Currently, there are about 8 billion people, which is only a small fraction of the total number of people who have ever existed, not to mention the number of animals that have ever lived on Earth. So, How Many Animals Have Ever Lived on Earth? According to David Jablonski, a geophysics researcher at the University of Chicago, perhaps the easiest way to start is by estimating the total number of species. Join KnowAllAnimals to explore this question in the following article!
1. How Many Animals Have Ever Lived on Earth?
According to the International Union for Conservation of Nature (IUCN) Red List, approximately 2.16 million animal species were officially described as of 2022. But a 2013 study in the journal Science found that 20% of those could be duplicates, recorded by multiple scientists. Assuming this estimate is accurate, the number of species is actually about 1.7 million.
1.1. This Number Is Not Fixed
Each year, researchers describe about 14,000–18,000 new animal species, which means they only have a general idea of the number of animals in the world.
In 2011, Camilo Mora, a biogeographer at the University of Hawaii, and his colleagues presented a study in the journal PLOS Biology and estimated the total number of eukaryotic species on Earth. Eukaryotes are organisms made up of one or more cells with a separate nucleus that contains chromosomes.
The final number they came up with was about 8.7 million, of which about 7.7 million are animals, and half of those are insects. This study has had a great impact and is still frequently cited today.
However, to know how many animal species have ever existed, experts need to look deeper into the past and use the fossil record. Life appeared on Earth 3.7 billion years ago. But the first living things were only very simple cells. Multicellular organisms only appeared 2.3 billion years ago. Animals may have appeared more recently, about 800 million years ago.
1.2. Only a Small Number of Those Early Animals Were Preserved in the Fossil Record
The reason is that organisms with soft bodies are very difficult to preserve, and even for organisms with hard bodies, the fossilization process only happens under certain conditions. In addition, the tectonic plates slowly and continuously stir the Earth’s surface, destroying ancient traces.
“The standard estimate is that 99.9% of all species that have ever existed are extinct. But of course, that is just a rough estimate,” Jablonski said. Assuming this rate is correct, the total number of animal species that have ever existed would be about 770 million. So, how can we calculate the total number of individuals of every animal species that has ever been on Earth?
Earth is home to about 8 billion people, 130 billion other mammals, 428 billion birds, 3.5 trillion fish, and 10 quintillion insects. Assuming that the current abundance is fairly stable, we can make a rough guess at the number. For example, if there are currently 3.85 million insect species on Earth, corresponding to 385 million species in the past, the number of individuals would be 3,85 x 1027.
Because insects are so numerous, that number is probably not too far from the total. So, we can roughly estimate that, including arthropods, invertebrates, and vertebrates, about 4,5 x 1027 animals have ever existed on Earth.
Calculating the number of animals helps scientists understand the basic biodiversity of Earth and how it fluctuates. Due to climate change, deforestation, pollution, and other factors, the world is nearing a mass extinction event. Experts need to know the baseline extinction rate to grasp the scale of the current crisis.
2. FAQs
1. Is it possible to know exactly how many animals have ever lived on Earth?
No, it’s impossible to know the exact number. Scientists can only estimate based on fossil records, evolutionary studies, and biodiversity models.
2. How do scientists estimate the total number of animal species in Earth’s history?
They use fossil evidence, genetic analysis, and evolutionary timelines to approximate how many species have existed over millions of years.
3. How many animal species exist today compared to the past?
Today, scientists estimate there are around 8.7 million animal species, but over 99% of all species that ever lived are now extinct.
4. Why did most animal species that ever lived on Earth go extinct?
Mass extinctions, climate changes, habitat loss, and competition for resources have caused the disappearance of most species throughout Earth’s history.
The history of life on Earth is a vast and captivating story that spans billions of years and includes countless species. While we can never know for certain exactly how many animal species have ever existed, scientific research has given us incredible insights into the diversity and evolution of life. From ancient marine creatures to today’s wild animals, every species has played a role in shaping our planet’s ecosystem. Learning about these past creatures not only satisfies our curiosity but also helps us better appreciate the fragile balance of life that continues today.
Thank you for reading Know All Animals‘ article, “How many Animals have ever lived on Earth?“. Remember to visit our blog section to explore more useful information about animals around the world!
References: https://en.wikipedia.org/wiki/Animal
