How life began

The theory is, about 15 billion years ago (15,000,000,000) the Universe was nothing more than a very small speck of mass. This speck was probably no bigger than the head of a pin. Everything in the Universe, all the galaxies, stars, planets, and even the matter making up your body, was squished up tightly in this tiny space.

Eventually, after a very long time, this speck exploded. All of a sudden, in a giant flash of unimaginable heat and power, the Universe was born. Over a period of billions and billions of years, the Universe became what we see today. Slowly stars began to form, and around these stars planets formed.

About 4.6 billion years ago our Earth looked very different than it does today. Instead of the beautiful blues, greens and whites of today, it would have looked red and orange. The surface of our planet was covered in oceans of hot lava. Instead of breathable oxygen, the atmosphere contained a mix of deadly poisons.

Still, there was no life. No fishes to fill these oceans, no plants to cover the rocky surface, no animals to graze the wilderness. Just a barren wet rock, orbiting the Sun. The Earth's atmosphere now contained a mix of very poisonous gases, including carbon monoxide, carbon dioxide, nitrogen oxides, hydrogen sulfide, methane, and cyanide. Breathing this air would cause death to most life forms as we know them.

What forces changed this barren wasteland into the beautiful garden that it is today?

Biologists believe that the process that created life is something called evolution. Earth's ancient oceans while lifeless, were filled with the chemicals needed for life. These chemicals were not alive, but they were there sloshing around. They call these chemicals “primordial soup.”
Instead of alphabet letters, this soup was filled with amino acids, proteins, lipids, and other basic components that are commonly found in lifeforms today.

The Miller Experiment About Life Began

When scientists set about solving the problem of how life began, they first looked for a source of the chemicals out of which living things are made. They devised an experiment, that under the primitive Earth’s conditions, the complex chemicals of life could form from simple, inorganic precursors. In 1953, Stanley Miller tested the theory:

1.  Miller essentially put methane, or natural gas, ammonia, hydrogen gas, and water vapour into a beaker, based on the theory of what the primordial atmosphere would have looked like.
2. Next, he simply put an electric charge through that mixture to simulate lightning going through an early atmosphere.
3. After sitting around for a couple of days, all of a sudden there was this brown ‘soup’ all over the reaction vessel.
4. On analysis of the vessel, rather than only having methane and ammonia, he actually had amino acids, which are the building blocks of proteins, fatty acids and other complex biological molecules.
5. So the chemistry that Miller was discovering in this wonderful experiment was not some improbable chemistry, but a chemistry that is widely distributed throughout our solar system.
6. The experiment used water (H2O), methane (CH4), ammonia (NH3) and hydrogen (H2).
7. The chemicals were all sealed inside a sterile array of glass tubes and flasks connected together in a loop, with one flask half-full of liquid water and another flask containing a pair of electrodes.
8. The liquid water was heated to induce evaporation, sparks were fired between the electrodes to simulate lightning through the atmosphere and water vapour, and then the atmosphere was cooled again so that the water could condense and trickle back into the first flask in a continuous cycle.
9. The chemicals found in the 'soup' of Miller's experiment were found to be accumulated in lakes and ponds, where they changed, combined, and re-combined in millions of different ways over vast periods of time.
10. Complexity increased until cell like structures appeared with the first major characteristics of life: the ability to reproduce and grow, feeding on materials from the ‘primordial soup’ in which they formed.

Life's Beginnings Organ of Earth

The presence of life in its present form would not be possible if the earliest life forms had not changed constantly, adapting to their environment and circumstances. Getting from the far left in figure 6 to the far right, where humans appeared, involved billions and billions of tiny changes, starting with the first cell that appeared about a billion years after the planet itself was formed.

1. Two types of prokaryotic cells were present when life began and are still around today: Archaebacteria and bacteria. (Single celled)
2. Prokaryotic cells increased in complexity over the time
3. Eukaryotic cells first appeared approximately 1.5 billion years ago. Development of the green pigment chlorophyll enabled the use sunlight energy to make food from water and carbon dioxide, releasing oxygen into the Earth’s atmosphere for the first time.
4. These, the first plants gave rise to the Plant Kingdom we know today. They not only maintain an oxygen rich atmosphere, but make the food upon which all other life depends.