Question: I previously asked a question surrounding consciousness and human perception. I had really insightful answers... but from those I found myself asking questions surrounding colours and sound. As a human we only have 3 colour receptors and we can only hear specific sound frequencies. In the future could we adapt this and change it using medical practises or have we really reached our biological limits as a human species? Thank you :)

David McGonigle answered on 8 Mar 2021:

Hiya again, Anastacia! Wow…another exciting question! Alex has already got straight to the heart of your topic, and is absolutely spot on – say we had some way to plug a new microphone into the brain that was able to record the ultrasonic ‘chirps’ bats use when they are navigating (these are 2/3x higher that the highest frequencies we can hear). What bit of the brain would we ‘plug’ this extra information into? There’s no ‘room’ in our auditory cortex, which contains a ‘map’ of sound frequencies rather like a piano keyboard, laid out along a strip of brain. The analogy doesn’t end there: like a piano, there is no easy way to just bolt on new keys with new frequencies to expand that range. You’re stuck!

But it *is* possible to change the wiring in your brain to accept inputs that are not perceived in nature by humans. Take our bat chirps: we could take the signal from our super-sensitive bat microphone, combine it with a bit of neurosurgical knowhow (again…not one to try at home!), and wire that input directly our auditory cortex. The problem is…again, as Alex says, there’s no room, so you’d need to lose something. It would be like taking your piano keys, cutting the connection between some keys and their ‘hammers’, and rewiring each one.
So have we reached our biological limits? Well, yes and no. Surprisingly (I had totally forgotten this until I googled it), there *are* human tetrachromats: people with 4 colour receptors, instead of 3 that most of us get by with! It’s quite a decent percentage of the population, with roughly 12% of women having 4 colour receptors…but don\t get your hopes up. Most tetrachromats report that their condition doesn’t allow them to see any ‘new’ colours – what it does do is tend to give them an ability to perceive colours – and the differences between them – in richer detail. Bummer! But not all is lost – if we can’t tweak our current senses, maybe we can borrow a new one? Back to our bats: there is a growing amount of evidence that humans can use a limited form of echolocation to get around. While it really started in the blind – this video is a lovely introduction https://www.youtube.com/watch?v=A8lztr1tu4o – the skill can be learned by sighted humans, as well. Have fun researching this a bit more!