Saturday, June 1, 2024

How many human species have lived on Earth?

Around 21 human species have lived on Earth.

Science & Industry

E ach one of the billions of people living on Earth today belongs to the same species: Homo sapiens. But we weren't always the only humans. The Smithsonian Institute estimates that some 21 different human species have roamed the Earth (though the number varies due to conflicting definitions of what is "human"). Many of those species are in the genus Homo, which has only one surviving species today (that's us). The list of hominids also includes other species considered by most scientists to be early humans, such as the Australopithecus afarensis, a member of the genus Australopithecus.

The first humans in the same genus as Homo sapiens were Homo habilis, Homo rudolfensis, and Homo erectus, and evidence suggests they coexisted in East Africa some 1.9 million years ago. This kind of cohabitation was a familiar fixture of human evolution. When Homo sapiens first appeared around 300,000 years ago, our ancestors lived among many other now-extinct human cousins. Modern humans famously fraternized with Neanderthals, Denisovans, and other populations. Homo sapiens also shared the planet with lesser-known species such as Homo floresiensis, Homo naledi, Homo luzonensis, and the straggling survivors of Homo erectus. But because some of these groups lived in remote communities, it's possible that modern humans never even laid eyes on them. Scientists theorize that our ancestors wiped out many of these human species (Neanderthals were the last to fall, beginning to go extinct around 40,000 years ago) by demonstrating superior strategizing and cooperation skills. Our ancestors' social intelligence helped them rise to the top of the food chain, and the population grew exponentially. Today, modern humans stand alone in the genus Homo, but we only have ourselves to blame.

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By the Numbers

Size (in inches) of the shortest hominin, Homo floresiensis, which lived on the modern Indonesian island of Flores

Estimated percentage of Neanderthal DNA found in people of European and Asian descent

Did you know?

Homo sapiens have been on Earth for only 0.0067% of its existence.

The lifetime of a planet is long, measured in several billions of years, but many species are lucky if they even make it beyond a couple million. Homo sapiens are a relatively young group, first appearing on the scene some 300,000 years ago, which means we've only been around for 0.0067% of Earth's history. Because humans have such a low genetic diversity compared to other primates, scientists estimate that Homo sapiens likely grew from only 10,000 breeding pairs — but we've been busy ever since. The human population reached the 1 billion mark in 1804 and 8 billion in November 2022.

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