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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

The chapter this week was all about stress and reminded me of one of our very own professors here at University of Alabama, Dr. Dressler. His work on cultural consonance and its connection in African Americans in Alabama and higher blood pressure levels is actually mentioned in the chapter we read. The chapter discussed how blood pressure and depression are some of the responses that occur from stressors. The article I decided to look at was “Does perceived stress mediate the effect of cultural consonance on depression?” In the article the researchers, Mauro Balieiro, Manoel Antônio dos Santos, José Ernesto dos Santos, and William Dressler were interested to see “does stress appraisal, as measured by the PSS, mediate the effects of cultural consonance on depressive symptoms? (Balieiro, Antônio dos Santos, Ernesto dos Santos , Dressler, 2011: 532).”

In the article, the study takes place in Ribeirão Preto, Brazil, looking at four different neighborhoods with varying socioeconomic status (SES). The four communities SES are lower class, lower middle class, traditional middle class, and upper middle class. There were four cultural domains that they were researching, including lifestyle, social support, family life, and national identity. To identify parts of the domain participants were asked to free list terms or things that are important to that domain, such as “ what things are important to have to live a good life? (Balieiro, Antônio dos Santos, Ernesto dos Santos , Dressler, 2011: 526).” This provides the investigators with many terms, these were then narrowed down to 20 to 30 terms that exemplify the cultural domain. Participants were then told to take these terms and sort them into piles based on similarities. Also participants were asked to rank order these terms from most important to that domain to least important. Depressive symptoms were measured using the Brazilian Portuguese version of the Center for Epidemiologic Studies Depression Scale. Perceived stress was measures using Cohen’s Perceived Stress Scale (PSS) that was translated into Portuguese. Three covariates were used, including age, gender, and SES. All tests were done during two separate time periods.

The results show that “the effect of cultural consonance in lifestyle is reduced to statistical non-significance (p<.10) when PSS is controlled (Balieiro, Antônio dos Santos, Ernesto dos Santos , Dressler, 2011: 531).” Also it was found that “the effect of cultural consonance in family life on depressive symptoms that is mediated by the PSS is statistically significant (z=2.75, p<.01) (Balieiro, Antônio dos Santos, Ernesto dos Santos , Dressler, 2011: 532).” It has been found that the being cultural consonant in a domain and being unable to obtain this results in depression in individuals. From these results it was concluded that the PSS somewhat resolves the depression that occurs from cultural consonance. This suggests that more research should be done, specifically looking at other cultural domains.

Balieiro, M.C., Antônio dos Santos, M., Ernesto dos Santos, J., Dressler, W.W. (2011). Does perceived stress mediate the effect of cultural consonance on depression?. Transcultural Psychiatry, 48 (5): 519-538.


Gregor Mendel

Johann Mendel was born to Anton Mendel and Rosine Mendel in what used to be Heinzendorf, Austria on July 22, 1822. His father was a farmer, so Mendel would help out with the chores around the farm. His family was not poor, but sending Mendel to school in Troppau at the age of 11 created strain on their finances. In 1840, he graduated from regular school. After his graduation from secondary school, he entered the Philosophical Institute of the University of Olmütz for two years. To make ends meet he would tutor other students. During this time he often had problems with depression, which resulted in him stopping studies at times. With his problem with depression Mendel was able overcome it and graduate in 1843.

This time of financial struggle is what influenced Mendel to enter the monastery of the Augustinians of Bruenn in 1843. He joined the monastery against his father’s wishes; he wanted him to take over the farm. This is where he received the name of Gregor. The monastery helped give Mendel access to a large library and experiment facilitates, as well as the research of his fellow members. In 1849, Mendel had worked himself to the point of being ill and was sent to teach in Znaim. In 1950, he failed a test to continue teaching and as a result was sent to continue his studies of science in 1851 at the University of Vienna, this was paid for by the monastery. While at the university, Mendel was able to study math and physics under Christian Doppler and botany under Franz Unger, which would later influence his work with pea plants. He graduated in 1853, and shortly after, was given a teaching post at a secondary school that he would keep for over a decade. The time that he was working as a teacher is when he was conducted his pea plant experiments from 1856 to 1863. In 1865, he gave two lectures on his findings from his pea plant experiments, though nothing resulted from them at the time. It is believed that Mendel was not confident in his work and that it he was just presenting already known information. In 1868, Mendel was hindered from doing scientific experiments by his failing eyesight and being elected abbot of the school he had been teaching at for over a decade.

            Mendel died in January 6, 1884. Unfortunately, Mendel did not get much credit for his work till after his death. In the 1900’s, scientists began to look at Mendel’s research and realize that is was not the usual genetic information that was being experimented on and published at the time.

Iltis, H. (1943). Gregor Mendel and his work. The Scientific Monthly, 56: 414-423.

Gregor Johann Mendel. (2014). The website. Found at:

Photo from:


Reading the chapter for this week about the history of human biology left me wondering what new information has come out since the publication of this chapter/book. Upon my search, I found an article in American Anthropologists discussing some of the major research that was published in 2012 that has helped to start shifting some long held theories. James Sun and colleagues did one of the main pieces of research discussed in this article. Sun’s research, along with others, has found that the “baseline rate of mutation, directly estimated from genomic sequencing, is slower than previously suspected (263, Van Arsdale).” This finding may influence the previous rate that evolution took place and more research has to be done before any large changes are made in the past research findings. The research I found the most interesting was that done by Herman Pontzer on the energy expenditure of hunter-gatherers. He studied thirty Hadza adults from Tanzani who are hunter-gathers, to compare to industrial populations. Ponzer found that the amount of energy expended by the Hadza was not significantly more than someone from the United States. This study helps to highlight the influence that energy consumption has on the cause obesity and how obesity is not all reliant on the lack of energy expenditure and lifestyle. The article also included a bit about open access journals and blogging one’s articles before it is published. I thought this part was an intriguing because it has some sort of reference to our class with the blogging we are doing. The publishers of journals do not like the blogging because it makes the articles irrelevant by the time they are finally published. I think this brings up a key question of what is more important making money off of these findings or sharing the information with people so that everyone can be better educated?

Overall, the article was insightful in showing how quickly research can come along that changes our ideas about a subject. The article featured the changing atmosphere of the academic world with the use of technology, which was really the first time I have seen how technology might change the way that influential journals, such as Human Biology, influence the research done as it has in the past.

2013. A shifting theoretical framework for biological anthropology in 2012. American Anthropologists, 115, 262-272.