Last month, Science published the results of an ongoing experiment conceived to determine, among other things, the minimum number of genes necessary for viability in a mycoplasma bacterium. Calling their engineered result Syn 3.0, scientists at the J. Craig Venter Institute (JCVI) rearranged and reduced the number of genes on the single chromosome of a M. mycoides bacterium and inserted it into a different mycoplasma called M. capricolum, whose genetic material had been removed. The new genetically rearranged mycoplasma had just 473 genes, 52 fewer than the 525 found in the naturally occurring smallest cousin M. genitalium. Starting with their first artificially rearranged viable mycoplasma, Syn 1.0, which had 901 genes, the JCVI scientists divided their artificial chromosome into roughly eight sections and began trial-and-error substitution and rearrangement until they arrived at the current frugal collection of possibly necessary but certainly sufficient genes for viability. While the bacterium successfully reproduces itself, I am not sufficiently skilled in taxonomy to determine whether or not the resulting organism is still a mycoplasma or something else altogether.
Regardless, the project has many benefits, the most significant of which is to learn which genes do what in the life of this bacterium. Out of the 473 genes in Syn 3.0, scientists are confident of the function of 324 of those genes. This means that the remaining 149 genes are necessary but mysterious as to what role they play in the life of this particular mycoplasma bacterium. Efforts continue in an attempt to gain a more detailed understanding of the function of these genes and to eliminate any remaining genes to arrive at the fewest genes necessary for viability, what I am calling the genetic prime pattern for this particular mycoplasma.
Wondering out loud: Is there a similar genetic prime pattern for human viability? Humans are estimated to have between 20,000 and 25,000 genes so any process to investigate this question is going to take infinitely longer than fiddling with 473 genes of a single-celled organism, not to mention the ethical prohibitions (currently) from conducting similar experiments on human chromosomes. Regardless, what would a genetic prime pattern human look like (genotypically and phenotypically speaking)? For instance, while such a human could, by definition, reproduce, would he or she seem human?
The last question is begging for a definition of humanity. Knowledge of an organism’s genetic prime pattern gives genetic engineers a viability starting point. Experiments such as Syn 3.0 point to our growing ability to rearrange and reduce genetic material, literally creating new genetic patterns (at least in mycoplasma) that are viable. Would the equivalent human genetic prime pattern be an adequate minimal definition of humanity?
After all, aren’t we just the sum of our parts?