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Emergent Epigenesis

Nature versus nurture?

Let’s never say that again! Is it the genes, or was it the environment? Everyone comes to the same conclusion and says, “Well in all of my vast knowledge I have determined through countless hours of taxing mental labor that it must be both. I’m a genius and the only one who has ever thought that!”

Which is to say, everyone says it’s an interaction these days, but that is a grotesque oversimplification of things. I’m hoping you will agree by the end of this explanation!

So where should we begin? How about with ducks? Ducks are fun, everyone loves ducks, especially Disney animators for some reason. You have duck billionaires, duck super heroes, and some ducks that need anger management. No matter what, ducks are always hanging out with other ducks. It just so happens that this really irked a psychologist named Dr. Gottlieb.

What did Dr. Gottlieb have against ducks? Well. EVERYTHING. He hated the way they quacked, the way they waddled, and the way they had trouble pronouncing words correctly in English. Okay, okay. Clearly this is a bit of hyperbole.

Dr. Gottlieb had a simple question, though. Why is it that a newborn duckling goes to its mother almost naturally? Is the gene code so incredible and complex that it can account for the sound of other ducks? That seems highly unlikely. In most cases genes do not get so specific. So Dr.Gottlieb devised a few tests.

In the first go around, Gottlieb raised the duck as normal. Before they hatched, he moved the mother away and placed a chicken in the cage with the mother. As the ducklings hatched, they always went towards the mother duck instead of the chicken. Well this angered Dr. Gottlieb once again, so he changed his study.

This time, he thought that the mother duckl must be making noise that the duckslings can hear. So the eggs were placed with chickens while they were developing.  As before, the ducks immediately went to the mother duckling after hatching.  Dr. Gottlieb was once again filled with a fowl rage (tee hee)!

“Why!!?!?” he shouted to the heavens. “Why must I be outsmarted by these ducks!!! Wait a minute….” Dr. Gottlieb began to think to himself. “OF COURSE! IT’S SO OBVIOUS! The ducklings pre-vocalize in the egg and they can hear what they should sound like! So when they hatch they go towards what sounds familiar!  Bawhahaha… BWAHAHA…. BWAHAHAHAHAHAHA.”

Why the crazy laugh? Well here’s why. To control the pre-vocalization of the ducks, Dr. Gottlieb glued their vocal chords shut while they were in their eggs without otherwise cracking the egg or ruining the prenatal environment. So when the ducks did finally hatch, they showed no preference to walk towards chicken or duck.

“TAKE THAT MOTHER NATURE!!!!” Screamed Dr. Gottlieb.  Really, though, that does seem like a rather insane thing to do, even if you were correct. Why go through all this trouble, though? Wasn’t the point of all this an answer to nature/nurture?

An egg is the penultimate genetic creation. Nothing goes in or out of the egg until it is hatched, right? How could you prove anything by skewing a genetic plan of development by breaking into the egg and altering the duckling? There is a point to his madness, actually.

The reason you want to alter the environment was to show, beyond a shadow of a doubt, that the environment allowed for the development to occur. Genetics did not actually create a duckling’s tendency to follow the sound of other ducks, it was the environment that allowed for this. This argument sits in a very gray area, though. We will always hear people argue that this proves nothing. The egg is in and of itself a course of guided development to create a normal member of the species. I know, I know, it’s seems strange to me as well. However, given the next study, we will see that Gottlieb was on to something.

Let’s leave mad scientists with a hatred for ducks behind for now. Let’s talk about psychologists who enjoy playing with mice instead! The foundation of behavioral sciences lays upon the shoulders of rodents after all! So what does emergent epigenesis have to do with mice? Everything, as it turns out!

Researchers wanted to see if genes or environment led one to become more intelligent. They decided to define intelligence as the speed a mouse could learn to navigate a maze. The faster they did it, the less errors they made, so they were probably smarter. They took the faster mice and named them the smart group. The slowest mice were named  the dull group. They allowed these animals to breed within their own group for about 4 generations, and observed that the smart mice stayed pretty smart, and the dull ones stayed pretty dull.

Sounds like intelligence is genetic then? Well let’s save our conclusions for now.

So now we have 5th generation mice and we create two new environments. We create a dull environment for the mouse to live which is an empty cage with only food and water. We create a standard environment which consists of a bit more room, an exercise wheel, and maybe a little tunnel to run around. Finally we create an enriched environment which has a lot of tunnels to run and hide in (sort of like a plastic hamster cage). So what happened with this new generation?

In the enriched environment groups, we see that the smart mice did really well, but the dull mice did equally well! Wow, we thought it was a completely genetic effect, but now we see how powerful the environment really was. We’ve completely mediated the power of genes through a new environment.

So now you must be thinking, “oh clearly it’s an interaction, but mostly environment!” Not so fast!

Let’s look at the “typical” environment. We see that mice from the smart group do well, and mice from the dull group do poorly. This is just like the previous four generations, so it is no surprise. So what about the last, poor, environment. In this particular case, having good genes for the task led to success.

In the unenriched environment, we see that both smart and dull mice do equally bad. This leads to some interesting conclusions.

Genetics must be setting the thresholds we need to achieve a high level of ability. For the smartest mice, they did not need to have an enriched environment in order to thrive, however the dull mice needed the enriched environment to do well. Both groups did poorly in the very unenriched environment as well. So even the best genes cannot overcome the worst environments.

Let’s look at this another way. Imagine that your genes are like plants and the environmental richness is like water.  If you go to a desert, very few things can thrive. Thus, some environments are too poor for even the most genetically durable to do excessively well. Other environments, like a rain forest, are so enriched that most plants can thrive. Finally, some environments, like a savanna, have enough for some plants, but too little for others.

So now we should understand that this “interaction” is dynamic. For intelligence, we could argue that one’s genes determine your needed environmental richness to thrive, but it does not determine your absolute potential. According to this model, once a person is in an environment of enough richness they will do as well as other “bright” members of the species.

So what’s our take home message? Well, psychologists apparently don’t much care for the welfare of ducks or mice! That aside, we can see the importance of environment. Environments allows a phenotype to be expressed (a behavior) which is moderated by the genotype (gene). We can say that our genes create a threshold needed for a phenotype to fully express. In this manner, genes can appear to limit us. It is the environment that is actually at  fault, I would argue. Because your environment can be altered while your genes cannot. Thus, create an environment that meets your genetic needs!

Finally, what about the ducks? Did Gottlieb really help our understanding with his experiments on ducks? We could say that his experiments showed that the course of development depends on environments interacting with our genes. The egg environment allowed for the development of hearing for this animal. When this ability was inhibited, its behavior was changed drastically. This was further proven when he opened the shells (allowing the ducklings to see) without breaking the eggs’ inner membranes. This time the ducklings would not wander towards other ducks. Why? Because their visual system was being developed when they audible system should have been. A change in environment changed the phenotype and changed the expression of the genes.

So be one of the cool kids. The next time someone says “it’s a combination of nature and nurture,” you should say this.

“That’s a gross oversimplification, sir! I believe you mean emergent epigenesis!”


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