Stepping Out: The Science of Baby’s First Steps

My nephew Malcolm walking, slightly encumbered, age 1. Photo by K. Blackwell.

My nephew Malcolm walking, slightly encumbered, age 1. Photo by K. Blackwell.

A baby’s first steps may seem magical to the proud (and possibly immediately wistful) parents, but you’d think developmental psychologists had long ago gotten a handle on how infants progress from being sweet infants crawling on the ground to trundling hellions bent on grabbing every breakable less than three feet off the ground. It is after all a simple motor process, nothing like the complex, invisible thought processes involved in sorting out perceptions of the world or deciding who to like. But don’t let the seeming simplicity of that first step fool you; we’re still sorting out exactly what goes on when a baby learns to walk.

Learning to walk upright is not a guarantee, something I discovered only this month when science writer Nicholas Day featured a family of adults who preferred to bear crawl – that hands-and-feet locomotion some children try before walking, that has always baffled me because for most of my adult life I haven’t even been able to get into that position, let alone move once I get there. These adults appear to have had some minor differences in their cerebellums – that small part of your brain right on top of your spine that controls motor functions and breathing – that made maintaining bipedal balance difficult, so they stuck with the mode of locomotion that was most effective.

This raises the question of why children ever learn to walk, when bear-crawling can be so efficient even as we grow larger, and walking has such a steep learning curve for keeping balance. Yes, there are advantages in keeping your hands free for carrying, but     there are also disadvantages. Early walking is often slower than crawling; as a toddler my elder nephew could keep up with his big sister on hands and knees, but would have been left in the dust if he stood up on two feet. In addition, certain spatial awareness skills may not survive the transition to a new posture for locomotion. What infants learn about using landmarks to orient themselves when crawling doesn’t seem to transfer when they start walking; once upright, they have to learn about landmarks all over again. And there is actually an ongoing controversy about whether infants retain knowledge about the benefits of avoiding steep drop-offs when they learn to walk, or have to re-learn* that too.

So why pull yourself up and start walking around when you’ll be unsteady and have to re-learn so much? Because Mommy thinks it’s such a good idea, of course! That’s right, a surprising number of the “milestones” parenting guides imply are universal turn out to be influenced by cultural expectations. (It’s worth following that link, just to find the link to my students’ favorite picture of a 1-year old calmly using a machete to cut open a fruit). This includes the milestone of walking: Jamaican mothers expect their children to walk at a younger age than British mothers….and so they do, even though all families were living in the same British city.

And then we come to the latest scientific research, published in November 2012, that uses modern technology (a carpet that measures footprints) to test the influence of a centuries-old parenting practice…diapers. The same 13-month old infant walking in a disposable diaper instead of naked isn’t that much more likely to fall (only 15% of carpet walks, instead of 9%) but they will take steps that are about 1 inch wider. It might not be enough for a parent to notice, but infants’ steps get narrower as they get more practice walking, and that 1 inch is the equivalent of 8 weeks of walking experience.

Parents can take heart from all this controversy and new discovery, knowing that their child’s first steps are still a “miracle”, in that we haven’t completely explained them. We’re always discovering more about how and why children start walking and what it does to their minds. It also highlights the daunting task developmental psychologists are undertaking, that we have yet to fully understand a development that seems so simple.

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*This research can also explain why baby walkers are banned in some countries: the baby stands upright, and immediately forgets everything she once knew about the wisdom of avoiding stairs. Walkers themselves are also a source of ongoing controversy, with some saying that their use delays infant development, others showing no difference in motor development, all of it hindered by the fact that the parents involved are the ones who choose who gets a walker and who doesn’t. 

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