Early trials editing human genetics have begun at the University of Pennsylvania in Philadelphia, according to NPR. Independent trials in the United States, Canada, and Europe are also set to begin soon, despite the controversy surrounding gene editing. How did gene editing begin and how has it progressed?
The clinical trial at The University of Pennsylvania in Philadelphia utilizes a controversial technology called CRISPR, which can manipulate very specific parts of human DNA and, its creators claim, cure diseases like sickle cell disease and certain forms of blindness. The road to specific DNA editing began with evolutionary theory, and it’s come a long way.
Editing Human Genes – 10,000-Year-Old Accidental Gene Manipulation
In The Origin of Species, Charles Darwin noted that trends in sowing and reaping crops and the breeding and domestication of animals have manually altered the evolutionary process—which he called “artificial selection”—for over 10,000 years. Studying artificial selection can guide us even further back into the past. “Wolves perhaps looking somewhat like domesticated dogs may have shared caves with Ice Age humans as early as 36,000 years ago, and they definitely followed nomadic humans around for millennia, especially after the Ice Age ended roughly 12,000 years ago,” Dr. Scott Solomon, Associate Teaching Professor at Rice University, said. “Next, domestic versions of sheep, goats, and pigs appeared (in that order) perhaps 11,000 to 10,000 years ago.” From 8,000 B.C. to the time of Christ, artificial selection aided the domestication of cats, cattle, horses, llamas, alpacas, chickens, ducks, and turkeys.
So where do identifiable genetics come in? “In 2014, researchers identified a possible genetic basis for tameness, located in what are called neural crest cells, a small cluster of cells in vertebrate embryos that later break up to control a variety of features around the body,” Dr. Solomon said. “In domesticated species, neural crest cells are linked to such changes as smaller skulls and tails; ears that are floppier; and more juvenile and less threatening versions of the face, snout, and teeth—and of course, their behavior becomes friendlier and less aggressive.”
Human Genes – 100-Year-Old Intentional Gene Manipulation
Humanity’s first intentional attempts at gene manipulation began in the 1920s with Herman Muller, a scientist who blasted fruit flies with mutagens, or “chemicals or radiation that cause mutations,” Dr. Solomon said. The forced mutations would often harm or kill the subjects, however, drastically minimizing observable changes in gene editing. Progress remained at a standstill for 50 years until the development of recombinant DNA, which involves extracting DNA from one organism and recombining it into another.
“In 1972, biochemist Paul Berg became the first person to find a way to successfully combine the DNA from two different organisms,” Dr. Solomon said. “He copied a short piece of DNA from a bacterial virus into a monkey virus.” His success was repeated by other scientists a year later and recombinant DNA continued another 40 years until the CRISPR tech was invented in 2012, which is what geneticists use today.
CRISPR (which stands for Clustered Regularly Interspersed Short Palindromic Repeats) is a piece of RNA that can search for a specific and problematic genetic sequence in DNA and, using the enzyme Cas9, cut the sequence before it can do any damage to the subject.
This technology saw some controversy last year when Chinese scientist He Jiankui announced that he had used it to edit the genes of two human embryos that lived, altering their DNA for generations to come. The new trials currently underway are only being used on people who are already grown individuals, which will limit the effects of the trials to the subject alone and not extending to his or her descendants.
Dr. Scott Solomon contributed to this article. Dr. Solomon is an Associate Teaching Professor at Rice University, where he teaches ecology, evolutionary biology, and scientific communication. He received his Ph.D. in Ecology, Evolution, and Behavior from The University of Texas at Austin, where his research explored the evolutionary origins of biodiversity in the Amazon basin.