History and Mechanisms of Evolution
Throughout history, evolution has been challenged as unproven, false, and downright scandalous. Most of science can be seen by the naked eye or high-powered microscopes, or at least tested by a series of experiments with well-designed controls. For some people, seeing is believing. When it comes to understanding evolution, jumping in a time machine is pretty difficult to do. Until we get a flux capacitor and a working DeLorean, time travel probably isn't going to happen. Bummer.
Evolution is a puzzle, and we don't have all the pieces. Since the events happened over millions of years, some pieces may be permanently lost underneath the couch, tossed out with yesterday's pizza boxes, or buried underground. But just like archaeologists can use ancient artifacts to piece together primitive cultures, science has been able to use fossils and carbon dating to gain clues about the world before we got here.
In addition to studying history to learn about evolution, scientists have been going to their lab benches to recreate it.
A famous experiment by Miller and Urey recreated an atmosphere similar to what Earth probably looked like when life began. By firing electricity into it, which mimicked lightening, they made amino acids from scratch.
One of the current hypotheses about how the world began is the RNA World hypothesis, which states that life was made possible by RNA able to act as both the original genetic material and an enzyme. Can RNA make a functioning cell? Not yet, but recent studies have shown that RNA can chemically interact with itself in a cell-like compartment.
Science has also done leapfrogs in genome sequencing, which tells us the exact order of every DNA nucleotide. We can use genome sequencing to see what genes organisms have in common, and to "watch" gene evolution progress through the tree of life.
We can even use this technology to sequence the genomes of species that have gone extinct, including the wooly mammoth. Their genome was sequenced using DNA extracted from woolly mammoth hair and comparing it to a modern day African elephant. If only we could make Woolly Park a reality. Or can we?
Watch out, we're bringing woolly back. Image from here.
But there's more. Science keeps trying to push the envelope. Other experiments of historical note include a more recent ability for scientists to synthesize artificial DNA and use it to re-create self-functioning, replicating, brand-spanking new bacteria.
Making the building blocks of life, sequencing our ancestors, and creating single-celled organisms are all pretty impressive feats. Is this recreating life from bare bones? Not exactly, but it helps scientists understand what is essential to life and how we might be able to prove our history.