Evolution usually allows animals to get better at avoiding death. However, new evidence reported by Vanderbilt University seems to find that the rise of early animals hundreds of millions of years ago was the cause of the first massive die-off of complex life — not a super volcano or a meteorite.
Scientists believe that for more than 3 billion years, microbes were the only life on Earth. At some point, a few of the microbes evolved to be able to photosynthesize, or convert sunlight into energy. The byproduct was toxic to most of the other microbes, who were used to an oxygen-free environment. But for the microorganisms photosynthesizing, the development allowed them to become complex, multicellular forms called Ediacarans, which took over the planet around 600 million years ago. Ediacarans were basically like plants: immobile marine life shaped like discs, tubes, fronds, or quilts.
Paleontologists call the ensuing period the "Garden of Ediacara," emphasizing the so-called peace of the era — that is, Ediacarans politely didn't eat each other. At least not until 60 million years ago, when they evolved even further into what we now call animals (vertebrates, mollusks, anthropoids, annelids, sponges, jellyfish).
It was these independently moving, hungry critters that caused the first extinction, by eating all the Ediacarans, the scientists say.
"This study provides the first quantitative palaeoecological evidence to suggest that evolutionary innovation, ecosystem engineering, and biological interactions may have ultimately caused the first mass extinction of complex life," Simon Darroch, the assistant professor of earth and environmental sciences at Vanderbilt University, told Science Daily.
Perhaps that's just a fancy way of suggesting that it's a dog-eat-dog world out there, and may the hungriest mollusk win. Jeva Lange