Human evolution; savannah theory fading (Introduction)

by David Turell , Saturday, July 09, 2022, 19:25 (650 days ago) @ David Turell

More and more evidence of forest and jungle usage:

https://aeon.co/essays/we-are-creatures-of-tropical-jungles-as-much-as-the-savannah?utm...

"The earliest hominins, dating from around 7 to 5 million years ago, show that our ancestors’ first experiments with bipedalism occurred in mixed forest and woodland settings...Not only that, but analyses of fossil hominin skeletons dating between 5 to 2 million years ago, including that of ‘Lucy’ and those of our own genus, show that many of them still had arms, shoulders and hands adapted to climbing (a skill necessary for life in the forest) even as their interactions with terra firma increased.

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"Researchers once assumed that bipedalism was driven by an expansion of grasslands. It was believed that, as those habitats spread, hominin physiology changed as it adapted to a new life on the open savannah. For this theory to hold water, these landscapes would have needed to expand roughly at the same time that physiological changes appear in hominin fossils. However, sediments from deep-sea marine cores show that ancient tropical African grasslands had already expanded by 10 million years ago, long before the first hominins took their first bipedal strides around 7 to 5 million years ago.

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"Although open environments played a major role in early human evolution, tropical forests and forest patches still provided a significant backdrop for our first hominin ancestors as they emerged in the tropics of Africa. They likely took their first tentative steps as bipedal mammals in tropical forests, or at least mixed forest habitats. Right until the appearance of the genus Homo, between 3 to 2 million years ago, tropical forests and woodlands remained an important source of food, and perhaps offered protection from predators.

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"There is growing evidence for the role of tropical forests in our species’ evolution and dispersal, and Batadomba-lena cave, where we started this essay, is a key site. This cave has rewritten tropical forests into European and North American accounts of human history. Over the course of the past two decades, tropical sites like Batadomba-lena (alongside nearby caves Fa-Hien Lena and Kitulgala Beli-lena) have produced some of the most important archaeological and anthropological insights into the evolution, behaviour and capabilities of early Homo sapiens. These caves in Sri Lanka have demonstrated that the first humans who arrived on this island did not head straight for the coasts or the open grasslands. Instead, the first human traces and fossils found here, dating back 45,000 years, come from dense tropical rainforests. Well-preserved fossils and artefacts in these cool cave environments have shown that humans hunted monkeys and giant squirrels with bow and arrow technology. They used carbohydrate-rich nuts and nearby freshwater streams. And they may even have made clothes to protect themselves – not from the cold, but from a myriad of vampiric pests.

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"In 2021, amazing discoveries at a Sulawesi limestone cave called ‘Leang Bulu’ Sipong 4’ found that tropical forests are home to the oldest cave art ever recorded, dating to at least 45,500 years ago. These drawings show figures hunting wild pigs – animals known to enjoy forest habitats. Tropical forests were not just a key part of our species’ experimentation with different ecologies, but also cultural materials and perhaps also an important setting for the emergence of storytelling.

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"Of course, other habitats are critical to the human story as well. There is now evidence that humans were making themselves at home in deserts, high mountains, and the Arctic circle by 45,000 years ago. Evidence found in tropical forests, as well as these other places, is encouraging archaeologists and anthropologists to move away from an exclusive focus on savannahs and coasts. They’re recognising that studying a plethora of Pleistocene climates and environments might provide the best clues to our origin story – and to what it means to be human.

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"Thanks to the array of revolutionary findings discussed above, the ‘savannah hypothesis’ is becoming increasingly unattractive in palaeoanthropological and archaeological discourse. Instead, environments such as tropical forests are playing a critical role in highlighting that climatic and environmental variability provided the setting for the grand evolutionary romp of our species and its hominin ancestors.

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"But it would be wrong to assume that palaeontologists and archaeologists are the only ones championing this new view of our diverse past. For centuries, if not millennia, Indigenous peoples have emphasised the long human history of tropical forests and the cultural heritage locked within them, though they have often been marginalised or ignored."

Comment: The idea that savannahs drove our evolution is shown as being much too simplistic. Not surprising as new research challenges old ideas. The evidence in this article shows we evolved to take advantage of new environments not as the result of new environments.