For by him were all things created, that are in heaven, and that are in earth, visible and invisible... Colossians 1:16
fascinated biologists since ancient times.
To Darwin, it became a
fundamental part of his theory of natural selection. Darwinian theory,
and then later Neo-Darwinism (which attributed variability to random
mutations) pictured the environment as a “driver” of adaptation.
----There’s
another way of understanding the fit of organisms to their environment,
however, that ascribes adaptation to intelligent causes. That way is
the newer science of epigenetics, in which internal factors “tune” the
genome to its surroundings quickly, without waiting for some “beneficial
random mutation” to show up.
One Sequence, Many Variations (The Scientist,
5 Oct 2022). At the Van Andel Institute, researchers have a new take on
what makes animals and plants adapt to their environment. It’s called
epigenetics, “above the genes.” Andrew Pospisilik is a founding member
of the VAI’s Metabolic and Nutritional Programming group. “Pospisilik
explores the epigenetic changes that give organisms the plasticity to
change in response to their environments.”
Is this a big change in thinking?
For years, scientists have been fascinated with how DNA mutations impart phenotypic changes. However, epigeneticists including Andrew Pospisilik think mutations are responsible for only a portion of the variation present in all organisms. Epigenetic changes from molecules attaching to DNA and histones—proteins that compact DNA into chromatin—and other factors that modulate gene expression allow organisms the flexibility to change according to their environment. These changes can be inherited, altering the phenotypes of future generations in the absence of mutations.
To the extent this happens, it represents a very different picture
from 
classic Neo-Darwinism. Neo-Darwinism places all phenotypic change
in random mutations—mistakes in the genes, whether from cosmic rays,
copying errors or other undirected sources—and claims that only those
that are mildly “beneficial” will be inherited, while the vast majority
are deleterious or neutral.
But if Pospisilik is right, organisms can get many variations from
one sequence, applying epigenetic factors built into the cell’s internal
operations (e.g., regulatory elements). He explains why the study of
epigenetics is important:
Ever since scientists discovered DNA, figured out what genes were, and started making mutations and sequencing genes, they saw how reproducible the consequences of strong mutations were and got lost in the default notion that everything must be genetics. As scientists map all the genetic differences between humans, we are finding that we are on course to understand, at most, one-third of the puzzle.
Mutations cannot tell the whole story, he continues. “For example, identical twins are not always identical.”
The missing piece is developmental plasticity, which is a major determinant of who and what we are. In organisms that originate from the same DNA template, factors have evolved to compress their variability and mediate their plasticity.
Whether these “factors” have “evolved” in a Darwinian sense, they are
not external, but internal to the organism. They exist within the
epigenome to give flexibility to organisms placed in new environments.
His claim that “factors have evolved to compress their variability”
might be a holdover from decades of Neo-Darwinian dogma. It is just as
possible to assert that epigenetic factors were built into the organism
from the start. If variations are resulting from within the organism,
they are not the consequence of mutations.
A designing intelligence, for instance, might pre-program variability
for robustness, similar to how the immune system generates millions of
antibodies in a targeted search for an antigen. A targeted search for a
match is different from a random search (or blind search), because the
outcome has been specified beforehand. This implies the pre-existence of
information that specifies the target and recognizes a successful
outcome.
The environment, oblivious as it is to an organism’s needs,
cannot be the source of information.
Usually, we think that DNA mutations drive this, butepigenetics allows the same DNA template to generate additional outcomes. For organisms that produce many offspring, such as fruit flies, it does not make evolutionary sense to have hundreds of truly identical offspring. If their DNA sequence makes them sensitive to an environmental perturbation, then they could all die. It is best to have variability in that system so that some of them can live.
“Variability in that system” sounds like something that requires
foresight. A designer of programmed robots, for instance, might build in
modules that drive variability such that some of the products would
flourish in a given situation. This would be very different from
traditional Neo-Darwinism, where the environment is thought to “drive”
adaptation via random mutations.
Pospisilik gives examples of how the same genome can generate
completely different phenotypes, depending on the epigenetic regulatory
factors. One dramatic example is honeybees: from the same genome, the
hive produces a queen, workers, drones and other members of the caste
system. What if varieties of bee, wasp, termite and ant colonies had
adapted differently based on epigenetic factors? This could explain why
similar species within a family have caste systems and others do not,
and why the caste systems are highly organized and successful.
Sometimes epigenetically-driven phenotypic plasticity can go awry. He gives an example:
In humans, the Dutch Hunger Winter is a famous example. It was a prolonged famine period during the Second World War. Scientists have found that offspring of people who lived through that period are more susceptible to cardiometabolic diseases a half-century later. Like the queen bee example, these seem to be direct early consequences of the fetus being reprogrammed.
In the remainder of the interview, Andrew Pospisilik shares ideas
about how knowledge of epigenetics can help treat diseases like cancer.
Based on his experience to this point, he thinks that
With his colleague Peter Jones, Pospisilik shares his opinion that the Van Andel Institute has a “world-class, forward-thinking faculty and scientific cores who are most interested in publishing great science.” Q: Will the great science of the 21st century abandon Neo-Darwinism and focus on epigenetics?
This
article is exciting because it appears to support ICR’s current research
program on Continuous Environmental Tracking (CET) as a model for
adaptation. Epigenetic matching of the genome
to environmental constraints is very different from Neo-Darwinism,
because it locates adaptation internally instead of externally.
ICR’s “engineering-based
biological model” rids biology of the mystical notion of a personified
natural “Selector” that picks winners and losers by chance, and puts the
design into the foresight and programming skill of the designing
intelligence.
No one yet
knows the extent to which epigenetics can account for adaptation. I
suspect, though, that this “engineering-based approach” to phenotypic
plasticity and variability within species up to the family taxonomic
level will prove fruitful, much more so than the current reliance on the Law of natural selection, which relies on sheer dumb luck." CEH
