Nature? Nurture? Scientists say neither

July 20, 2009

It's easy to explain why we act a certain way by saying "it's in the genes," but a group of University of Iowa scientists say the world has relied on that simple explanation far too long.

In research to be published today in Child Development Perspectives, the UI team calls for tossing out the nature-nurture debate, which they say has prevailed for centuries in part out of convenience and intellectual laziness.

They support evolution -- but not the idea that genes are a one-way path to specific traits and behaviors. Instead, they argue that development involves a complex system in which genes and environmental factors constantly interact.

"You can't break it down and say there's a gene for being jealous, there's a gene for being depressed, there's a gene for being gay. Those types of statements are simplistic and misleading," said UI psychologist Mark Blumberg, a co-author of the paper. "There is no gene for any of those things. At most, one can say there's a system of which that gene and many others are a part that will produce those outcomes."

The UI team believes are expressed at every point in development and are affected all along the way by a gamut of -- everything from proteins and chemicals to the of a family. These ideas are unified by a perspective called developmental systems theory.

"The nature-nurture debate has a pervasive influence on our lives, affecting the framework of research in child development, biology, neuroscience, personality and dozens of other fields," said lead author and UI psychologist John Spencer.

"People have tried for centuries to shift the debate one way or the other, and it's just been a pendulum swinging back and forth. We're taking the radical position that the smarter thing is to just say 'neither' -- to throw out the debate as it has been historically framed and embrace the alternative perspective provided by developmental systems theory."

The UI researchers illustrate the inadequacies of the debate by examining recent studies of imprinting, spatial cognition and language development that support the nature point of view.

Imprinting is a rapid form of learning in which animals develop preferences through brief exposure to things early in life. Nativists (researchers who align themselves with the 'nature' perspective) attribute the quick learning to a genetic predisposition, pointing to examples like ducklings following their mother's call as soon as they hatch. But research has shown that embryonic ducks, while still in the egg, are exposed to sounds from their embryonic siblings as well as sounds that they themselves make.

When these so-called 'talking eggs' are deprived of these embryonic experiences, they do not show a preference for their mother's call upon hatching. Clearly, Blumberg said, to say that imprinting in ducks is innate does not come close to capturing the elegance and complexity of the real process.

UI researchers also raised issues with studies proposing that children and animals have a built-in sense of direction as they move through the world around them and thus exhibit an innate reliance on geometric cues.

In a 2007 experiment, fish reared in a circular tank were placed in a rectangular tank to see if they would know where to find food when it was hidden in the diagonally opposite corners. They did -- which was presented as evidence of an innate ability to use geometry -- but the UI team pointed out that each fish had eight to 12 days of experience in the rectangular tank prior to the experiment and could have learned the behavior then.

"Researchers sometimes claim we're hard-wired for things, but when you peel through the layers of the experiments, the details matter and suddenly the evidence doesn't seem so compelling," Spencer said. "The problem is that it's much more complicated to explain why the evidence is on shaky ground, and often the one-liner wins out over the 10-minute explanation."

The challenge young children face when they encounter a new word has also been used to bolster nativist claims. When children are told a new word and shown a visual scene that contains unfamiliar objects, there are an infinite number of possible meanings for the word. But children are very good at figuring out which object in the scene the new word refers to. Given this amazing ability, researchers have suggested that kids have an innate ability to consider only some of the possible meanings of the word.

But in 2007, researchers at Indiana University placed cameras on children's foreheads to examine, from the child's perspective, how they found the correct referent for the word. They learned that a child's view of the nearby world -- which is limited by her small size and short arms -- is much more focused than originally thought. With few possibilities in sight, it's easy to figure out which object matches up with a novel word.

"When people say there's an innate constraint, they're making suppositions about what came before the behavior in question," Spencer said. "Instead of acknowledging that at 12 months a lot of development has already happened and we don't exactly know what came before this particular behavior, researchers take the easy way out and conclude that there must be inborn constraints. That's the predicament scientists have gotten themselves into."

UI psychologist Larissa Samuelson, a co-author of the paper, points to the "shape bias" as evidence that word learning is a cascading developmental process -- not an ability that's there from the beginning. Babies and toddlers learn to recognize solid objects with standard shapes -- things like ball, car, or book -- and those easy-to-distinguish objects typically become their first words.

"Language is so complex that people can't imagine how kids could do it so well without it somehow being innate," Samuelson said. "But if we steer clear of the nature-nurture debate and consider it from a developmental systems perspective, we can see how pieces of knowledge -- which may not even seem related to language -- build over time. It gets us closer to understanding the full complexity of language learning."

The UI authors realize their paper is raising eyebrows -- it has spurred several responses from other researchers that will be published in the same issue of the journal. And they understand that getting scientific peers to buy into their ideas will be a challenge -- after all, the debate dates back to Aristotle and Plato, and many scientists are passionately rooted on one side or the other.

"This is one attempt at getting the ideas out there and starting a dialog, continuing to educate the public and the scientific community, especially the younger generation of researchers," Blumberg said. "We know we don't have a sound bite that's as clean and simple and sexy as saying 'it's genetic.' But we're working on it."

More information: "Short Arms and Talking Eggs: Why We Should No Longer Abide the Nativist-Empiricist Debate," Perspectives

Source: University of Iowa

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1 / 5 (5) Jul 20, 2009
seems that the nurture people are about to lose the argument, so they are now going to claim there wasnt an argument.

Gene variations can be barometer of behavior, choices

By testing DNA samples from saliva in conjunction with computerized cognitive tests, researchers found that the certain gene variations could be connected to certain choices %u2014 focusing on decisions that previously produced good outcomes, avoiding negative outcomes, or trying unfamiliar things even though an outcome is uncertain.

"In some cases, single genes can have surprisingly strong influences on particular aspects of behavior," said Michael J. Frank, assistant professor of cognitive and linguistic science, psychology, and psychiatry and human behavior. Frank, lead author of the research, directs the Laboratory for Neural Computation and Cognition in the Brown Institute for Brain Science.

the arguments above sound grand till one realizes that it doesnt reflect ALL the information.

for instance, when a part of the brain is dysfunctional or missing. the person then is often incapable of learning what would have been specifically placed in the cubby hole designed to operate in those contexts.

if one knows the genetic information just starting to come up and the work on damaged people (for lack of a better term), then all they really are saying above is that the prior work of nurturists was very poorly done, and that when the work is done better, their results are not confirmed.

since they are not working with genes and such above, they really could not assert what is happening since they do not know what is actually happening inside.

Varations in two of the genes %u2014 DARPP-32 and DRD2 %u2014 independently predicted the degree to which people responded to outcomes that were better or worse than expected, by reinforcing approach and avoidance type behaviors. These genes affect dopamine processes in the basal ganglia portion of the brain. Frank said this is important for "simple reinforcement of learning processes that you might not even be aware of."

Frank and the other researchers also studied exploratory decision-making %u2014 the choices people make when they are in "uncharted territory." They found that variations in a third gene %u2014 COMT %u2014 predicted the extent to which people explored decisions when they were uncertain whether the decisions might produce better outcomes.

given the fact that human varied experience is not that varied, its possible that we have a huge amount of stuff that is inherent.

now this study isnt particularly earth shattering, but its not the only one.

over time we will find more and more of this. we will find more particular forms of this, where the genomic level represents the base structure and that learnign and such may tweak things in each cell more.

time will tell.

1 / 5 (4) Jul 20, 2009
this is bunk, I had a son I never met since birth. I recently contacted him after finding out he was my son. He's now 39. I've know him for 2 years now. Our likes and dislikes are almost identical, he does the same job I do in 2 fields, AC and electrical, he has a racecar, I have a racer also. there are way too many coincidential likes and dislikes to not be genetic and we never met till he was 38.
5 / 5 (3) Jul 20, 2009
this is bunk, I had a son I never met since birth. I recently contacted him after finding out he was my son. He's now 39. I've know him for 2 years now. Our likes and dislikes are almost identical, he does the same job I do in 2 fields, AC and electrical, he has a racecar, I have a racer also. there are way too many coincidential likes and dislikes to not be genetic and we never met till he was 38.

Dude anecdotal evidence is no evidence at all. I am sure there is someone else out there whose children have no identical likes and dislikes. Does that mean whatever you are saying is bunk?
3 / 5 (4) Jul 21, 2009
"this is bunk[...]"

"Dude anecdotal evidence is no evidence at all. I am sure there is someone else out there whose children have no identical likes and dislikes. Does that mean whatever you are saying is bunk?"

@jyro, @neuromancerz

Guys, remember the heading? "Nature, nurture, it's neither". What they're saying is, it's not one OR the other, but an intricate interplay of both.

I personally don't see the day when scientists find "the murderer gene", "the gay gene", or "the nuclear physicist gene".

Similarly, I don't see the day when the other party finds a way to "nurture", that makes *any child* become a nuclear physisist.

And, since we'll see neither day, we should just see that this is more complicated.

That said, of course, some traits, dispositions and behaviors, are more dependent on genes than other traits dispositions and behaviors, and others are less.

To successfully do research on this, one really needs to get rid of the dualistic thinking that it's either or.

And especially rid of the thinking that "this particular thing is 27% nature and 73% nurture", etc.
not rated yet Jul 21, 2009
jyro, perhaps the boy's mom is just so into techy racer guys and her preferences rubbed on him.

or you know, it is just a coincidence. with almost 7 billion people out there, i'd be surprised if no one had your experience.
5 / 5 (1) Jul 21, 2009
"Everything" effects "Everything"!
3 / 5 (2) Jul 21, 2009
For some time we have known that identical twins studies show concretely that genitics plays the dominant role. Its not anedotal, its very strong statistically. And that may indeed apply to offspring, but of course not as clearly. I dont see how this attempts to refute that. I think this article is trying to deal with subtleties that have little to do with the 'debate'. Instead of niether, 'Both' or 'the interplay of both' would be better.
1 / 5 (2) Jul 21, 2009
Yeah, this is soft science grabbing the opportunity to generate yet one more jazzy school of thought which will quickly be forgotten when hard science proves it wrong. All anthropologists and sociobiologists could do for a few generations was collect field data while waiting for genetics to reach the point where it could make some sense of it. That didn't stop them from concocting some unfortunate 'theories' in the meantime though-
5 / 5 (2) Jul 22, 2009
The physical body has never been just genes. The interrelationship of genes hormones and proteins from the different duplicate copies of genes are much more complex. Genes are the ABCs but they are not the story.

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