What is the half-life of an emotion?

"I think, therefore I am." 

With these words, Descartes summed up the nature of human existence. Whatever man is not, he is perhaps the only animal capable of abstract (and more rarely, rational) thought. Philosophers spent centuries trying to decipher the mysteries of the mind, before the era of scientific enlightenment pointed them in the right direction. The establishment of modern medicine lead to the discovery that what we consider to be the 'mind' or the innate 'soul', is nothing but the by-product of our neural processes. 

All you are is a thought, and your thoughts are nothing but a spark in the elaborate circuitry of your nervous system. These sparks, though not always, are at the mercy of the chemicals that bathe your brain. Everything you think, everything you feel. All of it can be boiled down to a set of neurons firing off in a set pattern. Reduced to chemicals released by the right gland at the right time. All your happiness and gloom, your misery and fortune, everything is born out of the cauldron of your neuro-endocrine system. 

In the past, emotions might have played a role in promoting group bonding and establishing social structure. What was once an essential tool for survival is now nothing more than a fossil, an evolutionary phantom limb that won't stop itching. Despite societal and cultural norms exaggerating the importance of these impractical remnants, one does realise (in due time, of course) that most emotions are ephemeral. 

No matter how much you loved your teenage sweetheart, you barely remember them once some time passes by. As the euphoria wears off, you realise that your feelings have atrophied and all that remains is the skeleton you lock away in the closet. Emotions are fleeting, and these fickle phantoms need to be exorcised (Mr Spock agrees). 

In an attempt to unveil the trickery behind these pesky pests that inevitably inhabit our skulls, I am going to write a series of blog posts revealing the biological processes that dictate our emotions. The intention is not to belittle what we feel, but rather produce a sense of comfort. 

The first emotion, of which we are all rather fond of, is the one I'll be tackling first in my next post. Love and attachment. In the meanwhile, I am open to suggestions and input regarding the same. 

P.S. This and the following posts do not seek to undermine what you may or may not feel. It is all a part and parcel of being human.

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? 

The Entropy Conundrum.

There's a question I've heard on more than one occasion.

"Doesn't evolution or life itself violate the second law of thermodynamics?"

The second law of thermodynamics states that the entropy of a closed system must always increase. And entropy is a measure of the disorderliness of a system.

So, I've been reading Nick Lane's book 'The Vital Question', and I've come across a few interesting ideas.

Apparently, there's a lot of difference between things that "seem disordered" and things that "are disordered".

An example is:

While an irregular mixture of oil and water might seem less orderly than the lipid bi-membrane of a cell, it is not so,

Lane argues that this conundrum arises because we tend to ignore the subtle balance between a system and its environment.

A lipid bi-membrane is a stable, low energy configuration of molecules, and in achieving that configuration, the molecules lose heat. The overall entropy increases.

I suppose the same argument might be applied to explain the evolution of some, if not all molecular machinery in the early cell prototypes.

While the example I've chosen here, from Lane's book, is quite simple, I would love to know about the changes in entropy when considering a more complex organic molecule,


Any input regarding the same, can be shared in the comments section.

P.S. I'll be sharing my thoughts on the book, as and when I read it. I would highly recommend reading "The Vital Question", as it tries to answer some of the most difficult, yet fundamental questions in biology.