Breaking the rules for life…

Wow.  There’s a place called Mono Lake, in California. It’s an ancient saline lake (3 times as salty as the ocean) with a pH of about 10, making it rather alkaline. It is also loaded with arsenic. Though you and I might think that would make it quite inhospitable to life, it supports a very diverse and interesting ecosystem, including brine shrimp and algae.

Mono Lake

Mono Lake, California


Most excitingly, NASA researchers recently discovered a bacterium living in the lake, that actually uses arsenic instead of phosphorus as the backbone for its DNA molecules. Up until now, phosphorus (along with oxygen, carbon, hydrogen, sulphur  and nitrogen) was thought of as one of the building blocks of life.

What does that mean for the possibility of life on Earth? And what about life on other planets? Should we pump lots of money into searching for it? And if organisms can adapt so well to their surroundings, perhaps we shouldn’t worry quite so much about climate change and damaging habitats, as surely, life will always prevail? Well I’m playing devil’s advocate here, but you could do the same in a classroom discussion!

One thought on “Breaking the rules for life…

  1. Micol

    On the other face of the medal, researcher Rosie Redfield has blogged critically about the NASA paper, stating that

    “NASA’s shameful analysis of the alleged bacteria in the Mars meteorite made me very suspicious of their microbiology, an attitude that’s only strengthened by my reading of this paper. Basically, it doesn’t present ANY convincing evidence that arsenic has been incorporated into DNA (or any other biological molecule).”

    read her analysis at:

    could NASA be exaggerating evidence to garner support for the search for extraterrestrial life? In a world where funding sources influence the questions reearchers explore, and where news sweeps across the planet in moments via the internet, it is important to keep those critical eyes peeled, and a mind open to ideas being corrected, revised, or even rejected.


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