One of the most interesting points repeatedly discussed in Bill Bryson’s A Short History of Nearly Everything is the astonishing variety of microbial life that exists on earth. Regardless of how you arrange your taxonomy, there is far more variety in single-celled life than in the more familiar multicellular variety. What’s more, it seems that single-celled creatures may be more diverse in the ways they carry out essential biological tasks like energy collection, movement, and communication.
One of the more interesting bits of research being done right now is the work of Craig Venter through the Global Ocean Sampling Expedition. Using samples taken from seawater from around the world and ‘scattershot’ techniques of genetic sequencing, some new information about that variety has been uncovered. This one program has tripled the number of genes that have been sequenced by humanity (from three to nine million). For instance, the project discovered a great deal about a class of messenger molecules called kinases. Previously, they were believed to consist of a single family of proteins, used by plants and animals. Now, nineteen new families have been discovered, all in bacteria.
In every age, there is a certain temptation to think we have most of the basic knowledge about how the world works mapped out. Projects like this help to reveal just how much there is left to come to grips with.
PS. Those curious about some of the ongoing debates in biology should have a look at two Wikipedia entries: Kingdom and Taxonomy. Some of that Kingdom-Phylum-Class-Order-Family-Genus-Species stuff we all learned in high school is coming under challenge, at the same time as there is a big schism between those seeking to categorize organisms by similarity in structure and those intent to do so on the basis of tracking genetic progressions.