From where

The ancestors of every person on Earth today can be traced back to Africa, where modern humans (Homo sapiens) emerged at least 300,000 years ago. Our ancestor Homo erectus, like his possible descendant Homo heidelbergensis, lived not only in Africa but also in Europe and Asia.

H. heidelbergensis gave rise to at least three hominin species in different locations, devoted to Neanderthals in Eurasia, Denisovans in Asia, and modern humans in Africa. Why exactly did H. heidelbergensis give rise to H. sapiens in Africa?

Brenna Henn, a geneticist at the University of California at Davis, says that to answer this question, we must first examine the early evolution of H. sapiens.

A 1987 article published in the journal Nature showed that: all modern human mitochondrial DNA comes from a single population in AfricaIt lived between 200,000 and 150,000 years ago. But Henn and other scientists question the idea that only one population gave rise to modern humans. They say that by the time modern humans began to emerge, our ancestors Homo sapiens had dispersed into dozens of populations across Africa. This is a huge continent with diverse ecosystems, so these populations had to adapt to their particular conditions.

In a 2023 study also published in the journal Nature, Henn and colleagues found: at least two of these populations were ancestral to H. sapiens. They proposed that although individuals from these populations lived separately for thousands of years, at some point they mixed together and formed a new basal population that eventually became our species.

Henn suggested that ecological diversity on the African continent and subsequent mixing of multiple populations may have been what allowed modern humans to evolve.

Because we have all this genetic and behavioral diversity, that’s what contributes to the complex complex that makes Homo sapiens who we are.
said.

Curtis Marian, professor of paleoanthropology and deputy director of the Human Origins Institute at Arizona State University, says scientists still cannot agree on which of the two theories is correct. But he thinks any of these are more acceptable to him. The newer Pan-African hypothesis states that humans evolved simultaneously across the entire African continent.

“This doesn’t fit with any of the theories we have about how evolution happens,” he said. The scientist agrees with Brenna Henn that Africa’s size created the genetic diversity that allowed modern humans to evolve with advanced cognition and social cooperation.

The more genetic diversity there is, the more likely it is that something interesting will emerge.
– he adds.

Although Europe and Asia combined are also very large, Africa’s warmer climate may give H. sapiens an advantage, he said. Ice ages, occurring every 100,000 years, would have surrounded hominids in Eurasia with ice; African H. sapiens, however, did not lose much of its range during these periods. With a more connected range, H. sapiens had more opportunities to diversify and greater access to each other; this contributed to greater gene exchange.

Marian emphasized that these are purely theoretical and many things have yet to be determined, such as which population (or populations) evolved into modern humans and whether language played a role in the cognitive development of modern humans.