I thought about posting this at parenting.SE and might cross-link to it, but for now I see it as somewhat of a claim that's tossed around and in the same bucket as some others (like not standing too close to a microwave). In any case, my parents bought my wife and I a video called "The Importance of Being an Infant" (LINK) (didn't realize how expensive those were until I looked for a link!). The video mentions that crawling for a certain amount of time and not moving on to walking too early is extremely critical for proper development.
We were having dinner the other day with some friends and they referenced that bit of "wisdom" and said that it was complete BS, referencing some of their siblings who never crawled but are great at sports.
The video is actually quite well done, referencing some reflexes and how such reflexes might not be grown out of if the crawling phase is skimped on, and prior to hearing my friends' comments, I had never really doubted it. There's other sources for this claim as well, for example THIS:
It appears that in some kids this reflex does not dissipate. The cause could be genetics, little time spent crawling or extended periods of time spent in walkers or exersaucer. Whatever the cause, there are some hypothesized negative outcomes for some kids when this reflex does not subside...
So, is there any scientific literature showing the critical/beneficial nature of a "proper" crawling period for childhood development?
I'd have to fire up the DVD, but I recall it giving a specific length of several hundred hours of crawling prior to walking and suggesting that parents not hold their kids in standing position to help them walk any earlier. A secondary question if the above is "Yes" is how much time is suggested.