Stated Clearly presents: What is Chemical Evolution? Scientists have reason to think that the first living cells on Earth came about through a natural process called Chemical Evolution. What is Chemical Evolution, how does it work, and how is it different from Biological Evolution?
To answer these questions we'll start by first dissecting the terms and then look at an example of how Ehemical Evolution can take simple molecules and organize them into complex structured systems, similar to those found in living cells. The word "Evolution" simply means change over time. Biological Evolution deals with changes in things which were able to reproduce: living creatures make copies of themselves.
The change over time that we see in Giological Evolution is not just random change, oftentimes it is adaptive change. Populations become better able to survive and reproduce within their environments. When conditions are right, biological evolution can even drive a species to develop brand new characteristics and abilities.
For this to happen, biological evolution typically requires three conditions: Reproduction, variation, and selection. Let's see how this works: Many species of Holly have smooth edged leaves. English Holly, however, is covered in spikes which protect the plant from deadly predators.
How did these weapons first evolve? Well, when a holly plant reproduces its offspring often show a random variation. They are slightly different from their parents, and slightly different from each other.
In a forest filled with grazing animals, individual plants which happened to be harder to eat then their siblings are more likely to grow up and have children or their own. Nature, simply by being difficult to survive in, selects who gets to reproduce and pass on their new traits and who does not. In this case mutations which simply caused the vanes that these leaves to extend past their edges, gave rise to a brand new weapon!
The discovery of biological evolution was an incredible breakthrough in science. It explained how new complex traits and abilities develop naturally in living things. The problem is Biological Evolution depends on reproduction in order to work.
Reproduction however, is an extremely complex process in another itself. This begs the question: How did reproduction first evolve? To try and solve this mystery, many scientists are looking into Chemical Evolution.
Chemical Evolution refers to changes in things that need not be capable or reproduction. Examples could be individual molecules or entire chemical systems. A chemical system is a group of molecules that interact with each other.
Molecules, structures, and chemical systems almost always evolve or change over time, but they often evolve towards simplicity. Solid iron corrodes into rust when it comes in contact with the water, proteins breakdown when exposed to too much heat. If simple chemistry is to give rise to something advanced enough to reproduce, there must be situations in which chemical systems can grow in complexity, form new structures, and gain new functions.
In order for this to happen, reproduction, which is needed in biological evolution, can be replaced with a much simpler process: repetitive production. On planet Earth and all throughout the universe, powerful natural events take place in regular cycles: The heating and then the cooling of day and night. The repetitive eruptions a volcanic geysers, the rise and then the fall of ocean tides.
These events repetitively produce, or give birth, to new molecules and chemical systems. These products increase over time and often develop new abilities as they interact with their environment. let's see an example of how this process works!
This here is a special molecule called a fatty acid. It's a collection of carbon atoms, hydrogen atoms, and oxygen atoms all stuck together in a specific pattern. Fatty acids are one of many complex molecules that living cells use inside their bodies.
They build fatty acids with atoms they get from their environment. Scientists used to think that living cells were the only things able to consistently built fatty acids, but check this out! Lab experiments have shown that when simple common gases: carbon monoxide and hydrogen, are heated up with minerals like those found in the Earth's crust, a variety of complex carbon molecules including fatty acids began to grow!
Living cells are not needed! This can happen naturally in underground chambers heated by the Earth's Magma. As pressure builds, these molecules can belch up into pools of water where a simplified version of Natural Selection then takes over.
Most particles blasted into water will either float or they will sink. Nature selects against them staying in the watery environment. Fatty Acids however, remain suspended in warm water, growing in number as the cycle repeats.
When fatty acid concentrations are high enough, they bunched together automatically self-assembling into a stable ball! This happens because water molecules are attracted to the oxygen heads of the fatty acids sorta like a magnet, but water repels their oily carbon tails. When fatty acids pass near each other, their tails are pushed together by water eventually forming a ball.
As fatty acid collections continue to increase, they join together to make a large skins! If fluctuations in the skins happened to make the edges touch, water forces those edges the fused together the end result is a stable hollow container similar to the membrane, or skin, of a living cell! These containers have a brand new ability.
They can trap other molecules inside, acting as an entirely new environment for chemical evolution to continue working within! It's important to note that these membranes do not qualify as living creatures. They can't reproduce on their own the same way living cells do.
That said, the development of these membranes along with many other molecules and chemical systems that scientists have observed, demonstrate an extremely important principle: Chemical Evolution can give rise to new characteristics and abilities. Because of this, scientists hypothesize that under the right circumstances chemical evolution could give rise to systems that are fully capable of reproduction! If they are correct, this would bridge the gap between Chemical Evolution and Biological Evolution, demonstrating that chemistry can indeed give rise to life!
Scientists at the Center for Chemical Evolution and other research groups around the globe are working hard to test this hypothesis. So to sum things up, the main difference between Chemical Evolution and Biological Evolution, is that Chemical Evolution can produce new characteristics and abilities without depending on reproduction. Because of this, Chemical Evolution is being investigated as a possible cause for the origin of life.
I'm Jon Perry and that's Chemical Evolution Stated Clearly. This animation was funded by the Center for Chemical Evolution, the National Science Foundation, NASA, and contributions from our viewers. Though we do receive grants from time to time, Stated Clearly is mainly funded by our viewers.
If you'd like to help out, visit us at statedclearly. com and click contribute. Special thanks goes out the Tyler Proctor who volunteered to work on sound for this project and to our team of science advisors Christopher Parsons, DrDavid Deamer, Nancy Miorelli, DrNicholas Hud.
and DrRam krishnamurthy. Until next time, stay curious!
