We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
In this concluding chapter, I draw conclusions about several important aspects of nature of science by drawing on the topics discussed in the various chapters of the book. Such conclusions include: that individual brilliance and creativity can make a difference; the historical milieu of the individual is equally crucial; that scientists are humans with weaknesses and concerns like all of us; and that gender may influence one’s opportunities to contribute to science.
In this essay I consider what myths are, and provide a very short sketch of Darwin’s life and work. I also suggest some possible reasons about the mythology around him, paving the way for the chapters to follow.
Many historical figures have their lives and works shrouded in myth, both in life and long after their deaths. Charles Darwin (1809–82) is no exception to this phenomenon and his hero-worship has become an accepted narrative. This concise, accessible and engaging collection unpacks this narrative to rehumanize Darwin's story and establish what it meant to be a 'genius' in the Victorian context. Leading Darwin scholars have come together to argue that, far from being a lonely genius in an ivory tower, Darwin had fortune, diligence and – crucially – community behind him. The aims of this essential work are twofold. First, to set the historical record straight, debunking the most pervasive myths and correcting falsehoods. Second, to provide a deeper understanding of the nature of science itself, relevant to historians, scientists and the public alike.
What are genes? What do genes do? These questions are not simple and straightforward to answer; at the same time, simplistic answers are quite prevalent and are taken for granted. This book aims to explain the origin of the gene concept, its various meanings both within and outside science, as well as to debunk the intuitive view of the existence of 'genes for' characteristics and disease. Drawing on contemporary research in genetics and genomics, as well as on ideas from history of science, philosophy of science, psychology and science education, it explains what genes are and what they can and cannot do. By presenting complex concepts and research in a comprehensible and rigorous manner, it examines the potential impact of research in genetics and genomics and how important genes actually are for our lives. Understanding Genes is an accessible and engaging introduction to genes for any interested reader.
To understand what genes “do,” we have to consider what happens during development. The first and most striking evidence that the local environment matters for the outcome of development was provided by the experiments of embryologists Wilhelm Roux and Hans Driesch in the late nineteenth and early twentieth centuries. Roux had hypothesized that during the cell divisions of the embryo, hereditary particles were unevenly distributed in its cells, thus driving their differentiation. This view entailed that even the first blastomeres (the cells emerging from the first few divisions of the zygote – that is, the fertilized ovum) would each have different hereditary material and that the embryo would thus become a kind of mosaic. Roux decided to test this hypothesis. He assumed that if it were true, destroying a blastomere in the two-cell or the four-cell stage would produce a partially deformed embryo. If it were not true, then the destruction of a blastomere would have no effect. With a hot sterilized needle, Roux punctured one of the blastomeres in a two-cell frog embryo that was thus killed. The other blastomere was left to develop. The outcome was a half-developed embryo; the part occupied by the punctured blastomere was highly disorganized and undifferentiated, whereas those cells resulting from the other blastomere were well-developed and partially differentiated. This result stood as confirmation for Roux’s hypothesis.
During the 1970s, more puzzling observations were made. The first was that the genome of animals contained large amounts of DNA with unique sequences that should correspond to a larger number of genes than anticipated. It was also observed that the RNA molecules in the nuclei of cells were much longer than those found outside the nucleus, in the cytoplasm. These observations started making sense in 1977, when sequences of mRNA were compared to the corresponding DNA sequences. It was shown that certain sequences that existed in the DNA did not exist in the mRNA, and that therefore they must have been somehow removed. It was thus concluded that the genes encoding various proteins in eukaryotes included both coding sequences and ones that were not included in the mRNA that would reach the ribosomes for translation. These “removed” sequences were called introns, to contrast them with the ones that were expressed in translation, which were called exons. The procedure that removed the intron sequences from the initial mRNA and that left only the exon sequences in the mature mRNA was named “RNA splicing.”
One important, and for some the most surprising, conclusion of genome-wide association studies (GWAS) has been that in most cases numerous single nucleotide polymorphism (SNPs) in several genes were found to be associated with the development of a characteristic or the risk of developing a disease. As already mentioned, the main conclusion has been that the relationship between genes and characteristics or diseases is usually a many-to-many one, as many genes may be implicated in the same condition, and the same gene may be implicated in several different conditions. In fact, the same allele may be protective for one disease but increase the risk for another. For example, a variation in the PTPN22 (protein tyrosine phosphatase, nonreceptor type 22) gene on chromosome 1 seems to protect against Crohn’s disease but to predispose to autoimmune diseases. In other cases, certain variants are associated with more than one disease, such as the JAZF1 (JAZF1 zinc finger 1) gene on chromosome 7 that is implicated in prostate cancer and in type 2 diabetes. Therefore, we should forget the simple scheme of gene 1 → condition 1/gene 2 → condition 2, and adopt a richer – and certainly more complicated – representation of the relationship between genes and disease. Additional GWAS on more variants in larger populations might provide a better picture in the future. But insofar as we do not understand all biological processes in detail, all we are left with are probabilistic associations between genes and characteristics (or diseases). The “associated gene” may be informative, but its explanatory potential and clinical value are limited – at least for now.