Cascade of Events Caused Evolution Explosion 520 Million Years Ago

About 520 million years ago, there was an explosion of animal life. Species began to evolve and change, forming the massive variety of creatures that we see today. Now, scientists have revealed that it was a combination of interlinked factors rather than a single underlying cause that led to this evolutionary event.

There are dozens of individual hypothesizes that try to explain this particular explosion of diversity that occurred during the early Cambrian period, known as the Cambrian Explosion. Over the years, scientists have tried to explain this event in three main categories--geological, geochemical and biological. Yet none of the theories fully explain how this phenomenon actually occurred.

"This is a period of time that has attracted a lot of attention because it is when animals appear very abruptly in the fossil record, and in great diversity," said Paul Smith, one of the researchers, in a news release. "Out of this event came nearly all of the major groups of animals that we recognize today. Because it is such a major biological event, it has attracted much speculation about its cause."

In order to learn a bit more about the Cambrian Explosion, the researchers decided to look at the fossil record. They spent four years working on data from a site in northernmost Greenland, facing the Arctic Ocean. This area is known for its wealth of fossil material and for the insights that it provides. After studying the material there, the researchers determined that it wasn't just one theory that explained the explosion of diversity; it was many.

"Work at the Siriuspasset site in north Greenland has cemented our thinking that it wasn't a matter of saying one hypothesis is right and one is wrong," said Smith in a news release. "Rather than focusing on one single cause, we should be looking at the interaction of a number of different mechanisms. Most of the hypotheses have at least a kernel of truth, but each is insufficient to have been the single cause of the Cambrian explosion. What we need to do now is focus on the sequence of interconnected events and the way they related to each other--the initial geological triggers that led to the geochemical effects, followed by a range of biological processes."

The findings reveal a little bit more about this event. They also show how this explosion of diversity was not just caused by one factor. Instead, like most things, it was created through a series of events.