Self-learning mechanical circuits have been invented without electronics.
Why it is true
Stanford researchers created self-powered mechanical circuits that learn and adapt to their environment. The system uses springs that become stiffer with movement, allowing purely mechanical machines to understand and respond to changes, without the need for electronics.
Source: Stanford
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.