Rocks and oceans lead him back to ancient times
Donald Canfield uses chemistry and biology to study the Earth's past. His work often causes the rewriting of textbooks on the history of the oceans - and thus also the history of life. He is the 2023 recipient of the Villum Kann Rasmussen Annual Award in Science and Technology.
“I never want to hear you say that again!”
These were the words of Donald Canfield's supervisor at Yale University, Bob Berner, when Canfield, as a young, newly minted Ph.D. and frustrated at not being able to find a job, in 1988 announced that he did not want to waste his life as a jobless Ph.D. Instead, he would rather give up research and open a bicycle shop.
But it never came to a bicycle shop. A job did come along, and so did a lifelong research career for American-born Donald Canfield, who is today a Professor of ecology at the University of Southern Denmark.
Donald Canfield is dealing with some of the big questions about the history of the Earth:
What did the Earth look like billions of years ago, and why does it look different today? Why did life evolve the way it did, and how was it even possible? What interactions between chemistry, geology and biology make Earth such a living and dynamic place with vital elements like oxygen, nutrients and carbon constantly circulating in global cycles?
Cyanobacteria in the window
He finds the answers in studies of rocks, in sediment samples from the seabed and riverbeds, in tanks with sea sponges and in trays with algae. Indeed, you can often find slimy green mats of cyanobacteria growing in plastic trays in his office window at the University of Southern Denmark. You also find his close colleagues at SDU, some of them he has known and worked with since his first visit in Denmark in 1990.It was the sea that originally inspired Canfield to become a researcher – more specifically, an oceanographer. As a child he loved to look at the sea, to listen to it, to be in it, to go fishing with his grandfather in the Florida Keys, and to watch the famous oceanographer Jacques Cousteau on television.
Canfield's most important contributions 1 - Canfield Ocean
When Donald Canfield came to SDU in 1998 and was waiting for his laboratory to be built, he used the time to write one of his most significant papers, which was published in Nature: a new theory for the primeval ocean.
It was common knowledge that the Earth's atmosphere and oceans became oxygenated to something like today’s levels during the "The Great Oxidation" event 2.4 billion years ago.
Canfield, however, saw something different in the available evidence and suggested that Earth’s atmosphere did not reach full oxygenation and that the oceans remained largely oxygen free for the next 1.7 billion years. This ocean state of low oxygenation has since been called the Canfield Ocean.
Canfield's most important contributions 2 - Animals and the chemistry of the oceans
When a worm or a crab burrows in the ocean floor, it performs bioturbation, meaning that the activity of living animals contributes to stirring the sediment and mud of the seabed to an extent that impacts the entire chemistry of the sea.
In a paper in PNAS, 2009, Canfield and his team show that 550-600 million years ago, living animals dug around in the ocean-bed to an extent that led to the oxygenation of the mineral pyrite. This led to raised levels of sulphate in the ocean water, and with time this was deposited as gypsym – one of the most common sulfate minerals in nature today. This paper helped raise the awareness that bioturbation can cause enormous environmental changes.
Canfield's most important contributions 3 - The evolution of animal life and oxygen
Most of us think that all animal life on Earth is so dependent on oxygen that oxygen and animals are inseparable partners: when there is not much oxygen on Earth, there cannot be animal life.
In a series of papers, Canfield and his team have shown that from about 1.7 to 1.0 billion years ago there was about 4% of todays’ levels of oxygen in the atmosphere. This doesn’t sound like much oxygen, but they further showed that the earliest animals, represented by sea sponges, did not need more oxygen than this to live.
As animals evolved some 700 million years ago, there was likely sufficient oxygen for early animals 1 billion years before animals evolved. In this case, factors other than oxygen likely controlled the timing of animal evolution.
”The thing about the history of Earth is that there are so few constraints that any crazy idea can get some kind of credence. I didn't want to be that guy. I wanted to be the guy that thinks carefully about it and understands what is going on
Meet the researcher
Donald Canfield is Professor of Ecology, Head of Research, Department of Biology, University of Southern Denmark Author of more than 350 scientific papers, cited nearly 55,000 times Member of the Royal Danish Academy of Sciences and Letters, Royal Swedish Academy of Sciences, Royal Society of London, National Academy of Sciences (US). Fellow, American Geophysical Union, Society for Microbiology, Geochemical Society and American Academy for the Advancement of Science (AAAS) Chair, Danish Institute for Advanced Study (DIAS) Villum Investigator Recipient of the Vladimir Vernadsky Prize (2010), the Urey Prize (2011) and the Order of the Dannebrog (2021) Married to Marianne Prip Olsen. Together they have the children, Lind Prip Canfield (27) and Ellen Prip Canfield (22).