There is a connection with the crawling action, with crossing over the left and right parts of the brain and children's development in regards to reading later on. It doesn't mean that a child who skips crawling altogether will definitely have issues but should be given lots of opportunities to play and crawl later on and to make those left and right connections. This can occur through simple games that kids play (like mine who pretend they are dogs ) and many schools do something called brain gym as it has been shown to really help kids with concentration and focus.