologists.
Dr. Lejeune :
Dr. Wilson :
A species is defined almost universally now-and it has become very
effective as an operational definition-as "a population or series of
populations isolated reproductively from other populations under natural
conditions." It has been demonstrated in many animal species, particularly
insects, that a single gene difference or a very small number of polygenes can
quickly produce species. Take this case, for example: a biological species is
reproductively isolated from another. Fertility is not required because
premating isolating mechanisms-that is, ones that stop any attempt to mate
prior to the actual formation of the fertilized egg-can be and demonstrably are
equally effective. Molecular changes in a single sex pheromone, for example,
have been sufficient to create species.
I was dismayed earlier by your analogy with the factory process.
Whereas the manager of a Ford assembly plant would definitely be unwilling to
stake the business on the success of a modification in the fender, this does
not reflect the situation in nature, where profligate discard of parts is
routine. There are between one billion billion and one hundred billion billion
organisms alive at any given time on the earth's surface, many of which have
life spans of only a few hours. Each one of these, depending on the organism,
has between one thousand and ten billion nucleotide pairs. Thus, the arena of
evolution by natural selection is almost unimaginably large. Nature's
prodigious discard of nonworking parts has resulted in the extinction of more
than ninety-nine percent of the species lines that have ever existed. Most
biologists, and not just neo-Darwinians, see this process as adequate for
explaining a large part of evolution.
You expressed puzzlement over the role of metamorphosis-the
transformation of tadpole into frog. This is no mystery at all. Metamorphosis
is easily fitted within the neo-Darwinian scheme. The relevant genotype evolved
over a long period of time. This genotype includes multiple sets of genes so
organized that the activation of one gene set produces one phenotype and the
activation of another gene set produces another. Molecular genetics can explain
this mechanism quite well. I must rise heartily to the defense of neo-Darwinian
theory. The group will find me substantially more dogmatic and inflexible in
this case than I was in the face of God.
Dr. Lejeune :
You say that only one percent of the geneticists now living are
dissatisfied with neo-Darwinism. Does this mean that less than one percent will
eventually accept a chromosomal hypothesis?
Dr. Wilson :
No, I meant that less than one percent of active biologists would
agree with your dismissal of neo-Darwinism. That is totally different from
saying that neo-Darwinism has fully explained everything. It is a non sequitur
to argue on the basis of large gaps in our understanding of developmental
biology and the speciation process that neo-Darwinism is bankrupt and must be
replaced with another orthogenetic theory.
Dr. Lejeune :
In that case, I fully agree that less than one percent of the
world's biologists would accept a new theory of evolution through chromosomes.
It is a pity. I say that in all seriousness. In the face of evidence derived
from all species that the chromosomal structure is so intimately involved in
the speciation process, how can you construct an evolutionary theory that does
not take this basic phenomenon into account?
Dr. Wilson :
I think there must be some misunderstanding. The role of
cytogenetics and chromosome mechanics as primary processes in evolution, and in
fact as part of the phenotype of evolution, is well worked out and integrated
into neo-Darwinian theory. I don't follow your argument that they have been
Dr. Lejeune :
The notion that chromosomal change is what is important in evolution
has significant implications. Chromosomal change will be selected against as
soon as it occurs. On the contrary, if a small mutation has even a tiny
selective advantage, it can grow in the population and be accumulate. That is
one basic difference between the two explanations. The second difference is
that we have strong reason to believe that chromosomal changes are not random,
while most mutations do appear to be random. Obviously, we are dealing with two
distinct ways of building an explanatory model.
Dr. James Courtright :
The gaps that have been talked about are in fact being closed. I now
of many instances in the last few years of recombinant procedures where genes
have been replaced in mammalian and other cells. Genes, by themselves, can be
put back into systems and expressed in a very specific way so that the gene
itself is responsible for its expression in a given tissue at a given time.
Moreover, we now know that enormous numbers of mobile genetic elements are
present in eukaryotic chromosomes and that they are responsible for changes in
these chromosomes. These discoveries are relevant to the questions Dr. Lejeune
has been raising. A great deal of molecular information exists that allows us
to understand evolutionary mechanisms in the neo-Darwinian context.
I thinly the gaps in neo-Darwinism's ability to explain evolutionary
change are there, perhaps even more radically than Dr. Wilson was
acknowledging. I am not clear, however, where you are taking this point, Dr.
Lejeune. Are you saying that these gaps will be filled by more complete
scientific analysis of the chromosome structure? Or that a more wholistic view
of the interaction of the total organism with the chromosome is required? Or
that, in the last analysis, chromosomal changes are not random but are
controlled by God or by some other force? Would you care to comment on the
religious significance of the gaps?
Dr. Lejeune :
I do not find any religious significance in these gaps. I do assert
that we do not take chromosomal mechanics and chromosomal physiology
sufficiently into account in explaining evolution. And, we are wrong. We will
do so sooner or later.
I don't know how long it will take before we can produce a more
refined model than neo-Darwinism. In my view, neo-Darwinism is like the
epicycles of Ptolemy: an explanation useful for the time it was proposed, buy
which did not exhaust the reality. In due course, Ptolemy's system gave way to
the Copernician system, a better explanation. I think we are in the same place
as regards evolution. Neo-Darwinism is a marvelous mathematical construct, as
the epicycles of Ptolemy were. But even Ptolemy himself knew his calculations
did not entirely fit. In the same way, we know that neo-Darwinism, as it is
taught in the universities, does not give us a really satisfactory explanation,
and we know further that there is one branch of science that is not
incorporated in the theory. Obviously, somebody someday will produce a much
better system. He will be evolution's Copernicus.
My interest in those gaps does not arise because I would like to
squeeze in divine action. I do not believe that God manifests himself only
where science fails! The fact that science exists at all is to me a clear
manifestation of God. But, our theories are far from satis-factory, and we must
fill the gaps with more and better science.
Now, there is one idea to which I am very open, however. Man is a
very extraordinary anomaly compared with the rest of the living kingdom. It
would not surprise me, as a scientist, if a touch of genius went into designing