We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Cope's Rule?

Michael Anissimov
By
Updated Feb 13, 2024
Our promise to you
AllTheScience is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At AllTheScience, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Cope's rule is one of several "biological rules" -- biological trends found in patterns across data about many plants and animals. Cope's rule states that population lineages tend to increase in size over evolutionary time. There are numerous examples throughout evolutionary history -- mammals increasing in size after the demise of the dinosaurs; reptiles increasing in size after the demise of the therapsids; amphibians increasing in size after making it onto the land; all animals increasing in size after the Cambrian Explosion 540 million years ago... and so on.

Greater size gives evolutionary advantages to both individuals and species for a number of reasons, the most superficial being that a larger beast is harder to kill and can kill or defend oneself more easily. In fact, larger size may be so evolutionarily beneficial that the only brakes on Cope's rule are that clades composed of larger individuals are more likely to go extinct in times of trouble (mostly because they have greater metabolic requirements than the small). However, there are other limiting factors -- for instance, biomechanics -- a bird that weighs too much cannot fly.

Cope's rule has been carried to the extreme in animals like whales, which evolved from land animals the size of wolves, and the extinct sauropods, dinosaurs that approached 200 ft (60 m) in length. There are many other examples, especially occurring in the wake of mass extinctions where all the larger animals are wiped out. Some scientists have proposed that Cope's rule could be an artifact caused by the fact that larger bones more readily fossilize, but the phenomenon seems sufficiently robust that this selection effect does not significantly diminish it.

Cope's rule unfolded most strongly in the Age of the Dinosaurs, when the average terrestrial vertebrate was much larger than those typical today. This may have something to do with climate, as the world was a much warmer, life-friendly place back then, while today it is in the midst of an extended Ice Age, with glacial maxima that cover much of the Northern Hemisphere and all of Antarctica in ice caps. This decreases the total amount of food available and makes what was once lush forests into chilly grasslands. In this environment, size can still be an advantage however, as it leads to warmth. This can be seen in the evolution of the woolly mammoth.

AllTheScience is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Michael Anissimov
By Michael Anissimov

Michael is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Discussion Comments

Michael Anissimov

Michael Anissimov

Michael is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology...

Read more
AllTheScience, in your inbox

Our latest articles, guides, and more, delivered daily.

AllTheScience, in your inbox

Our latest articles, guides, and more, delivered daily.