Chemical Senses Scientist

Julia Mennella, PhD
Monell Chemical Senses Center

My passion for science began long before any formal education. As a child, my father taught me how to problem solve and, perhaps more importantly, to separate out what is real from what is not. It was the excitement of discovery that first drew me to science and, quite frankly, it's what keeps me in it today.

During my senior year of undergraduate studies in biology at Loyola University, I took a required class that focused on research methodology and communicating research findings to peers. My intense involvement in and enjoyment of this class made me realize that research was the profession to pursue.

After receiving a masters in biology at De Paul University, I worked for 3 years as a research technician. While I was committed to a career in research, up until that point, I didn't know what field. Eventually I realized that, when asked to do research at the library, the articles that interested me the most dealt with behavior. That realization led me to The University of Chicago for my doctorate, where I studied biopsychology — the biological basis of behavior — with Martha McClintock and Howard Moltz.

During the course of my dissertation work on the social control of parental behavior in rodents, we discovered that mothers have developed strategies to protect their young from other animals of the same species through changes in their body odor during pregnancy and lactation. To learn more about the sense of olfaction, I left Chicago to do postdoctoral studies with Gary Beauchamp at the Monell Chemical Senses Center in Philadelphia.

Monell is a nonprofit research institute with a mission to increase understanding of the mechanisms and functions of the chemical senses. The center's multidisciplinary work is also of interest to many leaders in the fragrance, food and beverage, flavor and chemical industries who provide unrestricted annual support and frequently meet with Monell scientists. Although Monell's charter is to carry out basic and clinical research, training has become a central focus of the Center, especially for postdoctoral fellows who do not yet have expertise in the chemical senses.

My postdoctoral project was to study the role of the chemical senses in human development. I received a National Research Service Award to determine whether human milk, like the milk of other mammals, acquires the flavors of the mother's diet, and if so, whether the infant can detect such flavor changes. Throughout the years we have shown that this is indeed true. The breast-fed infant is exposed to a variety of flavors that reflects the foods of their mother, family and culture.

Quite by accident, I stumbled on one of my most significant research findings — that the flavor of alcohol transfers from a woman's diet through her breast milk. It happened during the course of a routine experiment. It was a placebo day, so the mother was asked to donate breast milk before and several times after she consumed a sugar capsule. The sensory panel, whose job was to evaluate whether breast milk flavor changed as a function of what the mother ate, sniffed one of the samples and described it as smelling "like it's fermenting." Lo and behold, I soon discovered that this particular woman had drunk a glass of beer an hour before we collected her milk!

This serendipitous finding opened up a whole new area of research. First, we verified that alcohol did indeed alter the flavor of breast milk and also discovered that, contrary to the age-old folklore that claims that alcohol is a galactagogue, breast-feeding infants actually consume less milk after their mothers drink an alcoholic beverage. I received a First Award grant from NIAAA to study the short- and long-term effects of alcohol on the behavior of breast-feeding infants during feeding, sleep and play, as well as on the lactational performance of their mothers.

After completing my postdoctoral work, I applied for a position at Monell. Now, in addition to the work on alcohol, my research program has expanded to determine whether early experiences — some of which may be occurring even prior to birth — impact on later preferences. For example, does the flavor of the mother's diet during pregnancy and lactation or the flavor of the infant's formula influence preferences during weaning and childhood? How does the scent of a toy and the child's prior experiences with that scent affect how he or she explores the toy? The fundamental question is how do early experiences influence why we like the things we do.

My work at Monell is rewarding because it involves much more than basic research. Through our contacts with industry, I get to see the practical applications of our work. I am often asked questions that cause me to think about my research in a different way, opening avenues of inquiry that I might not have considered otherwise. Interacting with lactation consultants and other health professionals at conferences gives me yet another opportunity to ask questions and learn about the unique issues that they face when counseling mothers.

In addition to doing research, I direct our research training program for high school and undergraduate students. It is very gratifying to see our students presenting their work at scientific meetings and being accepted at prestigious universities across the country. While we provide opportunities for students, they give back much more in terms of their fresh perspective.

A career in scientific research has both the joys of childlike wonder and the thrills of high adventure. An answer obtained from one experiment soon becomes the focus of your next research question. The field of the chemical senses is particularly gratifying because, as Lewis Thomas once wrote, a complete understanding of its mechanisms and functions is a task which contains all the mysteries of the life sciences.

(Originally published in the March/April 1998 issue of Psychological Science Agenda, the newsletter of the APA Science Directorate.)