Evening star. [volume] (Washington, D.C.) 1854-1972, 1908-07-15
HERED|Ty SHOWN IN HAIR
WHY SOME HAVE STRAIGHT
AND OTHERS CURLY LOCKS.
Variations in the Twist-Mammals'
Hair Nearly Always Circular
In Cross-Section.
From the Literary Digest.

From the Literary Digest
Data that appear to make It possible to
predict from the hair OF parents the form
Of hair Of the children-that IL. whether
1t will be straight. wavy. curly or "kinky''
have been gathered by Gertrude and
Charles Davenport Of the Carnegie Insti-
tutions station for experimental evolu-
ton at Cold Spring Harbor. N. Y. The
collection Of these data and the writer's
differences from them are described In an
article entitled ''Heredity Of Hair-form
In Man" in the American Naturalist. The
writer's describe at the outset the various
morphological types shown by human
hair. They say:
Between straight hair, on the one hand.
and woolly hair, on the other. there are
all degrees OF closeness Of spiral For
convenience three intermediate grades
may be recognized; wavy, having very
slight or open spiral involving the entire
hair from root to tip; curly. having a
closer spiral involving the distal half of
the hair; and frizzy or kinky, close tight
spiral Of small diameter. Now. although
the conditions thus named are not discon-
tinuous, they stand for types that are
fairly we'll appreciated and distinguished
popularity. 80 that in random lot OF
people practically all would place a given
sort Of hair in the same category.
Types Of Hair-Form.
These different types of hair-form are
associated with certain differences Of the
hair on cross-sec:ion as well as in it's
method Of growth. Thus straight hair Is
nearly circular on cross-section, while In
wooIly hair the cross-section Is elliptical
and the long axis is to the short as 1904
or 1880 In wavy hair the proportions
are as 10000 or 10. The straight hair Of
the Japanese has the proportion Of 1UO:S5.
Since the hair Of most mammals is
straight and nearly circular on cross.
section. we may regard this as the basal
condition and the flattened hair as a
specialized form marking an advance In
the differentiation of axes In addition to
this difference in cross-section hairs differ
in woolly hair not only hattened. but
curved In an arc through a quarter Of a
circle. Emerging from an incurvated
mold, 1t can only continue to roll up out
side, given especially its flattened shape;
it rolls up into spiral the plane of which
at the beginning. Is perpendicular to the
surface Of the skin AS all gradations
exist between straight hair and wool In
curvature. The intermediate nature OF
waviness is probably due to an interme.
date degree Of curvature beneath the
skin. This curvature Of the follicle. again
IS q departure from the usual mamma liza T
condition and is in the line of differentia.
ton or advance.
Data Collected.
1--WE are now In a position to formulate
our problem. How do the more special
| lied types of r-form-much flatteneC
| and much curved woolly hair and slight,
fattened. slightly curved wavy hair-be
have in heredity toward each other ant
toward the nearly cylindrical straight
/ hair?
1.-The data for this study include the an
cestral characteristics Of about five hun
dred children for two ascending genera
| tons About two hundred and thirty
| families are involved"
The data collected by the Davenport
indicate strongly that as between straigh
and spiral hair. the latter Is the dominan
! form. Regarding wavy hair. they con
clude that it carries both straight ans
| curly germ-cells. The results OF thei
study they formulate as follows, combin
ing them in part with those obtained 70
eye color by the same methods:
Two blue-eyed. straight-haired parent
| will have only blue-eyed, straight haire,
children. Two wavy-haired parents ma,
have straight. wavy. or curly haired chill
dren, but the chances for curly hair ar
slight Two curly-haired parents ma
have children with either straight. wav
or curly hair. and the proportion of curly
haired offspring will probably be large.
| o