Octopuses and squids defy the slow pace of evolution

Evolution is often thought of as a slow, creeping process. But when it comes to octopuses and squids, it seems nature works in quick, sharp bursts.

Over the last 500 million years, nearly all the evolutionary changes in these creatures have happened during short periods when new species appeared.

Scientists from the University of Auckland studied these remarkable animals, offering fresh evidence for an idea that’s stirred debate for decades.

The concept, known as punctuated equilibrium, was first introduced in the 1970s by paleontologists Stephen Jay Gould and Niles Eldredge. Instead of slow, gradual changes, this theory suggests that evolution typically moves in sudden jumps, with long stretches of calm in between.

New approach to evolution

Researchers in the University of Auckland’s Department of Physics took a new approach to studying evolution.

The team refined a probabilistic model and used BEAST 2, a powerful software tool for building evolutionary trees, to track how species changed over time.

The experts applied their method to cephalopods, a group that includes octopuses, squids, cuttlefish, and vampire squids.

By examining traits such as shell shapes, the number of tentacles, and fin structures, the researchers found that gradual evolution played only a “trivial role.”

Fast-paced evolution unveiled

The team also studied the evolution of Indo-European languages and ancient enzymes involved in genetic coding. According to the analysis, these too evolved in sudden, dramatic leaps that the researchers refer to as “saltative branching.”

The idea of saltative branching highlights a shift in how scientists think about evolution. It captures the idea that these rapid changes occur precisely when new species split off from the family tree.

Instead of a steady march, evolution – at least for cephalopods and other systems studied – seems to move in energetic, unpredictable bursts. It’s a reminder that nature often rewrites its own rules, and sometimes all at once.

Language, life, and leaps

The study extended beyond biology. The evolution of Indo-European languages revealed a similar pattern of fast paced change.

The findings support the “hybrid theory,” which suggests that these languages originated south of the Caucasus Mountains before spreading northward.

Even aminoacyl-tRNA synthetases – enzymes that trace back to life’s beginnings – show signs of evolving in quick bursts.

A theory gains momentum

For decades, punctuated equilibrium has sparked discussion and debate. It’s been applied to bacteria, dinosaurs, cancer, and even human culture. But questions about its general validity have lingered.

Niles Eldredge, curator emeritus at the American Museum of Natural History in New York, weighed in on the research. In an email to the authors of the study, Eldredge expressed optimism that this research might finally sway the skeptics.

“The new research may serve as a ‘tipping point’ for acceptance of the theory, which has remained controversial for decades,” he said.

Eldredge added that over the past 50 years, the concept has been used broadly but doubts about its widespread applicability remained.

Now, with the help of advanced mathematical techniques, the new study shows that rapid evolutionary changes almost always align with the appearance of new species. The paper, he said, “removes all doubt.”

What rapid evolution means for science

The idea that evolution can happen in fast paced bursts opens new doors for how scientists think about life’s history. It suggests that sudden environmental changes, genetic shifts, or even random chance could trigger these leaps, reshaping species in a relatively short time.

This challenges the long-held view of evolution as a steady, gradual climb. Instead, it points to a landscape full of sudden turns and quick adaptations.

For researchers, it means looking closer at the moments when species first appear, as these may hold the real action in evolutionary history.

The study also hints at how life might respond to today’s rapid changes in the environment. If evolution can move quickly when needed, it raises both hope and questions about how species will adapt to the pressures of climate change and habitat loss.

For now, the study of octopuses and squids adds another layer to our understanding of evolution – one that shows nature’s ability to move in quick, surprising steps when the time is right.

The research was published in the journal Proceedings of the Royal Society B Biological Sciences.

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