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3. Chemical Signature/ Isotopes
There are two commonly occurring carbon isotopes – carbon-12 and carbon-13. Life prefers to use the lighter isotope of
carbon which is carbon-12. Inorganic carbon sample always contains a small proportion of carbon-13.
On an island off the coast of Greenland, rocks about 3.8 bn years old with lower carbon-13 isotope have been found suggesting a biological origin. However these rocks have been subjected to high pressure and heat. So this line of evidence
alone is not conclusive.
While each line of evidence individually is subject to controversy, all three put together give us important clues about the
origin of life on earth.
References:
1.
Astrobiology course on Coursea.org (https://www.coursera.org/course/astrobio)
2.
Book: Life in the Universe by J. Bennett, S. Shostak (http://www.amazon.com/Life-Universe-Edition-Jeffrey-Bennett/
dp/0321687671)
WORDS: HENNA KHAN
Mumbai, India
Owner at Universe Simplified - [email protected] -http://www.universesimplified.com/
Astronomy/ Science Educator, Skeptic, Travel Freak, Proponent of Disrupt Education
ICY SCIENCE | QTR 1 2014