Symbolic AI and statistical AI are both over 50 years old.

https://en.m.wikipedia.org/wiki/Perceptron

Statical AI was delayed in practice because it was far more expensive than symbolic AI.

Symbolic AI is closer to 60 years old. Many of the fundamental concepts of the current wave are 30 years old.

I'm just taking the article on face value; from the very first line: "Just about every AI advance you’ve heard of depends on a breakthrough that’s three decades old."