Including a series of floating skulls australopithecus afarsky, Australopithecus Boisei (Also known as Paranthropus boisei), honest personNeanderthals (Homo neanderthalism) and modern humans (homo sapiens).(Image credit: Science Photo Library via Getty Images)

Origin of our species homo sapiensThe question has puzzled paleoanthropologists for generations, and the search for answers has become even more complicated with the discovery of massive fossils and the advent of genetic analysis. So where and when did our ancestors first appear?

At the moment, the answer is still up for debate: Researchers have so far found fossils attributed to our species dating back 300,000 years, and some scientists trace the origins of modern humans to 1 million years ago. One reason for the lack of clarity is the definition of genre: What do we mean? homo sapiens ?

What is a genre?

The concept of biological species is the best known; Members of a population that can interbreed are considered a single species. In 2010, through DNA analysis, scientists found that Neanderthals and humans interbred in Europe and the Middle East, and more recent research suggests they interbred as early as 250,000 years ago. Another close relative, Denisovans in Asia, also interbred with humans at least 50,000 years ago. Some anthropologists now think that Neanderthals and Denisovans were the same biological species as us. homo sapiens– but others argue that each is a separate species within a genus Homo.

But because scientists have been unable to obtain DNA from older samples in Africa, where DNA has not been preserved for nearly 20,000 years, paleoanthropologists are using an additional concept to try to understand the evolution of our species. In the phylogenetic or species tree concept, a specific group of physical characteristics, such as a rounded skull, high forehead, and prominent chin in humans, is used to identify members of a species. This is the primary way paleoanthropologists classify and understand fossils of our hominid ancestors. Additional evidence, such as the type of stone tool found in the fossil, can indicate which species the individual belonged to.

The current challenge for paleoanthropology is to figure out how fossils, archaeological data, and DNA evidence can be combined to understand where we came from.

So what is the oldest known fossil of a modern human? “In my view, it is the oldest known fossil that exhibits a similar morphological pattern to the current fossil,” Chris Stringer, head of human evolution research at the Natural History Museum in Great Britain, told Live Science in an email. sapiensThere is the skeleton of Omo Kibish 1 from Ethiopia, [якій] approximately 230,000 years ago.” This fossil skull has a high, bullet-shaped head and a human-like jaw, leading leading researchers to call it the oldest known fossil. homo sapiens from East Africa.

However, Stringer also noted that many researchers consider the Florisbad fossils found in South Africa and dated to 260,000 years ago, and the fossils in Morocco as early examples. homo sapiens.

“The oldest forms attributed to our species are fossils found at Jebel Irhoud in Morocco, dated to approximately 300,000 years ago,” paleoanthropologist Jean-Jacques Hueblin of the Collège de France, who dated the fossils, told Live Science in an email. Fossils found at the site included several skulls with similar faces, jaws and teeth, but with long meninges and thick brow ridges that were characteristics of our ancient ancestors. homo sapiens.

“It should be emphasized that these people were significantly different from modern humans,” Hublin said. “Evolution never stopped.”

“The Jebel Irkhud fossil is considered by many – though not all – to be a very early example of this. homo sapiens Eleanor Skerry, head of the Pan-African Evolution Research Group at the Max Planck Institute for Geoanthropology in Germany, said: “But it is very difficult to determine what the first members of our species looked like,” Skerry told Live Science in an email, “because different features are likely different in different groups.” emerged over time and eventually merged through gene flow.

Because archaeological examples of modern knowledge exist, such as tools and art that appeared around the same time as Jebel Irhud, “it’s important to look at different sources of knowledge, not just fossils” when classifying ancient hominins by species, Skerry said. . .

Do modern African genetics point to an older origin?

Even if we accept the oldest fossils and earliest behavioral evidence at face value, a date of around 300,000 years ago may be too recent to determine the origin of our species.

“For me homo sapiens It evolved in Africa between 1 million and 700,000 years ago, paleoanthropologist John Hawkes of the University of Wisconsin-Madison told Live Science in an email. “We know that genetic divergence of African ancestors from Denisovan Neanderthals occurred approximately 700,000 years ago,” Hawkes said, and there are additional genetic studies that suggest ancestral divergence of African groups began approximately 1 million years ago.

This 2023 study, published in the journal Nature, worked backwards on the genes of nearly 300 modern humans in Africa, modeling a continent-wide scenario of evolution and continuous gene flow. Essentially, their “population fragmentation and coalescence model” suggests that about 1 million years ago, there was an ancestral human population in Africa that split into Southern, West, and East African groups while maintaining genetic links with each other.

If this deep genetic model is correct, our ancestors may not have emerged in a specific place and time, but evolved slowly over 1 million years in Africa.

missing answer

The question of when our species evolved is unlikely to have a clear answer in the near future.

“Every single piece of this question is being questioned,” paleoanthropologist Sang-Hee Lee of the University of California, Riverside, told Live Science in an email. homo sapiens, definition of “first” and definition of “appearance”. These are exciting times.”

“More fossils, archeology and ancient DNA from different regions are needed to understand which regions in Africa played a role in our origins, what that role was, whether different regions played a larger role than others or whether they were all approximately equal.” , which ecosystems are included, and even whether there are areas that are excluded.

Stringer agreed. “We need a lot more evidence of better quality” to advance the question of our species’ origin, Stringer said. “Even in Africa, less than 10% of its territory has evidence of fossils.”