While we do NOT feel
that it is the Genetic engineering that is the
Primary problem with Human and other
synthetic insulins, we do not feel that these
problems are not adding to our diabetes
problems.
The current issue of GeneWatch
focuses on biological warfare: the ideologies
and policies that have driven its development,
and the misguided U.S. public health response.
You may now read online the first article,
"Rethinking the Biological Warfare
Problem" by Susan Wright.
To
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No one who reads the newspapers or scientific
journals can have missed the fact that this is
the 50th anniversary of the publication of the
correct three-dimensional structure of DNA. That
structure, a double helix of two chains of
nucleotides, has become a popular icon and the
very phrase, “double helix” has been spoken
and written so often as to become part of
ordinary discourse.
The fact that genes were composed of DNA had
already been established nine years before the
publication of Watson and Crick’s paper on its
structure, and the chemical, as opposed to the
spatial, configuration of DNA was also well
known before 1953. Yet, despite the obvious
importance of DNA in understanding the molecular
details of both heredity and development, it was
not until after the publication of the proposed
double helical structure that DNA started
increasingly to occupy the interest of
biologists and finally became the focus of the
study of genetics and development. The last
fifty years have seen the reorganization of most
of biology around DNA as the central molecule of
heredity, development, cell function and
evolution. Nor is this reorganization only a
reorientation of experiment. It informs the
entire structure of explanation of living
processes and has become the center of the
general narrative of life and its evolution. An
entire ideology has been created in which DNA is
the “Secret of Life”, the “Master Molecule”,
the “Holy Grail” of biology, a narrative in
which we are “lumbering robots created, body
and mind” by our DNA. This ideology has
implications, not only for our understanding of
biology, but for our attempts to manipulate and
control biological processes in the interests of
human health and welfare, and for the situation
of the rest of the living world.
The first step in building the claim for the
dominance of DNA over all living processes has
been the assignment of two special properties to
DNA, properties that are asserted over and over
again, not only in popular expositions but in
textbooks. On the one hand, it is said that DNA
is self-replicating; on the other, that DNA
makes proteins, the molecular building blocks of
cells. But both of these assertions are false
— and what is sodisturbing is that every
biologist knows they are false.
First, DNA is not self replicating. It is
manufactured out of small molecular bits and
pieces by an elaborate cell machinery made up of
proteins. If DNA is put in the presence of all
the pieces that will be assembled into new DNA,
but without the protein machinery, nothing
happens. What actually happens is that the
already present DNA is copied by the cellular
machinery so that new DNA strands are replicas
of the old ones. The process is analogous to the
production of copies of a document by an office
copying machine, a process that would never be
described as “self-replication”. In fact,
many errors are made in the DNA copying process;
there is protein proofreading machinery devoted
to comparing the newly manufactured strands to
the old ones and correcting the errors. An
office copier that made such mistakes would soon
be discarded.
Second, DNA does not make anything, certainly
not proteins. New proteins are made by a protein
synthesis machinery that is itself made up of
proteins. The role of the DNA is to provide a
specification of the serial order of amino acids
that are to be strung together by the synthetic
machinery. But this string of amino acids is not
yet a protein. To become a protein with
physiological and structural functions, it must
be folded into a three dimensional configuration
that is partly a function of the amino acid
sequence, but is also determined by the cellular
environment and by special processing proteins
that, among other things, may cut out parts of
the amino acid chain and splice what remains
back together again.
The other function of DNA is to provide a set of
“on-off” switches that are responsive to
cellular conditions so that different cells at
different times will produce different proteins.
When the conditions of the cell set a switch
associated with a particular gene to the “on”
position, then the protein manufacturing
machinery of the cell will read that gene.
Otherwise the cell will ignore it.
In this mechanical description of the relation
of DNA to the rest of the cellular machinery
there is no “master molecule”, no “secret
of life.” The DNA is an archive of information
about amino acid sequences to which the
synthetic machinery of the cell needs to refer
when a new protein molecule is to be produced.
When and where in the organism that information
is read depends on the physiological state of
the cells. An organism cannot develop without
its DNA, but it cannot develop without its
already existing protein machinery (unless it is
a parasite like a virus that has no synthetic
power of its own but gets a free ride on its
host’s protein machinery).
The unjustified claim for special autonomous
powers of DNA is the prelude to the next step in
building a picture of a DNA-dominated world.
This picture is simply the molecular version of
a biological determinism that has dominated
explanations of the properties of organisms, and
especially of humans, since the nineteenth
century. Differences in temperament, talents,
social status, wealth, and power were all said
to reside “in the blood.” The physical
manifestations of these claimed hereditary
differences could be seen by criminal and racial
anthropologists in the shapes of noses and heads
and the color of skins. With the rise of
Mendelian genetics, genes were substituted for
blood in the explanations, but they remained,
for the fifty years of genetics, merely formal
entities with no concrete description beyond the
fact that they were some bit of a chromosome.
The discovery that DNA is the material of the
gene, and the subsequent determination of the
correspondence between nucleotide sequences of
genes and amino acid sequences of proteins, then
provided a concrete molecular basis for a total
scheme of explanation of the organism. The fact
that organisms are built primarily of proteins
and that DNA carries the archive of information
for the amino acid sequence of the proteins gave
an immense weight to the conclusion that the
organism as a whole is coded in its DNA. A
manifestation of this view is the claim made, at
a symposium in commemoration of the 100th
anniversary of the death of Darwin, by a founder
of the molecular biology of the gene: that if he
were given the DNA sequence of an organism and a
large enough computer, he could compute the
organism. One is reminded of Archimedes’ claim
that, given a long enough lever and a place to
stand, he could move the earth. But while
Archimedes may have at least been right in
principle, the molecular biologist was not. An
organism cannot be computed from its DNA because
the organism does not compute itself from its
own DNA.
It is a basic principle of biology, known to all
biologists but ignored by most of them as
inconvenient, that the development of an
organism is the unique consequence of its genes
and the temporal sequence of environments in
which it developed. The current fascination of
developmental genetics is with the way in which
information from different genes enters into the
formation of the major features of an organism.
How does the front end of the animal become
differentiated from the back end? Why does the
egg of a horse develop into an animal with four
legs while the egg of a bird produces an
organism with two legs and two wings, and the
egg of a butterfly results in an animal with six
legs and two sets of wings? This concentration
on the major differences and similarities
between different species has resulted in a
genetically determinist view of development that
ignores the actual variation among individuals.
There is an immense experimental literature in
plants and animals showing that individuals of
the same genetic constitution differ widely from
each other in physical characteristics if they
develop in different environments. Moreover, the
relative ranking in some physical trait of
individuals of different genotypes changes from
environment to environment. Thus, a genetic type
that is the fastest growing at one temperature
may be the slowest at another. But even genes
and environment together do not determine the
organism. All “symmetrical” organisms show a
fluctuating asymmetry between their two sides
and the variation between left and right sides
is often as great as the difference between
individuals. For example, the fingerprint
pattern on the left and right hands of a human
individual are not identical; on some fingers,
they may be extremely dissimilar. This variation
is the manifestation of random growth
differences that arise from small differences in
the local tissue and cell conditions in
different parts of the body, and from the fact
that there is random variation in the number of
copies of particular molecules in different
cells. A consequence is that two individuals
with identical genes and identical environments
will not develop identically. If we want to
understand human variation, we need to ask far
more subtle and complex questions than is the
rule in DNA-dominated biology.
The other side of the movement of DNA to the
center of attention in biology has been the
development of tools for the automated reading
of DNA sequences, for the laboratory replication
and alteration of DNA sequences and for the
insertion of pieces of DNA into an organism’s
genome. Taken together, these techniques provide
the power to manipulate an organism’s DNA to
order. The three obvious implications of this
power are in the detection and possible
treatment of diseases, the use of organisms as
productive machines for the manufacture of
specific biological molecules, and the breeding
of agricultural species with novel properties.
The Human Genome Project has been largely
justified by the promise that it will now be
possible to locate genes that cause human
disease by comparing the DNA sequences of
affected and unaffected individuals. Once the
nucleotide difference has been established, that
difference can be used as a diagnostic
criterion, as a predictor of a future onset of
the disease, and as a basis for a cure by gene
replacement therapy. It is undoubtedly true that
some fraction of human ill health is a
consequence of deleterious mutations. However,
while family studies can strongly suggest that a
disease is being inherited as a single Mendelian
gene difference, the determination that it is a
consequence of mutation of a particular gene is
not a trivial problem. A blind search for a
genetic difference that is common to all
affected individuals is impractical given that,
on the average, any two humans differ from each
other at 3 million nucleotide sites. On the
other hand, if the biochemistry of the disease
is sufficiently well understood, it may be that
a few candidate genes can be singled out for
investigation. Alternatively, studies of the
pattern of inheritance may show that the
disorder is inherited coordinately with an
associated gene of known location in the genome,
greatly narrowing down the search for the DNA
variation implicated in the disease.
As in all other species, for any given gene,
human mutations with deleterious effects almost
always occur in low frequency. Hence specific
genetic diseases are rare. Even in the
aggregate, genes do not account for most of
human ill health. Given the cost and expenditure
of energy that would be required to locate,
diagnose and genetically repair any single
disease, there is no realistic prospect of such
genetic fixes as a general approach for this
class of diseases. There are exceptions, such as
sickle cell anemia and conditions associated
with other abnormal hemoglobins, in which a
non-negligible fraction of a population may be
affected, so that these might be considered as
candidates for gene therapy. But for most
disease that represents a substantial fraction
of ill health and for which some evidence of
genetic influence has been found, the relation
between disease and DNA is much more complex and
ambiguous. Claims for the discovery of “genes
for” schizophrenia and bipolar syndrome have
repeatedly been made and retracted. It is
generally accepted that cancer is a consequence
of mutations in a variety of genes related to
the control of cell division, but even in the
strongest individual case, the breast
cancer-inducing BRCA1 mutations, only about 5%
of such cancers are linked to these specific
mutations.
Up to the present we do not have a single case
of a successful cure for a disease by means of
gene therapy. All successful interventions,
whether in genetically simple disorders like
phenylketonuria or in complex cases like
diabetes, have been at the level of biochemistry
and were in place well before anything was known
about DNA. Of course, a successful gene therapy
for some disease may be produced in the future,
but the claim that the manipulation of DNA is
the path to general health is unfounded. In
fact, on a world scale, most ill-health and
premature death is caused by a combination of
infectious disease and undernourishment —
factors which genetic manipulation will never
solve.
The second implication, the possibility of using
genetically transformed organisms as factories
for the commercial production of biologically
useful molecules, has been realized in practice.
The most famous case, the mass production of
human insulin by bacteria, is particularly
instructive. Insulin for diabetics was
originally extracted from cow and pig
pancreases. This molecule, however, differed in
a couple of amino acids from human insulin.
Recently, the DNA coding sequence for human
insulin has been inserted into bacteria, which
are then grown in large fermenters; a protein
with the amino acid sequence of human insulin is
extracted from the liquid culture medium. But
amino acid sequence does not determine the shape
of a protein. The first proteins harvested
through this process, though they possessed the
correct amino acid sequence, were
physiologically inactive. The bacterial cell had
folded the protein incorrectly.
A physiologically active molecule was finally
produced by unfolding the bacterially produced
protein and refolding it under conditions that
are a trade secret known only to the
manufacturer, Eli Lilly. This success, however,
has a severely negative consequence. For some
diabetics this “human” insulin produces the
symptoms of insulin shock, including loss of
consciousness. Whether this effect is caused by
a manufacturing impurity, or because the insulin
is not folded in the same way as in the human
pancreas, or because the molecule is simply too
physiologically active to be taken in large
discrete doses rather than internal,
continuously released amounts calibrated by a
normal metabolism, is unknown.
The problem is that Eli Lilly, which holds the
patent on the extraction of insulin from animal
pancreases, no longer produces pig or cow
insulin. Hypersensitive diabetics for whom Eli
Lilly’s standard treatment is dangerous no
longer have an easily obtainable alternative
supply. The most widely known and contentious
application of DNA technology to production is
in agriculture. The introduction of DNA
sequences derived from widely divergent species
into agricultural varieties has resulted in a
struggle of immense proportions in both North
America and Europe. The proximate purpose of the
creation of varieties with DNA introduced from
other kinds of organisms is to produce
agricultural crops with novel features that
cannot be obtained by the usual methods of
selection because the relevant genes are not
present in the agricultural species. The
benefits to farmers, consumers and commercial
seed producers vary considerably from case to
case, although in every case the ultimate goal
of the commercial breeder is increased profit
and the protection of their property rights.
There are four cases to be distinguished. First
there is the introduction of pest and disease
resistance, as in the introduction of the BT
protein from Bacillus thuringiensis into maize.
This is intended to reduce the labor, chemicals
and machinery needed by the farmer for pest
control. Some of the cost reduction is lost in
the higher price of the commercial seed, but
saving labor is important to farmers. Second,
there is creation of varieties that are
resistant to herbicides used to control weeds.
The best-known examples are the Roundup Ready
varieties produced by Monsanto, designed to
coerce farmers into purchasing Monsanto’s
general herbicide (Roundup) as well as their
seed. The supposed advantage to the farmer is a
reduction in machinery and labor involved in
tillage, but again the cost saving is reduced by
the increased price of seed. The third case is
the pure protection of property rights of the
seed producers with no benefit to farmers or
consumers. The most infamous example is the
attempted introduction of “Terminator”
technology by the Delta Pine and Land Company,
which was later purchased by Monsanto.
Terminator seed varieties will germinate and
produce sterile crops, thus forcing farmers to
purchase commercial seed anew every year. (It
should be noted that this technology, of no
advantage to farmers or consumers, was produced
in cooperation with the U.S. Department of
Agriculture). The fourth case is the
introduction into mass produced field crops of
DNA coding for particular compounds normally
only produced by specialty species. This
technology has the potential to destroy much of
the economy of Third World countries that are
dependent on the export of agriculturally
produced commodities. An example is the transfer
into rape seed, a widely grown crop in North
America, of the DNA coding for palmitic acid
oils that are used in industrial processes.
Normally these oils are extracted from oil palm
seed grown in Southeast Asia.
While much of the opposition to transgenic
agriculture has been based on the “unnaturalness”
of the process, this objection misses the point.
No agricultural variety is ‘natural’,but is
the product of centuries of gradual, cumulative
genetic modification from its wild ancestors to
produce varieties that are utterly different
from the ancestral forms. Moreover, crosses
between different species have been a standard
method of plant breeding for more than a
century. The real issue is that DNA technology
provides a powerful tool for the control of
agricultural production by monopolistic
producers of the inputs into agriculture with no
ultimate advantage either to farmers or
consumers and with the possibility of destroying
entire national agricultural economies. All of
the elements that characterize the era of DNA
have in common an underlying simplistic view of
living organisms. By concentrating in practice
and in theory on the properties and functions of
a single molecule, biologists, both in their
professional work and in their public
statements, reduce the extraordinary complexity
of life processes to the structure and
metabolism of DNA. This emphasis ignores the
intricate and multiple ways in which organisms
are built and function. The intricacy is a
consequence of the structural and metabolic
functions of proteins and the interactions of
those proteins with each other, with other
molecules, and with the environment in the
course of development.
Moreover, for human life, no account at all is
taken of the role of social and economic
processes in determining health and life
activities and molding the processes of
industrial and agricultural production. We
cannot understand our size, shape and internal
functioning except by a detailed understanding
of the extremely complex web of interactions
among the various molecules which form the body
in concert with influences exerted by our
environments. We cannot understand the origin
and development of our mental states except by
an understanding of the map of nervous
connections and how that map is influenced by
experience. We cannot understand why
agricultural technology develops in particular
directions if we do not understand the social,
political and economic interactions that drive
technological innovation. The bottom line is
that life in all its manifestations is complex
and messy and cannot be understood or influenced
by concentrating attention on a particular
molecule of rather restricted function.
***
Richard C. Lewontin is an
evolutionary geneticist, philosopher of science,
and social critic. An early pioneer in the
development of molecular population genetics,
his works include Biology as Ideology, The
Triple Helix: Gene, Organism, and Environment,
and Not in Our Genes, co-authored with Steven
Rose and Leon Kamin. He is Alexander Agassiz
Research Professor at Harvard University, and
regularly writes for the New York Review of
Books.
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