Have you ever wondered how some animals seem to have stayed the same for millions of years? Let’s dive into the fascinating world of evolution and discover why some species appear unchanged over time, even though they are still evolving.
Evolution is a process where species change over time due to genetic mutations. These mutations happen randomly when organisms reproduce. Some mutations can be harmful, making it harder for the organism to survive, while others can be beneficial or neutral. Over time, these changes accumulate, leading to the evolution of species.
Not all species evolve at the same speed. Take gars, for example. These predatory fish have genes that change much more slowly than those of most other animals. This slow pace of evolution means that even though the alligator gar and the longnose gar last shared a common ancestor over 100 million years ago, they are still genetically similar enough to mate and produce offspring. Imagine if chimpanzees and kangaroos could do the same!
Some animals, like coelacanths and horseshoe crabs, are often called “living fossils” because they look similar to their ancient ancestors. However, this doesn’t mean they haven’t evolved. Horseshoe crabs have a body design that works perfectly in their environment, so any significant changes might make them less suited to survive. Coelacanths have evolved too, but their changes are so subtle that they often go unnoticed.
On the other hand, the tuatara, another so-called living fossil, has the fastest-evolving genes among vertebrates. Despite this rapid evolution, its body shape remains well-suited for its lifestyle, living both in and out of burrows. This shows that even fast-evolving species can maintain a consistent appearance if it benefits their survival.
Sometimes, evolution occurs in ways that aren’t visible in fossils. For instance, some ancient coelacanth relatives lived in freshwater, so modern coelacanths have evolved to adapt to saltwater environments. This shows that evolution can involve internal changes that help species survive in different conditions.
In conclusion, the idea of “living fossils” is misleading because all species are constantly evolving. While some may appear unchanged, they are still adapting in various ways to survive in their environments. Evolution is a continuous process, and the more we learn, the more we understand the incredible diversity of life on Earth.
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Create a timeline that illustrates the evolution of a species of your choice. Use research to identify key evolutionary milestones and depict these on your timeline. This will help you understand how species change over time and the factors that influence their evolution.
Participate in a class debate about the term “living fossils.” Research different species labeled as living fossils and argue whether this term is appropriate or misleading. This activity will enhance your critical thinking and understanding of evolutionary concepts.
Engage in a simulation game where you can introduce mutations to a virtual species and observe the effects over several generations. This will give you insight into how genetic mutations can impact evolution and species survival.
Conduct a study comparing the anatomy of a “living fossil” species with its ancient ancestors. Use diagrams and research to identify similarities and differences. This will help you appreciate the subtle changes that occur over millions of years.
Choose a species and design a project that explores its adaptations to its environment. Present your findings to the class, highlighting how these adaptations have helped the species survive. This project will deepen your understanding of the relationship between evolution and environmental adaptation.
This video is sponsored by Skillshare. More about them at the end of the video. One hundred million years ago, the ancestors of humans looked quite different. At the same time in history, the ancestors of gars, horseshoe crabs, and coelacanths also had distinct appearances. Darwin referred to species like these as “living fossils” because they seemed evolutionarily unchanged. However, Darwin was mistaken.
Hi, I’m David, and this is MinuteEarth. All species change over time; it’s a biological rule primarily due to how genes function. As individuals reproduce, DNA undergoes random mutations. Some of these mutations hinder the organism’s ability to survive and reproduce, so they don’t persist. Others may be beneficial or neutral, allowing them to remain in the population. Over time, these mutations accumulate, leading to changes in species. That’s evolution.
However, evolution does not occur at the same rate across all species. Predatory fish known as gars have genes that mutate much more slowly than those of most other vertebrates, although scientists are still investigating the reasons behind this. So, despite Darwin’s belief, gars are evolving; they are just doing so at an extremely slow pace. In fact, even though the alligator gar and the longnose gar last shared a common ancestor over 100 million years ago, these fish evolve so slowly and remain so genetically similar that they can still mate and produce fertile offspring. This is akin to if chimpanzees and kangaroos—who also shared a common ancestor around that time—were able to have offspring together. For clarity, that is not possible.
Not all so-called living fossils evolve slowly, though. Coelacanths and horseshoe crabs have genes that mutate at rates similar to those of most other animals. The tuatara, another so-called living fossil, actually has the fastest-evolving genes of any studied vertebrate. So why do these animals not appear to change?
For horseshoe crabs, their specific body plan—the classic domed shell and rudder-like tail—works exceptionally well in their marine environment and has for a long time. It may be that significant mutations altering this body plan make the crabs less suited to their environment, leading future mutations to revert to the successful form. The coelacanth has been evolving in ways that do alter its appearance; however, these changes are so subtle that they often go unnoticed. For instance, if you examine the skulls of a modern coelacanth and its ancestor, you can see that, despite their similarities, their facial bones are positioned differently.
As for the tuatara, the reasons for its rapid evolution are not entirely clear, but it appears that both subtle changes in its skeleton and its body shape being well-adapted for life in and out of burrows are occurring simultaneously. Lastly, a species could be evolving in ways that are not evident in the fossil record. For example, some ancient coelacanth relatives lived in freshwater, so modern coelacanths must have evolved adaptations to handle excess salt and buoyancy.
In conclusion, there is no such thing as a living fossil. Life on Earth is in a constant state of evolution. There are many ways to evolve, and for some species, the more things change, the more they remain the same.
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Evolution – The process by which different kinds of living organisms develop and change from earlier forms during the history of the earth. – Charles Darwin’s theory of evolution explains how species adapt over time through natural selection.
Species – A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. – The African elephant and the Asian elephant are two different species that have evolved distinct characteristics.
Mutations – Changes in the DNA sequence of a cell’s genome that can lead to variations in traits. – Some mutations can be beneficial and help an organism survive better in its environment.
Fossils – The preserved remains or impressions of organisms that lived in the past, found in rocks. – Fossils provide important evidence for scientists studying the evolution of life on Earth.
Survival – The ability of an organism to continue living and reproducing in its environment. – The survival of a species often depends on its ability to adapt to changing environmental conditions.
Ancestors – Organisms from which others have descended or evolved. – Humans and chimpanzees share a common ancestor from millions of years ago.
Genetic – Relating to genes or heredity, which are the units of inheritance in living organisms. – Genetic variations are crucial for the process of natural selection and evolution.
Adaptations – Traits that have evolved over time to help an organism survive and reproduce in its environment. – The thick fur of polar bears is an adaptation to the cold Arctic climate.
Environments – The natural world or ecosystem in which an organism lives, including all living and non-living factors. – Different environments, such as deserts and rainforests, support diverse forms of life.
Diversity – The variety of different species and genetic variations within an ecosystem. – Biodiversity is important for the stability and resilience of ecosystems.
