Were there other intelligent living organisms on Earth

(ORDO NEWS) — Our planet is 4.5 billion years old, and for 539 million years the era of “manifest life” (phanerozoic) has been stretching on it – that is, one when there are large, highly organized animals on the planet. The question naturally arises: perhaps among them was the mind?

When did species appear that could theoretically become intelligent?

Such questions received some nourishment in the 21st century, when it was established that synapsids, widespread even in the Permian period (299-251 million years ago), were not reptiles at all, as was believed in the 20th century, but the ancestors of mammals and, technically, mammals themselves – it is assumed that at least some of them nursed their young with milk.

As is now clear, synapsids could have been warm-blooded since the time of ophiacodons, who lived about 0.3 billion years ago.

At first glance, here they are, recipes for the emergence of intelligent species: warm-blooded and mammals, as you know, eventually gave rise to intelligence on Earth. But not everything is so simple. The fact is that in general, we are far from sure that mammals are needed for this.

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Ophiacodon (from synapsids), body length from 1.6 to 3.0 meters for various finds

Birds of the species living today know how to decorate themselves (cockatoos), and operate with tools, including those that they made themselves from improvised materials (New Caledonian crows).

Meanwhile, birds, as it has been found out in the last decades, are, in fact, dinosaurs, just that group of them that is devoid of teeth. Ancient dinosaurs, at least some of them, were also warm-blooded and covered in feathers.

That is, in theory, the basis for the emergence of intelligent species existed for hundreds of millions of years in a row, indeed, somewhere from the Permian period.

Encephalization index: how to look into the head of a creature from another era

About half a century ago, scientists developed the so-called encephalization index: the ratio of actually observed brain mass to that expected for a mammal of this size.

It’s useless to simply take the ratio of brain and body mass here, because, for example, it is the same for mice and humans (~ 1 to 40), but the complex formula for calculating the index made it possible to basically solve the problem of quantitative comparison of the brain in different species.

With his help, we managed to find out this. The raven (yes, the index is also applied to birds, although it was originally made for mammals) in terms of the ratio of the expected size of the brain to the body is analogous to chimpanzees, their encephalization coefficient (EC, a synonym for the index) is about 2.5. In bottlenose dolphins it is twice as high, in us humans it is three times as high.

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If large herbivorous dinosaurs, judging by the size of the brain relative to the body, really do not look like thinkers, then more carnivorous bipedal species are much less unambiguous characters

Against this background, herbivorous large dinosaurs, especially early ones, do not look like thinkers. Many sauropodomorphs had ECs in the region of 0.05. That is, the gap in this sense between them and a dog or cat was much greater than between a person and a cat.

At the same time, some Troodon that lived in the Late Cretaceous, before the extinction of the dinosaurs, had an EC of 5.8 . This is a very serious level, slightly higher than dolphins, and about the same as Homo erectus.

It is interesting that usually the EC of very large animals is lower than that of dolphins or higher apes (for example, in whales it is many times less than in bottlenose dolphins), but the tyrannosaurus may have been very “smart”.

His encephalization coefficient in at least one case is 2.47, the level of a chimpanzee and a crow. This is very difficult to explain: it is usually believed that such large predators should have led a solitary lifestyle, but today such a level of EC is found only in those animals that have a developed social life.

Maybe, after all, something like that was in tyrannosaurs? It is important to note that the early mammals known to us did not reach such a high level of EC.

By the way, the tyrannosaurus also lived towards the end of the dinosaur era, and in general, later dinosaurs show CE higher than earlier ones: they seem to have evolved significantly. However, there is a caveat: not a single dinosaur species known to us has upper limbs with signs of tool activity.

Normally, predators had free upper limbs, and these limbs were equipped with what looks like very specialized killing tools. Specialized limbs make it almost impossible to make tools. Simply put, there are no species in the fossil record that could be intelligent and “tool” before the genus Homo.

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One of the relatives of the Tyrannosaurus rex at a young age, as imagined by the artist. The remains of this individual were found in Burmese amber

Another important point: although size matters for the brain, it is not only important. For example, several years ago, scientists from Australia and South Africa discovered that gorillas, chimpanzees and orangutans, although they have the size of an Australopithecus brain, supply it with blood a couple of times better. This was determined by the diameter of traces from the blood vessels passing inside the skull.

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Efficiency of blood supply to the brain in different species of hominids. Lines of our ancestors are shown in red, parallel lines are shown in black, Ma is millions of years

It is believed that the main energy costs of the brain are associated with the number of interneuronal connections in it. Since it is this that determines intelligence, it turns out that the Australopithecus, who knew how to make erect walking tools, was still inferior in intelligence to chimpanzees and gorillas.

But even here there is a nuance: the Floresian man, who used tools, is sharply inferior to the chimpanzee in this parameter.

However, it is doubtful that a creature with a sapiens lifestyle was actually inferior in mental capacity to chimpanzees, who are known to lead chimpanzee lifestyles. It turns out that the blood supply to the brain is not a completely universal factor.

From this it follows that both by the size of the brain, and even by the diameter of the vessels supplying it, it is extremely difficult to accurately assess whether there were intelligent species on Earth before us. Additional limiting factors are needed.

No finds – no civilization?

The most obvious of these is the absence of traces of technological civilization. Contrary to periodic pseudo-sensations, such as the “metal spheres” from Klerksdorp , which in fact turned out to be ordinary nodules of natural origin, there are no such traces yet.

Meanwhile, the finds of stone tools of our ancestors literally dot the layers of the Pleistocene. It is unlikely that a technological civilization can do without tools.

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The unusual shape of these natural concretions from Klerksdorp still leads conspiracy theorists to call them traces of prehuman civilizations, and even say that they are made of a complex alloy of metals. In fact, they do not consist of any alloy or any one pure metal, as is often the case with natural nodules

Suppose that for some reason they made them only from wood – fantastic, but let’s say. Then the tools themselves will not be preserved, but other signs of civilization will still not be able to be disguised. For example, modern humanity burns 8 billion tons of coal per year.

There are about 7 grams of uranium and thorium in each ton of coal (even more in brown coal). It turns out that our civilization contributes more than 56 thousand tons of uranium and thorium per year to the geological layers.

Almost all of them are long-lived isotopes. It is clear that if in the past someone used fossil fuels on a noticeable scale, geologists would inevitably encounter a layer with an abnormally high content of uranium and thorium, and most of all in those areas where representatives of an ancient civilization would have lived.

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Sunken Zealand, with an area of ​​​​almost 5 million square kilometers, went under water almost completely. Its former borders are shown in red. By 23 million years ago, it sank almost completely: even from New Zealand, only a narrow chain of small islands remained. Since then, however, this part of the former mainland has risen and quintupled in area

There are similar traces for other types of fuel, for example, they change the ratio of carbon-12 and 13 isotopes found in the atmosphere, and so on. Zero traces are known to date.

Therefore, if there was someone smarter than a man on Earth, then he lived on some isolated piece of land, such as the continent of Zeeland, which drowned 20-30 million years ago. Consequently, all traces of him went under the water with him.

But this is also an unlikely scenario. And now we will explain why.

When did it become possible for the emergence of intelligence on our planet?

Oddly enough, in the history of science, scientists very rarely and late began to wonder why warm-blooded and complex organisms have existed for more than a quarter of a billion years, and the mind was given only now.

At the same time, very little time passed from the first guns (3 million years ago) to flights into space – about 1% of the time of the existence of warm-blooded animals on Earth.

One of the first attempts to answer this question was a work by climatologist Mikhail Budyko, popular in format, but not in content, in which he drew attention to the fact that it seems that the size and complexity of the brain in at least some mammals begins to grow seriously during the period major climatic fluctuations.

If we take the entire Phanerozoic (the last 539 million years), then approximately 80% of the time the average temperatures on the planet fit into +17 … -20, 10% of the time they were hotter than +20, and another 10% – below +17.

We live at an average planetary temperature of +15, while our Australopithecus ancestors, other Homo species, and our own species have lived in the range from +17 to +9 for the past millions of years.

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It is easy to see that in the Pleistocene (second from the right part of the graph) temperature fluctuations became much more sharp than typical for our planet in the last half a billion years. Smarter or die?

As soon as the average temperatures of the Earth fall below +17, periodic cycles of glaciations inevitably begin on it: once every several tens of thousands of years, the temperature drops by several degrees, and then, after another tens of thousands of years, it rises.

90% of the time in the history of the planet was warmer than +17, so regular glaciations were impossible. If something like this happened, then once in millions of years, and not at all in tens of thousands.

Regular glaciations turned out to be an exceptionally tough selection factor. The fact is that the colder the climate, the higher its tendency to fluctuate temperatures (and precipitation) from year to year.

If in the Cretaceous period some zone was arid, and some was wet, then they were so stable. During the ice age, a multi-year drought could hit the forests at any moment.

In addition, the content of carbon dioxide in the air dropped sharply: a cold ocean can contain much more CO 2 per unit volume than a warm one, so when the temperature drops, this compound becomes scarce in the atmosphere.

At CO 2 concentrations below 200 ppm, it is very difficult for trees to survive: they are crowded out by grasses with C 4 -photosynthesis, which can grow even with low carbon dioxide.

Therefore, in the last ice age, for example, there was not a single massif of the Amazonian jungle, nor a similar massif in the Congo, nor forests of noticeable size in Eurasia.

Animals were forced to develop complex adaptations that were simply not needed in more climatically stable – and forested – eras. Budyko believes that the transition of our ancestors to tool activity was an example of such adaptations.

The expansion of savannahs and the compression of forests (during the Ice Age) have been regularly replaced by interglacials for the last million years, when forests again occupied a noticeable share of the land.

That is, a species that is well adapted to the forest (chimpanzees) or savannah (baboons) is constantly under stress from the contraction-expansion of their habitat. And those who were able to “despecialize” enough to feel normal both in the forest and in the savannah received a great advantage.

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Periodic advances of savannas on forests and forests on savannas permeate the last couple of million years of earth’s history. And this is a deeply atypical situation that created special conditions for natural selection

Based on this, Budyko noted, reason as a means of adapting to the extremely harsh conditions of the “glacial pendulum” could not appear before modern and extremely atypical conditions for its history arose on Earth, that is, prolonged climatic instability caused by average temperatures below +17 .

It turns out that it is possible to look for intelligent species in the past of our planet, but even on sunken continents like Zeeland, success is extremely doubtful.

Intelligence appeared in the last 3 million years, and not in any previous 536 million years of the Phanerozoic, not by chance, but by cruel necessity. A necessity that simply did not exist until the last 2-3 million years, the same Pleistocene epoch in which our species appeared.


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