October 03, 2019
I posted a poll on Facebook and Twitter yesterday asked how long everyone thought it would take for us to be able to copy the human mind to a computer and I wanted to expand on that a little more. In my opinion it will be at least 100 years, though I do think it will happen eventually. Some philosophers and scientists are skeptical that it can happen at all, but for now I’m going to assume that it is possible (I do think it’s possible, I’ll post some discussion of some philosopher’s arguments and why I disagree in the future).
For starters I think it’s helpful to look at where we’re at in our understanding of biological brains. The human brain is extremely complex, so scientists have started out small and are attempting to work their way up. One of the biggest achievements in this area so far has been the mapping of a roundworm brain. The roundworm brain map was created by scientists and is now being used in the OpenWorm project, which is a really fascinating project. The OpenWorm project wants to recreate a roundworm entirely within a computer. To do this they have to understand every function of a living roundworm, such as the exact configuration and connections between neurons and the exact muscle layout and behavior. Then they have to build it within a computer model. If they can do that, it’s possible that the computer simulation would essentially be a real roundworm, or at least act identically to one.
Replicating a roundworm within a computer would be one of the first main steps on the path to copying the human brain into a machine. The first task necessary for modeling a roundworm was to map the roundworm brain, which means figuring out the location of every neuron and how they connect to each other. This map, or wiring diagram, of the brain is called a connectome, and the roundworm connectome has already been fully created. That’s a big and exciting achievement, but it’s also only the first major milestone of the OpenWorm project. Replicating the function of that connectome within a computer is likely several years away at the very least.
So to get an idea of how far away we are from transferring a human mind to a computer, we can make a very rough estimate based on progress on the roundworm connectome. The roundworm connectome has 302 nuerons. Let’s just say it took about 10 years to develop. This is a very loose estimate, but part of the development process is creating software that aids in more quickly mapping the connectome and developing better techniques, and we’ll ignore the years of work that first went into scientists’ basic understanding of roundworm biology before work began on the full connectome. 302 neurons over 10 years is roughly 30 neurons per year. One of the next big projects currently being worked on is creating a connectome of a fruit fly. A fruit fly has 135,000 neurons. Recently scientists have imaged the full fly brain (about 21 million images) and turned that into a full 3D model. You can even explore a 3D model of the images and slices online. But that’s at the macro scale, or the big picture map of the brain. The full neuron-level connectome will require mapping and connecting those millions of images, and that will probably require the development of some new technology and/or software.
So this is again very rough, but let’s assume the fly connectome might take 10 years to complete, which would be an average of 13,500 neurons per year. That would be about 450 times the rate of the development of the roundworm connectome. Let’s also assume that every 20 years our average speed at creating connectomes increases at a multiple of 450 times (the roundworm connectome was being worked on in roughly 2010 and my guess is the fly connectome might be mostly complete near the late 2020s). This multiplier represents the pace of improvements in technology that enable us to create these connectomes faster. So in the first 20 years you’re doing 30 neurons per year, the next 20 you’re doing 13,500 per year, and the 20 after that you’re doing 6,075,000 per year. The human brain is estimated to have about 100 billion neurons. So if we’re at 13,500 per year right now, 40 years from now we would be at 2.7 billion neurons per year. It would still take us 37 years at that rate to create a connectome of the human brain. But 60 years from now we would be at 1,200 billion neurons per year, easily fast enough to have already created the 100 billion neuron connectome of the human brain by then.
Where that leaves us based on this very crude guess at the pace of connectome development is about 50 years to develop a connectome of the human brain. And that’s all just for the first step, that’s not even including trying to replicate the connectome within a computer. Sure, some of the development of computer systems that can model functional connectomes will happen in parallel to the creation of the connectome itself, but recreating the connectome in a computer will likely take much longer than creating a connectome of the human brain.
It’s also important to note that all of the above is a bit simplified as well. Neurons aren’t just dots that turn on and off and are connected to each other by wires. They’re cells, and there may be more complex behavior going on within them or within the way they send signals. They may not just be pulsing on and off. Additionally, neurons communicate with each other through synapses, and synapses are constantly changing. So even if you map the brain and all its synapses, you have to understand how these synapses might change over time in order to more accurately replicate a living brain.
For all of the reasons above, I think it will be well over 100 years before we’re able to copy a conscious brain into a computer. We have a long way to go to get there and our understanding of the brain is still limited. It seems likely to me that even if we are able to create a human connectome within 50 years or so, we’ll hit roadblocks or be limited by technology or a lack of information about how the brain works when trying to replicate it within a computer.
My understanding of biology and the current state of brain research is very limited, so be aware some of what I said above is probably inaccurate. But I definitely recommend checking out the OpenWorm website to read more about it, and the 3D fly brain is really cool as well. It’s an exciting time to be alive, I hope within my lifetime we’ll see a lot of progress made in this area.