Hopi Hoekstra, Alexander Agassiz professor of zoology and curator of mammals in the Museum of Comparative Zoology at Harvard University, discussed scientist Charles Darwin, what he knew and what he didn’t know at the Earth and Space Sciences Building on Friday, Feb. 9, as part of the Living World Lecture Series of Science Open Nights.
This Monday, Feb. 12, will mark Darwin’s 209th birthday and 159th anniversary of his famous book “On the Origin of Species” in which he lays out the idea of evolution by natural selection.
“I think it’s fair to say very few fields, in the way the evolutionary biology can do, can trace its origins to a single man and a single elegant idea,” Hoekstra said. “It was remarkable how much he knew yet with so little information, at least, relative to what we know now, and how much he got right.”
Darwin recognized that traits are inheritable based on the resemblance between parents and offspring, but he didn’t know the mechanism through which traits were inherited.
“And this is arguably one of the few things he got wrong,” Hoekstra said.
“A century after Darwin’s publication, James Watson and Francis Crick uncovered the chemical structure of DNA, adding the missing link to Darwin’s theory, ” Hoekstra said.
To further understand how genetics could shape survival behavior of animals over time, aside from physical traits like height and hair color, the Hoekstra lab looked into a behavior that is crucial to many rodents: burrowing.
Different species dig different shapes, lengths and types of burrows. These unique digging patterns can be crucial in helping with survival functions like thermoregulation, shelter, mating and food storage, Hoekstra said.
“This is a behavior that he doesn’t learn from his parents but one that’s thought to be highly genetically driven,” Hoekstra said. “If this behavior of building a burrow is controlled by genetics then we can use the burrow as a trait of interest.”
The research‘s results “raise the possibility that genetic variants affect behavioral drive (i.e., motivation) to burrow and thereby affect both the developmental timing and adult expression of burrowing behavior,” suggesting a link between genes and behaviors.
Casey Youngflesh, a graduate student in the department of ecology and evolution, said he was surprised how big a role heritability plays in determining traits.
“You’d think that, you know, nature vs. nurture argument for behavior, at least, the nurture would have more to do with it,” Youngflesh said. “At least for these mice, that’s not true.”
Laurel Yohe, a postdoctoral researcher in the department of ecology and evolution, said innovative and creative approaches ranging from computer models that measure the movements of lab mice to foams that mold to the shape of their burrows, “make this sort of an elegant research and experimental design to be able to actually answer a very complex question about how something like how behavior evolves.”
Moving forward, the researchers will use a tool called a viral vector to inject genes from one species into other species with different burrowing traits. This could be the first step to altering behavior through genetic manipulation. “In terms of humans, what if you can change your motivation to study but that didn’t also affect your motivation to eat,” Hoekstra said.
“I would argue that if we’re able to do this final experiment — make little diggers build long burrows — this is a result that would certainly tickle Darwin,” Hoekstra said. “Both because it’s a connection between genes, but importantly, a connection between genes and behaviors, this idea that behavior just like morphology could evolve by natural selection if they’re heritable.”
