Almost two million years ago, hominins going east and wild dogs going west met, in the iconic paleontological site of Dmanisi, Georgia.
That is not to say that the meeting resulted in cries of mutual delight and vows of eternal amity: it more likely ended in one of the parties eating the other, or at least competing over food. But the social strategy of the two disparate species was apparently strikingly similar, and likely contributed to their remarkable evolutionary success, suggest paleontologists in a paper published Thursday in Nature Scientific Reports, reporting on the canid find in the same stratigraphic layer where remains of Homo erectus were found.
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The earliest known hominin exit from Africa was about two million years ago, long before our sapiens species began to emerge. The beings who reached Dmanisi were small-brained and primitive, but apparently already possessed the property of compassion, as evidenced by the discovery some time ago that one of them had been almost entirely toothless. These were Homo erectus and, going by the edentulous individual, they had the capacity for mutually beneficial cooperation, reciprocity and social behavior.
And who did these hominins meet in the area of their high-altitude cave in Dmanisi, as they spread toward eastern Asia? Wild dogs, aka hunting dogs, spreading in the other direction toward Europe, who also – in one of those bizarre coincidences – were capable of socially considerate conduct, says the study (based on many other studies).
Erectuses were found in several archaeological levels, representing a great span of time. In just one of these layers, researchers have found and identified the jaw of a large dog: a Eurasian hunting dog, Canis (Xenocyon) lycaonoides, a species that existed in the Early Pleistocene.
Separate work based on fossil evidence concluded that these Eurasian hunting dogs were – like humans! – cooperative pack hunters. Unlike many other large dogs, the Eurasian hunting dog was capable of social care toward kin and non-kin members of its pack, writes the team of Saverio Bartolini-Lucenti, Joan Madurell-Malapeira, Bienvenido Martínez-Navarro, Paul Palmqvist, David Lordkipanidze and Lorenzo Rook.
“Hominins and hunting dogs, both recorded in Dmanisi at the beginning of their dispersal across the Old World, are the only two Early Pleistocene mammal species with proved altruistic behavior towards their group members,” the team writes.
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No, the team is not implying that the amiable erectuses became friends with the amiable wild dogs, Bartoloni-Lucenti reassures Haaretz. No postulation of domestication is suggested here. It is coincidence that the place where science has found the earliest sign of Homo presence in Europe – Dmanisi – also boasts the earliest known European presence of this dog. If anything, the two hyper-carnivorous species would have been in competition over resources. Far from seeing one another as friend, they probably saw one another as ambulatory food.
Call it a dog
What was this dog that the erectuses encountered at Dmanisi? “There is a difference between the common use of the word ‘dog’ (made of different breeds, wagging tails at your sandwich) and ‘dog’ in zoology and paleontology,” Bartoloni-Lucenti explains. “Dogs” is a colloquial way of saying “members of the family Canidae,” just as “cats” is a generalization for “Felidae, felids.” That description encompasses everything from the tabby on your keyboard to the tiger, he explains.
As for “hunting dog,” Lycaon pictus still exists in Africa and is reasonably known as the African wild dog (aka African hunting dog; another wild dog still extant is the Indian dhole. Lycaon pictus, the terror of the African savanna, probably arose from Canis (Xenocyon) lycaonoides, the species found in the Dmanisi dig, he says – though there is a lot of uncertainty regarding the evolution of hyper-carnivorous canids.
As for the hyper-carnivory, technically that means they derived over 70 percent of their calories from meat, Bartoloni-Lucenti elaborates.
Regarding the Eurasian hunting dog, hyper-carnivory stands to reason. The theory that small-brained erectus was also a hyper-predator is new. A meta-analysis of about 400 studies published this year, conducted over decades by unconnected scientists, concluded that far from being omnivores, early humans two million years ago were specialized hyper-carnivores who only resorted to other sources of nutrition when we were forced to – for instance, after killing off all the big edible animals in the area.
But moving on from diet, the fact that the two species – hominins and hunting dogs – both evinced sociality, caring for pack-mates, arguably lay behind their success in terms of dispersion and colonization of vast areas of the world, Bartolini-Lucenti explains.
Successful? The extant wild dogs (the African wild dog and the dhole) both became the top predators in their respective habitats – which the team ascribes not only to their teeth but to pack hunting and their highly developed social behavior. The success of the hunting dog is elaborated at some length in the new paper, as is the theory for their Asian origin (which not all accept).
Out of China
The earliest find of a hypercarnivorous canid is a single jaw fragment found in the Zanda Basin in China from roughly 3.5 million years ago. The species was named C. (Xenocyon) dubius. Long story short, such ancient proto-hyper-carnivorous dog fossils are rare but pop up here and there. Then around two to 1.8 million years ago, large new forms of hyper-carnivorous dogs began to appear – including our Canis (Xenocyon) lycaonoides. It seems to have emerged in Asia and became widespread throughout that continent, and later in North and East Africa too.
So when the team writes that early human and early dog “lived alongside” one another at Dmanisi, it means they occupied the same general space, not that they lived in association.
By the way, paleontologists have also found the remains of what looks like a small wolf at Dmanisi. It wouldn’t have been domesticated either. (A separate study has shown why one can't have wolves as pets.)
Dog domestication from the wolf was relatively very recent – one theory is that it sprang from meat-sharing, possibly in Siberia about 23,000 years ago. There are other theories, but it’s clear the dog was the first animal to be domesticated, far predating the advent of orderly agriculture and the domestication of animals such as cows and goats.
As for who ate who 1.8 million years ago in Georgia, separate work has demonstrated that the hominins ate everything that moved, including wolves, mammoths and deer, and were eaten by anything that could catch them, such as big cats and giant hyenas (going by bite marks on bones), and likely wolves as well.
Today, 1.8 million years after an early wild dog and an early wild hominin met in Georgia, it cannot be said the African wild dog or dhole are a success nowadays. Both are critically endangered, which is entirely the fault of the human side of the equation encroaching on their habitat. Their sociality, communication, negotiation skills and caring for one another can’t help them against us anymore.