Editing 1605: DNA

In the comic, [[White Hat]] thinks that mapping the human genome is the same as knowing the {{w|source code}} for a {{w|computer program}}. By studying the source code for a program, a person can often understand why it does what it does, and make effective and fundamental changes to the program's operation. This may be a reference to the hyperbolic [http://scienceblogs.com/pharyngula/2010/08/17/ray-kurzweil-does-not-understa/ claims of Raymond Kurzweil,] author of {{w|The Singularity is Near}}, that {{w|DNA}} is closely analogous to a computer program. Kurzweil believes that since we have sequenced DNA, we will soon be able to reverse engineer the brain and program a computer to completely simulate all its functions.

[[Megan]] points out that even a complete knowledge of DNA would only provide a partial understanding of our body's workings. Complete knowledge would require an understanding of feedbacks and external processing (such as the interactions of the proteins created by DNA). In addition the comparison is not valid because the human body is so many orders of magnitude more complicated than the computers we have running programs. White Hat is not persuaded, even though Megan points out that DNA has been developed in the most aggressive optimization process in the universe (natural evolution), running for billions of years. White Hat's thought process may be similar to the physicist in [[793: Physicists]] who assumes that any other field is simple because it appears to be similar to something he's seen before.

Finally Megan {{w|Hacker koan|enlightens}} White Hat by making him look at the source code for {{w|Google}}'s front page. In a web browser, the page looks simple; a very plain white page with a search box in the middle plus a few text links and icons, and indeed back in the 1990s Google's {{w|HTML}} code for the page was quite simple. But in less than 20 years, Google developers have vastly expanded it, with over 300 kilobytes of {{w|Minification (programming)|minified}} Javascript and CSS. Looking at some obfuscated source code may make it clearer how misleading even simple looking code can be, and how unreadable correct and well working code can be.  This analogy causes White Hat to consider how much more complexity could evolve over billions of years through the relentless forces of nature.

What makes this even worse with DNA is that although it can be thought of as 'source code' it isn't for a language we fully understand, and this code was generated through various natural mechanisms such as {{w|natural selection}}, feedback loops like {{w|homeostasis}}, etc.; possibly even including processes that are not currently known to science. Further, program maintainability is not an issue, so there is no reason for the code to be easy to understand. Additionally, there are many other non-genetic factors such as {{w|epigenetics}}, {{w|maternal effect}} and {{w|environment (biophysical)|environment}}, which change how the genetic code is used. This means that not all parts make sense and that there may be all kinds of side effects and things that have several purposes.

The title text reference to finding the gene that is responsible "for mistakenly thinking we've found the gene for specific things" is a reference to the tendency of news organizations to run headlines making similar claims, often by oversimplifying or misrepresenting the actual study. These claims are based off the common belief that since DNA is a 'source code' for our body it should be possible to pin point the effect of individual genes in much the same way that we could describe the effect each line of code has in a very simple program; leading to people expecting one gene to be associated with each observable human trait. In reality even small traits are the results of hundreds of genes, sometime spread across multiple chromosomes, interacting through complex mechanisms; making it rare that a single gene, or gene sequence, can be definitively stated to be the sole, or primary, cause of a given trait.

The joke of the title text is that the responsible gene is located in ''the region between the start and the end of every {{w|chromosome}}'' meaning that the whole genome, not any one gene or DNA segment, must be considered responsible for the referenced trait, since the interconnected nature of DNA and environment during development means that every gene is at least partially responsible in generating any complex traits. [[Randall]] even includes the {{w|mitochondria}}, recognizing that the short DNA sequences present in these organelles, which are located outside the cell-nucleus, also contribute to development. The organismal chromosome or chromosomes are located in the nucleus, but mitochondria have their own tiny independent genome, reflecting their distant ancestry as separate but symbiotic organisms. This means that the DNA segments coding for any given human trait are not even necessarily all found on the main chromosomes in the nucleus.

Technically a gene is "a locus (or region) of DNA that encodes a functional RNA or protein product", which means that it is a single discrete unit of DNA, with human DNA containing over 20,000 genes. Thus the theoretical gene could not include the entire ''region between the start and the end of every chromosome'' since that region contains thousands of genes, any more than it's possible to say that the ace of clubs is the card everywhere from the top of the full deck of cards to the bottom of it.