Gods of Salt

« Certainly Nature, when she left the making
⁠Of animals like these, did well indeed,
⁠By taking such executors from Mars;
And if of elephants and whales she doth not
⁠Repent her, whosoever looketh subtly
⁠More just and more discreet will hold her for it;
For where the argument of intellect
⁠Is added unto evil will and power,
⁠No rampart can the people make against it. » – Inferno, Canto XXXI, 49-57


Consider the following facts:

#1: The Mediterranean Sea loses more water to evaporation than it receives from rivers: it only maintains its level thanks to influx from the Atlantic. Between 6.0 and 5.3 million years ago, in the late Miocene epoch, the closure of the Gibraltar Strait caused the Mediterranean to dry out. This is known as the Messinian Salinity Crisis, and it left vast deposits of gypsum and rock salt. At its apex, this event would have reduced the sea to a few puddles of hypersaline water, similar to today's Dead Sea, surrounded by scorching desert - with temperatures possibly reaching over 40°C due to high pressure. Its islands and peninsulas would have turned to massive mountain ranges up to 5 km tall ([1]). This event ended with the so-called Zanclean Flood, when the Atlantic waters rushed back into the basin, through not one but a series of waterfalls. The overall drop was more than a km, and the discharge of water has been estimated at a thousand time that of the Amazon River ([2]). That's enough to refill the whole Mediterranean in less than 20 years. A sumberged barrier, known as Camarinal Sill, forms the shallowest part of the strait, at only 280 meters below sea level ([3]).

#2: Nevertheless, despite its terrible conditions, the Mediterranean Basin still had enough hospitable land to allow animals to move from Africa to Europe, and vice versa. In fact, the climate, flora, and fauna of Africa and Europe were very similar in the Miocene. Dwarf species of hippopotami and elephants have been found in Cyprus, Crete, Malta, Sicily, Sardinia, the Balearics: all the main islands of the Mediterranean. The lowland-dwellers could have lived along rivers like Po, Rhone, and Nile, which would have cut much deeper valleys.

#3: The Miocene was also a time of great diversity of mammals. In particular, it was the golden age of elephants (which existed in every continent but Australia) and apes (which were even abundant in Europe). European apes included the swamp-dwelling Italian Oreopithecus, 9-7 million years old, which had a pelvis suited for an almost bipedal locomotion ([4]), and hands more capable of precision gripping than those of any living non-human ape ([5]). As for elephants, Primelephas, the likely common ancestor of mammoths and all living elephants, lived in Africa at the end of the Miocene.

#4: Molecular studies place the separation between the lineages of humans and chimpanzees between 7 and 5 million years ago, later than Oreopithecus, and corresponding with the Messinian event. Recent estimates push the divergence backward, even to 10-12 million years ago; however, controversial studies suggest that the two lineages exchanged genes as recently as 4 million years ago ([6]). Clearly the process of separation was more complex than we realized at first, and involved some degree of hybridization between the recent lineages.

#5: The Mediterranean region contains a vast diversity of halophytes, plants than can grow despite high concentrations of salt. Many of these are suitable for human consumption: the oil-rich salicornia (Salicornia sp., eaten both fresh and pickled), the cabbage-like sea kale (Crambe maritima, which grows spontaneously on sandy beaches), the spinach-like sea orach (Atriplex halimus, a close relative of which is grown in India as vegetable and livestock fodder). The argan tree (Argania spinosa) is extremely resistant to both salt and drought, and is prized in Europe and North Africa for its wood and oil. ([7])

#6: The list of Mediterranean halophyte species is actually much wider, but many plants that grow in these conditions are not useful to humans: for example, the Mediterranean beard-grass (Polypogon maritimus), a close relative of oat and wheat, much less nutritious than either. Note, however, that elephants (much more common and diverse in this region in the Miocene) have very low nutritional requirements, and can feed on almost any type of vegetable matter. Now, a key characteristic of the Miocene epoch is a wide spreading of grasslands, replacing the forests that earlier covered most of the globe, triggering a wave of adaptation and diversification among mammals. In fact, between 10 and 5 million years ago, the diet of elephants has switched from leaves to tall grass, a change that can be seen in the shape of their teeth ([8]). Only in the last million years elephants have reverted to eating leaves ([9]).

#7: Until recently, the divergence between humans and chimpanzees had been linked to this event: the ancestors of chimpanzees would have remained in the thick rainforests of West Africa, while humans evolved in the new savannas of the east. This places human evolution entirely in eastern and southern Africa until the last million years or so. This view has been challenged by recent finds. In 2002, the 7-6 million years-old Sahelanthropus tchadensis, a serious contender as common ancestor of humans and chimpanzees, was discovered in Chad, in North Africa. Its foramen magnum suggests an already bipedal pace, as with Oreopithecus ([10]). In 2017, curiously human-like teeth, 7.2 million years old, were attributed to Graecopithecus, in Greece ([11]). Finally, in the same year, 5.6 million years old footprints that clearly show bipedal locomotion were found in Crete ([12]). All of this suggests that the earliest human evolution occurred at first in the Mediterranean region.

#8: The intelligence of elephants is well known. Their brain, over 5 kg heavy, has more cortical gyres than any primate or cetacean, and they might rank in intelligence besides chimps and dolphins ([13]). They form matriarchal herds with extremely strong interindividual bonds and great capacity for cooperation and reciprocal help. They are the only known non-human animals that seem to have ritual behavior related to death ([14]). Pregnant elephants have been observed chewing on leaves of a Boraginacean tree, used to induce labor or miscarriage by Kenyan women ([15]). They can use branches as simple tools, cover water pools to prevent evaporation, and use logs to disable electric fences ([16]). They can recognize themselves in the mirror ([17]), and seem to have artistic inclinations ([18]). Such abilities are especially astonishing in view of such an energy-poor diet. Yet we have seen that their diet was very different in the latest Miocene - that there are plants that grow in the Mediterranean region, could be eaten by ancient elephants, increased in diversity at that time, and are closely related to our food crops.

#9: The elephants' trunk is a dexterous organ of manipulation, capable of handling single seeds and inspecting delicate bodyparts like eyes. Nevertheless, having only one grasping organ could be a handicap for an active tool user (the two fingerlike tips are unique to the African species, and probably didn't exist in Miocene elephants). The trunk can lift loads of hundreds of kilograms, but it's poor at grasping large objects, and can only wrap around them. In comparison, the hands of apes are much more versatile, especially after the innovation we have seen in Oreopithecus. In addition, the same amount of food that sustains an elephant with its single trunk can support not two, but several ape hands - especially since high-energy primate food can pack nourishment in a much smaller mass, even when inedible to elephants.

#10: African elephants in reserves readily initiate contact with humans, often forming long-lasting individual bonds, and often prefer to interact with humans than with other animals of their environment. Many of these elephants appear more relaxed and at ease near humans than near even other elephants. This effect has been documented in species with a long history of domestication by humans, such as dogs and horses. ([19]).

Let's place everything together. Six million years ago, near the end of the Miocene epoch, the natural closure of the Gibraltar Strait turned the Mediterranean Sea into a salty desert. The few inhabitable spaces provided a safe passage between Africa and Europe for many species; elephants and apes, which had been increasing in diversity for all the Miocene, were among them.
The depths of the new Mediterranean basin, on the other hand, were a hellish environment that must have forced many species into desperate adaptations. Many plants learned to grow in sand, long before the Sahara became a desert, with concentrations of salt that would kill most others. Elephants, we've seen, are good at finding and storing water, using tools to prevent evaporation from reserves. They must have evolved their characteristic intelligence to deal with the unique challenges of the Mediterranean Basin. Like the Khoisan hunter-gatherers of the Kalahari desert (or for that matter the earliest Homo sapiens) they needed advanced problem-solving skill, good memory, and the ability to cooperate and trust each other.
Their eventual solution to ensure themselves a food supply in the great basin was agriculture. Many Mediterranean halophytes are edible even in the seed- and fruit-focused human diet; but the sapient elephants of the Miocene could feed even on simple grass. Cereals like Polypogon - which are, after all, nothing more than especially nutritious grass - must have been a blessing. Perhaps they were even selected artificially to tolerate more saline soils, as could have been the precious argan tree.
Still, the burgeoning elephantine civilization was slowed down by their sluggish reproduction and by their limited capacity for manipulation. The trunk was very effective, but every elephant could only hold one thing at a time. They must have experimented with many forms of animal labor (as well as hydraulic, etc.), but none of the many animals of their region could help them handle objects, make cheap craftwork, or operate machines.
Eventually, they started working with apes. Maybe they took a sample of Oreopithecus descendants or Graecopithecus from the northern highlands. They were clever animals, forged by the same cruel environment, capable of understanding gestures and executing simple orders. They wouldn't take away the hard leaves and grass of their masters, but they would eat almost anything else (to the elephants, the ability to digest meat must have seemed extremely precious). They had hands: two hands to grasp a broad object without handles, to scatter seeds on a field, or to hold hammer and chisel in the making of a triumphal arch.
So the elephants found themselves ruling over a vast caste of small, nimble, infinitely versatile slaves. Surely they must have tried to enhance them through selective breeding, as humans did with dogs and horses, creating features similar to the short jaws and small teeth of humans, or the peaceful countenance of bonobos. Their genes still bear traces of closely related lineages being interbred. They certainly encouraged a bipedal gait, so that the precious hands remained always free. With ape-servants so common and useful, crawling all around like living robots, elephants must have had little incentive to improve their technology further.
Remember the air at the bottom of the Basin was very thick: it's likely the elephants were specially adapted to breathe it, and would feel much discomfort outside of their cradle. They never ventured beyond what today is the coastline of the Mediterranean, which must have looked like impassable mountains to them. However, they could have sent their servants in exploration on the great islands: leaving, for example, the mysterious footprints of Crete.
The proboscidean rulers probably didn't have much more concern for their primate slaves than humans have for cows in a slaughterhouse. Even though they couldn't eat them, they could still fashion their skins and bones into precious objects; sacrifice them to elephantine gods atop of a ziggurat raised by their work; make them fight in blood games or proxy battles; use them for carnal gratification or for medical experiments. The different proclivities of humans, bonobos, and chimpanzees can be understood as specialization for such tasks. We can only wonder what the apes could understand of their condition.
The civilization of elephants had 600,000 years to develop between the Messinian Crisis and the Zanclean Flood: thrice the age of our own species. Certainly they studied in depth their secluded world. As the sea level started to increase on the Gibraltar Strait, they would have probably predicted the danger, and built a massive dam to block the way of the Atlantic waters. Maintaining this dam must have been the highest priority. But there were certainly those who didn't believe this looming danger. And in the end the central sin of the elephantine empire must have caught up to them.
What could have distracted the elephants from preserving the Mediterranean Basin as they found it? Probably action from those who had nothing to lose from utter destruction - such as ape-slaves who had finally crossed the threshold of self-awareness. Or rather a preemptive action from those who feared a revolt more than their own annihilation? Some kind of sabotage action, perhaps, that ended a millennia-spanning history by breaking down the great dam, letting the ocean pour into the Basin with an unimaginable catastrophe, and turn it back into a sea.
Some survived, both apes and elephants. They must have been few, perhaps outcasts that had fled, or had been exiled, to the outer highlands. Gradually they accustomed themselves again to the thin air (maybe this didn't even require evolutionary adaptation, just individual assuefaction; but the lords below were used to comfort...). Some were stranded on the new islands, and became the dwarfs of Cyprus, Crete, Sicily. The others scattered into the wilderness of Africa and Europe.
Without the infrastructures of the submerged empire, unprepared for the different environment outside, they were unable to rebuilt their civilization. Most of them had been poorly inserted in society, and their intellective faculties weren't the highest, either as a cause or a consequence of their isolation. Alone, they reverted to wild animals, and became gentler than they ever had been when they were civilized beings. They still retain the vestigial skills of artists and doctors; they still mourn the death of their kin.
The surviving apes, now free, wandered back into the heart of Africa, passing through Chad. Some found shelter in the jungles of Congo and Nigeria, others in the savannas of Kenya and South Africa, that perhaps reminded them of the flat lands where they were bred into their new shape.
Five million years after that unimaginable disaster, silt has covered all the ruins on the Mediterranean seafloor, and the "domesticated apes" have left Africa in three waves of migration. Now they control the world, from coastlines to mountains, they remake its land into cities and farms, and they hold in their power the fate of the distant descendants of their ancient masters.
It remains to be seen whether they will choose to be merciful or vindictive. Aren't five million years enough to expiate any sin?


EDIT 23-07-21: A short story.
EDIT 24-07-21: rearranged the references a bit, and added point 10: many thanks to CleverFoolOfEarth for that.