The recent announcement that the human genome has finally been fully sequenced received the widespread recognition that it rightfully deserves. It was covered by PBS, Time, CNN, BBC and more. Notably, most of these stories reference the full about-face that geneticists have made since the publication of the first draft of the genome in 2003. This change in perspective regards highly repetitive DNA, some of the most difficult DNA to correctly sequence that has only been resolved this year. Arguably, the most important kind of repetitive DNA comes from transposable elements (TEs).
The PBS article explains scientists’ previous ideas about TEs: “Some scientists have described them as selfish DNA because they can insert themselves anywhere in the genome, regardless of the consequences.” The Time article states, “Scientists were also able to sequence the long stretches of DNA that contained repeated sequences, which genetic experts originally thought were similar to copying errors and dismissed as so-called ‘junk DNA.’”
A beautiful review of transposable elements published in Nature Reviews Genetics last year makes clear that TEs are far from junk. TEs represent as much as 46% of the human genome. Moreover, the review displays that TEs and their molecular partners play central roles in the formation of the placenta, in the earliest steps of fetal development, and in the genetic function of neurons. Their ability to move around the genome has allowed our ancestors to explore new genetic combinations, and those that have been most useful are the ones we now share.
While TEs may have selfish origins, and their ability to jump (or transpose) in our genome can be damaging, they represent almost half of the genetic inheritance we receive from our parents. So, if our ancestors dutifully copied and shared these sequences over the course of many generations, why did scientists ever doubt their usefulness?
These DNA sequences give every indication that they once had a parasitic relationship with our genome. They could have been a sort of genetic infection, but now they are largely held in check by a collection of cellular tools that serves as something like a genetic immune system. This process is reminiscent of the way that the human microbiota—the trillions of microbes that live on and in us—protect us from pathogens and train our immune system to fight really dangerous bacteria.
This idea that ‘selfish’ pieces of genetic material can be integrated into our genomes and then become good and necessary parts of our development is a beautiful reflection of what God does elsewhere in creation. Throughout Scripture, we read stories about God using the least likely of people. One of the most obvious examples is the apostle Paul, an adamant persecutor of early Christians until he encountered Jesus on the road to Damascus and his life was changed forever.
This enemy of the faith was transformed, adopted into God’s family, and powerfully used to spread the gospel. He traveled throughout parts of Europe and Asia, planted churches, and wrote letters that became part of the New Testament. Paul became a missionary, a church leader, a brother in Christ. He is living proof that God redeems and uses what was once a threat.
The same language used to tell Paul’s story can also be used to describe TEs. What began as an ancient infection—foreign DNA attacking our genome, compromising its integrity, and causing harm—was redeemed. Rebel TEs were incorporated into our genomes, given purpose, and co-opted as necessary participants in our development.
TEs are just one of the many ways that science showcases the redemptive work of God. Creation is broken and tainted by sin, but even events that seem devastating can be used for good. From the human microbiota to TEs, strangers are turned to partners; enemies become collaborators. And the same is true of us. Even people who seem hopeless—the stubborn, the rebellious, the disruptive, the depressed—can be adopted and used by God.
This is one of the most important lessons we can learn in our current time and place. Since every decision, every comment, and every social media post can be used to divide and exclude, we are in desperate need of cooperation and unity. Just because we don’t understand something doesn’t mean it’s junk. Just because we don’t agree with someone doesn’t mean they are useless. As followers of God and fellow human beings, we should work to adopt one another into God’s family and learn the value of our differences.
Whether we consider TEs as foreign invaders of our DNA or integral parts of who we are, we must recognize our inability to live without them. But we also need each other. The whole of creation shares a rich, complex history that sheds light on where we came from and reveals how deeply interconnected we truly are.
Perhaps learning about TEs promotes a greater appreciation for our interconnectedness, inspiring us to recognize and practice redemption in our own lives. And, if we feel unlikely tools for the work of redemption, remember that God has adopted us and put us to work too.
