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: Unearthing the Astonishing New Story of How We Became Human, written by Madelaine Böhme, Rüdiger Braun, and Florian Breier, published by Greystone Books in September 2020 (hardback, 376 pages)
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.
So, Graecopithecus and Danuvius, two important fossils, are one part of her argument that there were early hominins in Europe at a period 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.
Other recommended books mentioned in this review:
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The history of human evolution has become firmly wedded to the Out of Africa hypothesis: the idea that we evolved in Africa and from there spread around the world. Back in 2015, palaeoanthropologist David R. Begun gave the proverbial tree of life a firm shake with The Real Planet of the Apes, making the case that the picture is a bit more complicated than that. Providing an incredibly well-written overview of the deep evolutionary history of great apes and humans, an interesting picture emerges of species moving into and out of Africa over time. Some reviewers hailed it as provocative—but is it really?
The Real Planet of the Apes: A New Story of Human Origins, written by David R. Begun, published by Princeton University Press in October 2015 (hardback, 262 pages)
In case you are wondering why I am only now reviewing a book published in 2015: I had just started reading the foreword of the recently published Ancient Bones when it occurred to me that its spiel—our deep evolutionary history lies in Europe rather than Africa—sounded familiar, as did the name of its writer, David R. Begun. Where did I read about this before? One glance at my bookshelves confirmed that, yes, Begun wrote The Real Planet of the Apes which I bought some years ago but had not yet read. Better late than never.
With this book, Begun takes the long view, surveying the deep evolutionary past of the ancestors of great apes and humans, i.e. the period from approximately 35 to 7 million years ago (mya). His starting point is the split between the ancestors of New World monkeys (which went off on their own evolutionary experiment in South America), and the ancestors of Old World monkeys and hominoids (humans, lesser and great apes, plus all their ancestors). Begun would some years later contribute a very readable 10-page summary of archaic ape evolution to Gurche’s Lost Anatomies, but the executive summary would be: out of Africa, into Europe, and then back into Africa.
“[…] Begun takes the long view, surveying the deep evolutionary past of the ancestors of great apes and humans”
A bird’s-eye-view version of his argument starts with the great diversity of catarrhine* primates flourishing in Africa from the Oligocene into the early Miocene (~33 to 17 mya), including Aegyptopithecus (a “not-quite-ape”), Kamoyapithecus (“possibly the first ape?”), and the intermediate monkey-ape genera Proconsul and Ekembo. Then, by 17 mya, Afropithecus and the closely related Heliopithecus show up in East Africa and expand their range into Eurasia. While Asia sees its own flourishing of species in what is by now the middle Miocene, Europe is the epicentre of the overall story and sees the evolution of Griphopithecus and Dryopithecus around 15–13 mya. Four descendants of Dryopithecus (Hispanopithecus, Rudapithecus, Ouranopithecus, and Oreopithecus) are discussed here in particular.
Meanwhile, the fossil record in Africa seems to dry up. Are we yet to find crucial fossils from this period? Possibly, but Begun points out we have plenty of other fossil mammals from these areas and the environment back then would have been suitable for apes. There are some questionable African fossils from this period discussed here, but nothing convincing. By ~10 mya, climatic changes forced the Eurasian great apes to reinvade Africa where the first hominins appear by ~7 mya; Sahelantropus tchadensis is mentioned in particular.
Now, in case you think that this makes for a neat linear story, let me stop you there. For the sake of brevity, I have skipped over many side branches and dead ends that Begun discusses here. Evolution resembles a tangle more than a tree. Although his ideas are not accepted by everyone (show me a group of scientists not endlessly arguing finer points), are his ideas really this much at odds with the established Out of Africa story? Let me offer three observations.
“[…] your narrative depends on what period you take as your starting point and what groups you consider, which can make the whole Out of Africa narrative sound a bit arbitrary”
First, definitions matter. Casual use of the phrase “Out of Africa” in the popular press often fails to mention the when. Some researchers use it to talk about Pleistocene migrations into Europe by hominins such as Homo erectus, though it more commonly refers to the spread of anatomically modern humans from Africa between 300,000 to 200,000 years ago. Begun ends his story some 7 mya, which is when many popular accounts start theirs. Although I do not know if Mark Maslin agrees with Begun’s thesis, the scenario laid out in his book The Cradle of Humanity is perfectly congruent with it. Maslin’s starts around 5 mya and Begun agrees that the fossil record situates early hominins in Africa by this time. My thoughts after reading this book are that your narrative depends on what period you take as your starting point and what groups you consider, which can make the whole Out of Africa narrative sound a bit arbitrary. Even Begun’s ideas could be cast as an Out of Africa scenario.
Second, the recent ancient DNA revolution has splendidly revealed how populations have constantly moved and mixed. Though this technology only allows us to look back hundreds of thousands of years, there is no reason to think the pattern differed drastically before that. Especially as pretty much all palaeoanthropologists agree that climatic changes are an important driver of migration: Begun does so here, Maslin does, even the Leakeys—focused as they are on human evolution in Africa—do.
Third, Begun’s claims might be provocative, but his delivery is not. Instead, his account is tempered and reasonable, clearly indicating where and why his ideas diverge. He might not always agree with others but nevertheless goes on record here to praise their track record. The most severe criticism he expresses (and that is putting it strongly) is that he follows a philosophical approach of putting evidence before process (e.g. the Out of Africa hypothesis). In his opinion, others lean towards putting process before evidence, ignoring or downplaying evidence that does not fit. He thinks that most of the research community has mischaracterised the European branch of the ape family during the middle to late Miocene as little more than an exotic sideshow. But he also repeats throughout how he is open to changing his mind with future fossil finds. Basically, I see someone of intellectual integrity here.
“[…] Though [ancient DNA] only allows us to look back hundreds of thousands of years, there is no reason to think [migration patterns] differed drastically before that. Especially as pretty much all palaeoanthropologists agree that climatic changes are an important driver”
And there is much else to like here. Begun clearly, and if necessary repeatedly, clarifies terminology, whether it is cladistics or skeletal morphology. He also offers excellent explanations of how we reconstruct past climates. How the rules around taxonomical nomenclature work. How plate tectonics influenced biogeography, specifically how, as the Tethys Sea was closing up, rising and falling sea levels revealed and sundered land bridges, opening or closing migratory routes in the Mediterranean and Arabian Peninsula. And how, with modern technology (and often a lot of hard work) we can extract unbelievable detail from fossil teeth, which are frequently the only remains we find. Additionally, he spices up his writing with introductions to the typical fauna of the different periods, short excursions into the history of palaeoanthropology as a discipline, and personal anecdotes of old-guard researchers he met or worked with.
Seeing the book’s age, it is relevant to ask what has happened since publication to change or reinforce this idea. When I contacted Begun, he confirmed that there have been no major finds to overthrow his ideas, with new work adding further support. I will next turn to the 12-million-year-old finds recently described in Ancient Bones. Also of interest is the story of the 4.4 million-year-old Ardipithecus, one of the last species Begun mentions, which is told in more detail in the recently published Fossil Men.
I was not all that familiar with the earliest chapters of primate evolution, so, all in all, I found The Real Planet of the Apes an incredibly engaging and useful account.
* catarrhines are a taxonomical group that encompasses humans, great apes, hylobatids such as gibbons, old-world monkeys, and all their ancestors before these various groups split from one another.
Other recommended books mentioned in this review:
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