Ancient human advantages may have been key to outcompeting our ancestors, study proposes

Ancestral rivals to humans may have gained a distinct advantage, according to new research findings.

In a groundbreaking study published in the Proceedings of the National Academy of Sciences (PNAS), researchers at the University of California have discovered a potential key factor that may have contributed to the success of modern humans in evolution.

Led by David Gokhman, the team found that a single amino acid change in the enzyme adenylosuccinate lyase (ADSL) may have influenced the development of certain behavioral traits in modern humans. Interestingly, this effect was primarily observed in females, possibly due to differences in gene expression linked to sex hormones.

ADSL is a crucial component in the production of purine, a building block of DNA and RNA. In the study, female mice with the human variant of the enzyme were found to visit the water dispensing area more frequently when they were thirsty. This behavioral difference could potentially have significant implications for our ancestors, who may have relied on such adaptations to survive in their environments.

The less-efficient version of ADSL in modern humans makes the enzyme less stable and less effective in its production of purine. This inefficiency leads to the accumulation of certain protein molecules in organs, especially the brain, creating unique conditions that could have shaped our evolutionary journey.

However, the exact molecular and cellular mechanisms of ADSL that shape its influence on the human brain are still unknown. The team's findings suggest that certain changes in modern humans affect how our brains develop and function, but further research is needed to fully understand these effects.

The study also highlights the vast differences between modern humans and our extinct relatives, such as Neanderthals and Denisovans. Roughly 80 amino acid variants exist between Homo sapiens and Neanderthals, and one of these variants is found in the ADSL enzyme at position 429, where an alanine was replaced with valine in modern humans.

The first complete genome of a Neanderthal was sequenced in 2010, and the first Denisovan genome was sequenced two years later. These discoveries have provided valuable insights into our evolutionary history and the unique traits that set modern humans apart from our extinct relatives.

As scientists continue to identify behaviors that may have helped modern humans succeed while other hominin species died out, the role of ADSL in shaping our evolutionary success remains an intriguing area of research.

For more updates on the latest scientific discoveries and breakthroughs, sign up for CNN's Wonder Theory science newsletter. Mindy Weisberger, science writer and media producer, author of "Rise of the Zombie Bugs," brings you the most fascinating stories from the world of science.