Question: How did life form on Earth? And how come it didn't form on any other planet?
Louise Dash answered on 22 Jun 2010:
Life probably formed on earth when amino acids first formed themselves into proteins. I don’t know exactly how they did that though.
We don’t know that it hasn’t happened on other planets as well. We haven’t found any firm evidence of this yet, but there are clues that there may once have been primitive forms of life even on other planets in our solar system.
It’s also probable that there is life somewhere else in our galaxy! I’m not just making it up, there’s an equation that works out how many extraterrestrial civilization out there – it’s called the Drake equation and you can find out more about it here:
Jon Copley answered on 22 Jun 2010:
How life on Earth began is one of the greatest unanswered questions in science. And it may well have formed on other planets – we just haven’t found it yet.
The reason no-one has figured out yet how life on Earth began is because it is very hard to deduce something that happened probably around 4 billion years ago, when conditions on Earth were very different to today. And life has since left its fingerprints all over everything, so it’s hard to see what was there before.
But scientists are getting closer to understanding how it happened – for example, we now know there are lots of ways to make the “building blocks” for life (molecules such as amino acids) from scratch. But being able to make amino acids is still a very, very long way from being able to see how even the simplest of organisms came into being.
Zoe Duck answered on 22 Jun 2010:
It is thought that in the condictions of early earth some molecules came together to form something called RNA, if you dont know what this is look it up in your textbook or ask your teacher. RNA is self replicating, but it is quite error prone so you get mistakes. eventually, it is thought that deoxyribose sugar replaced the ribose sugar of RNA to give DNA which is much better at not making mistakes. Eventually groups of replicating DNA and RNA came together in a process that helped them to survive better and formed the beginnings of cells.
life may well have formed on other planets, we just don’t know about it yet!
It is a bit like evolution in reverse, things get less and less conplicated the further back you go.
Sharon Sneddon answered on 22 Jun 2010:
In the natural sciences, abiogenesis, or origin of life, is the study of how life on Earth could have arisen from imatter. this is different from evolution, which is the study of how living things change over time. Amino acids, often called “the building blocks of life”, occur naturally, due to chemical reactions unrelated to life. In all living things, these amino acids are organised into proteins, and the construction of these proteins is occurs by nucleic acids. So the really interesting question of how life on Earth originated is a question of how the first nucleic acids arose!
Some facts about the origin of life are well understood, others not. The first living things on Earth are thought to be single cell prokaryotes. The oldest ancient fossil microbe-like objects are dated to be 3.5 billion years old, just a few hundred million years younger than Earth itself. By 2.4 billion years, the ratio of stable isotopes of carbon, iron and sulphur shows the action of living things on inorganic minerals and sediments and molecular biomarkers indicate photosynthesis, demonstrating that life on Earth was widespread by this time.
On the other hand, the exact sequence of chemical events that led to the first nucleic acids is not known. Several hypotheses about early life have been proposed, including theories about RNA, but I’m not entirely sure what these are!