Origin of Life
Home Home to many animals, plants, insects, molds, invertrebrates, and other many species EARTH
How did we get here? It is the job of a biologist, or someone who studies life, to learn where life came from, how it developed, and to try and determine how life will continue to develop. Biologists today are not completely sure how life began on Earth, but after many years of studying life forms, they have come up with guesses. We call these guesses Theories.
Most common theories Big Bang Theory Evolution
Big Bang Theory According to this theory, 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.
Big Bang Theory 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.
Earth’s Beginning 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 was made of a mix of deadly poisons.
What Earth looked like 4.6 MYA
Earth For the first 500 million years, the Earth would remain as a giant lifeless ball of fiery lava. For another 300 million years after that, it would be too hot for liquid water to form. Finally, after 800 million years, an unimaginably long period of time, our home planet cooled enough for liquid water to begin to form. Everywhere rains began to fall, filling the lower portions of the Earth with water, forming lakes, oceans, and rivers.
Earth 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, hydrogen sulfide, methane, and cyanide. Breathing this air would cause death to most life forms as we know them.
So how did life arrive on Earth? What came first the chicken or the egg? A bit more complicated than that Evolution happens
Scientist Believe…. Life began on the shores of these ancient oceans, in pools of water called tidal pools. These shallow pools would have been full of this “life soup”. Over many millions of years, as the ingredients of life splashed around in these pools, possibly helped by lightning strikes, they formed the first cells.
What are cells? A cell is a basic unit of life. They are tiny packets, or bags of organelles or tools needed for the cell to survive. A cell can eat, move around, and reproduce. These first cells were very simple, and because there was little or no oxygen available probably did not need it to survive.
How did they survive? Protein, amino acids and lipids they became consumers (ancestors of animals) Over time food diminished and cells formed into producers using chemicals and the sun for energy (ancestors of plants)
Advanced Evolution Simple cellsmulti-cellular humanLIFE had a long way to go The first important advancement was the development of cells that use oxygen. Remember, the first cells could not use oxygen, because there was not enough of it in the air. However, as these first cells carried out the business of living, they released oxygen into the atmosphere. Over a very long period of time, our atmosphere changed from a poisonous and deadly mix of gases, to the atmosphere we know and love today
New atmosphere, new life Cells evolved that could use oxygen to carry out their bodily functions. Because oxygen is a much more efficient gas, this opened the door to larger, faster, and more complex cellular life forms.
Advances in multi-cellular life Creatures began to arise that were made up of two cells, ten cells, or even thousands, or billions of cells. These cells began to specialize in different jobs. Some acting as hearts, others as eyes, others as brains, allowing life to become very complex.
Survival of the fittest But wait a minute. Are we saying that life started as a simple soupy mixture of chemicals and then on its own grew to form hippopotamuses, elephants, and all other forms of life. Who decided what animals would look like? Who decided that ears would be on the side of an animals head, eyes in front, and a nose in the very middle. Didn't someone, or something have to direct this process?
Natural Selection This law says that the strongest life forms live, while those that are weaker die, and is often referred to as survival of the fittest. In other words, if there are 100 hippopotamuses in a heard, only the strongest will live to reproduce, or to create offspring.
But how does Natural Selection determine what an animal will look like? Think about it. Who do you look like? Your mother? Your father? Your uncle Lenny? You look like your ancestors. The people who created you. If only the strongest hippopotamuses survive to create baby hippopotamuses, then the babies are going to resemble the strong hippos. If these hippos have ears on the side of their heads, then so will the babies.
Evolution Example Now lets suppose that some of the hippos have bigger mouths. As a result, they are able to eat more food. As the bigger mouthed hippos eat all of the food, there is less for the smaller mouthed hippos. What happens? More of the bigger mouthed hippos survive to reproduce. Meaning that many of the baby hippos will have big mouths.
Evolution in a nutshell Over millions of years, plants and animals have evolved into many different forms. Some with big mouths, some with small mouths, some with sharp teeth, some with no teeth, eyes in the front, eyes on the side, two eyes, eight eyes, and everything in between. All of this evolution guided by the simple law of survival of the fittest.
Does Evolution Continue Today YES, evolution continues today. Guided by survival of the fittest, life forms are continuing to change and evolve. The plants and animals we know today will be very different in the future. Who knows what creatures will evolve. Who knows how Humans will evolve. Even our own offspring may look very different millions of years from now.