A new study suggests Earth's first animals evolved slowly because they reproduced asexually, limiting competition in ancient oceans. Researchers from the University of Cambridge say a later shift to sexual reproduction helped drive a surge in biodiversity during the Ediacaran period.
The findings, published in Nature Ecology and Evolution, focus on organisms from the Ediacaran period between 635 million and 539 million years ago. Many of these early animals, such as Fractofusus, reproduced through runners that created genetically identical offspring, similar to strawberry plants. Lead author Dr. Emily Mitchell said life was stable enough during that time that there was little pressure to evolve new traits. Co-author Professor Andrea Manica noted that connections via runners allowed organisms to share nutrients and avoid direct competition. The team analyzed fossils from Mistaken Point in Newfoundland using laser scanning, spatial analysis and artificial intelligence. Their simulations showed that greater dispersal distances linked to sexual reproduction coincided with rising environmental stress and higher species diversity. The research received support from the Natural Environment Research Council.