Homo Photosyntheticus Lab guest editor for PALM magazine

Homo Photosyntheticus Lab was invited as guest editor in the "New Visions of the Living World" in the PALM magazine of the Jeu de Paume.

Editorial: Homo Photosyntheticus

In 1972, atmospheric scientist James Lovelock undertook a scientific expedition on the Shackleton to the planetary oceans to measure the various levels of the abundant dimethyl sulfide (DMS), an oceanic sulfur gas known for its climate-cooling effect by decreasing the amount of solar radiation that reaches the Earth's surface. The degradation of DMS in the atmosphere condenses water vapor, leading to the formation of clouds. Lovelock was mostly interested in the fact that the organic sulfur mostly emitted by oceans sprays was coming from its precursor Dimethylsulphoniopropionate (DMSP), a compound found in phytoplankton and algae, and was thus able to reveal the climate feedback loop correlating DMS production by marine phytoplankton with cloud reflection of sunlight. This observation led him to publish, that same year, the first article on the Gaia hypothesis, “Gaia as seen through the atmosphere”¹. It is furthermore estimated that 50–80% of the Earth’s oxygen production comes from the ocean – from oceanic plankton, algae and some bacteria capable of photosynthesis. One species in particular, the cyanobacteria Prochlorococcus, which is the smallest photosynthetic organism of Earth, alone produces 20% of the oxygen in the whole of our biosphere. This percentage is higher than all terrestrial tropical forests combined and both examples are illustrating the extent to which phytoplankton and algae are important for the balance of the biosphere. But with the increase in green tides, harmful algal blooms and sargassum seas, algae and cyanobacteria have gained a bad reputation, even though these proliferations are caused by climate change, ocean acidification and global warming, chemical and nutrients discharges from deforestation, the petrochemical industries, industrial livestock farming and other anthropogenic causes.

The urgency of the environmental crisis demands societal change – reducing the collective carbon footprint, embracing sustainable energies, food alternatives and new ways of living.


And yet, algae offer huge potential for overcoming the environmental catastrophes of the Anthropocene. Algae can be used as biofuels, biomaterials, pharmaceuticals and cosmetics. Their nutritional role is recognized, rich in proteins, minerals, fatty acids and vitamins. Cyanobacteria known as spirulina and the micro-algae chlorella are promising food alternatives, and the food cultures of northeast Asia did not wait for the environmental crises of the 20th century to embrace macro-algae such as kombu, wakame and porphyra (nori) in their diets. The umami flavor of kombu seaweed was discovered in the early 20th century. Control of the lifecycle of nori seaweed by the British scientist Kathleen Drew-Baker² after World War Two gave a new start to the nori Japanese fishermen in need of resilience. A more recent scientific study conducted at the Roscoff Biological Station in the French department of Finistère³ even described how the microbiota of the Japanese has undergone evolutionary lateral gene transfer to better digest nori. Now, in the 21st century, global food cultures are slowly beginning to incorporate macro-algae such as kombu, wakame and nori into their diets, but how might we consume more algae around our tables?

In marine life, many species (the sea slug Elysia Chlorotica, zebrafish, Costasiella Kuroshimae or leaf sheep, etc.) have even successfully incorporated microalgae into their tissue over the course of their evolution in order to benefit from their photosynthesis. The evolutionary biologist Lynn Margulis was fond of mentioning Symsagittifera roscoffensis, the Roscoff marine worm from Brittany, a wholly photosymbiotic species that ingests but does not digest its symbiotic micro-algae, keeping it in its tissue and surviving entirely through its photosynthesis. In Microcosmos, Margulis and Dorion Sagan speculate on this animal-algae, expanding reflection toward a future “Homo Photosyntheticus” of the human species, a future in our evolution in which humans would become fully phototrophic, a human-plant with no need to feed⁴, thus approaching the early speculations of Vladimir Vernadsky, the scientist who defined the notion of the Biosphere in the 1920s. More recently, these marine photosymbioses have inspired medical and biomedical research. Many research teams are trying to take advantage of this photosymbiotic logic to integrate micro-algae on or in damaged human tissue for regeneration through their photosynthesis⁵. The speculations of Margulis and Vernadsky have also inspired speculative bio-artists and science fiction writers. From Quimera Rosa7 to Špela Petrič and Robertina Šebjanič, from Ursula Le Guin to Kim Stanley Robinson⁶, it is a future “Homo Photosyntheticus” that seems to be opening up to humankind.


So how to draw inspiration from this speculative shift to a “Homo Photosyntheticus”? Margulis and Sagan envisioned it as enabling humans to become multi-planetary. The European Space Agency’s MELISSA (Multi-Ecological Life Support System Alternative) program⁷ is considering circular systems for life on other planets, imagining the cultivation of spirulina as an alternative food and oxygen source. The Multicellular Marine Models aboratory at the Roscoff Biological Station⁸ is planning to study the Roscoff worm in space to better understand its photosymbiotic life cycle and its tissue regeneration capacities. Why? Perhaps because we still only know far too little about the oceans, holobionts and the life of algae, these protists that are “queering” conventional taxonomy. Is the objective to go from the ocean floor to outer space and back to Earth, the ocean planet? To finally leave the Anthropocene and enter this Chthulucene⁹ that the philosopher and zoologist Donna Haraway is calling for?


Ewen Chardronnet & Maya Minder

1J. E. Lovelock, « Gaia as seen through the atmosphere », P. Westbroek & E. W. deJong (eds.), Biomineralization and Biological Metal Accumulation, D. Reidel Publishing Company, 1983, pp.15-25. Online at: http://www.jameslovelock.org/g...

2Drew, Kathleen M. "Conchocelis-phase in the life-history of Porphyra umbilicalis (L.) Kütz". Nature. Vol. 164, 4174 (1949): 748–749. Online at: https://www.nature.com/article...

3Hehemann, Jan-Hendrik et al. “Transfer of carbohydrate-active enzymes from marine bacteria to Japanese gut microbiota.” Nature vol. 464,7290 (2010): 908-12. Online at: https://www.nature.com/article...

4Lynn Margulis & Dorion Sagan, Microcosmos, Summit Books, 1986.

5Chávez, Myra N et al. “Photosymbiosis for Biomedical Applications.” Frontiers in bioengineering and biotechnology vol. 8 577204. 6 Oct. 2020.

6Kim Stanley Robinson, Oral argument : a short story, 2015. Online at: https://www.kimstanleyrobinson...

7https://www.melissafoundation....

8https://www.sb-roscoff.fr/fr/e...

9Donna J. Haraway, Staying with the Trouble, Duke University Press, 2016.