James Smith

So if you have a road, you have people all driving on the right hand side of the road to swap over.

You can't just have one car at a time move that will just really get you in trouble in the traffic.

You need everyone to switch at the same time to get any advantage there.

Yeah, I mean, no one really knows how common it was.

for life to originate, for this process of abiogenesis to happen.

So it might be the case that it's just incredibly rare, and the life that we have was really unlikely to happen, and it happened once, and there just weren't other opportunities for mirror life to evolve.

If you think that abiogenesis is more common, then an answer here is that once any type of life was evolving, it was gaining a lot of fitness advantage and ability to use resources.

So any new life was going to be really feeble in comparison to it.

And when we're talking about engineering mirror life, we're not talking about starting with a really feeble life form, which is what you'd have in the kind of primordial soup.

We're talking about going across this full fitness cycle

to a new fitness peak completely in one go.

And so you don't have that disadvantage.

Yeah, so your body probably has antibodies that could in theory bind to mirror proteins, but it would be only making them in really small quantities.

The issue with mirror life is that

it wouldn't activate your antibody factories, your B cells, such that you produce enough antibodies for it to be able to kill the invading bacterium.

And that's because the innate immune system is probably not going to be activated properly, but also parts of the adaptive immune system, the kind of downstream of this binding, are not going to work.

Yeah, I think that's basically right.

The immune system has a lot of interdependency, but also redundancy.

Your immune system can actually be really dangerous to you.

So usually for things to be activated, you need more than one signal.