Europe
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This remarkable discovery was studiously ignored by Georges Cuvier. One of his dictums—which has not stood the test of time—was ‘l’homme fossile n’existe pas’ (fossils of humans do not exist).3 A devout Lutheran, he rejected any notion of evolution, instead proposing a theory of catastrophes and re-creations, which was more consistent with the Bible. Only the last cycle of creation, Cuvier posited, involved people—hence the lack of human fossils in older rocks. Although Cuvier managed to ignore the inconvenient femur, towards the end of the nineteenth century it was studied and named Paidopithex rhenanus. Today, it is thought to be from a late-surviving pliopithecoid that lived about 10 million years ago.4
Genetic studies indicate that the last common ancestor of the apes and Old World monkeys lived about 30 million years ago. But the oldest fossils, from Tanzania, are only 25.2 million years old.5 The oldest ape, Rukwapithecus, is known from one partial jawbone, while the earliest Old World monkey, Nsungwepithecus, is known from a jaw fragment retaining a single molar. Scientists estimate that Rukwapithecus weighed about 12 kilograms, and that Nsungwepithecus was a little lighter. Beyond that, almost nothing is known of these important ancestors. The ape superfamily that Rukwapithecus gave rise to is known as the Hominoidea (it includes the gibbons as well as the orangs, gorillas, chimps and humans). Hominoids differ from monkeys in several ways, the most striking being the lack of an external tail. Apes do, however, retain tail bones, which have evolved into an entirely internal, curved structure known as a coccyx. Because apes and Old World monkeys share many similarities, the identification of a fossil tooth or limb bone as that of an ape is necessarily speculative. But a fossil coccyx constitutes gold-plated evidence.
For millions of years Africa had been bulldozing its way north. We often talk of continental drift, but the term is too passive: continents buckle, lift or smash whatever is in their path. About 19 million years ago Africa began to rotate counterclockwise to pinch the Tethys Sea in the region of what is now the Arabian Peninsula. A day must have come when sand touched sand. The great Tethys was severed, and in its place a land bridge linked Africa with the Turkish section of Europe. Elephants may have swum the narrowing Tethys Sea ahead of the connection, but apes abhor Neptune’s realm: they would wait until a foot could be planted in dry sand—or perhaps even until a passage through a forest canopy could be negotiated.
The fossil ape Ekembo (previously included in Proconsul), from Kenya, lived between 19.5 and 17 million years ago. It was generally monkey-like, but probably lacked an external tail.* By around 17 million years ago, Ekembo-like apes had colonised Europe and undergone a rapid phase of evolution, transforming into griphopiths. Griphopiths are the earliest hominids, and their appearance in Europe at least a million years earlier than in Africa suggests that our family most likely arose in Europe—and not, as has been long assumed, in Africa. By 16.5 million years ago the Tethys seaway had again opened, isolating Europe’s griphopiths. They continued evolving in isolation until about 15 million years ago, when the road to Africa again opened, allowing them to enter Africa and become established there.6
The 15-million-year-old African Equatorius was a recent emigrant, being very similar to the European griphopiths, though more terrestrial. Its contemporaneous relative Nacholapithecus (also African) provides the earliest unequivocal evidence of that key ape characteristic—the coccyx.7 Beginning about 13 million years ago, the fossil record of apes dwindles in Africa, before disappearing 11 million years ago. There are abundant fossils of all sorts of other creatures, so it looks as if the apes became extinct in Africa, perhaps through competition with Old World monkeys.
It may seem paradoxical that monkeys could outcompete apes. But if we absent humans and ask ourselves whether the apes or the Old World monkeys have done better in evolutionary terms, the answer is clear. There are about 140 living species of Old World monkeys, distributed from the icy mountains of Japan to Bali and from the Cape of Good Hope to Gibraltar. The apes, in contrast, comprise just 25 species which, with the exception of our own, are mostly rare inhabitants of African and Asian rainforests. Indeed, the monkeys have been displacing the apes from various habitats for many millions of years, so that today the surviving apes are mostly large species that have avoided competition with the highly efficient monkeys by increasing their body size.
It seems highly likely that about 13 million years ago, just before the great dwindling of the African apes, Nacholapithecus, or a species very like it, used another short-lived land bridge to cross from Africa into Europe. Some of the migrants didn’t stay in Europe, however, but pushed on to Asia, where between 10 and 13 million years ago they gave rise to an ancestral orang utan. The apes that remained in Europe thrived, for their main competitors, the Old World monkeys, did not reach Europe until about 11 million years ago and did not become widespread there until about seven million years ago. Perhaps the more seasonal environment of Europe disadvantaged them.
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* Frustratingly, we cannot be absolutely certain of this based on the remains we have.
CHAPTER 18
The First Upright Apes
There is little evidence of mammal migrations between Europe and Asia, and even less with Africa, between 13 and 10 million years ago. During this period, momentous changes began to occur among Europe’s apes.1 The story of that transformation is best told through the bones of an ancient Catalan, a Hungarian and a Greek. About 10 million years ago, in a waterway that is now a rubbish dump at Can Llobateres, near the town of Sabadell in Catalonia, the bones of creatures including ancient rhinos, flying squirrels, horses and antelopes began accumulating. In the summer of 1991, palaeoanthropologists David Begun and Salvador Moyà-Solà began to search there for fossils.2 Ignoring the stench, they drove their picks into the sediment almost simultaneously, and to their astonishment exposed the skull of an ancient ape.
Over several years the partial skeleton of an extraordinary creature named Hispanopithecus crusafonti (Crusafonti’s Hispanic ape) emerged from the clay. The bones make up the most complete hominid skeleton ever discovered in Europe.* Its limb bones reveal that Hispanopithecus moved about like chimps and gorillas. But a surprise came when scientists examined its sinus cavities, which are large and of a shape seen only in gorillas, chimpanzees and humans. To judge from its sinuses, Hispanopithecus crusafonti is the earliest known hominine (the group including all great apes except orangs).
The bones of the second important specimen were unearthed in an iron mine near the town of Rudabánya in Hungary. The sediments exposed there were laid down in and around Lake Pannon, a now-vanished body of water that between 10 and 9.7 million years ago was about the size of the Great Lakes of North America. Freakish conditions at Rudabánya resulted in the capture of a ‘snapshot’ of an entire ecosystem.
Let’s once more enter our time machine and visit the wonder that was Hungary 10 million years ago. We arrive at dusk in a wet and verdant world. The first thing we notice is the din of the evening chorus. The cries of ducks, pheasants, ravens, frogs and insects fill the air, and the early flying bats are already flitting about. The place feels more like modern-day Louisiana than central Europe.
A shower—one of many in this place that receives at least 1.2 metres of rain per year—has left the ground marshy. As we step away from the time machine we disturb a large beast. It’s a tapir, emerging from the water and following the track left by a huge elephant—a deinothere—whose lower tusks have stripped bark from the trees beside the pad way. A mixed group of chalicotheres, rhinos and horses feed in woodland in the distance, stalked by a sabre-toothed nimravid and a hyena. The diversity of mammals is astonishing, with more than 70 present, including shrews, moles, bats, pliopithecoids, hares, many rodents including anomalures (strange squirrel-like creatures with scales on their tails, that can still be seen in central Africa), beavers and a wide variety of carnivores.3
Attracted by croaking we bend down and look into the reeds growing beside
a small puddle, where we see two kinds of toads. Picking up one of the smaller ones, we turn it over to reveal the rich yellow-and-black patterning of a firebelly. As we do so, the creature goes into its characteristic defensive posture, pushing its splayed legs high above its snout, creating a remarkable illusion that the toad’s arse is in fact its head.
The larger kind of toad is gigantic. It bears little resemblance to its only living relative, the Hula painted frog of Israel. Calling loudly from among the reeds, it looks safe enough, but climate change will one day expel its entire genus from Europe. The firebellies and the painted frogs are members of the family Alytidae, which includes the midwife toads. The Miocene has been kind to these venerable creatures.
Something springs from the grass beside our feet and grabs a firebelly. It’s a cobra, which, when it sees us, rises up and erects its hood. Soon cobras will be extinct in Europe, but this animal is entirely at home in the subtropical environment. There is one more surprise in store for us: a chimp-like call draws our attention and in the canopy we spy an extraordinary ape. Known as Rudapithecus, it was similar in some ways to Hispanopithecus, and is of exceptional importance to the story of human evolution.
The discovery of a skull of Rudapithecus at Rudabánya has greatly added to our understanding of this vanished ape. The specimen was found by Gábor Hernyák, a local geologist who had been working in the Rudabánya mine collecting fossils since the 1960s and had recovered many invaluable specimens. Hernyák had volunteered to work with David Begun on his 1999 dig at the mine but, according to Begun, had ‘little patience with the niceties of documentation’ of fossils, and without documentation the fossils are of reduced scientific value. So Hernyák was sent off to sweep up some loose dirt on a rock bench where the palaeoanthropologists had sat to eat their lunch. From millimetres below the surface that had supported their academic buttocks, Hernyák uncovered the jaw of Rudapithecus, which, with more excavation, led to the discovery of the all-important skull.4
Rudapithecus was the size of a chimpanzee and had a chimp-sized brain; older apes had much smaller brains relative to their body size, and Rudapithecus provides the oldest evidence for such a large-brained ape found anywhere in the world. Because of constraints on head size during birth, large-brained apes are born while their brains are still growing. In humans, this leads to a phenomenon known as the ‘fourth trimester’—the three months after birth when the brain is developing fast but is now exposed to social stimulation. Some researchers think that this phenomenon is responsible for our sociality and intelligence.5 If that is the case, then perhaps the foundations for these aspects of our species began on the shores of Lake Pannon, some 10 million years ago.
About half a million years after a few individuals of Rudapithecus died beside the great Pannonian Lake in what is now Hungary, a much larger hominid was haunting the vicinity of what is now Athens and Thessaloniki. Ouranopithecus was gorilla-sized, with heavy brow ridges, big jaws and a palate that were all distinctly gorilla-like. Its molars, however, were unlike those of gorillas but very human-like in that they were covered with thick enamel. Its canines were also short, again like our own and unlike the long, sharp canines of gorillas. Ouranopithecus is as tantalising as it is frustrating, for this critically important link in the story of hominid evolution has left us nothing but a few teeth and jawbones, and a partial skull. We cannot know how it got around, how large its brain was, or whether it had large sinuses. When it was first discovered researchers described it as a possible ancestor of the australopithecines—and therefore close to the human lineage. More recently it has been suggested that Ouranopithecus is equally distantly related to all African apes.
The discovery of some eight-million-year-old teeth from Ethiopia has prompted yet another theory. They are claimed as the earliest gorilla fossils, but they look very much like the teeth of Ouranopithecus.* So it may be that Ouranopithecus is an ancestral gorilla, and that gorillas evolved in Greece. If this is correct, then evolution has reversed itself in several ways: first, the thin enamel of gorilla and chimp molars must have re-evolved from the thick enamel of human-like molars; and, secondly, the formidable canines of the gorillas and chimps have evolved from short, human-like ones. If this is the case, the ancestor of humans, gorillas and chimps had short canines and thick molar enamel—features retained only in humans among living apes.
The importance of Greece to hominid evolution was given an enormous emphasis in May 2017, with the re-analysis of Graecopithecus freybergi.6 The story of this ape goes back to 1944, when threatened German troops stationed near Athens were digging a bomb shelter. As the soldiers dug desperately in the fine, reddish sediments, one exposed the badly degraded jawbone of a primate. Just how the eroded bone, which lacked tooth crowns, was noticed at all in the dire circumstances and how it was preserved, are not recorded. Nor is there any hope of re-excavating the site at Pyrgos Vasilissis, for the owners of the land, in what is now virtually a suburb of Athens, have built a swimming pool in the remains of the bomb shelter. Fortunately, the fossil can be dated accurately—to around 7,175,000 years ago.
After the war, the find fell into the hands of the Dutch palaeoanthropologist Gustav Heinrich Ralph von Koenigswald, who in 1972 named it Graceopithecus freybergi—Freyberg’s Greek ape.** Von Koenigswald was famous for his researches on Java Man (Homo erectus) but he was risking his hand in naming the miserable scrap of jawbone Graecopithecus. Indeed, the name was widely considered a nomen dubium—a doubtful name—and was in danger of being rejected by the International Commission on Zoological Nomenclature, which is a black mark indeed on the record of any zoologist. And there matters lay—until new technology revealed that the great professor had been right all along.
The roots of the premolars, it transpires, are key indicators of the hominin lineage, and CT scans of the tooth roots, along with the roots of a premolar found in Bulgaria, allowed the remains to be identified with some certainty as the oldest known hominin—that is, a direct ancestor of the upright apes including ourselves. This means that, in addition to democracy and gorillas, we must now credit Greece with being the cradle of the hominins—of which we humans are the only living representatives.
The reddish sediments that entombed the jaw have their own story to tell. Analysis of salt and minute rock particles show that they were carried to the Athens area from the Sahara, in dust clouds at least ten times larger than any seen today, indicating that the Saharan desert was already drying out seven million years ago and that its dust was falling on Europe in abundance. Elsewhere in the region, similar sediments have yielded the remains of ancient rhinos, horses, giraffes and large antelopes. Pollen from these sites reveals the presence of pines and oaks, saltbushes, daisies and grasses, while charcoal testifies to the occurrence of fire.7 All in all, the dry, open environment that Graecopithecus inhabited was very different from the moist habitats favoured by Europe’s earlier apes.
In 2017 an astonishing find was made near the village of Trachilos, on the island of Crete. There, sometime between 8.5 and 5.6 million years ago (with a most likely date of 5.7 million years ago), a pair of bipedal apes, perhaps accompanied by others, walked through the shallows on the edge of the sea, leaving tracks that would be preserved in great detail. At the time they were made, Crete was most likely a peninsula of mainland Europe.
The footprints left by these creatures vary in length between 9.4 and 22.3 centimetres, making them smaller than adult human footprints, but about the right size for Graecopithecus. They clearly show that the feet that made them had a ‘ball’ and a great toe aligned like ours. Only upright, walking apes have feet like this; it is probable that they were left by a relative of Graecopithecus, if not Graecopithecus itself.8
These footprints are the most recent evidence we have of hominins in Europe prior to the arrival of Homo erectus about two million years ago. It is touching to think that Europe’s upright apes may not have survived for long after the Trachilos footprints were made, for towards the e
nd of the Miocene Europe lost several species that continued to survive in Africa, including primitive giraffes like the okapi. The extinctions may have been caused by the same event that allowed the upright apes to migrate into Africa—the Messinian salinity crisis, when the entire Mediterranean dried out and a wide path to Africa was opened; though perhaps only briefly, before the basin became inhospitable to life.
The first possible hominin to appear in the African fossil record is Sahelanthropus tchadensis, which inhabited what is now Chad about seven million years ago. The next oldest is the 6.1–5.7 million-year-old Orrorin tuguensis, from Kenya. Known from a partial skeleton, it was definitely bipedal. Thereafter, Africa has yielded a rich array of upright apes spanning the gap between Orrorin and Homo. Mysteriously, almost no chimp fossils are known; a handful of half-a-million-year-old teeth from Ethiopia being the only ones identified to date.
Charles Darwin was right. Sometime about 5.7 million years ago, ‘a migration on the largest scale’ was made by apes walking from Europe to Africa. I’m sure that even the great man himself would have been surprised by the idea that the migration was made on two legs, rather than four. But following that event, until Homo erectus colonised Europe and Asia around 1.8 million years ago, the human story is all African.
A SUMMARY OF APE EVOLUTION DURING THE OLIGOCENE–MIOCENE
More than 30 million years ago The ancestors of Old World monkeys and apes, the pliopithecoids, evolve in Asia.
25–30 million years ago Rukwapithecus (ancestor of gibbons, orangs, gorillas, chimps and humans) evolves in Africa.