Where do humanity’s evolutionary roots lie? The answer has long been “in Africa”, but this idea is being challenged from various sides. I previously reviewed Begun’s The Real Planet of the Apes as a warming-up exercise before delving into this book. My conclusion was that its discussion of archaic ape evolution, although proposing that species moved back and forth between Africa and Eurasia, ultimately did not really challenge the Out of Africa hypothesis. Not so Ancient Bones. German palaeontologist Madeleine Böhme, With the help of two co-authors, journalists Rüdiger Braun and Florian Breier, firmly challenges the established narrative in an intriguing book that is as outspoken as it is readable.
Ancient Bones was originally published in German in November 2019 as Wie wir Menschen wurden. Less than a year later the good folk at Greystone Books have already published the English translation. The challenge to the Out of Africa narrative is twofold here: criticism by palaeoanthropologists and Böhme’s own discoveries. The latter are the novel part of this book and are told with much verve. Two fossils, in particular, take centre-stage.
First, there is the rediscovery of a tooth and a jawbone christened Graecopithecus freybergi. Originally found in 1944 near Athens, together with other animal fossils, they went missing for decades before Böhme tracks them down, in true Raiders-of-the-Lost-Ark–style, in the catacombs of the Nuremberg congress hall, a location infamous for the Nazi party rallies during World War II. With today’s technology, old fossils hold new value. Careful study of the jawbone with computed tomography scanning showed that the teeth resembled early hominins* more than other great ape fossils. Novel magnetostratigraphic analysis of crystals in sediment trapped inside the animal bones from the same dig allowed the whole lot to be dated to about 7.2 million years ago (mya).
“These two important fossils, Graecopithecus and Danuvius, were present in Europe at a time where conventional wisdom has it that Africa was the epicentre of hominin evolution.”
The second discovery is made by Böhme and collaborators in a southern German clay pit. In a nail-biting race against time – the pit is commercially operated year-round to turn the clay into bricks – they manage to recover much fossil material during three field seasons. This includes a partial skeleton of a new primate species named Danuvius guggenmosi dated to about 11.6 mya. Based on several physical characteristics, Böhme and colleagues argue it, too, resembles early hominins more than known great ape fossils.
These two important fossils, Graecopithecus and Danuvius, were present in Europe at a time where conventional wisdom has it that Africa was the epicentre of hominin evolution. The second challenge to the Out of Africa hypothesis comes from other palaeoanthropologists. For example, there is criticism of the earliest claimed African hominin, Sahelantropus tchadensis**, with some researchers arguing it is a great ape instead. Then there are several fossils from Asia (the Chinese Homo wushanensis, the Philippine H. luzonensis, and the Indonesian H. floresiensis), plus tools that overlap with the African timeline up to 2.6 mya, contradicting the Out of Africa hypothesis (specifically, the Out of Africa I variant).
“As with deserts, savannah ecosystems were in constant flux and integrated across Africa and Eurasia, a region dubbed Savannahstan by some. Perhaps that was the cradle of humanity.”
This criticism is embedded in plenty of background information that benefits tremendously from excellent infographics by freelance illustrator Nadine Gibler. Some topics covered are the history palaeoanthropological discoveries that, thanks in particular to the Leakey dynasty, shifted in focus from Europe and Asia to Africa from 1924 onwards. There is a recap of the history of archaic ape evolution that Begun told in The Real Planet of the Apes. And there is an overview of the anatomical characters that set apart apes and hominins.
Particularly relevant is the palaeoclimatological and biogeographical story. On the one hand, shrinking and growing deserts throughout northern Africa, the Mediterranean, and Asia provided a barrier to migration. On the other hand, the little known Messinian Salinity Crisis*** saw the Mediterranean Sea dry up about 5.6 mya, allowing migration of fauna between Africa and Eurasia, including a lot of animals we now think of as “typically” African. “Why should early hominins be an exception?” asks Böhme on page 194. As with deserts, savannah ecosystems were in constant flux and integrated across Africa and Eurasia, a region dubbed Savannahstan by some. Perhaps that was the cradle of humanity.
“It is not that the fossils found in Africa are not important, but […] the focus on any one particular continent is too narrow […]”
This material is divided over seventeen reasonably-sized, readable chapters in four parts. Depending on how widely you have read on human evolution, the final two parts of the book will already be familiar to you and feel like filler or will be a tasty sampler of other topics. Böhme changes gear here, introducing two questions. One, what made us human? She briefly discusses the hand, above-mentioned Asian Homo fossils and our wanderlust, long-distance running, Wrangham’s thesis that fire and cooking allowed our brains to grow larger, and the physical and genetic evidence for language (this section is a far cry from Rudolf Botha’s critical evaluation in Neanderthal Language). Two, why are we the last ape standing? Rather than Paul Martin’s Pleistocene overkill hypothesis, she favours the (to me novel) idea that that at least Neanderthals and Denisovans simply merged with us. Ancient DNA has revealed we all carry some of their DNA in us, but we do not all have the same pieces. Puzzle it all together, and an estimated 30% of the Neanderthal genome and up to 90% of the Denisovan genome is retained in the current human population.
Ancient Bones is not afraid to go against the grain and be provocative. Though it will no doubt ruffle feathers, my impression is that Böhme draws on a growing body of convincing evidence and arguments to make her case. It is not that the fossils found in Africa are not important, but Böhme’s conclusion on page 271 that the focus on any one particular continent is too narrow is hard to disagree with in light of everything she presents here. What is undeniable is that her decision to involve three others in the writing process makes this a top-notch example of an engaging book accessible to a broad audience.
*Hominins are a taxonomical grouping encompassing humans, chimpanzees, and bonobos, plus their extinct ancestors.
**There is a remarkable personal attack here on Sahelanthropus‘s discoverer who has withheld a thighbone from scrutiny by the wider scientific community for close to two decades pending his own investigations. It could answer whether Sahelanthropus was bipedal or not. When two scientists wanted to present our understanding so far at a meeting their application was rejected. “Could it be that Michel Brunet, one of the icons of French science, Knight of the Légion d’honneur, recipient of the Ordre national du Merité, did not want to be challenged?” (p. 128), is one of the things Böhme asks pointedly. Now, it is not that there are no big egos in science, because there are, but to publicly shame a colleague in a book for a general audience felt, to me, unnecessary. It would have been sufficient to write, as she does here, that his choice is unfortunate and holds back scientific progress.
***The Messinian Salinity Crisis is a fascinating geological event that cries out for a popular treatment. Though some books mention it, as far as I am aware, there has not been a book dedicated to it since 1983, even though our knowledge on it has increased tremendously.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
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