Developmental Milestones [Introduction]

Published: 13 Jan 2022

You’ve got to learn to crawl before you can walk.

This statement is regarded as a truism, and a metaphor for life. We say it whenever someone is beginning something new. And we take it as given.

It turns out that the inspirational motto is not actually correct. While we see crawling as a necessary precursor to become bipedal, our forebears knew something we don’t. You can learn to walk without crawling first. Crawling and walking are biomechanically unrelated. (More on that soon.) In fact, our ancestors did not want their children crawling. It was degrading. It was disgusting. It was inconvenient. Crawling, historically, was actively discouraged. (In various places around the world including some places in Turkey, Bangladesh, PNG, Jamaica, and more, it still is.)

Why? Isn’t crawling a major milestone as our infants grow from infancy to toddlerhood. 

It is today, but in some parts of the world (and in most places, historically), there was nothing hygienic enough to crawl on. I know someone right now is rolling their eyes as they think about their kids crawling in the dirt at the park but let’s get some context:

For centuries, homes used to have floors made of either dirt or, in even worse cases, rushes. A rush floor might be 10-20cm thick and it was literally the last place you might place a baby. Rush floors were seldom, if ever, changed. So the decaying plant life that formed the floor might be in place for several years. In addition to the creepy crawlies in those rushes, people would spit on the floor (it was called expectoration, and spitting indoors was common until a century and a half ago), vomit, urine (yep, centuries ago people kinda just relieved themselves wherever they felt like it), food scraps, and more. Let’s just say that living in medieval Europe also meant no showers, hygiene, or fresh air. And those homes (particularly the floor) were a remarkable breeding ground for vermin or disease. Disgusting enough?

Parents did not want their kids on the floor. (In Bali, today, crawling is still seen as degrading.) And parents believed that allowing a child to crawl would actually inhibit the child’s capacity for walking. Two legs? Good. All fours? Bad.

The fact is that you can skip crawling entirely and still function as an adult. The reason kids take so long to walk is because their brain mass is not sufficiently developed! Once their brain is big enough, walking becomes a matter of course.

Why am I telling you this? What does crawling or not crawling have to do with your parenting?

Developmental timelines

We have strong feelings about children and their development. Entire textbooks have been written about child development and milestones. Why? Most parents really crave, as they watch their children grow, knowing what is “normal'' when it comes to their child’s development. Most parents appreciate some reassurance that the kids will be OK. 

It wasn’t always so. 

Concern about developmental benchmarks is a relatively recent idea. It was a Yale psychologist, Arnold Gessell, who introduced the idea of tracking physical developmental milestones… in the 1920s! Around the same time a Swiss psychologist named Jean Piaget started to think about children’s cognitive developmental milestones as well. 

And so these men and the many researchers who have followed have provided us with two decades of developmental markers to obsess about as we watch our children grow and worry about whether they’re keeping up, doing what they “should”, or getting ahead like we hope. It’s because of these researchers that we can start asking questions like “When will my child stop wetting the bed?” and “When can I stop using child-lock on the rear doors in my car?”

The development of your child

Over these series of articles, I will provide an overview of typical child development and the major milestones you can expect your child to hit - and when. While I want to acknowledge those with atypical or neuro-diverse development, it is unfortunately beyond the scope of this short series to do them justice here.

Some brief notes before we go on:

  • Be careful with comparison. Every child develops on their own timetable. Sometimes a child does x before y. Other times they do y and z before x. This is normal and nothing to be concerned about. This is particularly important in that when anthropologists began looking at child development in other parts of the world, they found that a lot of what I’m going to share is not about biology as much as it’s the interaction of biology and the child’s surroundings. Nature AND Nurture. Children in some parts of the world (or from some backgrounds) do things way sooner or way later than children from where we are. 
  • If you are concerned about your child’s development, book a visit with your Doctor. They can advise you on specifics and if something needs to be done, your Doctor is best placed to offer guidance.
  • Finally, sooner or later most children are going to meet all of the relevant developmental benchmarks and grow to maturity with the capacity to function like an adult. Don’t be overly stressed if things aren’t going according to “schedule”, because the schedule is an approximation. It’s not a hard and fast timeline of what you should/must expect.

So let’s dive in!

I have broken development down into the key areas of social/emotional development, physical development, language development, and cognitive development across 5 key stages:

In the early age groups I allow for some overlap between infancy, toddlerhood, and preschooling, but become more distinct in later stages.


Childhood is busy. Our children are teeming with growth and development from the moment they are born until the day they leave the nest. These milestones are just a snapshot of the major developmental expectations we can have if our child is on a “typical” or “normal” trajectory. To watch a child grow - with our eyes wide open and alert - is a tremendous privilege and a wondrous miracle of life. The best part is to be a parent who can provide a safe environment and the secure, autonomy-supportive structure and involvement that leads to optimal growth.

Developmental Milestones [Part 1: Infancy] >




Your Growth Guide

What to expect from birth to adulthood





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