Expert calls for human-controlled evolution to be named 'genetic welding'

Humans are changing evolutionary trajectories via CRISPR tech. Perhaps now is the time to pause and think about what this all actually means.
Sade Agard
Humans are changing evolutionary trajectories via CRISPR tech
Humans are changing evolutionary trajectories via CRISPR tech

Bill Oxford/iStock 

An evolutionary geneticist proposes that we call evolutionary meddling "genetic welding," according to an opinion paper published in Trends in Genetics on March 28

By introducing easily distributed genes throughout whole populations, humans can quickly alter the evolutionary trajectory of animals or plants using the CRISPR-Cas9 technology. Therefore, he contends that before implementing genetic welding, its potential ethical and scientific ramifications must be carefully considered. 

Can evolution be controlled by humans?

"The capability to do genetic welding has only taken off in the last few years, and much of the thinking about it has focused on what can happen in the near term," said Asher Cutter of the University of Toronto in a press release.

"Ethically, before humans apply this to natural populations, we need to start thinking about what the longer-term consequences might be on a time scale of hundreds or thousands of generations."

It is common knowledge that genes have a 50:50 chance of being transferred from parent to child in classical Mendelian genetics. However, this isn't always the case. Some genes can bias their own transmission in a way that makes them much more likely to be inherited, a phenomenon known as "genetic drive."

The human-mediated equivalent of this is genetic welding, which involves introducing genes with an unfair heritability advantage into natural populations.

Expert calls for human-controlled evolution to be named 'genetic welding'
This is a figure explaining that gene drive transmission is non-Mendelian.

These genes generate considerably faster evolutionary change than the typical slow plod we observe from the natural and artificial selection because they spread freely and quickly through populations.

Genetic drives and welding can also preserve genes that don't always benefit the organisms that carry them. For instance, the latter has been suggested as a tool for managing invasive species and mosquito populations that carry diseases. 

Moreover, genetic welding could genetically modify threatened species to make them resistant to contagious infections that could otherwise wipe them out. 

"It raises the question of how much humans should intervene in processes that are normally beyond our control," stated Cutter. 

Opening up "a much bigger can of worms"

He warned that the prospect of using genetic welding as a tool would arise if ethicists, physicians, and legislators decide that it is appropriate in some circumstances to modify the germ line of humans.

"This would open a much bigger can of worms by virtue of the fact that genetic welding could change the entirety of a population or species, not just a few individuals that elected to have a procedure," he added. 

While it may be challenging to experimentally evaluate the long-term effects of genetic welding, Cutter argued that thought experiments, mathematical theory, computer simulations, discussions with bioethicists, as well as experiments in short-lived organisms with rapid reproduction could all play important roles.

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