Cassandra Extavour and Gonzalo Giribet

While Professors of Organismic and Evolutionary Biology Gonzalo Giribet and Cassandra Extavour specialize in the decidedly non-human, when it comes

While Professors of Organismic and Evolutionary Biology Gonzalo Giribet and Cassandra Extavour specialize in the decidedly non-human, when it comes to connecting to their students, they seem to have things under control.

Described collectively as “badasses” by a number of their students, Giribet and Extavour comprise the teaching team behind the class Organismic and Evolutionary Biology 51: “Biology and Evolution of Invertebrate Animals,” a class that combines their two specialties and amplifies what many of their students characterize as the professors’ intense dedication to their teaching.


Giribet’s work has taken him everywhere from New England to Australia, Sri Lanka, and Catalonia. In each location, he looks for specimens and uses his findings to infer the evolutionary history of families and phylums. “We have two main projects right now,” says Giribet. “In one we’re looking into more details of how the families and phylums relate to each other, and in the other we’re looking into the big relationship between all the major lineages.”

He and his team conduct extensive fieldwork to classify invertebrate organisms in an effort to better understand how living things are evolutionarily related. “I take my students with me,” says Giribet, who affirms that firsthand experience with organisms is an essential part of studying OEB. “I took several graduate students, as well as an undergraduate student, to New Zealand a few years ago.”

But while he states this matter-of-factly, as if to suggest that these opportunities for undergraduates are a must, Sebastian Velez, who is a teaching fellow for Giribet and has worked in his lab for the past two years, asserts that Giribet’s dedication is not particularly common. “I don’t know many professors who will sacrifice their Spring Break to teach students,” he says, referring to the trip to Panama that Giribet has offered yearly to the students enrolled in OEB 51.

While Velez describes Giribet as an “excellent teacher,” what most impresses him is Giribet’s abundance of energy. “He’ll wake up before everyone and go running, and then still get more done throughout that day than anyone else. When everyone is dog-tired from scuba diving and collecting and identifying organisms, he’s still awake working. We’ll all go to bed at eleven and he’ll stay up until one…and then still wake up before us. He’s the one bringing everyone up,” says Velez.


While Velez praises Giribet for his dedication, in her two years at Harvard, Extavour has also earned the respect and praise of many of her students. “She injured her rib at some point on the trip,” recalls Cameron D. Kirk-Giannini ’11, referring to the 2009 Panama trip he attended. “But she was so badass about it. She kept doing what everyone else was doing.”

Cindy J. Liu ’09, another student of Giribet and Extavour’s, praises Extavour’s dedication and adds that she is impressed by the professor’s vast knowledge of the field. “This is the first time the class has been taught with Professor Extavour, but she is very knowledgeable, and sets up especially good labs,” says Liu.

Extavour’s lab focuses on early embryonic development, and devotes more energy to observing the intricacies of germ cells than to the larger organisms in which Giribet specializes. “She creates an excellent environment in the lab,” says Franz Kainz, a graduate student who has worked with Extavour since July 2007. “We’re extremely productive but it’s still a great environment,” he adds.


While the class was initially conceived and taught by Giribet, soon after she arrived at Harvard, Extavour approached him about co-teaching so that she might be able to contribute her unique perspective. Giribet, who specializes in invertebrates, embraced Extavour’s focus on embryonic development and began teaching the course with her this year.

The two professors are in accord on the benefits of instructing on evolution together. “It’s been great to co-teach,” says Giribet, “you can bring much more expertise to the classroom.”

Students also appreciate the depth of knowledge the two bring to the table. “The things they teach go really well together,” says Kirk-Giannini. “Its one of my favorite classes, one of the best I’ve ever taken.”

With the professors’ outstanding dedication, rave reviews, and trips to Panama, it’s no surprise Kirk-Giannini feels as he does. Watch out professors: looks like you may be getting way more than 15 students next year.