how life on Earth began is the ultimate Cold Case most of the evidence has been lost along the way we do know a few things though one is that for the last 3.6 billion years Earth has been home to one bizarre life form after another and that at the cellular and molecular level all living living things are related that's right the simple DNA code that holds the recipe for all living things links all life on Earth to a single common ancestor so what was it and where did it come [Music] from one of the few
remaining Clues to our Origins lies in Western Australia these ancient rock formations called stromatolites are the earliest evidence of life on Earth they're the product of fossilized cyanobacteria or blue green algae ancient as they were these cyanobacteria were biologically complex they had cell walls protecting their protein producing DNA in fact they were so advanced scientists think life must have begun much earlier but evidence of earlier life has been hard to find and there's a pretty good reason why scientists think the cyanobacteria in these rock formations killed just about every form of life that came before
it so what happened our planet was a much harsher Place 3.6 billion years ago than it is today the atmosphere had no oxygen there were no plants animals or insects the sea was loaded with bacteria but most of it was anerobic the only kind capable of surviving in such an oxygen starved primordial soup then a stranger appeared on the horizon and little by little the planet changed Forever This upstart arrived D in the form of cyanobacteria cyanobacteria are photosynthetic they convert sunlight into energy and produce oxygen as a waste product as cyano bacteria flourished their
oxygen waste started building up in the water and atmosphere and as oxygen levels increased the existing Anor robic bacteria started dying off to them oxygen was toxic as the thriving blue green algae slowly poisoned the atmosphere the surviving anerobic bacteria fled to the Bottom of the Sea the oxygen users may have won the day but the die off destroyed all of the evolutionary links to our first ancestors the Anor robes how they made that first giant leap from non-living to living remains one of life's greatest Mysteries [Music] somewhere on Earth around 4 billion years ago
a set of molecular reactions switched on and became life creating little molecules these little molecules began interacting with each other the reactions produced compounds that fed back into the cycle creating more reactions and more molecules the process culminated in one of these molecules being able to copy itself and by doing that genetic information could be passed down but what was the switch that was flipped what breathed life into those first Franken molecules a number of theories have been put forward one early experiment set out to prove that lightning might have applied the energy needed to
trigger life on Earth in its early days researchers created an early Earth atmosphere by sealing water methane ammonia and hydrogen in flasks connected with a loop the liquid water was heated to induce evaporation when the researchers simulated Lightning by adding a spark they found that the solution in the flask contained something it hadn't before amino acids proteins play a crucial role in almost all biological processes and amino acids are their building blocks it seemed the lightning experiment worked but there are other sources of energy that could have triggered the same chemical reactions needed for Life
another popular theory is that simple metab olic reactions occurred near Ancient seafloor Hot Springs enabling the leap from a non-living to a living world these vents still fuel strange underwater ecosystems inhabited by giant tube worms blind shrimp and sulfur eating bacteria many researchers believe these complex high- press mineral-rich environments may be the source of all life on our planet but recently a radical new idea has been put on the table scientists are close to demonstrating that the building blocks of DNA can form spontaneously from chemicals thought to be present on early [Music] Earth that would
mean DNA could have formed before the birth of life then the question would become how did DNA originate we're still a long way from finding out how life appeared on Earth but Clues may be closer than we think our own DNA May hold the answer to one of life's greatest unknowns the mystery of life itself
