An Eye on the Invisible
Bacteria have achieved astonishing diversity through genetic innovation. In their 3.5-billion-year history, they have become the Earth’s living paint, covering nearly every surface imaginable and inhabiting a huge expanse of living and nonliving things.
How bacteria managed to dominate over the other two ancient kingdoms of life--the Archaea and the Eukarya--is still a mystery. But discoveries in recent years that they are far hardier than previously imagined--thriving in such places as boiling springs, Antarctic ice and radioactive waste dumps--have bolstered an intriguing theory: that bacteria, by surviving the ecological catastrophes that wiped out their potential competitors for habitats, were able to innovate in short, intense spurts at a time when they almost literally had the world to themselves.
The latest study to spur such speculation comes from environmental biologists Russell H. Vreeland and William D. Rosenzweig, who in this week’s edition of the journal Nature claim to have discovered and then achieved a “Jurassic Park”-like revival of bacteria that managed to live through the Permian extinction, which wiped out nearly all life on Earth 250 million years ago.
The notion that species innovate when given “ecological opportunity” is not in itself controversial. As Charles Darwin showed in the 19th century, lack of competition on the Galapagos Islands allowed finches that had emigrated from South America to innovate, developing 14 varieties of beaks specialized for harvesting different foods on each of the islands.
Biologists, however, disagree sharply over exactly when and how genetic innovation occurs. Proponents of a school of thought called contingency argue that every species on Earth today is the product of an unpredictable chain of genetic mutations occurring randomly over millions of years. Other biologists, however, advocate a view called convergence, which sees genetic innovation as a more “deliberative” process. They point to studies that show, in the test tube at least, that bacteria tend to achieve most of their genetic improvements in the first few generations after being introduced to environments rich with ecological opportunities.
Bacteria’s remarkable genetic diversity is increasingly profiting human industry today by, for example, enabling new biotechnologies like “bio-remediation” to clean up oil spills, bioengineering to develop new medications and bio-mining to extract valuable minerals.
But as underscored by the controversy over exactly how bacteria achieved their genetic diversity, we have only just begun to learn from the tiny, hardy creatures.
