Van Helmont's Early Discoveries on Photosynthesis

In the 17th century, Jan van Helmont initiated a series of discoveries leading to our current understanding of photosynthesis. He meticulously measured the weight of plants and the soil they grew in.

His experiments indicated that plants absorbed minimal soil mass, suggesting that their growth derived from other sources. While he speculated that water was the key factor, he overlooked the significant role of carbon dioxide.

Joseph Priestley later demonstrated that sealing a mouse or a burning candle in a jar depleted the oxygen. He further discovered that introducing a plant into the jar restored the oxygen levels over time.

Ingenhousz's Contribution to Photosynthesis

In 1779, Jan Ingenhousz replicated Priestley’s experiments and recognized that sunlight was essential for plants to replenish oxygen. Jean Senebier, in 1796, elaborated on how plants absorb carbon dioxide and release oxygen, while Nicolas-Theodore de Saussure confirmed Van Helmont’s notion that water also contributed to plant mass increase.

Dr. Emmanuelle Javaux, a biologist and zoologist at the University of Liege in Belgium, focuses her research on the earliest signs of life and the evolution of Earth's biosphere during the Precambrian era. Recently, a paper co-authored by Professor Javaux was published in the journal Nature. The research details the findings from the study of 1.75 billion-year-old fossils known as Navifusa majensis.

The Oldest Thylakoid Membranes

The study identified structures in these fossils called "thylakoid membranes," marking the oldest specimens of such membranes ever found, extending the fossil record back by over a billion years.

The research team examined Navifusa majensis microfossils from Australia’s McDermott Formation, as well as samples from the Congo and Canada’s Arctic regions. The Australian and Canadian specimens contained traces of the sought-after thylakoid membranes.

This discovery indicates that Navifusa majensis was a fossilized cyanobacterium—a single-celled organism crucial to the evolution of photosynthesis. This finding significantly rewrites the timeline of photosynthesis's history.

Extending the Fossil Record

“The oldest known fossil thylakoids date back to around 550 million years ago. Our findings extend the fossil record by 1.2 billion years,” explained Professor Javaux. Cyanobacteria, like those discovered by the University of Liege team, played a vital role in shaping Earth’s early atmosphere through their absorption of carbon dioxide and oxygen release, driving a phenomenon known as the Great Oxygenation Event (GOE).

Occurring around 2.4 billion years ago, the GOE's sequence of events and the types of cyanobacteria involved remain largely unclear. Professor Javaux noted, “The discovery of preserved thylakoids in N. majensis provides direct evidence indicating a minimum age of approximately 1.75 billion years for the divergence between thylakoid-bearing and non-thylakoid-bearing cyanobacteria.”

Foundation of Earth's Biodiversity

The evolution of photosynthesis is foundational to the incredible diversity of life on our planet. It is vital to understanding not only the origins of life on Earth but potentially throughout the cosmos. Scientists hypothesize that even earlier cyanobacteria fossils may contain thylakoids.

Additionally, these thylakoids might have been instrumental in driving the Great Oxygenation Event. The prevalent oxygen molecule, dioxygen, has been essential for the development of aerobic respiration and the more complex life forms it supports.

Professor Javaux concluded, “Microscopic life is remarkable, representing the most diverse and abundant form of life on Earth since life began. Exploring its fossil record with innovative methods will help us comprehend how life has evolved over the last 3.5 billion years. This research may also guide us in our quest to find signs of life beyond our planet!”

There is always more to discover if we are willing to learn.

Learn more:

• The evolution of photosynthesis better documented thanks to the discovery of the oldest thylakoids in fossil cyanobacteria
• Oldest thylakoids in fossil cells directly evidence oxygenic photosynthesis
• Photosynthesis signaling could boost crops and help cure cancer
• Trees and plants losing capacity to mitigate climate change
• Anthropocene represented by Milton Ontario’s Crawford Lake

I'm a freelance writer and commercial blogger providing content services to select B2B marketing clients. With extensive experience in content creation, technical writing, and training, I've held various roles in many of Canada's leading organizations. My specialties include Content Marketing, Social Media, Technical Writing, and Training and Development. View all posts by David Morton Rintoul

Originally published at http://daretoknow.ca on January 6, 2024.