How do we know GMOs are not harmful?

[teo123]

Here is the discussion Red and I were having on YouTube recently:

Great video! About GMOs, I think there is an excellent argument how they are safe: "You realize mutations happen all the time in nature, right? So, is not it better that they happen in a controlled environment than in an uncontrolled one? When a scientist modifies genes of some plant, he knows something about what he is doing. When random chance modifies genes of some plant, it by definition does not know what it is doing.".

That's a great point, people tend to make the appeal to nature fallacy here yet are completely unaware of what nature actually does.

Though, it is a bit complicated, when does this rhetoric apply? How do you know when you are in the position of a scientist usefully modifying a DNA of some bacteria (not understanding everything, but still enough to be overwhelmingly likely to do more good than harm) and when you are in the position of a medieval physician (full of misconceptions and more likely to hurt than to help)? I suppose it has to do with whether the system you are dealing with has its own regulation. Human body does regulate the amount of blood in itself (excess hemoglobin is converted to bilirubin and excreted via stool), therefore bloodletting is overwhelmingly likely to hurt rather than to help. A bacteria has no way of dealing with harmful genes in its DNA (it does not even have chromosomes so that the Mendelian genetics can apply to it), and thus, if you think some gene in bacteria is harmful to what you are trying to achieve, it quite probably is.

Where do we draw the line here? I suppose it is reasonable to believe scientists know enough about genetics to be able to modify genes of simple organisms such as bacteria and be reasonably sure what they are doing is safe. But is it reasonable to believe they are able to manipulate genes of complicated organisms such as plants? Aren't we quite in the position of medieval physicians if we try to do that?

[teo123]

I am aware of some success stories of GMO bacteria, such as genetically modified E. Coli producing insulin useful for treating humans. But I am not aware of any success stories of GMO plants or animals.

[joji]

It might partially be a process of trial and error, too. Like, we've been crossbreeding different plant species since the dawn of agriculture and we dispatch with the bad stuff. I don't mean to appeal to history here, I just want to highlight that crops are all frankencrops. Basically, GMO stuff, but now we've just got much better tools to it with. I presume the GMOs we eat have been rigorously tested enough that they aren't going to eff us up, but honestly, I struggle to think of a reason why simple editing the genetic makeup of a plant species would de facto be bad/wrong/harmful...

One example success story: billions of lives in India were saved from famine and starvation as a result of GMOs. Look up Norman Borlaug.

EDIT: I should say there is a risk of rogue species getting out into wild cropland and really messing things up. Everything has risks associated with it I suppose. I'm not super knowledgable on this stuff though so I'd need to dig into it all more...

[teo123]

It might partially be a process of trial and error, too. Like, we've been crossbreeding different plant species since the dawn of agriculture and we dispatch with the bad stuff. I don't mean to appeal to history here, I just want to highlight that crops are all frankencrops. Basically, GMO stuff, but now we've just got much better tools to it with. I presume the GMOs we eat have been rigorously tested enough that they aren't going to eff us up, but honestly, I struggle to think of a reason why simple editing the genetic makeup of a plant species would de facto be bad/wrong/harmful...

One example success story: billions of lives in India were saved from famine and starvation as a result of GMOs. Look up Norman Borlaug.

EDIT: I should say there is a risk of rogue species getting out into wild cropland and really messing things up. Everything has risks associated with it I suppose. I'm not super knowledgable on this stuff though so I'd need to dig into it all more...

Never heard of Norman Borlaug. I will look it up.