Survival
The phrase “survival of the fittest” is well known and often repeated when discussing evolution. It’s easy to imagine faster speed, sharper vision, or larger size as beneficial adaptations for survival. But what about the invisible adaptations that happen at the genetic level? What causes these changes, and how do they spread through the population?
Many of the adaptations that help people survive to reproduce arise from our constant battle with disease-causing microbes.
Microbes vs. humans
“Microbes are fascinating. They’re very powerful. They are one of the strongest forces shaping human evolution and they themselves evolve over time, so they’re always shifting,” said Dr. Pardis Sabeti, a geneticist who leads the Sabeti Lab at the Broad Institute of MIT and Harvard. “It is a true arms race because, like us, they are also in a struggle to survive.”
Dr. Sabeti is a leader in the Broad’s Infectious Disease and Microbiome Program where she focuses on infectious disease and genome biology. Her lab has helped create comprehensive approaches for detecting, containing, and treating deadly infectious diseases. The microbes she studies include Lassa virus, Ebola virus, Zika virus, and SARS-CoV-2. In 2014, TIME magazine named Sabeti a “Person of the Year” as one of the Ebola fighters.
In a Leakey Foundation Survival Symposium lecture in 2016, Dr. Sabeti described how evolutionary science gives humans an advantage in our battle against infectious disease.
Tracking genetic mutations
In her work, Sabeti uses computational genetics to better understand how humans have evolved in response to our environment. This includes identifying mutations in human DNA and investigating the roles infectious microbes play in shaping our genetic makeup.
“We have data from the entire genome,” said Sabeti. “We can look at the data from humans and other species to identify ‘footprints’ that occur when a new mutation emerges and spreads in the population. What we’re doing is trying to pinpoint what change occurred and what effect it had. Using DNA from individuals living in the world today, we can take that and we can begin to see patterns.”
Looking at mutations in DNA that occur over time can be useful in understanding changes in human response to infectious microbes. Pinpointing these mutations also show which genes help us adapt to repeated exposure. Analyzing the pathogen’s genetic makeup can give insight into modes of infection and transmission, even with microbes that evolve quickly. Looking at the bigger picture helps us to understand how both humans and pathogens evolve and interact.
Fossil-free archaeology
Modern genomic science now allows us to detect these evolutionary adaptations without relying solely on fossils. “There’s an archaeological record hidden in our own DNA that we can use to begin to understand the things that are biologically important,” said Sabeti. “I call this fossil-free archaeology.”
Understanding this evolutionary history is crucial for addressing today’s health challenges. By identifying genes that have been naturally selected for resistance to specific pathogens, scientists can develop better treatments and preventive measures.
As our population grows, cities expand, and humans push further into previously undisturbed ecosystems, we’re likely to encounter more pathogens. Climate change may also alter the ranges of disease vectors like mosquitoes. In this changing landscape, evolutionary science offers helps us prepare for and respond to emerging health threats.
Learn more about disease, pathogens, and human evolution
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📚 Book: Outbreak Culture: The Ebola Crisis and the Next Epidemic by Pardis Sabeti and Lara Salahi
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🎧 Podcast: “Evolutionary Arms Race”
Listen to Pardis Sabeti explore the evolutionary arms race between humans and disease-causing microbes
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🎥 Video: Survival Symposium playlist
Explore evolutionary insights on humanity’s greatest challenges.
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Survival is a Leakey Foundation program focused on using evolutionary science to understand and address the biggest challenges facing humanity today. This program is made possible by the generous support of the Wirthlin family.
