Because music is of no value to me, I don't mark any of life's milestones by it.
But there is one historical event that I find interesting due to my fascination with popular science and very basic biology and that is the discovery of what we are made of, and for that matter, what every living thing is made of.
DNA
The beauty of its paired double helix structure kept its secret from us until a couple of Cambridge researchers called Watson & Crick built on previous works to finally revealed it to the world.
Although they published in April of 1953, they discovered it on the morning of February 28th 1953, the day before I was born.