One
very common claim is that DNA is a blueprint that lays out the
complete specification of the human body. Another common claim is
that DNA is a recipe (or a library of recipes) for making an
organism. It is also sometimes claimed that DNA is like a computer
program for generating our bodies.
But
such statements are not warranted by the facts. Judging from the
facts, we must conclude that while DNA uses a code of symbolic
representations (the genetic code), DNA is not a blueprint for making
a human, is not a recipe for making a human, and is not a program or
algorithm for making a human. The facts indicate that DNA is not
anything close to a complete specification of an organism, but that
DNA is instead something much simpler, mainly just a kind of database
(or a collection of ingredient lists) used in making particular parts
of an organism.
To
get an idea of the true nature of DNA, it is a good idea to adopt a
conceptual model of DNA. In science, a model is a somewhat simplified
representation that helps us understand a more complicated reality. A
classic example of a model is the Bohr model of the atom, in which
the nucleus of an atom is compared to the sun, and the electrons in
an atom are compared to planets that revolve around the sun. The
atom is actually more complicated than such a situation (given the
weirdness of quantum mechanics), but the Bohr model is still useful
to help us get a basic grasp of what an atom is like. The Bohr model
is essentially accurate, because just as the great majority of a
solar system's mass exists at its center in the sun, the great
majority of an atom's mass exists at its center in the atomic
nucleus.
Now,
what model can we use to grasp the basic nature of DNA? A good model
to use is what we may call the chain-of-colored-beads model. Let us
imagine a long chain of colored beads, in which there are about
twenty possible bead colors, and each bead stands for a particular
type of chemical called an amino acid. That is exactly how DNA
works. We can imagine that one of these colors means kind of
“Start.” The amino acids are the constituents of proteins. So
after one of these “Start” beads appears in the chain, there is then a sequence of colored beads, with each color representing one of
the twenty amino acids. Altogether the long “chain of beads”
that is DNA specifies the ingredients of thousands of different
proteins.
A
particular snippet or section of DNA will correspond to a chain of
amino acids that is the starting point of a protein. The visual
below illustrates this schematically.
An
example of one-dimensional information is a telephone number, a
social security number, or a stock ticker tape. Such information can
always be presented with a single line or row, although some types of
one-dimensional information might require a long line or row. A more
complicated type of information is what is called two-dimensional
information. Such information requires both rows and columns. An
example of two-dimensional information is the information in a
calendar or a spreadsheet.
Another
more complicated type of information is called three-dimensional
information. Three-dimensional information specifies something that
can only be described using the dimensions of length, width, and
depth. An example is the information specifying the three-dimensional
structure of a car.
Now,
what type of information would be required to specify the physical
layout of a three-dimensional body such as the human body? To specify
such a thing, you would need three-dimensional information,
information involving length, width and depth. But there is no way that such three-dimensional information could exist in DNA, which has merely one-dimensional
information.
In
fact, it seems that in order to make a complete biological
specification of an organism, you would need not just
three-dimensional information, but four-dimensional
information. Time is often regarded as the fourth dimension. We can
describe four-dimensional information as information that involves
not merely aspects of length, width, and depth, but also an aspect of
time.
Why
would you need four-dimensional information to specify an organism
such as a human? For one thing, it is not true that humans just pop
into existence as adults. Instead, there is a long series of
transitions between the earliest state of a newly fertilized egg, and
that of a full-grown human. A full human specification would have to
specify each of these states. So the specification would need to use
the fourth dimension of time to specify this temporal progression in
human forms.
Another
reason why a full human specification would need to be
four-dimensional is that human beings are not static objects, but
intensely dynamic objects. Think of all the dynamic activity
occurring every day in your body. Blood and electricity is flowing
about, proteins are being synthesized according to specific time
tables, cells are being born and dying according to other time
tables, and so forth. A single snapshot of the state of a human body
is not at all sufficient to capture this dynamic activity. You would
need to have a specification that is four-dimensional. Similarly, if
someone from some small island in the Pacific had no idea of what a
city was, you would never specify what a city was by just showing
some maps. You would need to somehow specify the motion occurring in
the city: the subways moving, the cars moving, the people moving, the
water flowing through pipes, and so forth.
But
DNA can only specify one-dimensional information. So it is very
absurd to maintain that a biological specification of humans is in
the one-dimensional information of DNA.
The
table below lists on the left various types of information that would
be needed to have a full biological specification of an organism, and
on the right whether or not such information can be specified in DNA.
| Type of information | Can it be specified in DNA? |
| Linear amino acid sequence of a protein molecule | Yes |
| Three-dimensional shape of a protein molecule | No |
| Exact location where a protein is located in body | No |
| Layout of a cell organelle | No |
| Layout of a cell | No |
| Layout of a tissue type | No |
| Layout of an organ | No |
| Layout of an organ system | No |
| Layout of a full body plan | No |
| Structure progression from simplest tiniest form to fully grown form | No |
| Dynamic behavior inside an organism during a particular month or year | No |
Some
would disagree about the answer I have given in the third row, and
claim that the three-dimensional shape of a protein molecule is
purely a consequence of its sequence of amino acids. If this were
true, scientists would have long ago solved the protein folding
problem, and would be able to predict the three-dimensional shapes of
proteins from their one-dimensional sequence of amino acids. But
after decades of trying to do this, the protein-folding problem is
still unsolved, and (as discussed here) scientists still cannot accurately predict the 3D
shapes of large proteins from their amino acid sequences.
The
fact that DNA can only store one-dimensional information is a
decisive reason for rejecting all claims that DNA even half-specifies
the human organism. There are two other reasons for rejecting such
claims. The first is that no one has found any information in DNA
corresponding to human body plan information. The human genome has
been thoroughly studied through massive projects such as the Human
Genome Project and the ENCODE project. No one has found any gene
information specifying a human body plan, a structural plan for a
cell, a structural plan for an organ, or a structural plan for an
organ system.
The
second reason is equally enormous. It is simply that there exists
nothing in the human body that could interpret a specification of
human biology, if such a thing existed in DNA. Consider computer
code. Such code can only work because there is an enormously
sophisticated piece of software called an interpreter or compiler
that is smart enough to read such complex instructions. If it were to
happen that DNA stored instructions for making a human, contrary to
the evidence, we would only explain human development if we imagined
that somewhere in our biology was some enormously sophisticated
machinery or functionality capable of reading such highly complex
instructions and executing them. But no such functionality has ever
been discovered.
Is
it accurate to say that there are recipes in DNA? No it is not. A
recipe includes an ingredient list, and a set of instructions
explaining how to make a particular meal or dish using those
ingredients. DNA has lots of ingredient lists specifying the
ingredients of proteins. But nowhere does DNA specify a series of
instructions for assembling a protein molecule, a cell, an organ, an
organ system, or a full body. Protein molecules have
three-dimensional shapes that they assume for unknown reasons. Such
shapes are not specified in DNA.
At the end of this post (in which I cite additional very weighty reasons for rejecting the claim the DNA is a specification of a human), I quote eight different scientists (mainly biologists) who state that DNA is not a recipe or blueprint for making a human, or anything like a specification of the human form.
So
where is it that biological shapes and structures come from? This is
a gigantic unknown, which stands as a dramatic contradiction of all
attempts to explain biology in mechanistic or materialistic terms. We
do not know where the 3D shapes of protein molecules come from. We do
not know where the shapes of cells come from. We do not know where
the structure of tissues comes from. We do not know where the shapes of
organs come from. We do not know where the shapes of organ systems
come from. We do not know where the overall body plan of an organism
comes from. We therefore have a strong reason to suspect that such things are
mysterious inputs from some unfathomable reality outside of an
organism.
The
reality of DNA is something very inconsistent with the claims about
DNA made by many a science book, where we hear about DNA as a
blueprint for the body or DNA as some recipe for making a human. In
my next post I will look at one of these books, and the false and
wildly inconsistent claims the book makes about DNA. We
will see that the tall tales that the book tells about DNA are five
different claims that are all inconsistent with each other, resulting
in a kind of DNA mythology that is “all over the map.”
Postscript: The genome is an organism's DNA, while the phenotype is the set of observable characteristics of an organism (such as its external appearance and internal arrangement of organs). In the mainstream book "Frontiers in Ecology, Evolution and Complexity," a scientist states the following:
At the beginning of the 21st century, biology confronted an uncomfortable fact: despite the increasing availability of whole genome sequence data, it was not possible to predict, or even clarify, phenotypic observations. In fact, we now know that there is not sufficient information in the linear DNA of the complete genomes to recover and/or understand the diverse phenotypic states of an organism.
In statements such as this, scientists "fess up" that the idea of DNA as a human specification is not true. Another example can be found in this paper written by several scientists, in which we read this: "Because genes code for proteins, there are no 'genes for' phenotypes per se, including behavioral phenotypes." Here is another example. "DNA cannot be seen as the 'blueprint' for life," says Antony Jose, associate professor of cell biology and molecular genetics at the University of Maryland. He says, "It is at best an overlapping and potentially scrambled list of ingredients that is used differently by different cells at different times." Sergio Pistoi (a science writer with a PhD in molecular biology) tells us, "DNA is not a blueprint," and tells us, "We do not inherit specific instructions on how to build a cell or an organ." Michael Levin (director of a large biology research lab) states that "genomes are not a blueprint for anatomy," and after referring to a "deep puzzle" of how biological forms arise, he gives this example: "Scientists really don’t know what determines the intricate shape and structure of the flatworm’s head."
Postscript: The genome is an organism's DNA, while the phenotype is the set of observable characteristics of an organism (such as its external appearance and internal arrangement of organs). In the mainstream book "Frontiers in Ecology, Evolution and Complexity," a scientist states the following:
At the beginning of the 21st century, biology confronted an uncomfortable fact: despite the increasing availability of whole genome sequence data, it was not possible to predict, or even clarify, phenotypic observations. In fact, we now know that there is not sufficient information in the linear DNA of the complete genomes to recover and/or understand the diverse phenotypic states of an organism.
In statements such as this, scientists "fess up" that the idea of DNA as a human specification is not true. Another example can be found in this paper written by several scientists, in which we read this: "Because genes code for proteins, there are no 'genes for' phenotypes per se, including behavioral phenotypes." Here is another example. "DNA cannot be seen as the 'blueprint' for life," says Antony Jose, associate professor of cell biology and molecular genetics at the University of Maryland. He says, "It is at best an overlapping and potentially scrambled list of ingredients that is used differently by different cells at different times." Sergio Pistoi (a science writer with a PhD in molecular biology) tells us, "DNA is not a blueprint," and tells us, "We do not inherit specific instructions on how to build a cell or an organ." Michael Levin (director of a large biology research lab) states that "genomes are not a blueprint for anatomy," and after referring to a "deep puzzle" of how biological forms arise, he gives this example: "Scientists really don’t know what determines the intricate shape and structure of the flatworm’s head."
Agustin Fuentes, a professor of anthropology, states the following:
"Genes play an important role in our development and functioning, not as directors but as parts of a complex system. 'Blueprints' is a poor way to describe genes. It is misleading to talk about genes as doing things by themselves."
Two other scientists "fess up" in a similar way when they write the following about genes in the journal Nature: "Population genetics is founded on a subset of coding sequences that can be related to phenotype in a statistical sense, but not based on causation or a viable causal mechanism."
Regarding the DNA as blueprint idea a wikipedia.org article entitled “Common misunderstanding of genetics” lists the claim that “Genes are a blueprint of an organism's form and behavior” as one of the “common misunderstandings of genetics.” Jonathan Latham has a master's degree in Crop Genetics and a PhD in virology. In his essay “Genetics Is Giving Way to a New Science of Life,” a long essay well worth a read, Latham exposes many of the myths about DNA being a blueprint or master controller, and points out DNA does not even fully specify a protein. He states, "It is habitually, but lazily, presumed that DNA specifies all the information necessary for the formation of a protein, but that is not true."
Ian Stevenson M.D. cited quite a few biologists pointing out the genes and DNA cannot determine the form of an organism:
"Genes alone - which provide instructions for the production of amino acids and proteins -- cannot explain how the proteins produced by their instructions come to have the shape they develop and, ultimately, determine the form of the organisms where they are. Biologists who have drawn attention to this important gap in our knowledge of form have not been a grouping of mediocrities (Denton, 1986; Goldschmidt, 1952; B. C. Goodwin, 1985, 1988, 1989, 1994; Gottlieb, 1992; Grasse, 1973; E. S. Russell...Sheldrake, 1981; Tauber and Sarkar, 1992; Thompson, 1917/1942)."
Biologist B.C. Goodwin stated this in 1989: "Since genes make molecules, genetics...does not tell us how the molecules are organized into the dynamic, organized process
that is the living organism." A paper by Stuart A. Newman (a professor of cell biology and anatomy) discussing at length the work of scientists trying to evoke "self-organization" as an explanation for morphogenesis states that "public lectures by principals of the field contain confidently asserted, but similarly oversimplified or misleading treatments," and says that "these analogies...give the false impression that there has been more progress in understanding embryonic development than there truly has been." Referring to scientists moving from one bunk explanation of morphogenesis to another bunk explanation for it, the paper concludes by stating, "It would be unfortunate if we find ourselves having emerged from a period of misconceived genetic program metaphors only to land in a brave new world captivated by equally misguided ones about self-organization."
Referring to claims there is a program for building organisms in DNA, biochemist F. M. Harold stated "reflection on the findings with morphologically aberrant mutants suggests that the metaphor of a genetic program is misleading." Referring to self-organization (a vague phrase sometimes used to try to explain morphogenesis), he says, "self-organization remains nearly as mysterious as it was a century ago, a subject in search of a paradigm." Geneticist Adam Rutherford states that "DNA is not a blueprint," a statement also made by biochemistry professor Keith Fox.
Physician James Le Fanu states the following:
"The genome projects were predicated on the reasonable assumption that spelling out the full sequence of genes would reveal the distinctive genetic instructions that determine the diverse forms of life. Biologists were thus understandably disconcerted to discover that precisely the reverse is the case. Contrary to all expectations, there is a near equivalence of 20,000 genes across the vast spectrum of organismic complexity, from a millimetre-long worm to ourselves. It was no less disconcerting to learn that the human genome is virtually interchangeable with that of both the mouse and our primate cousins...There is in short nothing in the genomes of fly and man to explain why the fly has six legs, a pair of wings and a dot-sized brain and that we should have two arms, two legs and a mind capable of comprehending the history of our universe."
The false claim that DNA is a blueprint or recipe for making a human was denounced by Ken Richardson, formerly Senior Lecturer in Human Development at the Open University. In an article in the mainstream Nautilus science site, Richardson stated the following:
"Scientists now understand that the information in the DNA code can only serve as a template for a protein. It cannot possibly serve as instructions for the more complex task of putting the proteins together into a fully functioning being, no more than the characters on a typewriter can produce a story."
Writing in the leading journal Cell, biologists Marc Kirschner, John Gerhart and Tim Mitchison stated, "The genotype, however deeply we analyze it, cannot be predictive of the actual phenotype, but can only provide knowledge of the universe of possible phenotypes." That's equivalent to saying that DNA does not specify visible biological structures, but merely limits what structure an organism can have (just as a building parts list merely limits what structures can be made from the set of parts). A paper co-authored by a chemistry professor (Jesper Hoffmeyer) tells us this: "Ontogenetic 'information,' whether about the structure of the organism or about its behavior, does not exist as such in the genes or in the environment, but is constructed in a given developmental context, as critically emphasized, for example, by Lewontin (1982) and Oyama (1985)." Biologist Steven Rose has stated, "DNA is not a blueprint, and the four dimensions of life (three of space, one of time) cannot be read off from its one-dimensional strand." "DNA is not a blueprint for an organism," states Templeton Prize-winning physicist and astrobiologist P. C. W. Davies. On page 26 of his book Biology as Ideology: The Doctrine of DNA, biologist Richard C. Lewontin stated this:
"We are not determined by our genes, although surely we are influenced by them...Even if I knew the complete molecular specification of every gene in an organism, I could not predict what that organism would be....Even if I knew the genes of a developing organism and the complete sequence of its environments, I could not specify that organism."
A 2024 article says, "MartÃnez Arias, 68, argues that the DNA sequence of an individual is not an instruction manual or a construction plan for their body...The Madrid-born biologist argues that there is nothing in the DNA molecule that explains why the heart is located on the left, why there are five fingers on the hand or why twin brothers have different fingerprints."
Two scientists said this:
"We see no valid use for definitions of the genotype and phenotype in terms of blueprints, programs, or
sets of instructions, and their realizations or
manifestation....The program/manifestation metaphor is factually misleading, because it suggests that the genotype uniquely determines an organism’s phenotype. However, as is well known, all
it does is specify an organism’s norm of reaction to environmental conditions (Rieger et al., 1991, Lewontin, 1992)."
A 2022 paper in the journal Science (one authored by more than ten scientists) says this: "Although the genome is often called the blueprint of an organism, it is perhaps more accurate to describe it as a parts list composed of the various genes that may or may not be used in the different cell types of a multicellular organism....The genome in and of itself does not provide an understanding of the molecular complexity of the various cell types of that organism." A Duke University biologist and a Cornell University biologist have confessed this: " No information about the overall architecture of these body parts is present in the cells and tissues of the parts themselves, or in each organism’s genes."
Postscript: The term "body plan" is a profoundly misleading term that biologists love to use, a term that opens the door to deceptions about DNA. In biology literature the term "body plan" has a very limited meaning, something vastly different from a complete plan for constructing an organism. According to a scientific paper "a body plan is a suite of characters shared by a group of phylogenetically related animals at some point during their development." The wikipedia.org article on "body plan" tells us this: "A body plan, Bauplan (German plural Baupläne), or ground plan is a set of morphological features common to many members of a phylum of animals."
According to this definition, all chordates (including men, bears, dogs and fish) have the same body plan. So when biologists talk about "the human body plan" they
are merely referring to the common characteristics of all chordates, including men, bears, dogs and fish: basically just the existence of a backbone and bilateral symmetry (having the same things on both sides of the body). They are not referring to the structure of the 200 types of cells in the human body, or the structure of internal organs, and are not referring to the dynamic intricacies of human physiology. But anyone hearing the term "body plan" will think the term referred to a complete specification of a human body. So, most misleadingly, biologists may say that this or that "determines the body plan," when all they mean is the beginning of a bilateral organism with a backbone, something a thousand times simpler than the final product of the internally dynamic and enormously organized human body. This is as misleading as someone saying that he has built a starship, when he has merely built a boat in the shape of a star.
No comments:
Post a Comment