Rather recently the National Aeronautics and Space Administration (NASA) made progression in answering the age-old question of whether or not there is life in the depths of space. They did so by realizing that what scientists previously thought established the basis of life, which was carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorous did not hold true for all forms of life.
GFAJ-1 (grown on arsenic)
Image from Wikimedia Commons
What scientists discovered were bacteria by the name GFAJ-1 in Mono Lake, California cultured by Wolfe-Simon from sediments she and her colleagues collected along the shore of the lake. Mono Lake is known to be hypersaline and highly alkaline. It also has one of the highest natural concentrations of arsenic in the world. Arsenic is usually a toxic and poisonous substance to living things, but this particular bacteria used it in place of phosphorous it seems. When starved of phosphorus, it can instead incorporate arsenic into its DNA, and continue growing as though nothing remarkable had happened. This finding is remarkable because it expands the prevailing view of what it takes for living things to survive.
By introducing radioactive arsenic into the growth medium of some of the microbes, Wolfe-Simon learned that about one-tenth of the arsenic absorbed by the bacteria ended up in their nucleic acids. To confirm that this arsenic was being incorporated into DNA, she used a well-accepted molecular biology technique known as gel purified DNA extraction to isolate and concentrate DNA from GFAJ-1 cells. The value of this technique is that it ensures that no other material from the cell comes along for the ride. NanoSIMS measurement of these concentrated DNA extractions showed that arsenic was indeed present in their DNA.
What this revelation leads to is the idea that life can truly be out there. Our prior knowledge of what it takes to live has been debunked and a more advanced search can be done. Titan, one of Saturn’s moons has arsenic what this find could lead too is the discovery of bacteria living on Titan and utilizing arsenic for photosynthesis.
Clearly the paradigm of, believing earth to be the only planet harnessing life, is just about smashed. With so much we still do not know of the universe, so much grey area, who are we to criticize against life elsewhere?
This discovery in the field of astrobiology has opened the doors for many more to come. What exactly lurks in the universe millions of light years away or perhaps in our own solar system?
Whatever the future holds six things remain to share a few characteristics of living (at least on earth) they are: (from NASA)
- Living things need to take in energy
- Living things get rid of waste
- Living things grow and develop
- Living things respond to their environment
- Living things reproduce and pass their traits onto their offspring
- Over time, living things evolve (change slowly) in response to their environment