We tend to think of infant development as a tightly sequenced pattern of steps, one following the other in strict order, with little room for variation.
And, to a large extent this is true, no one walks before they smile, or talks before they sit.
A well-established sequence is in place for all human development, and it applies to every healthy baby born.
That sequence can be summarized with the following high points, in this order:
- Eye control allowing for a control of what one looks at
- Reaching then grabbing
- Comprehending language
- Speaking language
Each of these steps are required courses in the great college of development. Unless something is terribly wrong, every baby born goes through these steps, in this order, doing every single one of them.
But can you tell which two steps which are often included in this sequence are not listed?
There are two developmental steps which nearly every book on development lists with these, and I have not listed them.
Because they are not required. Not all babies acquire these two skills, in fact millions never do, and suffer no harm from skipping them.
These two steps also stand out because in contrast to the ones listed as necessary, these two steps are entirely unnecessary, they are only useful while waiting for the next step to happen. And, even in the majority of infants who do acquire these two skills, these skills are dropped as soon as the next level of ability is mastered.
This is far from the case for the required courses. One does not stop smiling once one can sit. And one does not stop sitting forever once one can walk. Each of these required, and fully universally achieved, skills remains central to normal human functioning the rest of your life.
Not so with the two I think of as electives. For both of these steps, once the next step is mastered, the need to do each vanishes, and most people rarely return to use them as they get older.
So what are these two mystery developmental steps?
- Rolling Over
Did you guess these were the two? If so, well done. If not, it’s understandable as nearly every reference on development puts them at the same level as walking and talking.
But take a look at each closely, and it will become rapidly apparent these two do not fit into the other list, they simply are optional.
Typically this step, if an infant chooses to pursue it, occurs around 4-6 months of age. It always precedes sitting. In some ways it is an early form of mobility, a method to get from one spot to another, and it works very well. We see about 10-20% of infants, however, never doing this, never rolling over. And all of these infants go on to sit, to walk, and to talk. They suffer no problem at all by choosing not to roll over.
And, every single infant who does roll over, soon stops doing so once they can move with the vastly superior option of walking. Just like us, children rarely get down on the ground and roll to a treat if they can walk.
The same can be said about crawling.
if an infant chooses to pursue it, it occurs around 9-12 months of age. It always precedes walking. As with rolling over, crawling is an interim step, providing an t is an early form of mobility. We see about 5-10% of infants, however, never doing this, never crawling. And all of these infants go on to walk, and to talk. They suffer no problem at all by choosing not to crawl.
And, every single infant who does crawl, soon stops doing so once they can move with the vastly superior option of walking. Just like us, children rarely get down on the ground and crawl to a treat if they can walk.
- Not all developmental steps are created equal.
- Some are universal, all healthy people must achieve them, like walking and talking, to function normally.
- But others truly are electives, they only offer a temporary benefit, and millions of people never do them, the chief examples of these are rolling over and crawling.
- If an infant fails to achieve a required developmental step, that is of course a cause of concern.
- But if an infant skips an elective step, like rolling over or crawling, it is of no concern at all.
To your health,
Dr. Arthur Lavin