'Living Fossils' Aren't Really a Thing

Summary

This PBS Digital Studios video script challenges the concept of 'living fossils,' suggesting that while some species may appear unchanged for millions of years, they are still subject to evolutionary processes. It dispels the myth that only certain organisms evolve, highlighting that all life is constantly evolving, even if changes are not always visible. The script uses examples like crocodylians and the tuatara to illustrate that while physical forms may remain similar, genetic evidence shows ongoing evolution.

Takeaways

• 🐊 Crocodiles, horseshoe crabs, and tuatara are often called 'living fossils' because they appear unchanged for millions of years.
• 🌳 The term 'living fossil' is somewhat problematic and can be misleading about the nature of evolution.
• 🦆 Charles Darwin coined the term 'living fossil' in 1859, noting that some animals like platypus and lungfish seemed unchanged over time.
• 🦕 The idea of 'living fossils' has been misunderstood to suggest that some organisms don't evolve or evolve only some of the time.
• 🐾 Many plants and animals resemble their distant ancestors, suggesting that 'living fossils' are more common than thought.
• 🐺 Jaguars, gray wolves, and even humans have ancient fossils that look similar to their modern counterparts.
• 🐊 Crocodylians have a complex evolutionary history with many forms now extinct, showing they have changed significantly over time.
• 🦈 Ancient croc-like reptiles like Postosuchus and Dakosaurus were very different from today's crocodiles, indicating evolution.
• 🐉 The tuatara, despite its ancient appearance, has DNA showing significant genetic changes over time.
• 🧬 Even organisms that look similar to their ancestors have experienced evolutionary changes, as seen in their genes and anatomy.
• 🌐 Evolution is a continuous process, with changes sometimes being subtle and not always visible in the physical appearance of organisms.

Q & A

What is the concept of 'living fossils'?

The concept of 'living fossils' refers to species that have remained seemingly unchanged for millions of years, appearing similar to their ancient ancestors as seen in the fossil record.

Why is the term 'living fossil' problematic?

The term 'living fossil' is problematic because it suggests that some organisms do not evolve, which is not true as all life is constantly evolving, even if the physical changes are not always visible.

Who coined the term 'living fossil'?

Charles Darwin coined the term 'living fossil' over 150 years ago in 1859, noting that some animals like the duck-billed platypus and lungfish had held onto the same basic body plan for millions of years.

What misconceptions has the term 'living fossil' become associated with?

The term 'living fossil' has become associated with misconceptions that some organisms evolve while others do not, or that living things only evolve some of the time.

Why is the 'living fossil' term not useful on smaller geologic time scales?

On smaller geologic time scales, the term 'living fossil' is not useful because many organisms, including humans, have changed over time, even if their physical appearance remains similar to their ancestors.

How has the crocodylian family evolved over time?

Crocodylians have evolved significantly over time. While today they are aquatic ambush predators, in the past, they included land-dwelling carnivores like Postosuchus and sea-dwelling forms like Dakosaurus, showing a range of adaptations.

What does the fossil record show about the ancestors of today's crocodiles?

The fossil record shows that crocodile ancestors, called crocodylomorphs, looked similar to modern crocodiles but that there were also many forms that have since gone extinct, indicating significant evolutionary changes.

How does the tuatara demonstrate the concept of ongoing evolution?

The tuatara, despite its ancient appearance and being the last remaining member of the Rynchocephalians, shows ongoing genetic change. A 2008 study found that its mitochondrial DNA is evolving faster than any other vertebrate.

What does the script suggest about the visibility of evolutionary changes?

The script suggests that evolutionary changes can sometimes be big and obvious, but other times they can be almost imperceptibly small, with even ancient-looking organisms carrying a record of their history in their anatomy and genome.

What is the significance of the PBS Digital Studios sponsorship by Curiosity Stream mentioned in the script?

The sponsorship by Curiosity Stream is significant as it allows PBS Digital Studios to create content. Curiosity Stream offers a platform for streaming documentaries and programs about science, nature, and history, including exclusive originals.

How can viewers get involved with PBS Digital Studios and Eons?

Viewers can get involved by subscribing to Eons on YouTube, visiting the PBS Digital Studios website, and engaging with the content in the comments section. They can also explore sister channels from PBS Digital Studios.