Recent research has suggested that a dramatic increase in Earth’s oxygen level cannot explain the sudden diversification of animal life in the Cambrian.
A new paper published in the journal Nature Ecology and Evolution attempts to find an alternative explanation. Drawing from cancer research, they propose that the same principles that are seen in multicellularity are also seem in tumours.
As geobiologist Emma Hammarlund of Lund university puts it, “tumours are successful versions of multicellularity.”
This is the basic premise of their approach.
“Specifically, they tested whether the same molecular tools exploited by many tumors -- to maintain stem cell properties -- could also be relevant to the success of animals in the Cambrian explosion. Cells with stem cell properties are vital for all multicellular life in order to regenerate tissue. For example, cells in the wall of human small intestine are replaced every 2-4 days, through the division of stem cells.
‘Hypoxia is generally seen as a threat, but we forget that oxygen shortage in precise periods and settings also is a prerequisite for multicellular life. Our stem cells are the ones that form new tissue, and they are extremely sensitive to oxygen. The stem cells therefore have various systems for dealing with the effects of both oxygen and oxygen shortage, which is clear in the case of tumors,’ explains [professor] Sven Påhlman.”
However, even this approach fails to tackle to basic question of why animals diversified so rapidly and dramatically. Oxygen can’t explain it. And neither can tumours.