Homo sapiens: We come in all shapes and sizes

  • June 06, 2011 | Matt van Onselen

																		The many different faces of modern humans seen at the Maropeng Visitor Centre

Can you describe the ways in which the facial features of Yoko Ono and Julia Roberts are different? Do you think people from West Africa generally have darker skin than people from Southern Africa? What’s the difference between a 100 metre sprint champion and a horse jockey?

We all know that humans come in all shapes and sizes. But how did we land up with such a variety of faces, skin colours, builds and hair? Why is it that people from Sweden are often pale and blue-eyed, while Native Americans are darker with black hair? The answer to these questions lies in the final chapter of the history of human evolution.

Maropeng, the official visitor centre of the Cradle of Humankind World Heritage Site, tells the story of our ancestors – all the hominid species that preceded us, including the iconic Australopithecus africanus (“Mrs Ples”, the Taung Child and Harry the Hominid) and Homo ergaster (which was first discovered at Swartkrans in the Cradle of Humankind in 1949).

But the story doesn’t end with the emergence of our species, Homo sapiens. The first humans left Africa to populate the rest of the globe, resulting in scattered populations, each with their own subtle genetic variations.  Projects such as the Human Genome Project, which aims to map out the entire human genetic code, tell us a great deal about the recent history of our species.

According to Professor Trefor Jenkins, professor emeritus in the Department of Human Genetics at the University of the Witwatersrand, the study of genetics has confirmed the “out of Africa” theory. “The broad picture we have of human evolution is accurate,” he says. “The Human Genome Project only reinforces the theories.”

Maropeng Curator, Lindsay Marshall, agrees, saying that the study of genetics has played in an important part in shaping our understanding of human ancestory: “There are many complimenting research areas that pinpoint Africa as the birthplace of humanity,” she says. “Genetics points to the same conclusion.”

																		The structure of DNA. Picture courtesy Brian0918/Wikipedia

“Humans moved out of Africa for survival,” Jenkins explains, “but also out of curiosity.” Our species began to populate the other continents about 50 - 60 000 years ago, he argues, eventually spreading to Asia and then the Americas. Then, over thousands of years, the populations lived separately from one another, ignorant of their journey out of Africa.

Slight changes in human physical features developed over time. “The differences are due to climate and isolation,” explains Jenkins. Those populations who lived in an extremely hot climate, for example, grew darker to protect them better agains the sun. Those who experienced extreme cold grew paler. Because the various populations were unaware that other humans were just around the corner, their genetic codes did not mix, and so people from one population developed similar physical features, such as the pale, blued-eyed Swedes.

“In the last 1000 years”, Jenkins adds, “people have moved [much more frequently than before] from one continent to another thanks to changes in travel.” Through this, modern people learned that there were humans scattered across the globe, and that they all had different physical appearances.

“But are there really major differences between humans?” asks Jenkins. “I don’t think so. In terms of genetics, the variation between humans is extremely small. All members of Homo sapiens share the same genetic code, but for a few superficial differences.”

So, humans dispersed across the world, and have now reunited in a global village. All of humanity shares an African heritage. We are one, diverse species across the globe, with our roots in Africa.

You can learn all about our journey out of Africa at the Maropeng Exhibition Centre.

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