Turning Junk into Us: How Genes Are Born
By Emily Mortola, Manyuan Long
You are garbage. Don’t feel too bad, though—so is everyone else. Now, geneticists are learning what the junk in your genome has been doing all along.
This Article From Issue
May-June 2021
Volume 109, Number 3
Page 174
For most of the history of genetics, the most prominent experts of the field have held that you, your mom, your great-great-uncle, Abraham Lincoln, all the emperors of Rome, and every one of Genghis Khan’s Mongol Army all inherited a vast amount of “junk DNA.” As we discovered in 2003 with the conclusion of the Human Genome Project, a monumental 13-year-long research effort to sequence the entire human genome, approximately 98.8 percent of our DNA was categorized as junk. The other 1.2 percent includes every one of the genes that determine the makeup of the human body and allow it to function. In molecular terms, about 6.4 billion of the individual organic subunits—known as nucleotides—that make up the DNA in each of our cells just sit there like the boxes in the back of your attic, doing nothing but taking up space.
QUICK TAKE
- Close to 99 percent of our genome has been historically classified as noncoding, useless “junk” DNA. Consequently, these sequences were rarely studied.
- An international project has revealed that these DNA are far from junk. Through mutations and natural selection, these DNA sequences can give birth to new genes.
- The rise of de novo genes is far from uncommon, suggesting that these genes play a bigger role in evolution and adaptation than once thought.
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