Might it be the humble pelvis that makes us human, and not the brain? Do butterfly hybrids mean evolutionary trees should look more like networks? What can deer mice teach us about genetics and inheritance? And what’s up with all the human bones at Roopkund Lake?
A quartet of Harvard doctoral students gave a glimpse of the future of evolutionary inquiry Thursday evening, describing the cutting-edge tools they’ve become adept at wielding to investigate conundrums that get to the heart of some of the most fundamental questions of our time: how we became human, what happened in our past, and how animals slowly become different.
The event, “Frontiers in Evolution,” drew about 100 people to the Geological Lecture Hall in Harvard’s Geological Museum building. Part of the Harvard Museum of Natural History’s “Evolution Matters” lecture series, the event was moderated by lecturer on organismic and evolutionary biology (OEB) Andrew Berry. It featured talks on varied topics by doctoral students in OEB and genetics Nate Edelman, Emily Hager, Éadaoin Harney, and Mariel Young.
Berry praised the museum for regularly hosting speakers who have made significant and thought-provoking contributions to their fields, but said that they are often senior faculty members and experienced researchers. By the time they’ve reached that stage, he said, much of their time is spent directing younger scientists, securing funding for the lab, and doing relatively little actual science.
“They’re not the ones doing the science — they are sitting in their offices writing grants, or probably jetting around the world giving keynote addresses,” Berry said. “The actual science — and this is perhaps science’s best-kept secret — is being done by graduate students. They’re the ones actually engaged with the scientific process. They’re the ones developing new tools. They’re the ones, if you like, hacking away at the rock face of knowledge.”
The evening’s event, he said, was dedicated to hearing from those still getting their hands dirty. Each student gave a brief presentation on his or her work and then took questions from the audience.
The walking-pelvis primate
Young, a doctoral student in the human evolutionary biology lab of Terence Capellini, Richard B. Wolf Associate Professor, calls the pelvis the most important “evolutionary bone” in the human body. Young, whose work examines the evolution of the pelvis, professes “an almost unhealthy obsession” with it.
That obsession is rooted in the fact that when you look at skeletons of humans and their closest animal relative, the chimpanzee, the differences in their pelvises stand out. The chimp’s is elongated and flattened, an illustration of the different ways the two species make a living — the chimp in trees and on all fours on the ground, and the human upright and walking on two feet. The broad sides of the human pelvis are designed to anchor the muscles needed for walking, while its basketlike appearance supports our guts as we stride around the countryside.
Young is using genetic analysis to understand how species that are so closely related can have pelvises that looks so different. The answer, she said, lies not in the DNA itself, but in the regulatory switches that determine which genes are turned on and off.
A key to the pelvis’ importance, she said, is that 3 million years ago, about halfway back to our most recent common ancestor with chimps, the famous chimplike human “Lucy” (Australopithecus afarensis) already had a pelvis a lot like modern humans but her brain was still chimplike. It was our pelvis, Young said, that first differentiated us and enabled our ancestors to better move across the landscape and secure the resources needed to develop our energy-greedy brains.
“I would argue that what makes us human is not necessarily our big impressive brain,” Young said, “but our pelvis itself.”
