Dr. Eva Jablonka discusses the role of epigenetics in evolutionary biology. This short take was shot during a break at Keystone Symposia’s meeting on Environmental Epigenomics and Disease Susceptibility held in March 2011 in Asheville, North Carolina.
Epigenetics in Evolution
Well, what I’m doing really is theoretical work, and I’m mainly interested in the evolutionary implications of epigenetic inheritance. So the more we learn about epigenetic inheritance, the more we understand how traits are epigenetically transmitted from one generation to the next, the more we can develop substantial models in evolutionary biology, about the evolutionary impact of epigenetics.
So at the moment, what is happening in evolutionary biology is that people are beginning to consider epigenetic variations and the inheritance of epigenetic variations as a factor in evolution. There is a lot of resistance to this, and the resistance is due to the fact that the epigenetic system has a dual role: it is both a response system – epigenetic control is part of regulation of gene expression; and it is also a memory and inheritance systems. Because of this dual role, induced changes that change epigenetic marks can be transmitted from one generation to the next, at least in theory and it seems also in practice, because we are seeing a lot of transgeneration effects that we don’t exactly know how specific they are, but sometimes they seem pretty specific and they’re inherited, sometimes transiently, sometimes for many generations.
Now this kind of thing is resisted because it is felt that this is going against the prevailing view of evolution, where natural selection is the only factor that is shaping adaptation. If you introduce epigenetic inheritance, and the inducible aspects of epigenetic inheritance into evolutionary theory, it looks like Lamarckian inheritance – it looks like you have the inheritance of a quiet epigenetic variation, which are or can be sometimes a specific response to the environment.
“…epigenetics is going to have an impact on everything – on every aspect of biology…”
Now a lot of people do not like this – a lot of people regard it, have a kind of knee-jerk response to it, “This cannot be true, we have learned in high school that this is not true. Lamarck was wrong.” Well, I think that we have to reconsider it, and that is why I think evolutionary theory – evolutionary studies has been lagging behind all other domains in biology in terms of the impact that epigenetic research is having on them. This is changing. I think what we need and what need really badly, in addition, of course, to empirical studies, are good models.
We need people who systematize the knowledge that we have at present, and the theoretical implications of variable transmissibility of epigenetic variation, of the inducability of epigenetic variation, and the variable expressivity of epigenetic variations which can be dependent on the number of generations of exposure on how many generations a particular chromosome or part of chromosome had undergone sequentially oogenesis, or spermatogenesis on the genetic background. All these things we have to understand to model, and once we will have good models we will also be able to do good experiments, both in the lab and in populations. Of course, this doesn’t mean that we should not do experiments now: we must have the ecological data, and this is being done. Ecological epigenetics is beginning to take off, especially in plants, but not on.
So I think that what we need is a lot of population studies, and a lot of modeling, because although people are doing modeling – individual people are doing modeling and there are some very, very interesting models in the field already, it is not all put together, and certainly there is not one person who has taken it upon himself to systemize this theoretical framework, and we need this.
Look, the genetics is going to be relevant to everything. And in the same way that genetics is relevant to everything, that you cannot – after we have understood when dealing in genetics, and genetics in general, and the role of DNA, for example, we understood that DNA variation is going to be relevant for everything – every aspect of biology is going to be impacted – it will have an impact on everything. In the same way epigenetics is going to have an impact on everything – on every aspect of biology: on the physiology and on our studies of morphology, and on our studies of disease and of health, and you name it – everything – because it is a fundamental part of what it means to be a biological creature. If epigenetic inheritance is important – if the inheritance of a genetic variations is important, then obviously it will impact, again, everything: health, disease – everything.
So I think that the research that we’re seeing today is convincing everybody, I think, about the important of epigenetics, and transgenerational epigenetic effects on the well-being of people. And how profound it is, I mean, this is work in progress, but I think that if we will understand the theoretical possibilities – if we will be able to explore the theoretical possibilities in a systematic way, I think this will be a great help for counsel research, for epidemiological research, and for every aspect of medical research.