How Far The Apple Falls

In case you’re wondering from the caption, no, this article is not about the decadence of a tech titan or the oft-repeated tale of Newton’s famous eye-opener to gravity. Rather, we continue our discussion from the previous post about the impact of nature and nurture on your individual being.

Before I kick off my verbal marathon, however, I’d like you to pause here for a moment and think for yourself: what affects a person the most – his parentage or his upbringing?

Some of you might believe that a person is more likely to follow the footsteps of his ancestors, or, as famously paraphrased – like father, like son. Others may say that a kid is most likely to be influenced by the kind of environment he receievs. Rest of you might be in a bit more generous mood today and see the answer beyond black and white, in shades of gray (hopefully not 50, though).

At best, the most layman answer to this question is that both heredity and nurturing play important roles in the person we become, albeit not independently. Both keep on manipulating each other, like Tom and Jerry.

Got the point? Good. Now be prepared for the gruesome details.

First, we’ll discuss the ‘nature’ part. Anyone who’s ever spent a waking moment during biology classes must’ve heard words like genes or DNA or chromosomes thrown around a lot. Sure, we all like to play sophisticated and somberly nod our heads as if we hold doctorate in genetics while engaging in casual discussion about these terms, but it would be nice if most people actually knew what differentiates a gene from chromosome.

Don’t worry, unlike your bespectacled and stern high school biology teacher, I’m not going to slam you with loads of arcane definitions that make your head hurt later. But it’s necessary that you have a clear understanding of certain concepts.

Genetics 101 (Or as easy as it could be)

Even a layperson knows well that children resemble their parents more than anybody else in the world, in one aspect or another. Oftentimes you get to hear compliments like ‘look, Harry has his mother’s eyes’ or ‘Ron has his father’s hair’ (although all Weasleys have red hairs, so to be fair you can say he has mother’s hair instead as well), especially after visiting a family with a newborn member. However, you don’t get to hear stuff like ‘Harry has brown-green eyes from both his parents’. That’s because instead of blending together, your parents’ characteristics are passed on to you in different but independent proportions. But how are these characteristics passed on?

chromosomes
Chromosomes are the functional units of heredity; they not only carry the genetics stock of parents in children, but also determine the type of species an organism would turn out to be

Your parents’ characteristics (seriously, I’m getting tired of repeating the word now) are packaged inside their sperm and egg cells in the form of chromosomes. Yeah, those X-shaped threads that preserve their biological information of your parents in you. They also determine your gender, but more than that they also define us as species. Every human being has 23 pair of chromosomes in a cell, one half from your dear ol’ dad and the other half from your mommy. If you were a banana, you’d have 11 pairs. If you were a fruit fly, you’d have 4 (but since you are reading this post, I can safely assume you’re neither banana nor fruit fly).

At the heart of these chromosomes lies DNA, which stands for deoxyribonucleic acid. It is akin to a blueprint for buildings. At a cursory glance, it appears simply a crazy doodle-shaped double-helical strand you must’ve seen juxtaposed with the word ‘DNA’ wherever your might have seen it, and that’s just how our DNA is actually organized. The toothpick shaped structures embedded inside that coil are called chemical bases, made up of four fundamental bases – A,T,G,C. The team of these fantastic four is like the English alphabet; just four bases are enough to mint entire language of living nature – from simplest bacteria to complex creatures like humans.

DNA
DNA (deoxyribonucleic acid) is basically a molecule containing the genetic information in form of four bases (notice these thin rods between two helical strands) – A,T,G,C, which form genes in particular sequences

These four letters join to become words (although in specific sequence, A with T and G with C), and then those words are arranged to become proper sentences that carry specific meaning. In this analogy, sentences are genes and they are responsible for creating proteins, which define our every body part and its function. In the early 90s, scientists took up a Herculean endeavor to map every gene sequence in human beings, or genome, and the project itself was named the human genome project, which finished finally in 2007. And they found that human beings’ genome contains about 25,000 genes and roughly 3 billion chemical bases. Furthermore, all humans share 99.5% of the genetic code, so that means all the varieties you see among humans emanate from that 0.5%, and looking at the world population currently more than 7 billion (excluding identical twins), we can see how large variation this teeny-tiny leftover produces.

Two more scary words that geneticists love to jam down our throats are genotype and phenotype. Genotype is basically your genetic makeup, while phenotype refers to your physical makeup (not kohl liners and lip-gloss, but your physique and appearance sans cosmetics). One question you must’ve been holding back for some time might be why don’t your parents’ chromosomes blend? Why don’t you inherit orange hair when your mom has blond and your dad has auburn hair? That’s because for every pair you receive from each parent, one set is likely to dominate the other, and hence, has monopoly over your appearance and physical being. Unless both sets are recessive, the dominant one will show up. If your mom contributes the dominant gene for hair, you will have blond hair. If your dad does, you will have auburn hair.

But stay assured – there’s no particular gene that is responsible for particular attribute. For example, there’s no single gene that decides how smart one would be, rather a cluster of genes does.

Another popular term in gene-speak is mutation. When the genetic code is propagated from one generation to another, it isn’t necessarily transferred perfectly (too bad our bodies haven’t yet caught up with USB’s smooth transfer capacities). There are likely to be few unexpected errors here and there, as a consequence of which a genetic sequence may be distorted. These errors usually show up in our phenotype, sometimes in the form of a serious condition, like Huntington’s disease. For all those who are X-men geeks, mutation won’t give you retractable claws or eyes shooting laser, but it’ll still land you in hospital.

X-men By Rob Young from United Kingdom (Lego X-Men) [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
If you think mutation would grant you superpowers like X-men, you couldn’t be more mistaken. At best it can give you disorders with sophisticated names
 No, really – nature or nurture?

Now that you’ve crossed the lake of fire aka genetics 101, we can return to looking human nature through genetic lens. But I mentioned in the beginning what we become is influenced by both our genes and environment. Is there any way to separately measure and quantify the impact of both?

Luckily for us, scientists are smart fellows: they devise ingenuous experiments that appear rather simple in hindsight, but actually are tricky to conjure the first time. One clever example is the adoption study: by observing the similarities and dissimilarities between kids early in their lives and their biological as well as adoptive parents, factors for genetic as well as environmental influences for different characteristics can be accounted for. If a child is closer to his biological parents than the adopted ones for a particular trait, then nature plays a major role for that attribute. Otherwise, nurturing does. Another brilliant research method is twin study: observing differences between identical and fraternal twins. If identical twins display similar tendencies than fraternal twins, then genes are in the centerpiece. If not, then rearing does. Scientists use various measures like concordance rates and heritability to compare and contrast the power play of these two juggernauts.

On the other hand, for the environment factor supporters (nothing to do with the Greenpeace movement), two main schools of thought proposed are behaviorism and ethology. Whereas the former emphasizes on everyone coming to this mortal planet brainwashed and learning everything here, the latter believes in some innate behavior as the package deal. Behaviorists believe that everyone’s like Pavlov’s dog, who responds to incentives like rewards and punishments, a view somewhat constrained to laboratory experiments and economics, while the ethologists argue that like the chicks of herring gulls who know from birth that pecking at the red marks on mother gull’s beak is a signal for attention, human babies also come with certain learned patterns (like the hot potato in linguistics world – the ability to learn language).

Pavlov's dog By Maxxl² (Own work - vectorized Pavlov dogs conditioning) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)], via Wikimedia Commons
Behaviorism views every behavior based on a system of rewards and punishments. You can even trick a dog into salivating without any food just with a bell, that’s what Pavlov’s classic example is about.
But these two factors rarely operate in isolation, as I mentioned in the beginning. Genes and environment influence each other. Sometimes, they can even override their natural directives. For instance, human beings have a natural self-preservation instinct, as like almost all the other animals. Whenever we are in a dangerous situation, be it in the form of powerful tsunami waves heading our way or a terrorist holding us hostage in a cafe, we’ll struggle the best we can under the circumstances to save our skin. But this natural impulse to protect oneself can also be reversed, if somebody else’s life, especially of our beloved, is at stake (Richard Dawkins wasn’t so crazy when he titled his book ‘The Selfish Gene‘ after all). Sacrifice isn’t a virtue that comes naturally, at least not naturally in most animals unless their kids are involved; it’s fed to us humans through lessons in morality, patriotism, or religion, and more of such kind of culturally induced values (not all of them need be positive, however) can deviate our actual behavior from the expected one.

Allow me to be a bit more elaborate; of all the psychological hallmarks humans possess, none surpasses these two giants – intelligence and personality. We’ll tackle the two one-at-a-time, intelligence first in the line. Using statistic measures like heritability, scientists have concluded that intelligence is fairly influenced by genes as well as the shared environment (the environment which a person shares with others, like with family at home and peers at school), but to realize the full genetic potential of one’s IQ, one also needs the proper environment, so bye bye Call of Duty and hello Encyclopedia Britannica. But this love isn’t one sided: genes also influence environment.

‘How?’ you’ll be tempted to ask now.

If a person’s parents have had higher IQs and they were able to cash on it, they’re more likely to furnish a kid with greater opportunities like proper education and learning resources, including all the right gadgets and (obviously) a decent connection to the Internet, as well as regular doses of motivation. On the other hand, imagine kids in a deprived shantytown in Afghanistan, no matter how brilliant they are or could have been, do not receive the same facilities as an average American kid and thus, have lower chance of fulfilling their genetic potential (which, in case of intelligence, is gauged in terms of something called reaction range, the difference between maximum and minimum IQ one can have).

While supplementary resources (like education or access to Wikipedia) are necessary for nurturing intelligence, same doesn’t hold true for personality. Even if you were Brainiac who could hold the information of entire galaxy in his head, it wouldn’t matter much to others if you had particularly unappealing persona. As Samuel Jackson sums it up so neatly in Pulp Fiction – ‘Personality goes a long way‘. Researchers discovered that genes play only moderate role in your personality (unless any of your ancestors had history of schizophrenia, which means you also have higher chance of being diagnosed with this disorder) and shared environment has also insignificant influence. However, the factor of unshared environment (environment in which you taste unique experiences on your own, like being bullied in school or reading some dusty, forgotten philosophical texts nobody else dares to touch) plays a greater role in determining your personality type.

darwin
Charles Darwin, the man behind the most controversial theory of all time – theory of evolution

Another very interesting viewpoint concerns evolution (or the devil’s mischief, as more popularly thought of by fundamentalist Christians). According to it, through the process of natural selection, those characteristics that ensure the survival of a species are the ones passed on from generation to generation, plus adapting in response to any new challenge from the environment. Cultures rose in response to the specific adaptations made by people in a specific place in specific time. As our predecessors learned to hunt and cooperate in groups, the desire to stay and act within a society became embedded into our primal instincts. In a way, evolution’s like a self-correcting system; those traits that hinder the progress of overall species are likely to go Dodo’s way.

But here’s food for thought: if evolution’s supposed to flush all imperfections out of us, then why are we still far away from being perfect? Why we still suffer from genetic disorders like cystic fibrosis and sickle cell anemia? Is there some grand plan to evolution?

First we need to clear up certain misconceptions about evolution: it’s not an end, it’s a journey. Human beings constantly manipulate the environment around them, and in the last couple of hundred of years, we’ve radically altered the landscapes, going from archaic stone manors and clay houses to high-rise apartments and skyscrapers in congested locations. Furthermore, we’ve changed our habits and lifestyle, too, shifting from working as helping hands at a farm to pencil pushing to keyboard click-clacking. Average human beings don’t even do half the physical labor done by our predecessors, all thanks to tractors, vacuum cleaners, and computers. Stress levels are up, health and tolerance levels are down. With these shifts in living paradigm, we are bound to see a host of new problems. Like radiation, for instance. We have been stockpiling nuclear arms and building nuclear reactors for almost over half a century now, and in case of a nuclear outbreak in any way, whether through war or reactor meltdown, every living creature is going to be affected by radiation (it’s one of notorious causes of cancer, so that can’t be good). Exposure to it will cause some very undesirable genetic mutations in the living beings (in fact, some of the butterflies have already mutated in response to the recent Fukushima disaster), and trust me, you don’t even want to see the most unfortunate plight of human babies born after the mutations caused by radiation.

Unless we are subjected to such extreme conditions, however, natural selection is a pretty glacial process; it takes place gradually on a wider timescale (tens of thousands of years) to reflect any significant changes in our phenotype. So you can’t really blame it for not keeping up and adapting to the myriads of problems we have created in such shorter periods.

Also, in eyes of the evolution, what appears to be a curse now may actually have been a boon in disguise; take the case of sickle cell anemia. It’s a genetic disorder commonly associated with the people of African descent, and it reduces life expectancy significantly. Why, you might ask, hasn’t it been obliterated yet by nature? But be careful – there may be more than meets the eye here. The gene responsible for this disorder is also responsible for resisting against malaria, a threat pervasive in the African environment and quite deadly in nature (well, that is, before Ebola came along). Anyway, you see now there can also be positive flip-side to evolution’s lapses.

Finally, there’s no endgame to evolution. Natural selection isn’t a process that will terminate even when humans have finally learned to plug the World Wide Web directly to their brains; rather, it will adapt. It will simply adjust the future generations in response to do the best it could to make us live longer as race.

Okay, I think that’s enough for today (after all, it’s the festive season, the time of the year you’d rather drool over the shiny and nicely wrapped gifts and mouth-watering dinners rather than your computer screen, unless you’re a hardcore geek or else got nothing better to do). I hope you might have better understanding of the way one’s behavior is shaped by both nature and nurture, though. As always, I’ve linked further resources down below, in case you’re interested to split the hairs (although not most likely, thanks to the holidays).

And the three magical words before I disappear: Merry Christmas, everybody!

Xmas
Merry Christmas everyone. Image creditL XKCD

Resources