|By Margaret A. McIntyre - "The cave boy of the age of stone", Public Domain, https://commons.wikimedia.org/w/index.php?curid=2897126
Reich, David. 2019. Who we are and how we got here: ancient DNA and the new science of the human past, (ebook).
The study of the human past-- as of art, music, literature, or cosmology -- is vital because it makes us aware of aspects of our common condition that are profoundly important and that we heretofore never imagined.I think another quote from David Reich in the same book talks about our ancestry that is also important for us, as genealogists, to understand. Here is the quote:
The problem is not just that people have mixed with their neighbors, blurring the genetic signatures of past events. It is actually far more difficult, in that we now know, from ancient DNA, that the people who live in a particular place today almost never exclusively descend from the people who lived in the same place far in the past. Under the circumstances, the power of any study that attempts to reconstruct past population movements from present-day populations is limited.The past is far more complex than any of the simplistic, unfounded conclusions that we may draw from our limited knowledge of the initial conditions of our human existence. Whatever we know now about human genetics will undoubtedly be looked upon by our descendants as just as foolish and misguided as our views of medicine and genetics dating back to Aristotle and as continued to be practiced and believed well into the 20th Century and even into the 21st Century.
One more quote from David Reich:
Today, many people assume that humans can be grouped biologically into "primeval" groups, corresponding to our notion of "races," whose origins are populations that separated tens of thousands of years ago. But this long-held view about "race" has just in the last few years been proven wrong -- and the critique of concepts of race that the new data provided is very different from the classic one that has been developed by anthropologists over the last hundred years.It is quite common among those that I frequently come in contact with to hear stories from those who are taking DNA tests about the "racial" surprises they are encountering. These discoveries, including the ones alluded to by the quote above, challenge all of our concepts of race and dismiss out of hand any claims to "racial superiority."
Up until the mid-1800s, the concepts associated with inheritance relied heavily on environmental factors as the cause of genetic changes. Charles Darwin's book, On the Origin of Species by Means of Natural Selection, or the Preservation Favoured Races in the Struggle for Life, published in 1859. although clearly relying on the idea of inherited traits is devoid of any mention, other than external forces, of the terms "gene" or "genetics" The mechanism for the changes noted by Darwin began to be explored by Gegor Mendel between 1856 and 1863. His paper, "Versuche über Pflanzenhybriden" ("Experiments on Plant Hybridization"), was first presented at two meetings of the Natural History Society of Brno in Moravia on 8 February and 8 March 1865 and then after publication in 1866 in the Verhandlungen des naturforschenden Vereines in Brünn was ignored and forgotten. See Wikipedia: Gegor Mendel.
Chromosomes were not discovered until 1882 by the German biologist, Walther Flemming. Here is a quote from the DNA Learning Center: Walther Flemming about him and his discovery:
Walther Flemming was born in Sachsenberg, Mecklenburg, now in Germany. He was a military physician during the Franco-Prussian War. Flemming held positions at the University of Prague (1873-76), and at the University of Kiel (1876-1901).
Flemming was one of the first to devote his time to cytology, the study of chromosomes. Cell division had been described as early as 1842 by Carl Nageli, who thought it was an anomalous event. Flemming was the first to detail the chromosomal movements in the process of mitosis. In 1879, Flemming used aniline dyes, a by-product of coal tar, to stain cells of salamander embryos. He was able to visualize the threadlike material as the cells divide. He described the whole process in his book Zell-substanz, Kern und Zelltheilung (Cell-Substance, Nucleus, and Cell-Division), which was published in 1882.Here is the citation to his book.
Flemming, Walther. 1882. Zellsubstanz, Kern und Zelltheilung mit 24 Textbildern und 8 Tafeln. Leipzig: Vogel.
The word "gene" was not coined until 1905 by the Danish scientist Wilhelm Ludvig Johannsen (1857-1927). See Etymonline.com/word/gene.
Is it any wonder that what we presently know about the subject of genetics and particularly DNA testing should be considered to be only the barest of beginnings about the complexity of these subjects?
In about 1900, Mendel's forgotten work was "rediscovered. Here is a quote from the National Human Genome Research Institute, 1900: Rediscovery of Mendel's Work.
Three botanists - Hugo DeVries, Carl Correns and Erich von Tschermak - independently rediscovered Mendel's work in the same year, a generation after Mendel published his papers. They helped expand awareness of the Mendelian laws of inheritance in the scientific world.
The three Europeans, unknown to each other, were working on different plant hybrids when they each worked out the laws of inheritance. When they reviewed the literature before publishing their own results, they were startled to find Mendel's old papers spelling out those laws in detail. Each man announced Mendel's discoveries and his own work as confirmation of them.
By 1900, cells and chromosomes were sufficiently understood to give Mendel's abstract ideas a physical context.Two years later, in 1902, Archibald Garrod observed that the disease alkaptonuria was inherited according to the rules set forth by Mendel. See the following:
Garrod, A. E. The incidence of alkaptonuria: a study in chemical individuality. Lancet, II:1616-1620. 1902.
One of the main limitations on the rapid advancement of understanding genetics was the physical limitations of the test equipment available at the time and the lack of computers to tabulate and help explain the processes involved. Rapid advances did not begin until the advent of computers and highly sophisticated testing procedures and equipment in the 1990s.
To be continued, of course.
See these previous posts:
Part One: https://genealogysstar.blogspot.com/2019/04/the-history-of-development-of.html
Part Two: https://genealogysstar.blogspot.com/2019/05/the-history-of-development-of.html