700 million years ago, an inconspicuous creature emerged in the ancient seas of Earth, laying the foundations for the bodily structure of most complex animals, including humans. This creature, the last common ancestor of Bilaterians, played a crucial role in the evolution of vertebrates and invertebrates.
A study conducted by scientists from the Genomal Regulation Center (CRG) in Barcelona and published in the journal Nature Ecology and Evolution revealed that over 7,000 gene groups present in 20 species of Bilaterians, such as humans and sharks, trace their origins back to this ancient ancestor. Approximately half of these genes developed specialized functions, particularly in the brain and reproductive tissues.
The evolution of Bilaterians involved the duplication of genes, leading to the emergence of new functions as these gene copies evolved. A significant moment in vertebrate history was the appearance of tissue-specific genes during two instances of complete genome duplication, enabling one set of genes to perform essential functions while the other contributed to evolutionary innovations.
Specialized genes led to the evolution of new functions in various tissues. For instance, Tesmin and Tomb genes, stemming from a common ancestor, independently took on specialized roles in the testes of vertebrates and insects. At the molecular level, these changes facilitated the development of complex nervous systems, such as the formation of myelin sheaths around nerve cells in vertebrates for rapid nerve signal transmission.
In insects, specialized genes were involved in muscle and external covering formation, enhancing their ability to fly. Meanwhile, in octopuses, skin genes specialized in light perception allow them to change color, camouflage, and communicate with other octopuses.
This groundbreaking research prompts a reevaluation of gene roles and functions in evolution. Co-author of the study, Professor Manuel Irimiy, highlights, “Our work challenges our understanding of genes, demonstrating how essential genes, preserved over millions of years, can easily acquire new functions, reflecting the evolutionary balance between maintaining crucial roles and exploring novel pathways.” This discovery underscores the profound connection between ancient organisms and the intricate modern life we see today, including humans.