Mixed Race Studies

Scholarly perspectives on the mixed race experience.

When two proximate species of mankind, two races bearing a general resemblance to each other in type, are bred together—e.g.. Teutons, Celts, Pelasgians, Iberians, or Jews—they produce offspring perfectly prolific: although, even here, their, peculiarities cannot become so entirely fused into a homogeneous mass as to obliterate the original types of either. One or the other of these types will “crop-out,” from time to time, more or less apparently in their progeny. When, on the other hand, species the most widely separated, such as the Anglo-Saxon with the Negro, are crossed, a different result has course. Their mulatto offspring, if still prolific, are but partially so; and acquire an inherent tendency to run out, and become eventually extinct when kept apart from the parent stocks. This opinion is now becoming general among observers in our slave States; and it is very strongly insisted upon by M. Jacquinot. This skillful naturalist (unread in cis-Atlantic literature) claims the discovery as original with himself; although erroneously, because it had long previously been advocated by Estwick and Long, the historians of Jamaica; by Dr. Caldwell; by Professors Dickson and Holbrook, of Charleston, S. C.; and by numerous other leading medical men of our Southern States. There are some 4,000,000 of Negroes in the United States; about whom circumstances, personal and professional, have afforded me ample opportunities for observation. I have found it impossible, nevertheless, to collect such statistics as would be satisfactory to others on this point; and the difficulty arises solely from the want of chastity among mulatto women, which is so notorious as to be proverbial. Although often married to hybrid males of their own color, their children are begotten as frequently by white or other men, as by their husbands. For many years, in my daily professional visits, I have been in the habit of meeting with mulatto women, either free or slaves; and, never omitting an opportunity of inquiry with regard to their prolificacy, longevity of offspring, color of parents, age, &c., the conviction has become indelibly fixed in my mind that the positions laid down in the beginning of this chapter are true.

J. C. Nott, “Hybridity of Animals, Viewed in Connection with Mankind,” in Types of Mankind: or, Ethnological Researches, Based Upon the Ancient Monuments, Paintings, Sculptures, and Crania or Races and Upon their Natural, Geographical, Philological and Biblical History [Second Edition], J. C. Nott and Geo. R. Gliddon, (Philadelphia: Lippincott, Grambo & Co., 1854), 397-398.

The Great Migration and African-American Genomic Diversity

Posted in Articles, Census/Demographics, Health/Medicine/Genetics, History, Media Archive, Slavery, United States on 2016-05-29 14:29Z by Steven

The Great Migration and African-American Genomic Diversity

PLOS Genetics
2016-05-27
27 pages
DOI: 10.1371/journal.pgen.1006059

Soheil Baharian
Department of Human Genetics
McGill University, Montreal, Quebec, Canada
Genome Quebec Innovation Centre, Montreal, Quebec, Canada

Maxime Barakatt
McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada

Christopher R. Gignoux
Department of Genetics
Stanford University School of Medicine, Stanford, California

Suyash Shringarpure
Department of Genetics
Stanford University School of Medicine, Stanford, California

Jacob Errington
Department of Human Genetics
McGill University, Montreal, Quebec, Canada
Genome Quebec Innovation Centre, Montreal, Quebec, Canada

William J. Blot
Division of Epidemiology
Vanderbilt University School of Medicine, Nashville, Tennessee
International Epidemiology Institute, Rockville, Maryland

Carlos D. Bustamante
Department of Genetics
Stanford University School of Medicine, Stanford, California

Eimear E. Kenny
Department of Genetics and Genomic Sciences
The Icahn School of Medicine at Mount Sinai, New York, New York

Scott M. Williams
Department of Genetics
Institute for Quantitative Biomedical Sciences, Dartmouth College, Hanover, New Hampshire

Melinda C. Aldrich
Division of Epidemiology, Department of Thoracic Surgery
Vanderbilt University School of Medicine, Nashville, Tennessee

Simon Gravel
Department of Human Genetics
McGill University, Montreal, Quebec, Canada
Genome Quebec Innovation Centre, Montreal, Quebec, Canada

Fig 3. Pairwise genetic relatedness across US census regions among (A) African-Americans, (B) European-Americans, and (C) African-Americans and European-Americans. (D) Census-based prediction for African-Americans (see Materials and Methods). On each map, the line connecting two regions shows the average relatedness between individuals in those regions, and the thickness and opacity of the lines are on a linear scale between the minimum and maximum values shown above the map. Relatedness between regions with fewer than 10,000 possible pairs of individuals is not shown (see Materials and Methods for details). All numbers are in units of cM. (E) Decay of average IBD (shown in logarithmic scale) as a function of distance using IBD segments of length 18cM or longer from HRS (dots), compared to the analytical model (lines).

Abstract

We present a comprehensive assessment of genomic diversity in the African-American population by studying three genotyped cohorts comprising 3,726 African-Americans from across the United States that provide a representative description of the population across all US states and socioeconomic status. An estimated 82.1% of ancestors to African-Americans lived in Africa prior to the advent of transatlantic travel, 16.7% in Europe, and 1.2% in the Americas, with increased African ancestry in the southern United States compared to the North and West. Combining demographic models of ancestry and those of relatedness suggests that admixture occurred predominantly in the South prior to the Civil War and that ancestry-biased migration is responsible for regional differences in ancestry. We find that recent migrations also caused a strong increase in genetic relatedness among geographically distant African-Americans. Long-range relatedness among African-Americans and between African-Americans and European-Americans thus track north- and west-bound migration routes followed during the Great Migration of the twentieth century. By contrast, short-range relatedness patterns suggest comparable mobility of ∼15–16km per generation for African-Americans and European-Americans, as estimated using a novel analytical model of isolation-by-distance.

Author Summary

Genetic studies of African-Americans identify functional variants, elucidate historical and genealogical mysteries, and reveal basic biology. However, African-Americans have been under-represented in genetic studies, and relatively little is known about nation-wide patterns of genomic diversity in the population. Here, we study African-American genomic diversity using genotype data from nationally and regionally representative cohorts. Access to these unique cohorts allows us to clarify the role of population structure, admixture, and recent massive migrations in shaping African-American genomic diversity and sheds new light on the genetic history of this population.

Read the entire article here.

Tags: Carlos Bustamante, Carlos D. Bustamante, Christopher Gignoux, Christopher R. Gignoux, Eimear E. Kenny, Eimear Kenny, Jacob Errington, Maxime Barakatt, Melinda Aldrich, Melinda C. Aldrich., PLOS, PLOS Genetics, Public Library of Science, Scott M. Williams, Scott Williams, Simon Gravel, Soheil Baharian, Suyash Shringarpure, William Blot, William J. Blot

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