Life on Earth
What is life?
DNA lays the foundation for organisms. In order to be considered a living organism, it needs to be able to adapt to changes in their environment, reproduce, and have a metabolism. DNA paves the way for evolution, as there are various forms of DNA codes and sequences that make up different organisms. When organisms adapt to their environment sometimes a new species is formed. Then once a new species is formed, it needs to reproduce to continue its survival. Finally, the species need to find a source of energy to function.
How did life begin?
There are two different scientific theories as to how life began. One theory is that there was a meteor that crashed to Earth and already had life on it, called transpermia. The theory that scientists most commonly recognize is that life on Earth began 3.5 billion years ago, in the deep ocean trenches near underwater volcanic vents. The energy released by these underwater volcanoes was enough to have a chemical reaction and create the compounds in DNA; adenine, guanine, thymine, and cytosine.
What if the asteroid that ended the dinosaurs, missed?
If the asteroid missed there would still be dinosaurs on Earth considering the possibility that no other catastrophic event occurred. If dinosaurs were still alive they would most likely still be dominating. We wouldn’t have the modern animals like giraffes or elephants simply because they would not have evolved. Dinosaurs could have adapted very well to the environment but there would be no way for them to help us with like milk and wool. If dinosaurs hadn’t been extinct then our ancestors probably wouldn’t have emerged. If it wasn’t for that asteroid humans probably would not have existed.
RECIPE FOR LIFE ON EARTH:
Ingredients and Goldilocks Conditions:
- Complex chemical compounds
- DNA
- A rocky planet (contains large supplies of different chemical elements)
- Just the right amount of energy (enables diverse and stable chemical reactions)
- Liquid water (makes it easy for atoms and molecules to combine and recombine)
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New complexity:
- New organisms with the ability to…
- maintain and fuel themselves (metabolism)
- adjust to changes around them (homeostasis)
- copy themselves (reproduction)
- gain new characteristics over time (adaptation)
Bibliography:
https://www.newscientist.com/article/mg21528795-500-dna-could-have-existed-long-before-life-itself/
http://news.bbc.co.uk/2/hi/science/nature/6444811.stm
Featured image: https://i.ytimg.com/vi/uXdzuz5Q-hs/maxresdefault.jpg
Big History Project Group 