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Sudbury researcher’s work could push back earliest animal life by 350M years

Published in the journal Nature, a fossil discovered by Dr. Elizabeth Turner — which seems to be an ancient sponge — could be the earliest evidence of animal life, 890 million years ago

 

Science is incremental. It moves slowly, adding each brick of new understanding to build a wall of knowledge. 

In some cases, that can mean you find something as a young person working on your PhD, something intriguing, and the passage of time allows for research to deepen your understanding, then a research grant can support the work to establish a clearer picture of what you found.

Then, you realise what you found could be proof of the existence of life on earth 350 million years earlier than previously thought.

This is the story of Dr. Elizabeth Turner and the Horny Sponge. (Worst children’s book title, ever.). The sponge, one that you may find in a store today under the name Mediterranean bath sponge, may prove the existence of animal life 890 million years ago, far earlier than previous evidence, which showed animal life emerged some 540 million years ago. 

It is a revolutionary understanding of the existence of life on earth. She published an article in Nature and was soon interviewed by CNN about her findings. 

“This is a story about slow science,” Turner told Sudbury.com. It is a story about the incremental advancers in research, and the ways each researcher can build off the knowledge of their colleagues.

When Turner, now a sedimentary geologist, research scientist and professor at Laurentian’s Harquail School of Earth Sciences, was in the Northwest Territories for her PhD research, she found an interesting sample.

“I initially encountered the material in my PhD samples, several decades ago. It was an accident that I encountered the material,” said Turner. It was an accident as she was collecting a vast number of samples from their area, but that particular sample wasn’t related to her research at the time, even though she found it intriguing.

The samples she was viewing were about 890 million years old, but as her research focused on cyanobacteria, she wasn’t able to pursue further understanding. But there was something that nagged at her. 

“When I looked at them under the microscope, hundreds and hundreds of these samples, in just a few of them, I found something that didn't fit,” said Turner. “Something a whole lot more complicated than one would expect in rocks of that age.”

Not only was the sample out of place, but Turner noticed something familiar. 

“It looked similar to sponges that one finds under the microscope in the younger reefs,” said Turner. “But I couldn't prove it, it wasn't the objective of my thesis at the time.” 

But rather than be upset she couldn’t pursue it further, Turner said she’s actually glad. Now that so much time has passed, she can build an understanding of the sample's place in the world and in time, because she has the work of other researchers upon which to base her hypothesis.

“This work from other people had to reach a certain critical mass for me to be able to use it as a foundation to present my own similar, but much older material,” said Turner. 

Incremental science, or “slow science,” as Turner puts it, made it possible to find an answer where Turner would have come up empty. 

“What allowed the study to come to fruition was the work of other people,” said Turner. “And by that, I mean the people out there in the world that do wonderful, seemingly esoteric work on how sponges get preserved. Because they're not normal fossils.”

This fact, the abnormal aspects of how sponges preserve, make Turner’s an important find. To a layperson’s understanding, fossils are bones or hard structures that have been preserved in almost their true form. This is because they are already hard, said Turner. 

When an animal — and the term ‘animal’ includes bacteria and algae, as well as people — dies, there is decomposition. If an animal is entirely soft-bodied, no hard shell or bones that would mineralize over time, there is not likely to be fossilized remains; no minerals in the body, essentially, no rock-like qualities, then no mineralized fossilization.

Therefore, it is difficult to understand life previous to this understanding, this 541-million-year point at which mineral fossils become the key. 

“Earth is four and a half billion years old,” said Turner. “Life has been around, in general, for at least three and a half billion years; but most of that time, most of that three and a half billion, is represented by microbial life — by bacteria and and not really much else.” 

Turner said the oldest of all single-celled algae, which are not bacteria, are approximately 1.5 billion years old. 

“The oldest true multicellular, microscopic algae is about one billion years,” said Turner. “The oldest known fungus, probably around 900 million years, the oldest, well-preserved animal fossils are younger, and only in rocks that are younger than 540 million years.” 

But the complexity of the structures — the animals with shells and large bones to preserve —  and the complexity of the diversity of the different types of organisms presented at that time, “implies that there has to have been a serious back history of animal evolution prior to the time when animals developed the ability to make ‘hard parts’,” said Turner.

That complexity points to evolution, and to evolve from something, it must first exist in a simpler form, one that perhaps could not be fossilized.

And now, to the horny sponge. A sponge of the dictyoceratida and dendroceratida group, the horny sponge can still be found on reefs (and even in your shower), commonly known as a Mediterranean bath sponge. 

“When we look at deep time evolution, there are ways of predicting time using molecular clocks,” said Turner. “Major organism lineages in molecular-clock estimates suggest that sponges probably appeared around a billion years ago.”

Turner said sponges are the most basic type of animal in the animal tree of life. 

“So the earliest animals should probably have been something sponge-like,” said Turner. 

It’s about looking at the span of time, she said, and looking for possible evidence. Here comes that sample once again. 

“I'm proposing that I have found something that may be an early sponge, fossils that are 890 million years old.”

Turner notes again that science is incremental, and with geology, not at all black and white, so she is clear that there is no, “Holy grail, this is the end” when it comes to research. Rather, one new find begets another, and so builds the wall of knowledge.

“If you really want black and white answers, or to depend entirely on numerical answers, and you think every study is an end unto itself, well, geology is not for you,” said Turner. “Because you have to have a tolerance for gray areas, and the fact that you may not arrive at a perfectly conclusive end to your study.”

But even with room for new conclusions about the sample she found, Turner is confident in her research and findings. 

While most people would see “wiggles in rock” as Turner puts it, it is the specific nature of these wiggles that are special. 

“The thing that makes this microfossil so distinctive is the fact that, yes, microscopic wiggles in rock, but the wiggles do something very geometrically distinctive,” said Turner. 

The ‘wiggles’ are not random, but rather, branched. And those branches do something specific: they rejoin each other. 

“Rejoining is something that most types of branching organisms don't do,” said Turner. “And not only do they branch and rejoin, they do it in three dimensions to make a meshwork.” 

That meshwork is the same in all directions and “it is very, very distinctive,” said Turner. “Microbes don't do that, cyanobacteria don't do that, like microscopic filamentous algae don't do that; even fungi, which have a distinctive branching pattern, do not do this,” said Turner.  

The branching pattern also matches that found by paleobiologists, but those samples are significantly younger than the 890 million year old sample found by Turner. These biologists have also researched how these sponges decay, which also assisted Turner in developing her hypothesis.

“There's a pretty obvious connection between the material,” said Turner. “I have the exact same microstructure in fossil sponge bodies and modern day sponges, like the Mediterranean bath sponges.”

Turner hopes that her discovery, the potential for evidence of life on earth far earlier than ever proven before, is a brick for others to build on.  

“My purpose here was to present this novel kind of information, and give what I think to be the most parsimonious explanation, logical interpretation that is minimalist, and then just put it out there for the scientific community to evaluate,” said Turner. “So that's what's going to happen.”



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Jenny Lamothe

About the Author: Jenny Lamothe

Jenny Lamothe is a reporter with Sudbury.com. She covers the diverse communities of Sudbury, especially the vulnerable or marginalized.
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