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Dr. Lori Marino wants to know what drove our little-brained forebears to become big-brained us. In the anatomy and behavior of the cleverest nonhuman animals on earth, she seeks clues to how, perhaps even why, intelligence evolved.
"Ultimately it would be nice if I could find out something about the dolphin brain and its evolution that is surprising, or that revealed something about evolution," says Dr. Marino, leaning back in her chair, excitement magnifying her ancestral New York accent.
Her office resides in one wing of Emory University's Psychology building, but there are no portraits of Freud on the wall, no books on mental illness lining her shelves. Dr. Marino is part of a new breed of scientist plumbing the depths of the mind. She earned her doctorate not in psychology, but in psychobiology. And rather than studying humans, or even our closest living relatives, the great apes, she is studying that other most intelligent family on Earth: the delphinidae.
It was Dr. Marino who first pointed out a still little-known fact: even once the difference in body size has been accounted for, dolphins have bigger brains than chimpanzees. Bigger, even, than Homo habilis, one of our tool using ancestors. This measure, known as encephalization, would mean little if not for the fact that, by every reasonable measure, encephalization correlates with intelligence.
And while intelligence is a difficult if not impossible quantity to measure with any exactness, Dr. Marino's research indicates that dolphins independently evolved intelligence of a complexity on par with that of our not too distant ancestors. Using dolphins as a previously overlooked basis for comparison, Dr. Marino seeks not merely to describe one branch of the history of life on earth, but also the rules which governed the unfolding of that history.
"The main question I'm shooting for is to determine whether or not there are some general principles that underlie the evolution of intelligence and the brain."
By her own account, her research bears on everything from whether or not dolphins are sentient to conjecture about the odds of intelligent life occurring elsewhere in the universe.
A Brief History of Dr. Marino
Dr. Marino's interest in science began early in life.
"I guess I always was interested in nature and biology and other animals- I just always thought that this was what I would do."
Her parents were supportive, but neither had attended college. At a relatively young age, she discovered the science she found fascinating, and to some extent the role model she needed, in Carl Sagan.
"[He] was probably the most influential person. I remember in high school at least, going to the library, picking up Dragons of Eden, and picking up some of his other stuff on extra-terrestrial intelligence."
She went to a Catholic, all girls high school, where she met sister Winnifred Doyle, "who was a really good model for a critical thinking, hard-thinking scientist."
In 1982, she got her B.S. in NYU's then new program in Psychobiology. From there she went to graduate school at the University of Miami in Ohio, where she would eventually get a degree in Psychology, with a concentration in experimental sensory and perceptual processes.
While there, she met a fellow grad student who did research for NASA on astronauts' sensory and perceptual adaptations to weightlessness. At his suggestion, she got a position as a researcher at the Space Biomedical Research Institute in Houston, where she worked for two years while she completed her Masters degree.
As engrossing as the work was, it was then that she realized that space biomedicine wasn't exactly her cup of tea.
"I realized then that the reason I was interested in why astronauts got sick in space was really because I was interested in how they came to evolve on this planet the way they are, to begin with. I started realizing that what I was really, basically interested in was evolution, and how basic sensory perception and cognitive processes evolved, and so I decided to make a turn in my career."
Dr. Marino's next stop was a Ph.D. program at the State University of New York at Albany, where she had the good fortune to work with Gordon Gallup, a world authority in primate cognition. Gallup conducted the original experiments that suggested that chimpanzees are "self aware" because they can successfully identify themselves in a mirror.
And while she found such studies valuable and interesting, Dr. Marino also knew that researchers crowded the field of primate cognition. Many of them were already trying to reconstruct the evolution of intelligence by comparing human and primate psychology.
So Dr. Marino hunted for a way to study the evolution of intelligence that, unlike the study of primates, remained relatively uncharted. Then she hit upon the idea of studying dolphins.
"Because I was so interested in evolution and adaptation and differences among organisms, I decided that what I would do was sort of eke out my own niche and study another highly encephalized mammalian group, which was the cetaceans."
So she made the encephalization of cetaceans the subject of her Ph.D. thesis. At the time, there was little good data available on dolphin brains, and what did exist was scattered throughout the literature. Dr. Marino commenced an exhaustive search for the numbers that she would need: measurements of the size of dolphin brains that could then be compared to body size in order to obtain a table of encephalization data from which conclusions could be drawn.
"I went through everything written on dolphin brains back to the 1800s."
She even went so far as to journey to the National Museum of Natural History at the Smithsonian Institution in Washington, D.C. While there she measured the cranial volume of 17 adult specimens by filling their skulls with plastic beads.
A year before she finished her work, Dr. Marino left SUNY Albany to follow her husband, Scott Lillienfeld, himself a psychologist, to Emory University. Within a year, the researcher she was to work with had left, and she was offered his courses.
Dr. Marino didn't have the chance to do a post-doc; rather, like so many of her colleagues, she was faced with the demanding task of continuing her research while she taught.
"There's a tradeoff: its a simple tradeoff.... I had to do it all on my own. You get really resourceful. I taught.... and I also had to work really hard to keep my research program going."
Current Research Projects
Structural neuro-anatomy in living cetaceans
What do the brains of all these clever mammals have in common?
Using an MRI scanner to peer inside preserved dolphin brains, Dr. Marino obtains information about the dimensions and volume of various structures. She then compares this data with that of other intelligent mammals in order to determine whether or not the ratio of the size of one structure to another is similar across species. (If they are, it might suggest that these ratios are a consequence of the way intelligence evolves rather than an incidental consequence of the history of an individual species.)
Comparing climate data to the fossil record
(in conjunction with the Smithsonian Institution)
When the going gets tough, do the tough get smarter?
Dr. Marino uses CAT scans of fossilized cetacean skulls to infer changes in cetacean brains as the the toothed whales evolved over time. This data can then be correlated with paleo-climatological information. In other words, Dr. Marino is attempting to see if dolphins became smarter in response to relatively quick shifts in climate. These shifts could include everything from ice ages to asteroid impacts.
"Ultimately what I want to do is get enough data on these animals' brain structure to then map that on to paleo-ecological data and get a sense of what was going on at the time, and could it be that maybe the same selective pressures that existed back then were similar to what produced large brains in humans? That's the crux of it: are there certain environmental conditions that give rise to more intelligence or large brains?"
General comparison of dolphin and primate encephalization to behavioral ecology
Just what does having a bigger brain mean, anyway?
In this study, Dr. Marino attempts to relate the relative size of a particular species' brain to that species' behavior and environment. By looking for similarities across species, Dr. Marino's research yields themes in, or perhaps even general rules governing, the environmental requirements for and behavioral expressions of intelligence.
"What I try to do is look for patterns that are well established in the primate literature.... Are the same patterns that were seeing in other mammals, especially primates, there?"
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