Junk DNA Deforms Salamander Bodies yet...

Junk DNA Deforms Salamander Bodies - Yet the unfit creatures survive, challenging our long-held view of evolution

Douglas Fox

...DNA is often called the blueprint of life. It contains the precise information that determines the structure and function of every cell in every species. But the latest discoveries about salamanders upend this long-held notion of a fine-tuned genome. They reveal that DNA also shapes its owner in ways that have nothing to do with its informational content. DNA can distort bodies and organs like a funhouse mirror; a species can tolerate only so much DNA before experiencing those side effects....

The salamanders would be on death’s door if they were human. “Everything about having a large genome is costly,” Wake told me in 2020. Yet salamanders have survived for 200 million years. “So there must be some benefit,” he said. The hunt for those benefits has led to some heretical surprises, potentially turning our understanding of evolution on its head.

...It’s one thing for a salamander to regenerate a severed leg; Sessions wanted to test the limits of this ability. Sure enough, “within six weeks they were regenerating their brains,” Sessions says.

The experiment showed that salamanders could regrow body parts they don’t normally lose in nature. That concept was at odds with a basic evolutionary principle—that abilities arise in response to environmental stressors...