FREQUENTLY in newspapers,
magazines, and other forms of
popular literature where precise
accuracy cannot be expected, and only
a little less often in technical journals,
one meets the following statement or
its equivalent: "In the last quarter
century, the span of life has been
lengthened."^ There is not the slight-
est evidence that the span of human life
has been lengthened in the last two
thousand years, let alone the last
twenty-five. What the ignorant or
careless users of phrases like that
quoted really intend to convey, of
course, is that the mean or average
duration of life has lengthened in the
last quarter century. It is probably
hopeless to expect that workers in the
biological sciences will in the near
future, at any rate, use words with
that precision, and with that careful
regard for their rigorously defined mean-
ings, which students of mathematics
and of physics have for a long time
been accustomed, and indeed com-
pelled, to exercise. But it so happens
that the one field of biology in which
prevails the same standards of preci-
sion in the definition of concepts that
we are accustomed to in physics, is
that field which has to do with dura-
tion of life, and is commonly called
actuarial science. Hence the medical
or other writer who misuses terms in
this field cannot attempt the alibi
that, there being no definitions recog-
nized as standard, his are as good as
another's.
In the actuarial universe of discourse
''span of life" has no status whatever.
^Journ. Amer. Med. Assoc. July IS, 1925, p. 197.
26
When it is desired to discuss what the
writer of the quoted editorial note
wanted to talk about, the expression
"expectation of life at birth," or "mean
after-lifetime, at birth" is used.
"Mean (or average) duration of life"
has the same significance and is an
entirely acceptable substitute even in
technical writing, provided it is made
clear that the writer is not confusing
''me.'^Tn duration of life" and "mean
age at death" in his thinking. These
two things are the same in a stationary
life-table population, but may be
distinctly different in actual general
populations, as Farr long ago pointed
out.
"Span of life" denotes a concept
impossible to define precisely. It is
correctly used when one says: "The
span of life of horses is roughly 20 to 25
or perhaps even 30 years, while that of
man is somewhere about 100 years."
The span of life, in short, is its total
extension between its biological lower
and upper limits. Limiting values of
any thing are extremely difficult to
determine precisely. In the present
state of knowledge it is impossible to
define the span of either equine or
human life any more exactly than is
done in the second sentence of this
paragraph. Furthermore, there is no
such thing as an absolutely fixed and
determinate biological upper limit to
the life span. The upper limit of
human longevity is quite certainly
a variable matter, for which an aver-
age value may be determined if one
has sufficient data, but there is no
particular single age at which the ax
inevitably descends. Individuals alive
SPAN OF LIFE AND AVERAGE DURATION OF LIFE
27
at any particular age, no matter how
high, still have an expectation of life
after that age. This expectation may be
difficult to measure, because of lack of
data, and it may be minute in magni-
tude to the point of seconds of time,
but alwaj^s an average after-lifetime is
theoreticall}' calculable. This is even
true of the cohort composed of the one
person who has lived longer than any
other one ever did. Theoretically he
has a calculable expectation, but prac-
tically it cannot be determined merely
because of lack of statistical data.
But if it is difficult to measure the
biological upper limit of life, it is
even more trying to extend it. On the
other hand the mean duration of life
not onty has a precise significance, but
as events have shown, can be greatly
extended, so far as human beings are
concerned, by proper attention to
sanitation and the application of cura-
tive and preventive medicine. The
accomplishments in this direction are
notable and redound enormously to
the credit of the medical profession.
They have so far been made chiefly
by lowering steadily the death rates in
infancy and the early portion of the
himian life span. When the death rates
from say age 75 to 100 have been
measure the extent of the accomplish-
ments in this direction with anything
like really scientific; accuracy. Life
table studies made in the Department
of Biometry and Vital Statistics of the
School of Hygiene and Pubfic Health
of this University show that for Balti-
more City in 1870 and 1920 the expecta-
tions of life at birth were respectiveh-
33.7 years and 51.5 years. These
figures relate to the whole population
(male and female, white and colored)
and are approximate only. The 1870
figure is probably a little too low, owing
to defective statistics for that year,
but the discrepancy probably does not
amount to as much as two years, and
the 1920 figure is probably not in
error from the unknown true value by
as much as a half year. We see here
the very substantial gain of 17.8 years
in mean duration of fife in this com-
munity in a half century, taking the
figures at their face value, and it may
be regarded as certain that the gain
has been as much as 15 j^ears. For the
larger and more heterogeneous popula-
tion of the original registration states
(which include the New England
States, New York, New Jersey, Dis-
trict of Columbia, Indiana, and Michi-
gan) we have the following data^
EXPECTATION OF LIFE AT BIRTH. ORIGINAL REGISTRATION STATES
Gain
Gain
Gain
1901
1910
1919-1920
1901-1910
1910-1920
1901-1920
White males
48.23 yrs
50.23 yrs
54.05 yrs
+2 . 00 yrs
+3 . 82 >Ts
+5.82 \TS
White females
51.08 yrs
53.62 yi-s
56.41 yrs
+2 . 54 yrs
+2 . 79 yrs
+5.33 JTS
Negro males
32.54 yrs
34.05 yrs
40.45 yrs
+ 1.51 yrs
+6.40 jTS
+7.91 5TS
Negro females
35.04 yrs
37.67 yrs
42 . 35 yrs
+2.63 yrs
+4.68 yrs
+7.31 yrs
equalty lowered, w^e may perhaps then
appropriately begin to speak about
" lengthening the life span."
While every one knows that the ex-
pectation of life at birth is increasing,
it is surprisingly difficult to get data to
enabfing a comparison over roughly
the last fifth of a centur3^
iData for 1901 and 1910 from Glover, J. W,, United
States Life Tables, Washington. Government Printing
Office, 1921. Data for 1919-1920 from Foudray, E.,
United States Abridged Life Tables, 1919-1920.
Washington, Government Printing Office, 1923. Both
of these are official publications of the Bureau of the
Census.
28
NATURAL HISTORY
For London it is possible to make
reasonably accurate comparisons of
the expectations of life at birth over a
longer period. The following table is
quoted from a recent paper by Sir
George Newman.'
to the improvement of the negro
mortality than have been applied to
the white population. Perhaps the
most probable explanation is that when
the general level of mortaUty is as high
as it is among the negroes in cities, any
LONDON LIFE TABLE, 1841-1922
Period
Expectation of life (years)
Period
Expectation of life (years)
Males
. Females
Males
Females
1841-50
1851-60
1861-70
1871-80
1881-90
34.6
36.4
35.7
38.0
40.1
38.3
40.4
39.9
42.4
44.5
1891-1900
1901-10
1911-12
1920-22
41.2
47.2
49.5
53 . 8
45.4
51.9
54.5
59.1
From these figures the following
differences appear:
improvement in sanitary conditions
will produce a more marked effect than
GAIN IN EXPECTATION OF LIFE AT BIRTH, LONDON
From 1901-10 period to 1911-12
From 1911-12 period to 1920-22
From 1901-1910 period to 1920-22
MALES FEMALES
+2.3 +2.6
+4.3 +4.6
+6.6 +7.2
It is apparent from these figures
that the gains in expectation of life
at birth have been somewhat higher,
over the nearest comparable time
period, in the population of London
than in the population of the Original
Registration States.
The explanation of the generally
greater gains of the negroes as compared
with the whites, especially since 1910,
is not entirely clear. It can scarcely be
seriously maintained that more, and
more effective, pubhc health efforts
have been directed during these years
it will in a population already enjoying
a low mortahty rate.
Now while all these gains in expecta-
tion of hfe at birth are extremely im-
pressive, the case wears a wholly differ-
ent aspect when expectation of Hfe ( =
mean after hfe time) at age 77 is con-
sidered. This odd age is taken rather
than 75 or 80, in order to compare Miss
Foudray's figures directly with those of
the earlier years, without interpolation.
From the same sources as before, we
have for the Original Registration
States the following data:
EXPECTATION OF LIFE AT AGE 77. ORIGINAL REGISTRATION STATES
Gain
Gain
Gain
1901
1910
1919-1920
1901-1910
1910-1920
1901-1920
White males
6.09 yrs
6 . 04 yrs
6.17 yrs
— .05 yrs
+ .13 yrs
+ . 08 yrs
White females
6 . 54 yrs
6.41 vrs
6.61 yrs
— .13 yrs
+ . 20 yrs
+ .07 yrs
Negro males
5.96 yrs
6 . 15 yrs
5.92 yrs
+ . 19 yrs
— .23 yrs
— . 04 yrs
Negro females
7.32 yrs
6.91 yrs
6 . 88 yrs
— .41 yrs
— .03 yrs
— . 44 yrs
^Lancet July 25, 2925, p. 165
SPAN OF LIFE AND AVERAGE DURATION OF LIFE
29
The irregular gains (+ sign) or
losses ( — sign) of a few hundredths of a
year shown by these figures are with-
out significance. It is to be hoped that
an3^ person who is suddenly seized with
an urge to write about the lengthen-
ing of the span of human fife will call
to mind in time that its upper Umiting
values are in fact staying about where
they presumably' have been for a very
long time.
But the question as to the possibility
of lengthening the human Ufe span at
some future time must not be unfavor-
ably prejudged because the evidence is
that it has not yet been discernibly
altered in tliis sense. There arises here
a consideration which I do not recall
having seen discussed, but which
obviously has an important bearing
upon the case. I can illustrate it best
by a form of diagram much used in
actuarial work. Su])pose the passage
of time as measured by years of the
Christian era be plotted as abscissa,
and age be plotted as ordinate. Then a
straight line inclined at an angle of
45 degrees (provided a year has the
same value on both scales) drawn
between the dates of an individual's
birth and death, will represent the
passage of his Ufe.
In the present case let us apply this
principle of graphic representation to
the data regarding the expectation of
Ufe of white males in the original
registration states at age 77. The
resulting diagram is shown as Figure 1.
The persons aged 77 in 1901 were
born in 1824, so the uppermost or 1901
Une starts from the base (0 age) at the
date 1824. Those aged 77 in 1910
/OO
90
80.
70
60
kl
yj 50
30
ZO
10
iVHITE MALES
1820 30
70 80
DATE
Fig. 1. Showing the expectation of hfe of white males in the original registration states
reaching the age 77 in the years 1901, 1910, and 1919-1920. The dotted Hnes are the expecta-
tions of life and the soUd lines the years hved prior to attaining age 77. For further explanation
see text
30
NATURAL HISTORY
were born in 1833, and the second or
1910 line starts from age on that date.
Now if a perpendicular be erected from
1842-1843 to cut the 1901 and 1910 hfe
Hues, and another perpendicular be
dropped from the 1901 line to cut the
base at that date, a parallelogram will
be included by these two perpendiculars
and the 1901 and 1919-1920 life hues.
This parallelogram is crosshatched in
Fig. 1. This shaded parallelogram
defines the overlapping portions of the
lives of persons in the three cohorts
under discussion. During the 58.5
years from 1842-1843 to 1901 all of the
persons in these three cohorts were
alive together. Whatever environmen-
tal stresses, whatever improvements
in sanitation, whatever discoveries in
medicine, acted upon the men in one
of these cohorts, acted also during this
period of nearly 60 years upon those in
the other two cohorts. But this
period is a major portion of their whole
lives. If it were true, as it may well be,
that improved environment, better
sanitation, better preventive medical
service aj'e just as effective in reducing
mortality rates at the upper end of life
as they are at the lower end, one would
not expect to see from them any but a
slight effect in cohorts not more than
20 years apart at birth. Too great a
portion of the whole life of Ijoth cohorts
would have been spent under the same
environmental conditions.
Summari'/,ed the situation is this :
The evidence available does not indi-
cate that any increase is occurring now,
or has occurred in the recorded expec-
tation of life of persons who live to the
age of 75 or more. Still less is there any
evidence that the biological upper
hmit of the human life span has been
raised. Whether in the future, as a
result of what is being done now in
public health and preventive medicine,
the expectation of life at advanced ages
will be raised, is a question impossible
of answer at the present time. But
in the meantime the expectation of
life at birth, or the mean duration
of life, has been and is being notably
increased.
Above the sea of clouds in the Sierra Nevada de Santa Marta, Colombia, the land of
the Arhuaco Indians
Coast and Crest in Colombia'
AN EXAMPLE OF CONTRAST IN AMERICAN INDIAN CULTURE
By J. ALDEN MASON
Curator of the American Section, University Museum, University of Pennsylvania
TO the ordinary layman reader the
term "Indian" calls to mind a
vision of a tall, high-cheeked,
red-skinned man, decorated with feath-
ers and gaudy beads, taciturn in dis-
position, his character a curious melange
of nobility and treachery. The Scot
ma}^ differ radically from the Welsh-
man, the German have little in common
with the Frenchman, but the Indian is
still an Indian, whether he till his
patches of sun-burnt corn on the arid
flats of Arizona or spear fish by the
humid marge of a lethargic Brazilian
river. Even those persons of wider
reading who recognize the great varia-
tions in physique, in psychology, in
language, and in culture, which obtain
among the many hundreds of tribes
and nations of American Indians, sel-
dom realize the full extent of these
differences or how sharp the division
'Photographs taken by the author while on an expedition
between groups which may be close
neighbors.
Differences in language, in physical
type, in religion, social organization,
and similar respects, more or less
transcend the boundaries of geographi-
cal and ecological areas, but differences
in material culture are to a large
extent dependent on the natural en-
vironment upon which the tribe must
subsist and to which it must adapt
itself. In the United States, variations
in these environmental conditions,
though great, are never sudden and
abrupt, with the result that the
boundaries of material culture areas
are never sharp-cut and variations
from group to group are slight. In
other parts of America, however, and
especially in western South America,
abrupt changes in altitude produce
natural environmental areas of the
to Colombia for the Field Museum of Natural History.
31
32
NATURAL HISTORY
greatest divergence within the space
of relatively few miles, and these in
turn have produced, or at any rate
support, native populations of widely
different character.
Such a region of diverse natural
environmental conditions is found on
the northern or Caribbean coast of
Colombia between the Magdalena
River and the Lake of Maracaibo.
Here is a little-known and seldom-
visited region, dominated by the little
seaport of Santa Marta, the oldest city
on the South American mainland,
which last year celebrated its four-
hundredth anniversary, having been
founded in 1525. For the first few
years of its history it enjoyed a slight
meed of prosperity as the seaport of
Colombia, from which sailed the galleons
laden with the treasures of the land of
El Dorado to enrich the insatiable
coffers of Castile and Leon, if perad-
venture they escaped the even greedier
clutches of the Enghsh gentlemen-
pirates of the Spanish Main. Then it
lapsed into centuries of somnolence
from which it is only just awakening
bj'' virtue of the new golden harvest,
the banana, which today leaves its
portals in the immaculate steamers of
the United Fruit Company. Behind
Santa Marta the majestic mountains
of the Sierra Nevada, whose summits
have never known the foot of man, rear
their peaks to heights of eternal snow.
In the cool valleys near the foot of the
chill treeless -paramo dwells a nation,
or group of tribes, of peaceful, seden-
tary, inoffensive Indians, practically
untouched by civiHzation, the Arhua-
cos. Occasionally, to carry down the
blocks of brown sugar or panela
which they trade for steel implements
and other civilized products, a few of
them descend to the hot seacoast at
Dibulla, a little settlement largely
inhabited by negroes. Here they may
meet a few members of another abso-
lutely different Indian nation, also
wanderers from their native heath, the
Goajiros. But they avoid each other
like lepers, pass with averted eyes on
opposite sides of the street, and ignore
each other's presence. The Arhuaco
fears the reputed ferocity and physical
strength of the Goajiro and the latter
dreads the magical power and "strong
medicine" imputed to the Arhuaco.
Though their territories impinge so
closely, it is difficult to imagine two
beings of the same race more different
in all respects.
Approximately one hundred miles
east of Santa Marta one comes to the
open roadstead of Rio Hacha, the
seaport for the Goajira Peninsula which
extends a hundred miles farther east.
Here the lofty wooded mountains have
disappeared with their humid verdure,
and instead the peninsula is low, arid
and torrid. In place of the majestic
caracoli, mahogany, and other tropical
trees, cacti, and thorny bush cover the
ground. Herds of stock, — cattle, sheep,
goats and horses, — browse on the
scanty vegetation, and their hides,
together with the divi-divi, brazilete, and
logwood which are gathered by the
Indians, form the principal exports of
Rio Hacha.
In 1922 and 1923 I spent upward of
a year in the region of Santa Marta for
the principal purpose of pursuing
archaeological investigations for the
Field Museum of Natural History of
Chicago, with which I was then con-
nected and to which I am indebted for
the use of the notes and photographs
herein used. During this time I was
enabled to spend several months with
the Arhuacos and to make a short visit
to the Goajiros.
As examples of diverse and contrasted
COAST AND CREST IN COLOMBIA
33
cult iircs a sliglil ly more detailed exposi-
liou of the life of tlu>S(> two uei^hhoi-iiiji;
tribes may perhaps he of interest.
The Arhiiaeos are an undersized
folk, the men averaging little more
than five feet in height, and the
effect given by this shortness is intensi-
fied by their childlike natures. Bash-
ful, reticent, suspicious of all strangers,
only in wrest lino; ^tiid liair-piilliii<.',;. ^^Ijq
women are especially hashful and arc
seldom in evidence^.
Living as they do in the rustncssos of
the mountains, separated from the
civilized settlements on the coast by
great stretches of virgin forest, they are
unbelievably ignorant of modern busi-
ness and are exploited in a pitiful
A group of Arhuaco Indians in a neighboring "civilized'' village. Their slight stature
is striking in comparison with a tall negro. A woman stands at the right
especially civilized persons, the un-
announced visitor is nearly certain to
find their villages suddenly abandoned
at his approach. But he who, like
ourselves, comes accompanied by their
friends and preceded by a good repute,
finds them friendly and affable. Never
boisterous and seldom demonstrative,
quietness seems to be the keynote of
their natures. Onh^ under the influence
of their home-brewed chicha, made of
cane syrup, or the stronger imported
rum, do they expand, and even then the
usual effect is a maudlin lugubriousness,
and the rare disagreements result
fashion by the few civilizados who
live on the outskirts of their country
and trade them machetes and other
needed modern tools in return for
loads of jyanela, the blocks of unrefined
sugar which are their sole object of
export. Money is nearly unknown to
them and they accept it in pay for
services and products only on the
advice and instructions of the village
head, always a man who has had some
dealings with civilization and who does
his best to protect his charges from
exploitation. Any offer of pay is
referred to him who passes upon the
34
NATL'h'AL HISTORY
fairness of the offer and the vahie of the
proffered coin. "A\'e do not Hke youi'
practice of trade," said one Indian.
"We prefer that you should make nie a
gift, and then I will counter by making
you one." It was a most difficult
matter to secure any specimens fi-om
them. Never once was an article
voluntarily offered for sale or barter
and only by dint of continued pleading
was a small representative collection of
their goods secured !)y listing desired
objects and soliciting the aid of the
village heads in obtaining them.
Dressed in long tunics which fall to
the knees, under which are worn loose
baggy trousers — the latter probably a
civilized adaptation, — with their long
unkempt hair falling over their should-
ers and frequently with rather thick
beards, the men present a patriarchal
appearance such as the imagination
ascribes to the Judean shepherds of old.
These garments are made of cotton
grown, spun, and woven by the men,
rather heavy and frequently decorated
with violet stripes. But they are gener-
ally frayed, worn, and dirty, and the
ensemble is unkempt, notwithstanding
the fact that the people bathe frequent-
ly in the cold mountain streams. The
women wear blouses, generally with
one arm bare, and short skirts of the
same cotton fabric. Their sole orna-
ments are necklaces which are largely
composed of the beads of roseate
carnelian found in the graves of the
ancient Taironas near the coast. Thej^
fear to molest these graves themselves,
but eagerly purchase from local treas-
ure-hunters beads of second quality,
those without high polish known as
muertos, being unable to compete
with the wealthier Goajiros for the
polished beads known as livns.
While the men spin and wxave the
cloth worn by both sexes, the women
knit the l)ags carried by the men.
Every man or boy bears one or more
of these knitted bags in which he
carries his flint and steel for making
fire, — the modern substitute for the
ancient fii'c-making sticks, — his poporo
and icmii, and his coca leaves. The
poporo is the ubiquitous companion
and constant solace of every man, and
its acquisition marks the boy's attain-
ment of man's status. It is a pear-
shaped gourd in which he carries the
powdered lime obtained by burning
shells and which is mixed with the coca
leaves for chewing. This chewing of
coca leaves is one of the characteristics
which connect the Arhuacos with the
people of the highlands of southern
Colombia, Ecuador, and Peru, where
the custom has persisted since time im-
memorial, as is attested by the finds of
dried coca leaves and gourds of lime in
the ancient graves. This coca, Ery-
throxylon coca, is the plant from which
our medicinal cocaine is obtained, and
the chewing of its leaves has, in a minor
degree, the same anaesthetic effect as
the administration of cocaine; it
deadens the sensibilities to hunger,
fatigue, and pain and enables the hard-
ships of primitive life to be better
endured. His tin}^ plantation of coca
is a man's most valued possession;
the failure of his crops or the burning
of his house he can endure with resigna-
tion and fortitude, but the destruction
of his hayal is a calamity of catastrophic
magnitude. Such is the insatiable
demand for the leaves that the plants
are never allowed to reach a state of
efficient production, but the leaves of
immatui-e size are gathered by the