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Friedrich Leopold August Weismann


Educational Background/Training

Weismann was born on 17 January 1834 in Frankfurt am Main, in the German Confederation. His mother, Elise Eleanor Lübbren, was a musician and painter, and his father, Johann Konrad August Weismann, was a classics professor. Weismann studied music, particularly the works of Beethoven, and he studied nature, from which he collected butterflies. He noted diverse patterns and colors of butterflies, information that later informed his research on the development and evolution of butterflies and caterpillars.

In 1856 Weismann got his medical degree from the University of Göttingen in Göttingen, in the German Confederation. After graduation, Weismann worked as an assistant in a hospital for three years in Rostock, in the German Confederation, before becoming a physician in Frankfurt am Main in 1859. From 1861 to 1863, Weismann was the private physician for Archduke Stephen of Austria. In 1861, Weismann studied at the University of Giessen in Giessen in the German Confederation, with Rudolf Leuckart for two months, working on the ontogeny (development) and morphology (form) of animals, insects in particular. That year, Weismann read Charles Darwin’s On the Origin of Species two years after it was published in 1859, after which he adopted evolutionary theory. Weismann studied different factors he thought might cause morphological transformations in insects, including natural selection.

In 1863, Weismann became a docent in zoology and comparative anatomy, a mid-ranking academic position, in the University of Freiburg in Freiburg in Breisgau, also in the German Confederation. In 1864, Weismann’s eyesight declined, which left him partially blind and limited his ability to use microscopes. Nonetheless, he studied the metamorphosis and development of butterflies. Weismann became the founding director of the Zoological Institute at the University of Freiburg in 1867. That year, he married Marie Dorothea Gruber from Genoa, Italy. The couple had at least five children. Along with his students and assistants, Marie aided his experimental and observational studies after his eyesight failed. Marie died in 1886, but Weismann remarried at the age of sixty in the mid-1890s to Willemina Tesse from the Netherlands, a marriage that lasted six years.

Summary of Research

            August Friedrich Leopold Weismann studied how the traits of organisms developed and evolved in a variety of organisms, mostly insects and aquatic animals, in Germany in the late nineteenth and early twentieth centuries. Weismann proposed the theory of the continuity of germ-plasma, a theory of heredity. Weismann postulated that germ-plasma was the hereditary material in cells, and parents transmitted to their offspring only the germ-plasma present in germ-cells (sperm and egg cells) rather than somatic or body cells. Weismann also promoted Charles Darwin's 1859 theory of the evolution of species. Weismann argued that only changes to the germ cells, and not body cells, could be inherited, a theory that influenced theories of heredity throughout later centuries.

From 1881 onwards, Weismann published a series of essays about heredity. Those essays were collated in English in 1889's Essays upon Heredity and Kindred Biological Problems. The essays discussed topics including senescence, acquired characteristics, and the germ-plasma theory. For example, in the first chapter, "The Duration of Life," a translation of an essay originally published in German in 1881, Weismann detailed his evolutionary theory of senescence, the name given to the gradual deterioration of function of most life forms after they mature to adults. Weismann argued against theories that associated the length of an organism's life with the size or complexity of its body, or with how active it appears to be. Instead, he appealed to natural selection, arguing that it adapted organisms to reach reproductive maturity, and that it would not select for the capacity of the organism to live any longer once it was past reproductive age. He further argued that the death of male bees after they reproduced was selected for by nature to save nutrition for the colony, a phenomenon that precluded those organisms that had already reproduced from consuming resources.

Linking his work to broader context

When Weismann’s germ theory is paired with that of Gregor Mendel’s on inheritance we are provided the basic understandings of how humans and other animals inherit their traits from their parents. Weismann used his germ theory to explain that, “natural selection favors organisms that pass on their germlines before conspecific and before extrinsic factor cause their death (Crews and Ice, 2012: 639).” This statement has been used to create the concept of life history theory for many different species, including humans. For life history theory, we see that the goal to reproduce is in conflict with the maintenance of the body. This result in trade-offs that the body goes through in order to chose one of these actions over the other. The allocation of resources between reproducing and somatic maintenance created a way for researchers to compare and to structure their research as to why these chronic diseases and changes in old age occur. Through these trade offs in life history theory is how Weismann can be connected to this chapter. This chapter discusses the aging and senescence of humans. Senescence occurs when the body begins to function less efficiently and cell begins to functioning deteriorate as life progresses. The chapter discusses the different ways that the body ages in multiple areas, including hormones, immune system, cardiovascular, body composition, bone, dementias, and reproductive aging. All of these areas are altered through the aging of an individual based on the life history course that has been taken. One problem with Weismann’s concept of life history is that it does not allow for the environment and culture to alter these stages. Even in the chapter there is little discussion on the environment and its effects on life history. Yet, with the time that Weismann came up with this theory there must be credit given for his ability to come up with these conclusions that further lead to our understanding of how the body works.

Crews, D.E., Ice, G.H. (2012). Aging, senescence, and human variation in Human Biology: An Evolutionary and Biocultural Perspectives, Second Edition. Edited by Stinson, Bogin, O’Rourke. John Wiley and Sons, Inc.: Hoboken, New Jersey.

(2008). August Weismann found at


Duana Fullwiley is a medical anthropologist who graduated in 2002 from UC Berkeley and UC San Francisco with her Ph.D. Fullwiley has conducted a multi-sited field research in the United States about the emergent technologies that measure human genetic diversity among populations and between individuals. Her main interest is how scientists promote genetic citizenship. This was Dr. Fullwiley’s second book project and explains exactly how U.S. political concepts of diversity, usually glossed as “race,” function in genetic recruitment protocols and study designs for research on complex diseases, “tailored medicine,” ancestry tracing, and personal genomics.

Dr. Fullwiley’s first book is The Encultured Gene: Sickle Cell Health Politics and Biologicalss Difference in West Africa. This book was written in 2011, and received the 2014 Robert B. Textor and Family Prize for Excellence in Anticipatory Anthropology from the American Anthropological Association, and the 2011 Amaury Talbot Prize for African Anthropology from the Royal Anthropological Institute. This book used data gathered from ethnographic fieldwork in Senegal, France, and the United States. She uses her fieldwork data and weaves together postcolonial genetic science, the effects of structural adjustment on health resources, and patient activism between Senegal and France to show how African sickle cell has been ordered in ethnic-national terms at the level of the gene.

She used to be a professor at Harvard and is now an associate professor at Stanford University teaching courses in medical anthropology and anthropology of science. She is currently in the research stages for her second book Tabula Raza: Mapping Race and Human Diversity in American Genome Science.


Rebecca L. Cann is a geneticist who, along with her colleagues, is best known for the Mitochondrial Eve hypothesis (1987). Mitochondrial Eve explains that our human mitochondrial DNA can be linked back to a single African mother from over 200,000 years ago. The Mitochondrial Eve is the ancestor of us all. Since the publication of her paper in 1987, Cann's finding have had a huge impact on human society by contributing evidence for the "(Recent) Out-of-Africa" model.

Rebecca Cann was originally born in Burlington, Iowa. She moved to San Francisco right before starting high school. After graduation, she earned her bachelor's (1972) at the University of California, Berkeley. In the gap between earning her Bachelor's in Genetics and enrolling for graduate school in the Anthropology Department (1972-1974), Cann's interests in human variability and personalized genomes ignited while working as a night-time quality control chemist. Her job exposed her to a lot of scientific journals and articles that made her very inquisitive in how human genotypic variation creates such different phenotypes. Upon learning about restriction enzymes in 1974, Cann decided to enter graduate school to work in molecular anthropology and human evolution. She earned her doctorate in 1982 under the supervision of Dr. Allan Wilson. She worked her Postdoctoral at Howard Hughes Medical Institute until joining the faculty of Univerity of Hawaii's Department of Cell and Molecular Biology in 1986. The following year Cann's "Mitochondrial DNA and human evolution" paper was published Nature (1987).

Currently Cann is a professor at the University of Hawaii.

"Raymond Pearl." Via Wikipedia -
"Raymond Pearl." Via Wikipedia - Raymond_Pearl _o.jpg#mediaviewer/ File:Raymond_Pearl_o.jpg

Raymond Pearl, Professor of Biology in the Medical School and in the School of Hygiene and Public Health of the Johns Hopkins University, died at Hershey, Pennsylvania, November 17, 1940, at the age of sixty-one years. At the age of 16 he entered Dartmouth College, expecting to make the classics his chief field of study. During his first year he was more interested in the opportunities for free activity than in his studies; a fact which was reflected in the low grades which he received. But in that first year biology was a required subject, and this opened his eyes to what became his main interest. He graduated from Dartmouth with the degree of A.B. in 1899. According to the Class Report before cited "Pearl was the youngest graduate in our class." During his senior year he was assistant in the course in general biology, of which the present writer was at that time in charge. He showed at that early period the masterful and competent personality that marked him throughout life.

In the fall of 1899, Pearl went to the University of Michigan, while for three years he was an assistant in Zoology while at work as a graduate student. He took part in the Biological Survey of Great Lakes, founded and led by the late Jacob Reighard working on variation in fishes (1900- 1902). He received in 1902 from the University of Michigan the degree of Doctor of Philosophy, at the age of twenty-three. From 1902-1906 he was a professor of Zoology at the University of Michigan. It was in the laboratory of the University of Michigan where he met Maud. M. De Witt, who became his wife. They were married in 1903, and upon his death bed she became managing editor of the journal “Human Biology”, and assistant editor of the ‘Quarterly Review of Biology”- the two journals founded and edited by Pearl. In the year of 1905-1906, Pearl he decided to enter the field of the application of statistical method of Biological problems with Karl Pearson at the University College, London. During the same visit to Europe he worked also at Leipzig and at the Marine Biological Station at Naples. Pearl returned to America in 1906, and was an instructor in Zoology at the University of Pennsylvania in 1906-1907. In 1907, he went to the University of Maine in Orono, as head of the department of Biology of the Maine Agriculture Experiment Station, remaining there until 1918. In 1918, Pearl was called at instance of Dr. William Welch, to become professor of Biometry and Vital Statistics in the newly found School of Hygiene and Public Health of John Hopkins University, where he spent the remainder of his educational career and training.

Before Pearl received his doctorate, he published a number of contributions. His dissertation was on the actions and behavior of Planarians. He next contributed a series of papers on genetic problems in lower organisms in which he worked with Karl Pearson in London. Also while in London, he finished and elaborated statistically a valuable piece of work on assortative mating in Protozoa. While at John Hopkins University, his interest in many subjects was so intense that at any given moment he might seem a partisan and propagandist of a particular method of biological science. Among the seven hundred and twelve titles (including seventeen books) in the list of Pearl’s writing hereto appended will be found contributions on the most varied fields of aspects biology or as human affairs as a division of biology. There are papers on animal behaviors, to Protozoa to man; on general physiology; many of various aspects of genetics (on abnormalities, variations on the breeding of Drosophila, of poultry, of cattle, of corn, of cantaloupes, on tongue colors in cattle, on the color hen’s eyes, etc.) There are many technical contributions on the care and breeding and fowls (fertility and diseases of fowls, plumage patterns, egg production, keep fowls free from lice, and folk-lore of hens’ eggs). Furthermore, many papers deal with the biology of man: papers on longevity and mortality, on the effects of alcohol and tobacco, on eugenics, and race culture, on the biology of superiority, the biology of death, infant mortality, and contraception.