This is one of the interviews in our meet-a-scientist series.
Interview conducted for Science Journal for Kids by Maxine Mouly
The road to becoming a scientist
Kendra Sirak got into genetics almost by accident.
Growing up in Pennsylvania, Kendra didn’t know what field to pursue until she was exposed to anthropology in the formal classroom setting.
As an avid runner and lover of the outdoors who was intrigued by documentaries about ancient civilizations, Sirak studied biological anthropology as a field hockey student-athlete at Northwestern University. Upon taking a class about the evolution of humans and conducting hands-on independent research exploring a human subspecies, Kendra grew more curious about bones.
For graduate school, Kendra joined the anthropology department at Emory University where she discovered that her quest to study bones lay not in their physical structure, but rather internal.
After consulting with one of her professors about her ambitions to study the human skeleton in around 2012, Kendra was told genetics was a newer, emerging field that would make an important impact in science.
“I didn’t really want to do it at first, it was really unfamiliar to me,” Kendra said looking back on that time in her life.
Having no background in genetics, Kendra didn’t know what the work would entail but ultimately dove into the unknown as she didn’t want to disappoint her professor. Within one week, she had fallen in love. By looking at DNA preserved in bones for hundreds of thousands of years, Kendra could help decipher human history.
Kendra went on to attend Harvard University to obtain her post-doctoral degree where she recently took a job as a senior staff scientist, spending her time studying ancient DNA in different contexts around the world.
Using ancient DNA to discover where the first people in the Caribbean came from
Day-in and day-out, Kendra studies past populations using DNA. She identifies a research question of high interest about the past and ponders what ancient individuals can be used to answer that question.
By analyzing the DNA sequences of individuals who lived anywhere from hundreds to hundreds of thousands of years ago, Kendra can compare it to the genetic composition of people who lived before or after that time period. If there was a cultural change in an area — for instance farming was introduced or there is evidence of ceramics use in the archaeological record — she can identify if there was also a genetic change among the people inhabiting that area.
Essentially, this helps Kendra understand if a new group of people brought that technology into the area or if it was spread through cultural diffusion.
In the Caribbean — a region known for its lush vegetation and that has perplexed many regarding its proper pronunciation, which Kendra said is correct both ways — humans have lived for a shorter period of time relative to the rest of the world. Decades of archeological work has revealed information about early Caribbean people, but the question of where the first people in this region migrated from remained unanswered.
“Everyone wonders where they came from and who their ancestors were,” Kendra said.
In her search for answers, Kendra set out to study the DNA of hunter-gatherers who lived during the Archaic Age to uncover where they came from originally. Furthermore, she wanted to determine where the Ceramic Age people came from, if the two groups were genetically distinct, and what the nature of their interaction was.
Published in December 2020 and adapted by Science Journal for Kids, the study Kendra co-authored reveals the genetic history of the first people in the Caribbean.
Archeologists, anthropologists, museum curators, physicists, geneticists, and many other scientists alike came together to conduct this study, creating a melting pot of unique backgrounds and skill sets. Kendra underscored the importance of this group effort, noting that the best part of the study was being a part of the team.
What has become the largest study of ancient human DNA in the Americas, Kendra revealed the innate challenge of retrieving DNA as it doesn’t preserve well in hot, humid climates characteristic of the Caribbean. Collecting an ample amount of high quality DNA is vital to ensure the conclusions scientists draw are authentic and not skewed by contamination, which ultimately allowed the entire study to happen.
DNA, Kendra said, is a “new lens into our past” as it’s a tool that can be used in every corner of the globe to help answer many different research questions. She hopes people will become more excited about DNA’s potential to unlock information about the past.
In the end, Kendra said there is no such thing as a pure human group. People move and adapt to different environments, more likely to exchange genes with individuals who are closer. But despite these geographic-based differences, DNA shows the world that “we share a deep common human history that’s in every one of us,” Kendra said.
Science through Kendra’s eyes
“Just give it a try” is a phrase Kendra generally lives by.
Her advice to students is to never say no to any opportunity that comes their way because her open-mindedness allowed her to become what she loves: a scientist.
Lacking the formal educational background in genetics when her professor suggested she immerse herself in the field, Kendra worked tirelessly to catch up by reading and talking to more experienced colleagues.
Every scientist defines themselves in a different way. To Kendra, being a scientist means you are curious about the world, you are willing to work with a diverse group of people to answer a question, and you refuse to stop until you feel confident you have done the best possible job you can do.
“Even when things get tough and you feel like giving up, you pursue through,” Kendra said.
Genetics is a relatively new field that is constantly evolving; the first ancient DNA study was conducted in 1984 and the human genome was sequenced by 2003. To keep up, scientists were forced to develop their ethical guidelines very quickly.
Given this history, Kendra has been working intensively over the past few months to create a set of ethical guidelines for ancient DNA analysis that can be applied in most research contexts worldwide. Kendra noted the importance of these guidelines because she and her colleagues study the deep ancestors of people who are alive today.
“It’s really important that scientists who are doing the work also have a hand in helping to develop and articulate the standards that we’re going to hold ourselves and our academic community to,” Kendra said.
Kendra’s life is emblematic of seizing all opportunities, working with others, and not stopping until she’s tried her best: a true scientist through Kendra’s eyes. What does being a scientist mean to you?
See all of our ‘meet-a-scientist’ interviews and read Kendra’s research paper below:
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