|Philip Ball: How Life Works
In his new book How life works science writer Philip Ball makes fun of the gene-centric and DNA-centric view of biology. The figure below illustrates this view. First, there is DNA, then complex stuff happens, and then ... there is life. What's wrong with that view?
The popular view of how genes create living things
according to Philip Ball
According to Ball understanding genes will not enable us to understand life. Genes are not alive, cells and organisms are alive. Genes were never alive. If there is anything like a language of life, it will not be found in the genome. The genome as a "blueprint" for the creation of an organism is a favourite but misleading metaphor. There is no 'book of life'. DNA is no 'instruction book'. In biology every explanation starts with DNA. But according to Ball, it is trying to understand literature with a dictionary. (In my opinion, you can't learn a language without learning the words first! And that is what biologists are doing!). The complete sequence of the human genome did not produce insight in what life is. It is more complicated than that. DNA doesn't solve all the problems of biology. DNA doesn't tell us how cells work. The cell is not a machine. The cell is not a computer. No computer today works as cells do. The problem is we put genes at the start and bodies at the end. Genes are not a sufficient explanation of the organism. DNA is not the Master. DNA is the servant. That is Ball's new view of biology. In short.
My reaction is: There are good reasons to start with DNA. Crick's so-called Central Dogma of molecular biology (the illustration is in Balls' book) starts with DNA for a good reason. The information flows from DNA to RNA to proteins. The defining property of the central dogma is: directionality. The information flows from DNA to proteins, not from proteins to DNA. Crick's central dogma starts with DNA because that is how information flows. There isn't a process in the cell that creates DNA. DNA isn't the endpoint. So, necessarily DNA must be the starting point.
Secondly, Darwin had a very speculative and wrong theory about heredity. We now know that DNA is the carrier of heredity. Not proteins. DNA is by far the most important substance that is transmitted from parents to children. It explains why children are similar to their parents. Delete DNA from the egg cell and forget about the baby. The complete DNA sequence of a species defines the species. It is the difference between us and chimpanzees. Humans produce humans, chimps produce chimps because of different genomes. All this is not denied by Ball, but he isn't impressed by this kind of biological knowledge.
I think, we should not underestimate the enormous progress in scientific understanding of life, heredity and evolution. If we have a look at the history of biology since Aristotle, we can certainly claim that we finally know what Mendelian genes are, finally we know what chromosomes are made of, finally we can link genes and chromosomes and explain Mendelian laws in molecular and chromosomal terms, finally we know that species are characterized by the number of chromosomes, equally that males and females differ in their chromosomes, finally we understand sex in chromosomal terms, finally we know that genes, not proteins, are the material basis of heredity, finally we know the chemical structure of DNA (Watson & Crick), finally we know precisely how genes code for proteins (the genetic code), finally we know the complete sequence of the genetic material in an individual (the genome), finally we know in biochemical detail what mutations are, finally we know that mutations are necessary for natural selection and evolution. We can now explain many genetic diseases. We can even correct some of them. These are powerful scientific explanations previous generations of scientists only dreamed of. This is a tremendous scientific progress fully comparable to what Newton and Einstein did for the physical sciences. Ball seems to forget all this.
In chapter 2 Ball points out that despite all our new knowledge of genes and genomes, biologists still don't understand life. But hold on, which of the natural sciences could claim complete understanding of the field they study? Furthermore, is it really true that progress in molecular biology is slowing down? Or has come to a standstill? Is there really a crisis?
|12 Feb 1809
"I must stress there is nothing in this new view that conflicts with the neo-Darwinian idea that evolution shapes us and all other organisms and that it depends on the genetic transmission of information between parent and offspring. However, in this new view genes are not selfish and authoritarian dictators. They don't possess any real agency at all, for they can accomplish nothing alone." (Prologue) .
No real agency? Accomplish nothing alone? Viruses like SARS-CoV-2 know that very well. They absolutely need the help of the human host. They can accomplish nothing alone. Without the help of humans SARS-CoV-2 could not have caused a pandemic.
Note. In a next blog I will continue writing about How Life Works.See Wikipedia about Philip Ball: Ball holds a degree in chemistry from Oxford and a doctorate in physics from Bristol University.