The earliest life forms we know of evolved around 3.7 billion years ago. The world’s oldest known animal, Dickinsonia, dates to about 540 million years ago. A discovery in a remote region of north-west Canada is about to change what we understood until now. According to a study published in the journal ‘Nature’, fossils of ancient sponges found in rock samples may be the earliest sign of animal life. They look like the skeletons of modern sea sponges, and date back 890 million years. That’s about 350 million years older than Dickinsonia – the oldest undisputed fossils of any animal. The fossils were unearthed in a rugged mountainous terrain that was a prehistoric marine environment. Apparently, these simple creatures were thriving in underwater reefs many millions of years earlier than previously thought.
Move over Dickinsonia
The history of animals – and by extension ours – is now back in the spotlight. “We are animals,” geologist Prof. Elizabeth Turner of Laurentian University in Canada who conducted the research told ‘USA Today’. “And we have a big brain, and we’re capable of wondering about stuff, and we wonder how we came to be. What happened before, and what was it like? How did it begin? This is really digging into that. I’m shaking up the apple cart.” “The earliest animals to emerge evolutionarily were probably sponge-like. This is not surprising given that sponges are the most basic type of animal both today and in the fossil record,” Prof. Turner explained in a ‘Reuters’ article. “The existence of a protracted back-history is not surprising, but the sheer duration of it – a few hundred million years – may be a little unexpected for some researchers.” “I believe these are ancient sponges — only this type of organism has this type of network of organic filaments,” Joachim Reitner, a geobiologist and sponge expert at Germany’s University of Göttingen told the ‘Associated Press’. “What’s most stunning is the timing,” added Paco Cárdenas, a sponge expert and researcher at Sweden’s Uppsala University. “To have discovered sponge fossils from close to 900 million years ago will greatly improve our understanding of early animal evolution.” Dr Cárdenas added: “This would be the first time that a sponge fossil has been found from before the Cambrian, and not only before, but way before — that’s what’s most exciting.”
Let the debate begin
Some within the scientific community are cautious about the findings. The reason is because of ancient Earth’s oxygen levels and the circumstances under which the sponges lived. “Here I am saying, ‘Uh-oh, the first animals appeared before that.’ So they didn’t require that oxygen. So people may be not so comfortable with it,” Prof. Turner commented in the ‘USA Today’ article. “This is not the holy grail. It’s just a step toward a better view on animal evolution. We know there has to have been a time, an episode or an interval of hidden evolution in animals prior to 540 million years ago. The question is – how far back did it go, and what was it like? That’s the big hole.”
sponge, fossil, animal, Dickinsonia