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Ancestral traits parental populations and hybrids.

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Ancestral Traits, Parental Populations, and Hybrids '
WILLIAM S. POLLITZER
Department of Anatomy, Department of Anthropology, Genetics Training
Committee, and Carolina Population Center, University of N o r t h Carolina,
Chapel Hill,N o r t h Carolina
The distance traveled over the centuries by any human population is
ABSTRACT
a rocky road; the fusion of the paths of two meandering populations often leads to
a n even rougher one. Tracing such a wayward child of history back to its long-lost
parents presents complex problems for the physical anthropologist. For those parents
may share unequally in their legacy to their offspring a t the start of the journey.
Many genes may disappear into the gutters of genctic drift; some byways may stop
at the barricades of selection; fresh migrants may join by side roads to swell the stream;
and inbreeding may narrow the roadbed.
Searching for the genes that the hybrid population holds in common with alleged
parents provides one clue to the relative role of the ancestors. Comparison of measurements of the living hybrid with the nearest known relatives of the presumed parents
yields another clue. Resuscitation of ancestors from their bones and teeth supplies
yet another link. Distinctive features of such skeletal remains are most valuable
where their inheritance is understood. Bones may yield another clue from substances
left within them of known genetic control. And finally all the evidence of history,
every glimpse caught of the population along the route, gives knowledge of the contribution of the forebears to the living people. The ideal estimate will utilize a wide
variety of information about the known groups.
While the most primitive of human societies have recognized the vast distinction
between themselves and their neighbors, it
is only in recent times that sophisticated
scientists have sought to measure the precise degree of difference between two or
more populations and the probable contribution of parental peoples to hybrids.
Increasing technological skill adds to the
procedures available to the anthropologist
who indulges in this endeavor.
Materials available from extinct people
are bones and teeth, which can be measured in considerable detail for comparison
with similar remains of other populations.
Distinctive and unusual traits such as
Carabelli's cusps noted among them provide clues to affinity. Where inherited disease, such as sickle cell anemia, leaves its
tell-tale stamp on a skull table, x-ray may
aid the eye in suggesting classification in
the past. Where bones from a larger number of persons, identifiable as individuals,
are available, ABO typing by inhibition
methods should at least provide supplementary data. First performed by Candela
('39) and by Boyd ('39), and rightly questioned by others (Thieme and Otten, '57),
these tests for blood group substances in
ancient bones were greatly advanced by the
AM. J.
PHYS.
ANTHROP.,30: 41-20.
work of Gray ('58) who controlled bacterial contamination. We have been able
to show that the bacteria cultured from
excavated ancient bones are not for the
most part the ones known to have a significant amount of A, B, and 0 substance. The
further chemical purification of the material from cancellous bones holds promise
for future identification. In our study of
the Catawba Indians (Pollitzer, '67) we
were able to relate the present remnant
of these Siouan people to similar populations of the Carolinas some 400 years earlier, and even to the Shell Mound people
of Indian Knoll of 3000 to 5000 B.C., using
primarily cranial measurements. Krogman ('62) has contributed methods for
correcting from skeletal measurements to
measurements on the living. The typing
of remains of 16th century people of the
Yadkin River as 24 Group 0 and 2 Group
A, while in line with living Indians of the
area, is far too small a sample for significance.
As bones of the past and their interpretation will be skillfully examined in subsequent talks on this symposium, I may be
forgiven this mere skeleton outline of the
1 Dedicated to m y mother in memory of m y father,
Dr. R. M. Pollitzer (1883-1969).
415
416
WILLIAM S. POLLITZER
topic as I hasten to flesh out a consideration of the living.
Since the days of Karl Pearson, methods have been sought to estimate “racial
likeness” from physical traits. Guha advanced such methods through his study of
the peoples of India (’31). Mahalanobis
and his colleagues (’49) contributed D2 as
a measure of “distance,” i.e., dissimilarity
between populations. Employing the correlation between traits as well as the difference between traits in the populations,
he analyzed the people of India for their
relative “distance.” One inherent shortcoming of the Da procedure is the increase
of distance with each trait added. We are
beset, too, by the choice of traits: Is total
morphological face height a preferable
parameter to upper face height? Is bizygomatic better than bigonial width? We must
be careful to study only those who have
reached maturity for growth alters these
relationships, and not necessarily at the
same rate in all people. We should calculate a different distance for males and for
females, a procedure which can result in
estimating that the men of tribe A are
closely related to the men of tribe B, while
their women are (perhaps understandably)
more “distant.” Basically such measures
as Dzrest upon likeness, whether of genetic
Rature or not. Since morphologic traits
are governed by several genes, it is possible for the same phenotype to be expressed
by quite different gene combinations. And
the same genotype in different environments may be phenotypically different. If
we choose those traits most unlike in the
populations to be compared, we have a
greater chance of finding homozygosity at
the loci involved. Under an additive genetic
model similar phenotypes for a given trait
in a hybrid between the two will indicate
the same proportion of genes for that trait
even if the underlying genotype varies.
Genetic drift is less likely to alter these
morphologic traits due to the coadaptation
of the genes underlying them. Where
great passage of time and distance are involved selection may also operate to obscure the fundamental kinship between
populations.
While the use of such monogenic traits
as the blood types do not suffer from the
same defects they have their problems, too.
By the use of ABO genes alone one can
prove that the Eskimos are “blood brothers”
to the Bantu tribes of Africa. By the use of
Rh positive and negative alone, a hybrid
population of an equal mixture of Chinese
and Englishmen appear identical to American Negroes. These single gene traits are
subject to genetic drift, especially where
the bottlenecks of history have reduced a
flourishing river of people to a thin stream.
And the alterations due to selection, such
as disease associations, are only now coming to be considered if their cause is not
as yet defined and evaluated. But with the
large number of loci made available
through modern technology, it is now possible not only to calculate the similarity
between two related populations, but to
compare the answer to this problem given
by each genetic system.
The contribution of one population to
another to form a hybrid provides a relatively simple model of gene flow, successi d l y used by Glass and Li ( ’ 5 3 ) to calculate admixture of Africans and Europeans
in the formation of the American Negro
and even to calculate the rate of admixture.
Roberts and Hiorns ( ’ 6 2 ) devised a least
squares method of greater general applicability in the dynamics of racial intermixture, providing for more than two parental
populations. They eliminate one allele
from each system, and the estimate obtained depends on which is eliminated.
Krieger et al. (’65) proposed a maximum
likelihood solution to the problem using
a modcl that actual data do not fit. Elston
in as yet unpublished work has devised an
improved least squares estimate and suggested changes in the maximum likelihood
estimate, utilizing all alleles of each genetic system.
In all calculations of the relative contribution of parental to hybrid populations,
mere similarity does not prove descent,
and the supportive evidence of history is
needed to prove derivation, while language
and culture may provide additional clues.
With the population as with the individual
i t is a wise child who knows his own father.
Let us now turn to certain populations
of the United States Southeast and explore
their composition.
The Melungeons are a people of uncertain origin, distinctive features, and tawny
ANCESTORS AND HYBRIDS
coloration who have long inhabited the
crests of the Appalachian mountains in
western Virginia and eastern Tennessee.
The source of the name is in dispute; it
has been attributed to French “melange”
for “mixed,” to Portuguese “melungo” for
“shipmate,” to Greek “melan” for “colored,”
and to a possible corruption of two surnames common in the isolate. The earliest
writings viewed the Melungeons as a whiteIndian-Negro mixture, and Dromgoole
(1891) believed there were Cherokee Indian, African Negro, English, and Portuguese elements in the population, each of
which was indicated by distinctive surnames. The people themselves have long
iavored the idea of Portuguese ancestry.
In his thorough demographic study Price
(’51) noted an aggregation of about 1,000
in Hancock County, Tennessee, 500 in adjacent Lee County, Virginia, and smaller
pockets in the neighboring highlands. From
careful study of the census he concluded
that the nucleus of the Melungeons were
“free persons of color” who had migrated
from North Carolina in the last decade of
the eighteenth century. Today the isolate
has contracted through out-migration, and
new elements have joined it through
marriage.
In our survey of 177 persons studied in
1965-1966, 128 were adults and 49 were
children. Of birthplace recorded for 125
adults, 118 were born within Hancock and
Lee counties. Blood samples were obtained
on young and old, and physical measurements on the adults. Skin color determinations by reflectometry bore out the wellknown tendency of women to average
slightly lighter than men, and older people
were lighter than younger. In general morphology, hair form and pigmentation, they
resemble whites more closely than Indian
or Negro groups. Striking among blood type
findings is the 50% incidence of Group A,
half of which have the A, gene. The M
gene is almost twice as coinmon as N.
Phenotypes with Rh, comprise over half
the sample; and Rho, like Hgb. S, is absent.
Haptoglobin 2-2 patterns are more than
twice as frequent as 1-1. Using ABQ, M-N,
Rh, Hgb., and Hp. loci it is possible to test
several hypotheses of probable parental
populations and their contribution to the
hybrid. If we consider English, Portuguese,
417
Negro, and Indian gene frequencies we
find that all methods agree that Portuguese
is the more likely of the two European ancestors, contributing the majority of the
genes with the remainder contributed more
by Indian than Negro. The data are best
fitted by a 90% Portuguese component,
with some Indian and Negro admixture.
If we assume Portuguese are the only European component and there is no Negro
component, the Portuguese contribute 94%
of the genes, and the Indians account for
the remaining 6 % . If we assume that
English was the only European component,
they account for 94% of the genes of the
hybrid and the remainder can be explained
by Negro admixture or by Negro and Indian admixture.
Although these computations agree that
European ancestry predominates, and that
Portuguese is one likely origin of the
European genes, they suggest even more
forcibly that with several possible parental
populations, different answers are equally
likely. When we reflect that only a few
individuals from any of these populations
entered into the isolate initially our estimates become more suspect. (While we
say “triracial” no three individuals mate;
in the language of the statistician we not
only lack the “means” but such a practice
would constitute more than a “standard
deviation.”) Physical appearance, history,
and census reports combine with genetic
studies to suggest that the Melungeons are
probably derived primarily from a European people, possibly Portuguese but
equally other ethnic groups as well, plus
some Indian and (perhaps) Negro strains.
Let us next turn our attention to the
Seminole Indians of Florida. Numbering
a thousand, they cluster in three reservations: Dania, just north of Miami; Big
Cypress, on the edge of the Everglades;
and Brighton, on the northwestern rim of
Lake Okeechobee. Disease, warfare and
slaving raids virtually destroyed the native
Indian population of Florida by 1715, a
void slowly filled primarily by Creeks from
Georgia. One group of Muskogean speakers, derived from the Lower Creek tribe,
the Oconee, settled at Alachua, near present Gainesville, in north central Florida in
1750; they formed the nucleus of the Cow
Creek Indians, who later settled in the
418
WILLIAM S. POLLITZER
Brighton area and speak what is now
known as the Seminole language. A second group, speaking the Hitchiti dialect,
settled at Appalachee around Lake Miccosuke near Tallahassee, in northwestern
Florida; and subsequently peopled the Big
Cypress community, where they still speak
the distinctive but related Mikasuki language, The population of the Seminoles of
Florida has varied widely from a peak of
5,000 in the 1820's, 500 in 1853, to 208 in
1884, and back up to 590 in 1930 and a
thousand today, MacCauley in his report
of 1884 describes the men as dark, coppercolored, tall, with square faces; the women
as under average height and shapely; he
reports with evidently equal favor that
their health was good, that education was
stoutly resisted, and that Christian missionaries had had little influence on their
religion.
We were able to obtain blood samples
and pedigree information on 416 Seminoles six years and over on their three reservations, and measurements on the adults.
In shape and appearance they resemble
other living Indian tribes. They are somewhat shorter, more round-headed, roundfaced and wider-nosed than the full-blood
Sioux of the plains. In two-thirds, hair is
straight and in three-fourths it is deep
black. Females are shorter, lighter, and
more long-headed than males, and show
a curious tendency toward marked obesity
in the lower half of the body beginning
in their early 30's. In blood factors the
Seminoles are very similar to the Cherokee
Indian full-bloods.
In their general morphology, the Indians
of Big Cypress are distinctive from those
of Brighton, in keeping with their history.
While the sickle cell trait and Diego occur
only in Big Cypress the differentiation of
the peoples of this reservation from those
of Brighton and Dania is not as clear cut
for monogenic traits as it is for the polygenic ones. This probable operation of
genetic drift is also indicated when blood
factors in those under 2 1 are compared
with those 2 1 and over. The younger
people show no Group B, 5 cases of Ns,
and 3 of rh negative, while the older
people show three instances of Group B
and none of Ns or rh negative.
Computations based on genetic loci in
Seminoles and parental populations show
the very high Indian component, but they
also reflect variations on the three reserv a tions.
These studies remind us of the pitfalls
as well as the possibilities in estimating
the genetic contribution of parental groups
to hybrid population. Due to the fundamental theoretical difference between a
morphological estimate like Da and one
based on gene frequencies, any combination of the two remains difficult and arbitrary. When we know more about the
role of selection on both kinds of traits,
when we have information on the genic
foundations of the morphology, and when
we use a large battery of measurements on
a large number of people, we shall be able
to make the wisest estimates. Even so, we
would do well to check all available historical and archeological data for the continuity of the populations over the span OP
space and time.
In conclusion, I want to thank all those
who made the migration here today. While
I may not have produced any mutation in
your thinking, I hope I have made such a
wise selection of materials that all of you
have been able to follow my genetic drift.
ACKNOWLEDGMENTS
I am deeply indebted to Dr. D. F. Roberts
at Newcastle-on-Tyne, and to Dr. Robert
Elston at the University of North Carolina
for their development of methods and their
calculations of parental contribution to hybrid populations. I am also grateful for
the help in blood typing given by Dr. Jerry
Niswander and Mr. Chad Leyshon at the
National Institutes of Health, and for the
determination of serum proteins and red
cell enzymes made by Dr. Don Rucknagel
and Dr. Richard Tashian and Dr. Lowell
Weitkamp at the University of Michigan.
I am particularly appreciative of the assistance given by colleagues at Chapel Hill:
Mr. W. H. Brown, Mrs. Lois Tillman and
Mrs. Mikki Austin for collecting blood samples; Dr. David Phelps (now at the University of Florida) and Miss Margot Hall
for the work on the blood typing of bone:
Dr. Tom Donnelly and Mrs. K. Namboodiri
for analysis of data; Miss Cassi Parrish
and Mrs. R. M. Bock (now at the Univer-
ANCESTORS AND HYBRIDS
sity of Chicago) for construction of pedigrees. I am happy to thank Dr. W. F.
Hill in Florida and Dr. Truett Pierce in
Tennessee for obtaining the cooperation
of the subjects, and, finally, to thank the
subjects themselves.
These studies have indeed been “group
research,” and I am well aware of the
criticism that group research is founded
on the theory that if one makes nine
women pregnant he can produce a baby in
one month. I can only reply that it has
been fun trying.
These studies have been supported by
grant GM-10601 from NIH and by funds
from the United Medic21 Foundation of
North Carolina.
LITERATURE CITED
Boyd, L. T., and W. C. Boyd 1939 Blood group
ing reactions of preserved bone and muscle.
Am. J. Phys. Anthrop., 25: 421-434.
Candela, P. B. 1939 Blood tests on stains,
mummified tissue and cancellous bone. Am.
J. Phys. Anthrop., 25: 187-214.
Dromgoole, W. A. 1891 The Malungeons. The
Arena, 3: 470-479.
Elston, R. C. Personal Communication.
Glass, 13. B., and C. C. Li 1953 The dynamics
of racial intermixture - a n analysis based on
the American Negro. Am. J. Hum. Genet., 5 :
1-20.
419
Gray, M. 1958 A method for reducing nonspecific reactions i n the typing of human skeletal material. Am. J. Phys. Anthrop., 16: 135139 and Personal Communication.
Guha, B. S. 1931 Census of India, V. 1, part
I11 A.
Krieger, H., N. E. Morton, M. P. Mi, Eliane
Azevedo, A. Freire-Maia and N. Yasuda 1965
Racial admixture i n Northeastern Brazil. Annals Human Genetics, 29: 113-125.
Krogman, W. M. 1962 The human skeleton in
forensic medicine. Charles C Thomas, Springfield.
IXacCauley, Clay 1884 The Seminole Indians
of Florida. Bureau of American Ethnology.
Annual Report.
Mahalanobis, P. C., D. N. Majumdar and C. R.
Rao 1949 Anthropometric survey of the
United Provinces, 1941: A statistical study.
Sankya, 9: 89-324.
Pearson, K. 1926 On the co-efficient of racial
likeness. Biometrika, XVIII: 106-117.
Pollitzer, W. S., D. S. Phelps, R. E. Waggoner
and W. C. Leyshon 1967 Catawba Indians:
morphology, genetics, and history. Am. J.
Phys. Anthrop., 26: 5-14.
Price, E. T. 1951 The Melungeons: a mixedblood strain of the southern Appalachians.
Geographical Review, 41 : 256-271.
Roberts, D. F., and R. W. Hiorns 1962 The dynamics of racial intermixture. Am. J. Hum.
Genet., 14. 261-277.
Thieme, F. P., and C. M. Otten 1957 The unreliability of typing aged bonc. Am. J. Phys.
Anthrop., 15: 387-398.
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