In Medium-Message Fit, we showed how a given medium (like brains or text) determines the kinds of messages that can live on it.
But the medium is not fixed. Memes can change their information layer.
As an example, early sapiens made two changes to increase our memetic bandwidth for verbal communication.
First, we moved our larynx down which increased the pharynx area and allowed us to more clearly enunciate the vowels a, i, and u, which are found in all human languages.
Second, we moved various pieces of our eardrum to hear higher pitches, which allowed us to hear the consonants t, f, k, and s. Early hominins couldn't hear that high of frequency, but we could.