"
musician or adventurer or leader of men. These and all other native
traits are already determined and latent within it; and the only
question, regarding such traits, is whether the environment is going
to be such as to enable this young individual to live and mature and
unfold what is latent within it.

Reactions Appearing at Birth Must Be Native

For the first few months of the individual's existence, sheltered as
it is within the mother's body, there is no chance for any
acquisition, except of certain abnormalities such as were alluded to
above. What occurs during this prenatal period is natural development,
not learning or any effect of experience. The traits displayed by the
new-born child are, accordingly, native traits. His breathing, crying,
starting at a noise, squirming, stretching, grasping, sucking and
swallowing, and other movements made from birth on, are to be counted
as native reactions, that is to say, as {92} reactions executed by
sensory, muscular and nervous machinery that have become ready for use
by the mere process of natural growth. This is the first and clearest
sign of a native trait, that it shall appear at birth.

Reactions That Cannot Be Learned Must Be Native

But native traits continue to make their appearance as the child's
development proceeds after birth. Inherited anatomical traits, like
stature and build, hair color, beard, and shape of nose, though
certainly determined by native constitution, do not fully make their
appearance till maturity. In fact, what does maturity mean, except
that the natural characteristics have finally reached their complete
development? And it is as true of internal structure as of external,
that natural development, far from being complete at birth, keeps on
till maturity. The neurones continue to grow, and their synapses in
the nerve centers to become closer knit, just by virtue of natural
growth; and thus reflex arcs, and other reaction machinery, one by one
reach the ready-to-use stage during the individual's growing-up,
especially during the first few years. With the growth to a functional
condition of their sensori-neuro-muscular mechanisms, mental and motor
reactions that are native, though not present at birth, make their
appearance. The native intelligence of the child gradually unfolds,
likewise his special native "gifts" and his inherited emotional and
impulsive traits.

Of course it is more difficult to make sure that a trait is native