Just read some of the responses...
Yeh, we are absolutely pushing children academically too young. Has anyone read Boys Adrift by Leonard Sax? It's a very scary book that talks about the lack of motivation we're seeing in young men these days. He cites several reasons for this, one of them being changes in school standards for 5- yr olds. He said tat 5-yr old boy's brains are at the maturity level of a 3-yr old girl. The book is a little alarmist, I think, BUT everything he talks about is based in research and I have also seen this phenomenon of unmotivated men myself. It's a very interesting read and I highly recommend it to anyone who works with children or has children.
But, while the research suggests that boys are (for the most part) not ready to read at age 5, their little bodies are ready to be trained by around 3. I don't think it's unreasonable to expect a boy to be trained sometime in their 3-yr old year.