Can Your Lifestyle Affect Your Unborn Child? (Part 2)

This is the second of two articles on the subject. If you haven't read the first part, read it here.

Last time, we talked about Lamarckism and epigenetics, which will now help us answer the original question.

First, let us refresh our memory really quickly.

Lamarckism: The idea that organisms can pass on characteristics that it has acquired throughout its life.

Epigenetics: Change in expression of the genetic material (DNA), rather than a change in the coding sequence. 

Now, we'll combine the two ideas to reveal something that was discovered relatively recently.

Epigenetic Lamarckism.

Sounds kind of cool, right? But what is it? As the name suggests, epigenetic Lamarckism is the idea that epigenetic patterns that govern the expression of genes can be passed on from parent to offspring. As the expression of genes is related to the events in an organism's life, the inheritance of epigenetic patterns can be termed Lamarckian. Sounds like a neat little hypothesis, but is there any evidence-based research that supports the suggested form of Lamarckian inheritance?

Well, while it has not yet been experimentally demonstrated in humans, there is some evidence from rodent models. For example, a 2010 study showed that male rats that were fed a high-fat diet were more likely to have obese female offspring. Another study, published in 2013 showed that mice that were trained to fear the scent of a chemical, produced offspring that were as likely to be scared by the same scent. A study on birds shows that the circadian rhythm (the body's internal time-keeping system) of a mother can be epigenetically inherited by their offspring. Creepy?

So, should you be concerned? While trans-generational epigenetic inheritance hasn't been observed in humans, based on the evidence from model studies, it would be reasonable to assume that our lifestyle choices (what we eat, when we sleep) may affect our unborn kids.

The good news is that epigenetic inheritance is what we might call soft inheritance, which means that it is unstable and might revert to normal expression once the stimulus inducing it has been eliminated. Unlike hard inheritance, where the gene undergoes a permanent change in the form of a mutation.

However, there is some evidence to suggest that the predisposition to certain diseases could be epigenetically inherited by offspring in humans. So, we'd rather be careful not to pass on our habits to our children by maintaining a relatively healthy lifestyle. Stay healthy. Keep your unborn kids healthy. And yes, give my post a like.

Until next time! Bubye!

Can Your Lifestyle Affect Your Unborn Child? (Part 1)

This is the first of two articles on the subject, the second article will be posted on or before the 10th of June, 2017. 

Darwin's theory of natural selection provided us with a beautiful explanation for all the life we see around us. But not many of us know that there were other competing theories, that were ostensibly eliminated through natural selection. 

One of the most interesting theories of the origin of species was proposed by Jean-Baptiste Lamarck, a French naturalist in 1809, almost half a decade before Darwin published his book 'On The Origin of Species'. Why then, couldn't Lamarckian theory survive the test of time? Well, while Lamarck may have been the first to suggest the theory of evolution, the process he described was very different from Darwin's gradualism. Lamarck's theory is what is now called the use-disuse theory. 

Simply, there are two ways to explain the long neck of a giraffe. A Lamarckian explanation would suggest that the ancestors of giraffes that stretched their necks to get to the foliage on higher trees would pass on the information to their unborn offspring, causing them to grow longer necks. While this does sound like a plausible theory, it would predict the appearance of newer forms of life in a much shorter span of time. That, as we know, is not the case. 

Why am I talking about hungry giraffes and theories of evolution? Am I not supposed to deal with the question in the title of this article? All in good time.

See, the crux of Lamarckism is that we are somehow able to pass on acquired characteristics to our offspring. For humans, this would imply that our lifestyle; the way we eat, sleep, etc would have an indirect effect on our future offspring. But considering that the theory has been abandoned, that's not true, right? Or, is it?

As mentioned in my previous article, genes work by encoding information which is then decoded by a pathway that is usually called the central dogma. Remember? DNA makes RNA makes Protein. Well, DNA does not literally make RNA (same for RNA and proteins), but you get the point. But if that's the case, and all the cells in our body have the same DNA, why doesn't your eyeball have hair? Any such questions can be answered with one word: Epigenetics.

If genes are our master puppeteers, epigenetics is what keeps those genes on a string. This is usually done by processes such as acetylation, methylation and differential condensation of the DNA and these processes may be interconnected in regulating the differential expression of these genes. These processes basically involve the addition of a methyl or acetyl (tiny molecules) tags that affect whether the DNA sequence is expressed as protein or not. 

Okay, you get that. But, what does it have to do with whether or not you can affect your unborn child with your lifestyle choices? That is a related and slightly more complicated issue, which I shall deal with entirely in the second part of this article. 

P.S. I have split the subject into two articles to make it less tedious for the reader. A really long article would cause the reader's interest in the subject to wane midway. Apologies for that. 

One Gene, One Behaviour?

Erwin Schrodinger, the brilliant Austrian physicist, is best known for his wave equation that describes the movement of particles on a quantum level. Perhaps among his lesser-known contributions is that he laid the foundations of quantum or molecular biology in his book 'What is life?'.

Schrodinger was one of the first to hypothesise regarding the nature of the hereditary material responsible for the way we are. He suggested that if such a molecule exists, it would most certainly be an aperiodic crystal. This implied the presence of a molecule that was able to hold information using an aperiodic sequence of molecules connected by covalent bonds (related to the information theory interpretation of entropy, a blog post for another day). Schrodinger (as did most scientists) assumed that the most likely candidate were proteins, being composed of 20 different monomers called amino acids.

This was proven wrong in a few decades, with the establishment of DNA as the puppeteer that held the strings to life. Francis and Crick were hailed as the pioneers of a new age for biology (Apologies, Rosalind Franklin). Methods were developed to find out how stuff works, which lead to what we call the central dogma. Simply put: DNA makes RNA makes Protein. All we are was reduced to a tightly regulated clockwork of molecules that we now call life.

Now, I assume that the reader has some knowledge of how DNA works, so I'm going to skip right to the good bit. Genes produce proteins through a dizzyingly complex process, and proteins keep us alive by keeping those (and many other) processes running. This was neatly summarised in Beadle and Tatum's one gene-one enzyme hypothesis, which said that each gene produces one enzyme that affects one step in a metabolic pathway. 

But that's a bit too simple, yes?

What I think about is, whether genes affect our behaviour? Yes, yes. Anyone would agree that they do.

But, could we extend the one gene-one enzyme hypothesis to a one gene-one behaviour hypothesis? I mean, could one gene somehow contribute to a complex action or behaviour, as we might call it? There's data to support this, but we have yet to uncover the subtle intricacies of the issue.

I recall an experiment that Professor Dawkins mentions in his book The Selfish Gene. W. C. Rothenbuhler, an entomologist interested in the behaviour of bees, found that a complex behaviour for maintaining beehive hygiene was controlled by genetics. Grubs are sometimes affected by a disease called foul brood. Some strains, called the hygienic strains, get rid of this problem by committing infanticide (GASP!). That includes: locating the infected grub, removing the wax cap from its cell and dragging the poor thing out and yanking it off the hive.

Now, one might conclude that this behaviour is genetically determined. True. However, what's astonishing is that this complex behaviour can be sub-divided into its elements, as can be seen above. Cross-breeding between hygienic and unhygienic strains produced hygienic as well as unhygienic strains. However, a third strain went half-way. While it plucked off the wax cap on the grub's cell, it did not get rid of the diseased grubs. Further cross-breeding proved that the behaviours for uncapping and throwing out were defined by two genes. How fascinating.

Could it be that our behaviours are defined by our genes? Truly, they are. But, could we ever be able to know how? Surely, it is far more complex to understand how a gene might affect synaptogenesis (creation of connections between neighbouring neurons in the brain) in a brain as complex as ours, producing a defined behaviour. And despite its many triumphs, neuroscience is surely in its infancy, for we know more about what's on our mind than within it.

Could we identify genes that define our behaviours? And if we do, could we in the future, engineer humans that have certain behaviours built into them? Surely, we talk about designer babies (back in the news again. Thanks, CRISPR!), but the arguments are mostly limited to physical attributes and eugenics (humans are so obsessed with aesthetics, aren't they?). A good way to search for such genotypes would be to dice human behaviours into their fundamentals, and then, look for a genotype corresponding to each of those behaviours.

Some questions that arise are: Suppose we find a genotype that predisposes a human being to be more aggressive or violent. Wouldn't that correlation lead, inevitably, to genetic screens that would seek to identify such behaviours based solely on their genes? Would that be ethical? How much control do we have over our genetic impulses? How guilty are we for our follies, if we are cursed to follow our genetic destiny? 

Laplace's Demon and the Question of Free Will

Pierre-Simon Laplace was a French mathematician and physicist born in the mid 18th century who made enormous contributions to the development of the natural sciences. But he also made contributions to modern philosophy with his idea of causal determinism. Closely related to predeterminism, Laplace's ideas were rooted in scientific thought. 

In A Philosophical Essay on Probabilities, Laplace argued for scientific determinism in the following words:

"We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atoms; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes."

Sounds a lot like God, doesn't it? 

Simply, consider an atom; any atom, that is part of your body. Now, you go back in time, thousands, millions, and then billions of years. You watch that atom skip and jump through a series of events back to the singularity that resulted in the big bang. Now, press play. You see? Everything that has happened since is the result of a series of events that are a product of particles coming in contact with other particles in their vicinity. Thus, one might assume that knowing the position and quantum state of the particles in a space, their evolution in space-time is pre-determined. Neat.

Thinking about it, does this not negate the idea of free will? Does it not imply that everything we do is the result of a series of events that can be predicted based on the position and states of the particles that make us? It would require loads of computation, really. But since Laplace's demon can compute and predict the universe, we're possibly simple too. 

But there's one little problem. Werner Heisenberg, a brilliant theoretical physicist from Germany, introduced an idea called the 'Uncertainty Principle'. Simply put, the principle states that the position and velocity of a particle cannot be determined without disturbing the system when we observe it. The observer effect can be used to argue for the anthropic principle, but that's a story for another day.

Heisenberg's uncertainty seemed to yank the rug from under Laplace's Demon. Or did it?

Yes, quantum mechanics is fundamentally probabilistic and certainly uncertain. But, that has to do with the observer effect, right? What really goes on when we're not looking? Is there another set of rules that govern quantum particles when unobserved? We would never know. Does the Demon know of a way to observe the quantum particles without letting them know they're observed? We'll never know that, either.

Another stumbling rock in the Demon's path is what we call the Butterfly Effect, one of the central tenets of chaos theory. The smallest change in the initial state of a system will lead to an entirely different outcome. Tying in with the uncertainty, it sounds like the Demon has been exorcised for good.  Right? Although, I tend to differently.

What do I believe in? Well, belief is a strong word. But I do think that quantum particles behave entirely differently when unobserved, and if those laws are static, the universe is fundamentally predictable in its entirety. Simply, I am unsure whether we are ever in control of anything. I think time exists as a block, stretching from the big bang up to the end of the universe (if there is one). We merely exist to play our part in the play, living through the snapshots that make up time, snapshots that we call now.

Do you find the idea liberating? Knowing that whatever screw-ups you've had, were the result of a deterministic system? Or do you find it suffocating? Knowing that you're never in control. That you'll forever be a puppet in the hands of time and probability.