eli5 Why do people have a brain center for reading comprehension (areas 39, 40) when we clearly did not need to have this skill for the majority of our history as a species?
In: 16
I’m not sure you are thinking about this carefully enough. The observation that damaging a particular area of the brain reliably destroys the ability of someone to read does not mean that that region of the brain is a region that is entirely responsible for reading, or that the evolution of the brain in that region was driven at all by its relationship to the ability to read.
As an analogy, imagine you are an alien anthropologist. You are aware that human beings are a tool making species, and you are trying to figure out the function of a particular tool. You put me in a room where I have a piece of wood, some nails, and this tool. You tell me that if I can pound in the nails, you’ll feed me for the day and if I can’t, I go hungry. You observe that if I have the tool, I can pound in the nails, and that if I don’t have it, I’m completely unable to pound in the nails. You have done the same experiment with many other humans and always observed these results: if they have the tool, almost all of them can use it to pound in the nails (some are unable for whatever reason); on the other hand, if you put them in the room without the tool (just the nails and the wood) no human has ever been able to pound in the nails.
As an alien anthropologist, you therefore conclude that obviously the tool you’re studying was designed specifically to pound in nails.
Unfortunately, your conclusion is incorrect. The tool you are studying is actually a screwdriver. It wasn’t intended to be used to drive in nails. But, in a situation where I have an incentive to pound in the nails and I only have a screwdriver or my bare hands, of course I’m going to use the screwdriver. I can’t drive the nail with my bare hands.
This is reasoning that is similar to your reasoning here. Humans obviously have physical limitations on the size and configuration of their brains. As you note, writing (and therefore reading) is a relatively recent invention. Yet we can observe that a specific area of the brain is needed to be able to read. You think that this indicates that part of the brain evolved specifically to allow us to read. It doesn’t mean that at all. All it means is that whatever that portion of the brain is doing is a necessary component of reading. It doesn’t mean that part of the brain is the only necessary component (after all, if I remove the crankshaft of an internal combustion engine, it won’t work anymore, but the same is true of many other parts). And it certainly doesn’t mean that that part of the brain is only used for reading.
Latest Answers