How many animals have ever existed on Earth?
There are about 8 billion people living in the world, only a small fraction of the number of people who have ever existed, and this number is still very small compared to the number of animals that have ever lived on Earth.
It is extremely difficult to estimate the total number of animals that have ever lived on Earth. The first way to do this is to start by estimating the total number of species, according to David Jablonski, a geophysicist at the University of Chicago.
According to the Red List of the International Union for Conservation of Nature (IUCN), as of 2022 about 2.16 million animal species have been officially described. But according to a study in Science magazine in 2013 as well as the opinions of many scientists, 20% of them may be copies. Assuming this estimate is accurate, there are approximately 1.7 million officially described animal species.
This number always increases each year because about 14,000 -18,000 new animal species are discovered every year. This means that scientists have only a rough grasp of the number of animals in the world.
In 2011, Camilo Mora, a biogeographer at the University of Hawaii, and his colleagues estimated the total number of eukaryotic species on Earth (organisms made of one or more cells with a separate nucleus containing chromosomes). ) is about 8.7 million, of which about 7.7 million are animals and half of these are insects.
However, with the question 'how many animal species have ever existed on Earth?, experts need to look deeper into the past and use fossil records.
Life appeared on Earth 3.7 billion years ago but was only very simple cells. Multicellular organisms only appeared 2.3 billion years ago. And animals probably appeared about 800 million years ago. Due to many factors, only a few of those early animals are preserved in the fossil record.
An estimated 99.9% of species that have ever existed are extinct, Jablonski said. If this estimate is correct, the total number of animal species that have ever existed would be about 770 million.
So, what is the total number of individuals of every animal species ever present on earth?
According to speculation, there are about 8 billion people and 130 billion other mammals, 428 billion birds, 3.5 trillion fish and 10 trillion insects existing on Earth.
From the above assumption, scientists can roughly infer the number of animals that have ever existed. For example, if there are currently 3.85 million insect species on Earth, corresponding to 385 million species in the past, then the number of individuals would be 3.85 x 10^27.
It can be roughly estimated that the number of all arthropods, invertebrates and vertebrates is about 4.5 x 10^27 animals that have ever existed on Earth.
Scientists rely on calculating the number of animals that have ever existed to understand the Earth's underlying biodiversity and how it fluctuates to grasp the scale of the current crisis.
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