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An open question in biology is, how do the shapes of creatures come about? How does, for
example, a certain frog species obtain its particular shape and not some other?
How do its legs and toes and claws always get their particular shape and not some other?
The same question for all the internal bits: the spine, the liver, the brain.
How do each of these always come to the same shape and interconnect in the same way, particular
for this species and no other. Most textbooks still repeat the 70-year old idea
that the DNA alone, somehow determines everything, though there is surprisingly
little evidence for this. I would like to highlight some of the evidence for the role of electricity
in how plant and animal shapes come to be, and also say a few words about the role
of electric fields in how inorganic objects obtain their shapes.
I was motivated to give this talk after reading about the work of the Michael Levin lab
at Tufts University in Boston. For more than a decade, the lab of
Dr. Levin has been overturning some long-held beliefs about how biological shapes arise.
Back in the late 1950’s, when DNA was being discovered and its role was
starting to be understood, Watson and Crick championed the idea that
the DNA determines everything about the organism. They called this the ‘Central Dogma’
of biology. For the past 70 years, most textbooks and funding have
unquestioningly followed this Dogma. It is a form of predeterminism
all over again, since it assumes that the information flows only one way from the DNA out
and nothing an organism could do would ever change that. Crick was very vocal that finally,
he a mere man, had once and for all eliminated the need for a god,
or any intelligence in the universe, since everything about us flows from our DNA.
Bombastic cheekiness aside, we can still run experiments to test the idea.
Over the past 70 years, many thousands of experiments have been run
to elucidate the role of DNA in developmental biology.
But try as we might, we could never show that genes actually create any forms.
What exactly in the DNA determines that an arm be shaped just so, and not otherwise?
How is the inside of the mouth formed just right, to meld with the nose above and the
throat below? Search the literature and you will find that the best we can do
is to show that disabling certain sections of DNA, will cause some body part to form
incorrectly. But this does not mean that the DNA is causing the form
of that body part. I was always surprised at such sloppy thinking.
That would be like me showing that I can prevent you from driving to the store if
I give you a flat tire. Correct, you cannot drive to the store if you have a flat tire,
but the tire was never the cause of you going to the store.
Just because mucking with some DNA causes an arm to form incorrectly, does not mean
that the genes cause the shape of the arm. Using a cooking metaphor,
which is surprisingly accurate, ingredients do not by themselves cause anything.
You need a recipe that tells you what to do with the ingredients.
And what is the meal? How many people are you cooking for? What is the order of the evening? All
that makes a real difference. Our genes do not necessarily tell our
bodies what to make, or when to make it. These decisions are made mostly outside
the genes. Everyone should know that we do not really understand
DNA. Every decade, the advanced text- books need to be rewritten because we find
out that the system is way more complicated than we previously thought. What we call
genes are really a very small part of the total DNA. Genes are that small part of the code
that contain the blueprint for building proteins. We still do not know what
most of the DNA does. The collection of all the genes in your DNA
is much like a giant ingredient list. If you had a cookbook of all the recipes
you could ever make and you made an index of all the ingredients needed for
all those recipes, that is what the genes are. All the blueprints for how to make each
of the ingredients you might ever need. But again, genes constitute only a very small part of the DNA.
The work in Dr. Levin 's lab is impressive by any measure. These are virtuoso
level skills. They alter the DNA of individual cells to change the number of
ion pumps the cell makes for itself. This makes these particular cells more
or less electrically polarized relative to what they would have been in the wild-type.
At certain times in the development of the embryo, if enough cells in one place
can be tricked into creating just the right electrical alterations, then body parts will grow
in that location. An eye will grow inside of a stomach, a toe might grow on an elbow.
The 70-year old Central Dogma of biology states that DNA, isolated inside the nucleus,
causes all shapes and forms to appear. What does Levin's result show?
That an electric field external to the nucleus, caused the shapes and forms to appear
when and where they did. It does not mean that the fields create the form itself,
but it does mean that the field can cause the shape to appear.
What does this mean for the Central Dogma? Things get really tricky,
because Dr. Levin, in altering the genes in the cells, which cause
more ion channels to form on the cell wall, which causes a different electrical
potential of the cell relative to its surroundings. So you could argue that the DNA is
controlling everything. But the argument has become muddied.
Why does the entire eye form in the electrified location and not just
pieces of an eye? And how is it that we instinctually know that the eye
should not be in the stomach? In Levin 's cancer research, they show that changing wild-type
electrical fields can start and stop cancer cell growth. Highly malleable cells,
such as stem cells and cancer cells, have less-defined electrical potentials
relative to their surroundings. Whereas healthy, mature cells have higher
electrical potentials. One of the hallmarks of cancer cells is
that they have lost their relationship with the larger body.
They are an out-of-control growth of cells that are part of nothing.
They have no function beyond their self-interests. Here Levin 's results come very close to
actually disproving Crick's Central Dogma with regard to the form and function,
since electric fields, external to the nucleus, can destroy all form and function.
On a more personal note, the Levin lab results are terrifying to me, because here we are
again, bumbling into areas we do not understand with tools too powerful for us to wield
with wisdom. Has this new technology allowed us to add
beauty to the world? Not so far. To date we are only making grotesque monsters with legs
growing out of their heads. The poor creatures live, somehow and it turns my stomach to
imagine that. I'm afraid we are right back where we were with the DNA story.
We knew that mucking with the DNA will cause monsters. And now we know that mucking with the
electric fields will cause monsters. It does not prove the DNA is causing the
proper shape, nor does it necessarily prove that the electrical field
is causing the proper shape. Dr. Levin 's lab is justifying all this with the
promise of new medical treatments, if we can just make it through a few
more decades of producing monsters. I am also surprised that Dr. Levin does not
seem to reference Dr. Robert Becker, who already showed most
of these principles 40 years ago. You can see a good summary of Becker's work in his book,
The Body Electric. Dr. Becker, a practicing physician, discovered that
controlling electric fields could heal burn victims and could let salamander tails grow back
properly. Why not give credit where credit is due? I fear it is because it became known
that Robert Becker had a spiritual side. He maintained that humans were more than
just sacks of chemicals. I fear that since Dr. Becker did not believe in pure materialist
reductionism, many journals will not allow reference to his work.
Let us look at two more sets of experiments from Dr. Levin 's lab.
Then we can step back and ask, why does it all matter?
These experiments involve planarian flat worms. In the wild, if the tail of the worm gets
chopped off, then a new tail will grow. If the head of the worm gets
chopped off, a new head will grow, brain and all. Pretty amazing.
The wild-type worm has an electrical gradient along its body,
more positive towards the head. The researchers cut off the tail.
Then artificially gave that end a positive charge. This caused a new head to grow off the
back end. We now have a new shape: a two-headed worm.
This new two-headed worm then propagates. It reproduces asexually, as all
planarians do. Is this a new species? I think so. Yet the DNA has not changed. You can see
that the connection between the DNA of the animal and the shape of the
animal is becoming less clear. How could the DNA remember that this new worm species
has two heads? So, all future progeny must also have two heads.
Returning to the cooking metaphor. It looks like the genes are available to get the raw
ingredients produced, but the recipe and the plans for the full meal are
being handled at quite another level, quite outside the world of genes.
In a different experiment, they went to the wild-type, cut off its head,
then while the new head was forming, they modified the electrical potential of some
cells and ended up producing the head and brain types of another species
of planaria. Let that sink in. The DNA is still that of the original species,
but the form, the shape, of the new worm head, is that of a related species of worm.
We have created a new species, but we have not altered the DNA.
In my opinion, any notion of DNA determining the shapes of creatures
is on pretty shaky ground. Why does any of this matter? It matters
because the story of DNA that we grew up with and still teach to our children,
is not only wrong. It is actually harmful to our spirit because it gives us a false
understanding of ourselves and of our relationship to the universe.
We were told that a simple molecule with sequences of four molecular letters determines
everything about us. We were assured that not only our shape, but our entire
being is supposedly a simple unfolding of some molecular computer program into
which we have no input. I find all aspects of this dogma incorrect
and harmful. As a scientist, I am trying to reconstruct a cosmology that is more accurate
and more meaningful. In the second half we will look at the question of whether matter
is even capable of organizing itself. And if not, then where could all these shapes be coming from?
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