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 genes are expressed at every point in development and are affected all along the way by a gamut of environmental factors -- everything from proteins and chemicals to the socioeconomic status 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" [emphasis added] 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."

Whether it's getting a cold during exam time or feeling run-down after a big meeting, we've all experienced feeling sick following a particularly stressful time at work or school. Is this merely coincidence, or is it possible that stress can actually make us sick? In a new report in Perspectives on Psychological Science, a journal of the Association for Psychological Science, psychologist Janice K. Kiecolt-Glaser from the Ohio State University College of Medicine reviews research investigating how stress can wreak havoc on our bodies and provides some suggestions to further our understanding of this connection.

The field of psychoneuroimmunology (PNI) investigates how stress and negative emotions (such as depression and anxiety) affect our health. Over the past 30 years, researchers in this field have uncovered a number of ways that stress adversely affects our health, and specifically, how stress can damage our immune system. Numerous studies have shown that stressed individuals show weaker immune responses to vaccines, and as Kiecolt-Glaser observes, "The evidence that stress and distress impair vaccine responses has obvious public health relevance because infectious diseases can be so deadly." Stress and depression have been shown to increase the risk of getting infections and also result in delayed wound healing.

Inflammation is the body's way of removing harmful stimuli and also starts the process of healing, via release of a variety of chemicals known as proinflammatory cytokines (e.g., interleukin-6). However, too much inflammation can be damaging and has been implicated in the development of many age-related diseases, including Alzheimer's Disease, Parkinson's disease, arthritis, and Type II diabetes. Negative emotions and psychological stressors increase the production of proinflammatory cytokines. A recent study revealed that men and women who serve as caregivers to spouses with dementia (and thus are under constant stress) have a four times larger annual rate of increase in serum interleukin-6 levels compared to individuals without caregiving responsibilities.

What's more, the changes in interleukin-6 levels among former caregivers did not differ from current caregivers, even following the death of the impaired spouse, indicating that chronic stress may cause the immune system to age quickly. Kiecolt-Glaser notes, "These stress-related changes in inflammation provide evidence of one mechanism through which stressors may accelerate risk of a host of age-related diseases."

Kiecolt-Glaser argues that our environment should be taken into account when studying the link between stress and our health. For instance, diet may modify interactions between psychological and immunological responses: Omega-3 fatty acids (found in fish and walnuts) can reduce production of some proinflammtory chemicals and increasing levels of omega-3 fatty acids may result in positive effects on mood and the immune system. Environmental toxins (such as pesticides and air pollutants) can have extremely negative effects on the immune system and these effects may be intensified in stressed individuals, increasing their risk for developing allergies, asthma, and viral infections.

Kiecolt-Glaser suggests that to most effectively tackle the questions raised by recent PNI research, cross-discipline training needs to be emphasized for students. Psychology students who gain a strong foundation in areas such as biology and physiology will be able to enter into powerful collaborations with scientists conducting immunology research. Kiecolt-Glaser concludes that the questions answered by these collaborations will advance PNI as well as psychology in general.

"By providing key data on how stressful events and the emotions they evoke get translated into health," she suggested, "psychology will assume a more dominant role in the health sciences, in health promotion, and in public health policy."

Research confirms identity of human umami receptor

Using a combination of sensory, genetic, and in vitro approaches, researchers from the Monell Center confirm that the T1R1-T1R3 taste receptor plays a role in human umami (amino acid) taste. They further report that variations in the genes that code for this receptor correspond to individual variation in sensitivity to and perceived intensity of umami taste. "These findings bolster our understanding of human taste variation and individual differences in tastes for essential nutrients," says senior author Paul A.S. Breslin PhD, a sensory geneticist at Monell.

Umami is the taste quality associated with several amino acids, especially the amino acid L-glutamate. High levels of glutamate are present in many protein-rich foods, including meats and cheeses, in vegetables such as mushrooms, peas, and tomatoes, and in human breast milk. Amino acids are the building blocks of protein, an essential macronutrient. Commenting on clinical implications of the work, Breslin says, "Protein-energy malnutrition is one of the leading causes of death in children worldwide. Increased understanding of amino acid taste receptors may help nutritionists target the appetites of protein-malnourished children to provide good-tasting dietary supplements that kids will readily accept."

The findings, published online in the American Journal of Clinical Nutrition, strengthen the claim that umami is a fundamental human taste quality -- similar to sweet, salty, bitter and sour -- that indicates the presence of amino acids, peptides and related structures.

In the study, Breslin and his team first conducted sensory tests on 242 individuals, who were asked to discriminate the taste of weak L-glutamate from salt. Approximately 5% were unable to tell the two tastes apart, indicating that certain people are highly insensitive to umami and thus have difficulty detecting low levels of this taste quality. An additional 87 individuals were asked to assess the intensity of glutamate's umami taste. The subjects tasted five concentrations of glutamate and rated the umami intensity of each on a scale that ranged from 'no sensation' to 'the strongest imaginable.'

The researchers next examined DNA from these 87 individuals to look for variations in the genes that code for T1R1 and T1R3, two protein subunits that combine to form the G-protein coupled receptor T1R1-T1R3. Comparing DNA structure to the glutamate taste responses of each individual, they found that variations (known as SNPs; single nucleotide polymorphisms) at three sites on the T1R3 gene were associated with increased sensitivity to glutamate taste.

A fourth set of studies used in vitro cell biology techniques to provide additional evidence that T1R1-T1R3 is a human amino acid taste receptor. When human T1R1-T1R3 receptors were expressed in a host cell line, these cells were able to respond specifically to L-glutamate.

Together, the findings demonstrate that the T1R1-T1R3 receptor significantly affects human sensitivity to umami taste from glutamate, and that individual differences in umami perception are due, at least in part, to coding variations in the T1R3 gene.

"We want to further understand the degree to which these genes account for umami taste perception," said Breslin. "This will in turn help in the discovery of other taste receptors that may play a role in umami taste and aid in our understanding of protein appetites." He also speculates that because these same receptors are also found in the gastrointestinal tract, liver and pancreas, coding variation in the T1R3 gene may also influence how proteins and amino acids are processed metabolically.

Psychologist urges critical thinking to cure 'primitive' notions

We see the face of the Virgin Mary staring up at us from a grilled cheese sandwich and sell the uneaten portion of our meal for $37,000 on eBay. We believe in ESP, ghosts, and angels over the scientific theory of evolution. While science offers a wealth of rational explanations for natural phenomena, we often prefer to embrace the fantasies that reassured our distant ancestors. And we'll even go to war to protect our delusions against those who do not share them.

These are examples of what evolutionary psychologist Hank Davis calls "Caveman Logic." Although some examples are funny, the condition itself is no laughing matter. In Caveman Logic: The Persistence of Primitive Thinking in a Modern World (Amazon.com, $13.59), Davis encourages us to transcend the mental default settings and tribal loyalties that worked well for our ancestors back in the Pleistocene age. Davis laments a modern world in which more people believe in ESP, ghosts, and angels than in evolution. Superstition and religion get particularly critical treatment, although he argues that religion, itself, is not the problem but "an inevitable by-product of how our minds misperform."

"Caveman Logic is a whirlwind tour through the deeper recesses of our evolved mind. Hank Davis brings to bear cutting edge research from the cognitive sciences to reveal how mental tools designed to serve the needs of our ancient ancestors continue to exert an influence, both subtle and powerful, on human thought and behavior today," said John Teehan, Associate Professor of Religion, Hofstra University and author of In the Name of God: The Evolutionary Origins of Religious Ethics and Violence.

Davis says Caveman Logic: The Persistence of Primitive Thinking in a Modern World is the product of more than two decades of pondering, teaching and writing about "the powerful influence of irrational, delusional thinking that is anchored to our Pleistocene-era brain circuitry." He asserts that much of this primitive thinking is supported by modern social institutions. For example, a 2007 poll found that nearly 70 percent of Americans believe angels and demons are active forces in the world, while a 2009 survey concluded that only 39 percent believe in Darwin's theory of evolution. Even non-religious persons often thank God or "the heavens" in response to good news.

"Ways of thinking that were both reasonable and advantageous in caveman days become illogical—and potentially destructive—when they are overextended to modern times," says Madeleine Van Hecke, author of Blind Spots: Why Smart People Do Dumb Things (Amazon.com, $13.59).

Maggie Jackson, author of Distracted: The Erosion of Attention and the Coming Dark Age (Amazon.com, $17.15) adds, "Hank Davis reveals the deep roots of humanity's weakness for superstitions, blind assumptions and primitive thinking, and shows how we can start to overcome 'caveman logic.'"

Davis advocates a world in which "spirituality" is viewed as a dangerous rather than an admirable quality, and suggests ways in which we can overcome our innate predisposition toward irrationality. Davis points out that, "biology is not destiny." Just as some of us succeed in watching our diets, resisting violent impulses, and engaging in unselfish behavior, we can learn to use critical thinking and the insights of science to guide individual effort and social action in the service of our whole species.

College students with depression are twice as likely as their classmates to drop out of school, new research shows. However, the research also indicates that lower grade point averages depended upon a student's type of depression, according to Daniel Eisenberg, assistant professor in the University of Michigan School of Public Health and principal investigator of the study.

There are two core symptoms of depression -- loss of interest and pleasure in activities, or depressed mood---but only loss of interest is associated with lower grade point averages. "The correlation between depression and academic performance is mainly driven by loss of interest in activities," Eisenberg said. "This is significant because it means individuals can be very depressed and very functional, depending on which type of depression they have. I think that this can be true for many high achieving people, who may feel down and hopeless but not lose interest in activities. "Lots of students who have significant depression on some dimension are performing just fine, but may be at risk and go unnoticed because there is no noticeable drop in functioning."

Students with both depression and anxiety had especially poor academic performance. "If you take a student at the 50th percentile of the GPA distribution and compare them to a student with depression alone, the depressed student would be around the 37th percentile -- a 13 percent drop," Eisenberg said. "However, a student with depression and anxiety plummets to about the 23rd percentile, a 50 percent drop."

In the study, Eisenberg and his colleagues conducted a Web survey of a random sample of approximately 2,800 undergraduate and graduate students about a range of mental health issues in fall 2005, and conducted a follow-up survey with a subset of the sample in fall 2007. The dropout rate for University of Michigan students is about 5 percent per year, which is much lower than the national average, Eisenberg says. This likely reflects the type of high-achieving students Michigan attracts, along with U-M's support network for students experiencing emotional problems or depression. "Michigan does seem to be a leader in many respects in terms of things the university has done related to student mental health," said Eisenberg, who noted that the next step in the research is a large scale study. "I see this study as suggesting that there is value in a large randomized trial of screening and treating depressed students, in which the academic outcomes are measured carefully. That's what it will take to really see what the value is in reducing the dropout rate and improving GPA. As far as I know this has not been done."

Many students with depression -- as with the general population -- remain untreated. "Maybe the biggest reason is only about 50 percent of people with depression say they think they need help," Eisenberg said. "College students in particular may feel that stress is normal." According to Eisenberg's research, certain types of students have higher levels of stigma. Males, students from lower-income backgrounds and Asian students, in particular, report higher levels of stigma about mental health.