A Brave New World
It’s been a little while since I wrote about the CRISPR system, which I must admit I still don’t fully understand.
Put simply, the CRISPR system is a gene editing technology — borrowed from ancient bacteria — that allows gene editing down to single specific strands of DNA, strands that cause disease, or just some other feature of a living organism.
Even though CRISPR was originally discovered to be part of the immune system of bacteria in their never ending titanic struggle with viruses, we now know that CRISPR is part of every living organism, including microbes, plants, insects and yes, us. It can be used to edit any part of a living creature’s genome.
Initially, it looked like CRISPR might be limited in the main to curing diseases — by removing bad gene sequences and replacing them with good gene sequences — in fully formed creatures having those diseases. Some of the diseases currently under investigation for being cured via CRISPR are HIV, Muscular Dystrophy, Alzheimer’s Disease and most any cancer.
In the last two years, it has quickly become apparent that CRISPR can be used to modify creatures that carry disease, like mosquitoes that carry the malaria parasite.
Also within the last two years, scientists have explored whether CRISPR can be used to change the human germline by editing the genes of a human embryo. Not only would the embryo, if brought to term, not have the bad genes, but all subsequent offspring of that now human would be free of the bad gene and could therefore not pass on that gene’s undesirable traits.
Of course, it logically follows that genetic editing of human embryos would lead not only to (mostly) disease free babies, but also designer babies, babies with preferred features, like being smart, or tall, or pretty, or strong, or any combination of so-called preferred features.
One might argue that genetically modified embryos are subject to Mendel’s rules of inherited traits, so a single designer baby’s preferred trait might easily be lost within a few generations.
But CRISPR scientists have “fixed” that limitation as well, by using something called gene drive, whereby successive generations of a designer baby (or any living creature) pass on not only the preferred trait, but also the CRISPR mechanism to make that trait the only trait that can be passed on.
To put all of this in perspective, scientists have now not only modified mosquitoes to be unable to carry the malaria parasite, but these same mosquitoes, when mating, exclusively produce offspring unable to carry the malaria parasite.
Since malaria kills over 1200 children per day worldwide, replacing all of the world’s mosquitoes with those that are unable to carry the malaria parasite would seem to be an obvious no brainer. But what if doing so might catastrophically affect some other aspect of the world’s ecosystem?
One negative example given for this is gene driving Asian carp to be sterile and therefore die out. This would be great for the Great Lakes region, where the carp outcompete native fish species for plankton , but not great for Asia, where Asian carp are part of the food chain.
The “elephant in the room” in this discussion is the possibility that a madman/dictator might create a “master race” that could gene drive “undesirable” or “inferior” genetic traits out of the human race.
Clearly, CRISPR has now advanced to the point where the human race is literally in charge of its own evolution, as well as the evolution of all other living organisms. We are truly in a brave new world, but one we never anticipated living in.
If you are a podcast person, be sure to download this episode of Radiolab that talks about the pros and cons of the CRISPR revolution.
To learn more about the “dreaded” gene drive, see the video below.
Of Clocks and Calendars
The Vernal Equinox will soon be with us, so I thought I would share a very good explanation of what a day really is, and why we add leap days according to the rule you learned as a child.