Researchers are creating new lifeforms that are chemically unrelated to any other life on earth. In fact, for the first time ever, scientists in Japan have built an artificial synapse, from the molecules up. What?! How can this be? Read on, intrepid voyager of the unknown, and discover for yourself.
The basic idea is that a team of researchers have built an inorganic synapse, and taught it to change its connectivity patterns in response to different sorts of chemical signals.
The “inorganic” part is a big deal, because, as far as we know, all synapses in nature – and in fact, all life on earth – is organic (carbon-based). That means biological chemistry is based on carbon, as well as on elements like hydrogen and nitrogen, which like to interact with carbon in all kinds of badass ways. Lots of other elements on earth – most of them, in fact – are excluded from playing major roles in biochemistry because (for a whole variety of reasons) they don’t play well with carbon. So, while there’s no scientific consensus that life has to be carbon-based, all life on earth certainly does seem to be.
Which brings us to the idea of inorganic life – life that’s not based on carbon. In theory, silicon always looked like the top contender, because it also likes to hook up with hydrogen, in its own kinky range of ways. But for decades, silicon-based life was sci-fi stuff – until, in the past few years, researchers began to have success creating silicon-based cells.
I gotta make this clear: we’re not talking about using silicon parts (like computer chips) to simulate biological components – no. This is actual working biology, from the molecular level up. These silicon cells are alive. In cutting-edge labs around the world, alien lifeforms are being born.
And now, a Japanese team have tackled silicon-based biochemistry from an intriguing new angle, the journal Advanced Functional Materials reports. Instead of building inorganic cells from scratch, these researchers have focused on synapses – points of contact between neurons, where electrochemical information is exchanged. In the human nervous system, the ions potassium (K+), sodium (Na+), chlorine (Cl-), and calcium (Ca2+) help control the way these signals are passed on (here’s more detail on how this works).
But for silicon-based synapses, the ion of choice is copper sulfide (Cu2S):
The plasticity of the Cu2S inorganic synapse is controlled depending on the interval, amplitude, and width of an input voltage pulse stimulation.
In short, this silicon synapse changes its connections with its neighbors based on the rhythm and power of stimulation it receives – just like organic neurons do. So this isn’t a simulation of a synapse – it actually is a synapse. And it changes and grows just as organic synapses do:
Time-dependent scanning tunneling microscopy images of the Cu-protrusions grown in air and in vacuum provide clear evidence of the influence of air on their stability.
I think that right there is the most incredible part of the whole story – the researchers got the synapse to grow new copper-based connections with its neighbors. In organic nervous systems, this ability to form new connections in response to specific stimuli is what allows organisms to learn. So not only can the silicon synapse communicate with its neighbors – the system as a whole can learn and adapt.
Not bad for a form of life that’s only existed for a few months. Whatever happens with this particular project, our near future is gonna hold some challenging questions about what we really mean when we say “alive”- and about the ever-blurrier boundary between simulation and actuality.
What do you think – can we handle our new-found power?