I think you'll find that backpropagation was essentially developed (multiple times) during the 60s in the field of control theory and first implemented in the e

I think you'll find that backpropagation was essentially developed (multiple times) during the 60s in the field of control theory and first implemented in the early 70s. Indeed. The book Talking Nets: An Oral History of Neural Networks[1] covers a lot of this ground. Read it and you'll see many people who were involved in the early history NN's mentioning how backprop was discovered and re-discovered over and over again. [1]: https://www.amazon.com/Talking-Nets-History-Neural-Networks/dp/0262511118 https://www.amazon.com/Talking-Nets-History-Neural-Networks/...