As this is a blog, maybe a suitable topic for a post is doing scientific research, or slightly more accurately, reviewing scientific research, by blog. In December 2010, NASA-funded scientists published a paper in Science. In an article, a senior NASA administrator said “The definition of life has just expanded,”. The response in blogs of scientists working in the field was pretty clear: “No, the definition of life is pretty much as it was last week”.
I am not an expert in the field, so see for example Rose Redfield’s post at the time for careful arguments by someone in the field. However, the authors Wolfe-Simon and her coworkers made a very striking claim.
To understand it you just need to know a little about the structure of DNA. DNA is a double helix and winding round the outside are what look a little like the bannisters of a spiral staircase. These are the sugar-phosphate backbone of DNA that holds the molecule together. As the name suggests, this backbone is made of sugar and phosphate molecules. The phosphate molecules are the orange and red things in the image above.
Before the paper was published the evidence was that all life on Earth, absolutely all of it has genetic information encoded by DNA (or RNA for some viruses) and that all this DNA and RNA has backbones with phosphate molecules. Wolfe-Simon and her coworkers suggested that a species of bacteria living in a nasty aresenic-rich lake uses not phosphate but arsenate in its DNA.
There are many problems with this contention. Rosie Redfield has discussed possible problems with how the experiments were done, as has Alex Bradley. It is also very hard to see how this bacterium could have evolved. I don’t have anything to add to this discussion of the paper.
But if we take it that the paper is indeed wrong, then I would say we can conclude that science is working. Scientists make mistakes like everyone else, but science works when these errors are corrected. Here the error has been found out, and so people working in this field will not be mislead by the error, and further scientific progress can be made. However, both the Science journal and NASA may need to rethink things.
The paper has not one but many points which should have a raised a red flag; it is disappointing that apparently none of the reviewers and editors of the journal spotted any of them. It is also disappointing that NASA released a hyperbole-filled article, and then keeps it up without any caveats, despite the fact that the research it reports uncritically has been undermined.
