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From: kaiser@jaws.DEC (Pete Kaiser, HLO2-1/N10 225-5441)
Newsgroups: net.kids
Subject: Re: Walking before they crawl?
Message-ID: <1772@decwrl.UUCP>
Date: Mon, 22-Apr-85 22:54:20 EST
Article-I.D.: decwrl.1772
Posted: Mon Apr 22 22:54:20 1985
Date-Received: Thu, 25-Apr-85 07:56:03 EST
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Mireille was pulling herself up and cruising at 5 months ("cruising" is when the
baby holds on to something, like the rail of its crib, and sidles along holding
onto it).  She was so good at it we expected her to walk unaided any day, but
what actually happened was that she began crawling at about 9 months -- a very
ordinary age to crawl -- and to walk at about a year, also a very ordinary age.

An infant's ability to walk depends on nearly a single thing: the degree of
myelinization of its nervous tissue.  Myelin is a fatty whitish material that
insulates the conducting fibers of nervous tissue; this insulation speeds up the
conduction of nerve impulses.  When there's enough myelin covering nerve tissue,
the speed of nerve impulses is fast enough for the baby to be able to walk.  And
at that age it will walk, even if, for example, having its legs in casts has
prevented it from ever crawling or locomoting "normally".

This myelinization, by the way, has nothing to do with muscular development or
intellect; it's just a physiological condition, like eye color.  So although
some babies do walk earlier (later) than others, this has practically no bearing
on anything else about the baby's development.

---Pete

Kaiser%JAWS.DEC@decwrl.arpa, Kaiser%BELKER.DEC@decwrl.arpa
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