A study led by the University of Oxford has shed new light on the evolutionary origins of complex brains, identifying ancient genome duplication events as a key driver in the emergence of diverse brain cell types. The study, published in Nature, was co-led by Professor Sebastian Shimeld (Professor of Evolutionary Developmental Biology, Julian Huxley Fellow and Tutor in Zoology) and Professor Peter Holland, with Yuanzhen Zhu (Balliol 2023, DPhil Biology) as first author.
The research team compared gene activity in individual brain cells across five species, including humans, mice, lizards, lampreys, and amphioxus, one of the closest invertebrate relatives of vertebrates. By tracing the evolutionary history of different brain cell types, the researchers found that two whole-genome duplication events, which occurred more than 500 million years ago in the ancestors of vertebrates, provided the genetic material that enabled new and increasingly specialised brain cells to evolve.
Professor Shimeld said: ‘Our findings reveal that two genetic doubling events were foundational in enabling the evolution of complex brains. By duplicating every gene in the genome, nature gained raw material that could be repurposed to build new types of brain cells.’
Commenting on the work, co-author Professor Peter Holland highlighted the contribution of first author Yuanzhen Zhu, noting that the analyses were ‘mind-bogglingly complicated’ but led to a clear conclusion: ‘new brain cells needed new genes. And not just any genes – these were the extra genes spawned by accidental doubling of DNA before ethe first fish swam in the sea.’
Yuanzhen added: ‘I feel incredibly fortunate to have been part of this research. We found what may be the first evidence of radiative evolution in neuronal cell types, while another team independently observed a remarkably similar phenomenon in blood cell types. It has been exciting to see these parallel discoveries emerge from different biological systems. We also developed new ways of understanding and classifying cell types. I am genuinely thrilled by these advances and deeply grateful for the opportunity to work with such exceptional collaborators.’
The paper ‘Whole genome duplication shaped cell 1 type evolution in the vertebrate brain’ has been published in Nature.