“We study the relationship between the innate and the learned,” says Dr. Marlin. She’s especially curious about biological mechanisms by which experiences, particularly traumatic ones like malnutrition and parental neglect, get recorded on parents’ chromosomes and handed off to subsequent generations through a process called  transgenerational epigenetic inheritance. 

“We study how trauma in parents affects the brain structure and sensory experience of their offspring,” Dr. Marlin says. Using behavioral studies with rodent parents and pups, her research team models social relationships and experiences. With neural imaging, the team uncovers where those experiences elicit changes in the brain. And with molecular genetics techniques, they trace out epigenetic pathways by which those brain changes become embodied and codified on chromosomes inside sperm and egg cells of parents, and from there into the cells of their offspring.

Dr. Marlin started along this research trajectory at NYU where she studied how the hormone oxytocin shapes the brain. In the journal Nature, she and colleagues reported their findings with mice about how social interactions affect parenting. The researchers documented how caring behavior of mothers toward their pups retuned the brains of other female mice nearby who had never given birth. These virgin females behaved like co-parents, even shuttling pups squealing in distress into the safety of mothers’ nests. In the virgin mice, the mothers’ modeling of care activated brain cells that release the oxytocin. This hormone is known to promote maternal care by, for example, helping to sensitize cells in the brain’s auditory cortex to recognize distress calls.

“This amazing discovery shows that it’s possible to elicit, just by creating a certain social context, changes in the brain that can make a less successful caregiver into a better caregiver,” says Dr. Marlin. 

During her entry years to the Zuckerman Institute, as a Postdoctoral Research Fellow in Dr. Richard Axel’s laboratory, she asked the next question: how do parents promote survival not only in their offspring, but also pass on survival traits to subsequent generations? This is where epigenetics comes in, that is, the mechanisms by which an organism’s experience can toggle which genes turn on and which ones turn off, and even pass those settings of gene expression to subsequent generations. 

Dr. Marlin’s current work, since 2021 as a Principal Investigator in her own Zuckerman Institute lab, has focused on uncovering these epigenetic mechanisms. An early step in this project has shown that association by a male mouse of an odor, such as almond, to stressful and perhaps dangerous situations leads to the generation of more olfactory cells (a type of brain cell) sensitive to that odor. And not just for the male mice. The pups of this almond-sensitive dad also are more sensitive to the danger-indicating odor, the research revealed.

“It’s like there’s a message going from the nose to the sperm all the way to the second generation,” Dr. Marlin says. “If so, this epigenetic inheritance could prepare future generations for environmental challenges that a current generation faces. It suggests that personal and societal circumstances can influence the biology, and perhaps the health and survival, of our offspring and of their offspring.” 

Society-anchored stressors, ranging from poverty to structural racism, have been facts of life for centuries. Different groups have borne them the most and been the ones to foist them the most on others. Dr. Marlin’s research is showing that the effects of these experiences reach DNA-deep and can stay with society for generations. They are problems to solve for everyone who shares a society, she says. 

“It’s my obligation to take the neuroscience we’re learning, including the biological survival mechanisms we’re uncovering that pass information down through the generations, and apply that knowledge to society,” Dr. Marlin says.