NEWMAN, HORATIO HACKETT

(b. Near Seale, Alabama, 19 March 1875; d. Clearwater, Florida, 29 August 1957)

genetics.

Newman was the first of four children born to Albert Henry Newman, a distinguished professor of theology, and Mary Augusta Ware Newman. He grew up in a highly literate, middle-class household. When Newman was six, the family moved to Toronto, where his father became professor of church history at Toronto Baptist College (now McMaster University, in Hamilton, Ontario). Newman’s mother was active in the Baptist church and in missionary work. Despite his strong Baptist upbringing, Newman’s scientific work shows no religious influence—for instance, he soundly rejected vitalism.

Newman received a B.A. from Toronto Baptist College in 1896 and was a special student at the University of Toronto for one year before teaching biology and Latin at Des Moines College for one year (1897–1989). He entered the University of Chicago in 1898 and received a Ph.D. In Zoology in 1905, having taken off four years to teach biology and chemistry at Culver Military Academy in Indiana (1900–1904). After teaching at the University of Michigan (1905–1908) and heading the department of zoology at the University of Texas (1908–1911), Newman was appointed associate professor of zoology and embryology at the University of Chicago in 1911 and professor of zoology in 1917. With Frank R. Lillie and Charles M. Child, he was responsible for raising the zoology department at Chicago to the first rank. Following his retirement in 1940, he ceased active research and divided his time between Clearwater, Florida, and Go Home Lake on Georgian Bay, Ontario.

Newman married Isobel Currie Marshall in 1907; they had a daughter and a son. Following the death of his wife, he married Marie E. Heald on 5 June 1954. A robust man, he prided himself on his athletic prowess and remained physically active until his final illness.

While at Toronto Baptist College, Newman received honors in the classics but primarily studied natural science, writing a series of entomological sketches for the college magazine. He worked under Charles O. Whitman, William M. Wheeler, and Lillie at Chicago. He was most influenced by Whitman, and throughout his professional life continued to advocate the latter’s views supporting orthogenesis and de Vriesian mutation as the mechanism of the origin of species.

Newman’s dissertation was on the meaning of variations in the armor of Chelydridae, the land tortoise. He viewed the supernumerary scutes that always occurred in the same locations as reversions to ancestral conditions, examples of systematic atavism in the sense of Hugo de Vries. In focusing on how the number of scutes had been reduced over the evolutionary development of the most generalized family of land tortoises, he hoped to throw some light on the phylogeny of Chelonia and arrive at the hypothetical ancestral type.

From 1907 to 1923 Newman used the nine-banded armadillo and teleost hybrids to probe the crucial questions puzzling embryologists at the turn of the century: What are the relative contributions of heredity and epigenesis to the character of the individual? What is the precise role of the spermatozoon in early embryonic development? What are the relative contributions of the maternal and paternal germ plasms?

Newman rejected Edwin G. Conklin’s theory that differentiation of the embryo is determined by the egg cytoplasm rather than by the nucleus. He found in 1910 that the developmental rhythm of the young embryo of a Fundulus hybrid was distinctly influenced by the spermatozoon as early as fourteen hours after fertilization. However, by 1914 he admitted that early cleavage was not controlled by the nucleus. He distinguished between heredity and embryonic development. In work on teleost hybrids Newman concluded that although foreign sperm may materially alter the rate of early development, they play no role in the heredity of the organism until embryonic differentiation is well under way.

In later hybridizing experiments on teleosts. Newman’s results did not support the hypothesis of Jacques Loeb that heterogenic hybrids are purely maternal in all their hereditary characters and that sperm only initiate development. Newman found unmistakable cases of paternal heredity even in suborder crosses. He maintained that the modes of inheritance in teleost hybrids support Mendelian particulate inheritance.

In 1909, while at the University of Texas, Newman made a fortunate choice of research animal when he chose to study the natural history of the ubiquitous Dasypus novemcinctus texanus, the nine-banded armadillo. When Newman and J. Thomas Patterson discovered that this armadillo species always bears quadruplets from a single zygote, Newman began to concentrate on a causal theory of twinning. Their findings comprised the first direct embryological evidence that one-egg twinning occurs among mammals. Newman and Patterson dissected hundreds of armadillo uteri, studying various stages of fetal development from the late cleavage stage, in which there were only eleven embryonic cells, to a fullterm armadillo egg. In later studies Newman confirmed that members of a litter are as closely similar to one another as are the right and left sides of a single individual.

Newman advanced his first theory of twinning in 1913. Although he would refine it over the next ten years, he consistently argued that twinning is only a variation of symmetrical division, like the development of the right and left sides of a single individual. He saw the whole process as quantitative.

The traditional view of twinning as advanced by William Bateson was that twins resulted from physiological isolation of the two-cell stage of cleavage. Newman argued that twinning could occur at varying stages of embryonic development. In armadillos twinning does not occur until three weeks after ovulation, when gastrulation is complete. This three-week period of inhibited growth disorganizes the integrational relations of the embryo, Newman wrote in 1923, weakening the polarity of the egg so that all parts of the embryo are left on parity.

Newman elaborated on his twinning theory in The Biology of Twins, an important book published in 1917 that focused attention on human twins and their possible uses as research materials. Not since Francis Galton compared the differences between monozygotic and dizygotic twins in 1875 had significant work been done on human twins. Newman’s work, along with a keen interest in engenics in the United States and western Europe, initiated a spate of nature-nurture studies during the period between the two world wars.

In The Physiology of Twinning (1923) Newman brought together for the first time all previously published data on one-egg twinning in the animal kingdom and noted that twinning is especially common in the vertebrates and echinoderms because early cleavage cells appear to be totipotent, that is, each cell is able, if isolated, to produce a whole new individual.

Newman’s primary interest from 1913 to 1940 was how to account for differences between genetically identical individuals. Because of this interest, Newman studied the inheritance of variation in armadillo armor. He assumed that the degree of difference among the quadruplets should indicate the potency of epigenetic factors, while degree of similarity would serve as a criterion for the relative strength of predeterminative factors. After analyzing the armors of nearly 200 sets of quadruplets and their mothers, Newman found that epigenetic disturbances effect alterations in the end result ranging from 2 to 8 percent. Although at first he attributed this inequality among quadruplets to some profound inaccuracy in mitosis during early cleavage, he later viewed all epigenetic effects as the results of asymmetry reversal.

Newman wrote extensively on the effects of asymmetry reversal in human identical twins. While studying armadillos he frequently noticed that an asymmetrical peculiarity inherited from the mother would appear on the left side of one twin, the right side of another, and sometimes on both sides of a third. In human twins, Newman noted similar in equalities: one twin was right-handed, the other left-handed ; one twin had a clockwise hair whorl, the other a counterclockwise whorl. He published several studies on the reversals in palm print, fingerprint, and toe print patterns in monozygotic twins. He explained these inequalities by noting that one twin had been derived from a partially differentiated left side, the other from a partially differentiated right side of a single embryo.

Newman studied twins with varying degrees of asymmetry reversals from identical identicals to conjoined twins who were significantly different in physiology, temperament, shape and size of head, height, and weight. He assumed that monozygotic twins are products of the division of a single bilateral embryo that, if not separated, would form the right and left sides of a single individual. The most similar monozygotic twins represented a separation very early in embryonic development, perhaps at the four- cell cleavage stage. By contrast, conjoined twins separated after gastrulation was complete and the two sides of the embryo had become asymmetrically differentiated.

Newman predicted that identical twins with many asymmetry reversals would show more intrapair differences in mental and physical characters than those with few asymmetry reversals. This was not borne out in studies of sixty-nine sets of identical twins. There was no greater degree of difference between twins with extensive asymmetry reversals than between more identical twins.

In 1926 Newman began an extensive study of fifty pairs of indentical twins and fifty pairs of fraternal twins reared together. Working with his University of Chicago colleagues Frank N. Freeman, a psychologist, and Karl J. Holzinger, a statistician, he examined tha physical characters and administered a battery of intelligence and personality tests. They extended the study to nineteen pairs of identical twins reared apart. Their results were published in Twins: A Study of Heredity and Environment (1937). They compared the physiological, mental, and personality differences of these pairs of twins, the first time such a study had been done. They concluded that identical twins reared together are more alike in physical dimensions, intelligence, and educational achievement than fraternal twins reared together, but not much more alike than fraternal twins in personality and temperament.

Newman wished to attribute all differences not only in physical characters but also in mental and personality traits in identical twins reared together to prenatal influences such as asymmetry reversals and unequal blood supply and nutrition to the two fetuses. Holzinger and Freeman, on the other hand, recognized that identical twins in the same family can have slightly different postnatal environments and that mutual association can actually cause them to exaggerate their differences.

In their study of monozygotic twins reared apart, the authors noted that differences in the twins correlated with differences in their environment. The closest correlation was between schooling and educational achievement, the next closest between schooling and intelligence. They concluded that environmental differences that are real and large have a marked effect and that differences in mental ability are brought about by different social environments. They did not find a correlation between environmental differences and personality differences, Personality traits offered the most contrast between identical twins reared apart. Individual interviews revealed even greater personality differences between them than did the tests. They concluded that some features of the personality are more modifiable by environment than are others. The authors were equivocal on the results of the overall study. They could offer no definite solution or simple formula on the nature -nurture problem and stated that what heredity can do, environment can do also.

This twin study is recognized as a classic in the field, and the statistical methods developed are still considered valid. However, in the individual case studies of twins reared apart, the authors gave only superficial treatment to such crucial factors as psychological environment, parent-child relationships, neuroses, and sexual behavior. Moreover, the twins raised apart had a mean age of twenty-six years, whereas the twins reared together had a mean age of thirteen years. With such an age discrepancy between the two groups, it is hard to determine the nature or the degree of any environmental influence other than age. The sample of identical twins reared apart was biased in favor of twins who were extremely similar. Newman advertised and sought any information about twins who were remarkably similar and who lived apart. He rejected at least one pair of possible monozygotic twins because they wrote him that they were very different in some respects, and he feared they might be fraternal.

The book shows the basic disagreement between Newman and his colleagues over the relative influence of environment and heredity on intelligence and personality traits. In 1932 Newman warned against placing an extreme environmentalist interpretation on the data already collected, noting that the tests were biased toward measuring mental achievement rather than innate mental ability. He found the data pointing to a marked environmental influence disconcerting, and stated his deep-seated conviction that hereditary differences are perhaps twice as influential in determining mental ability as differences in environment.

In 1940 Newman revealed that he had given in to the environmentalist interpretation of his colleagues because most twin studies prior to theirs had overemphasized the force of heredity. Newman said he had always been much more impressed by the very great intrapair similarities after the identical twins had been exposed to marked environmental differences. He believed that environment could have a marked effect only during early embryonic development.

Newman did not confine his scientific activity to the laboratory. He was committed to educating the public and the average university student about the basic principles of evolution and genetics. In 1920 he offered a general course on evolution, genetics, and eugenics that drew large numbers of Chicago students from outside, the field of biology, Newman’s Evolution, Genetics and Eugenics was written as a text for the course, and its three editions went into numerous printings. He also edited The Nature of the World and of Man as a text for a general course, by the same name, required of all freshmen and sophomores at Chicago.

Newman journeyed to Dayton, Tennessee, in 1925 to testify at the trial of John T. Scopes. Although the judge did not allow expert scientific witnesses to testify in court, Newman was one of seven scientists whose statements were placed in the trial record. He found no conflict between science and religion, and noted that most major theologians were evolutionists. Newman wrote The Gist of Evolution in 1926 to explain the principle of evolution to the general public. In it he urged readers not to equate Darwinism and evolution. Like many biologists of his time, Newman rejected natural selection acting on minute variations as the major mechanism of evolutionary change.

BIBLIOGRAPHY

I. Original Works. Works by Newman include “The Process of Heredity as Exhibited by the Development of Fundulus Hybrids”, in Journal of Experimental Zoology5 (1908), 504–561; “A Case of Normal Identical Quadruplets in the Nine-Banded Armadillo, and Its Bearing on the Problems of Identical Twins and of Sex Determination”, in Biological Bulletin, 17 (1909), 181–187, written with J. Thomas Patterson; “The Development of the Nine-Banded Armadillo from the Primitive Streak Stage to Birth; with Especial Reference to the Question of Specific Polyembryony” in Journal of Morphology, 21 (1910), 360–423, written with J. Thomas Patterson; “The Limits of Hereditary Control in Armadillo Quadruplets: A Study of Blastogenic Variation”, ibid., 22 (1911), 855–926, written with J. Thomas Patterson; “The Modes of Inheritance of Aggregates of Meristic (Integral) Variates in the polyembryonic Offspring of the Nine-Banded Armadillo”, in Journal of Experimental Zoology, 15 (August 1913), 145–192; “Modes of Inheritance in Teleost Hybrids”, ibid., 16 (February 1914), 447–499; “Heredity and Organic Symmetry in Armadillo Quadruplets”, in Biological Bulletin, 29 (July 1915), 1–32; “Development and Heredity in Heterogenic Teleost Hybrids”, in Journal of Experimental Zoology, 18 (May 1915), 511–576.

The Biology of Twins (Chicago, 1917); “Hybrids Between Fundulus and Mackerel : A Study of Paternal Heredity in Heterogenic Hybirds”, in Journal of Experimental Zoology, 26 (August 1918), 391–421; Vertebrate Zoology (New York, 1920: repr. 1926); The Physiology of Twinning (Chicago, 1923); “Studies of Human Twins. II. Asymmetry Reversal, or Mirror Imaging in Identical Twins”, in Biological Bulletin, 55 (October 1928), 298–315; “Differences Between Conjoined Twins”, in Journal of Heredity, 22 (July 1931), 201–215; Twins: A Study in Heredity and Environment (Chicago, 1937), written with Frank H. Freeman and Karl J. Holzinger; and Multiple Human Births (New York, 1940).

Correspondence between Newman and Frank R. Lillie is in the library of the Marine Biological Laboratory, Woods Hole, Massachusetts.

II. Secondary Literature. A brief biographical memoir is Herulf H. Strandskov, “Horatio Hackett Newman, Pioneer in Human Genetics”, in Science, 127 (1958), 74.

Mary Morrice Bogin