First cephalopods (ammonites, nautiluses, squid, octopuses, cuttlefish); the term ammonite derives from the Egyptian god Amun, whose horns resemble the ammonite’s spiral. These were the first cephalopods, from which octopuses would soon evolve. Studies highlighted and conducted by Peter Godfrey Smith point to a complex intelligence on the part of modern octopuses, and probably even self-awareness. This therefore poses a dilemma: either self-awareness evolved independently at least two or three times (us, octopuses, crabs, etc.), or it evolved only once, but long ago, before the emergence of cephalopods. The last common ancestor between cephalopods and Homo sapiens dates back 600 million years. The octopus’s nervous system is very different from ours, essentially having a central brain (with two hemispheres and no corpus callosum connecting them above) and eight large groups of neurons distributed throughout each tentacle. It’s unknown how these eight “brains” interact, but one hypothesis is that different modalities are used in different circumstances (independence of the tentacles or central control of the brain in the octopus’s “head”). Octopuses also possess some characteristics found in other species (including Homo sapiens), such as REM sleep.

The worm Pikaia Gracilens is the first known creature with a backbone, making it a candidate for the ancestor of every vertebrate (including us).

Mass extinction of living species

In what is now Yoho National Park, a submarine landslide is forming, covering the future fossils of the Burgess Shale: specimens of soft-bodied organisms preserved in astonishing detail. These are ancient representatives of all four major groups of arthropods, the dominant animals on Earth: trilobites, crustaceans, chelicerates (such as modern spiders and scorpions), and uniramids (insects). But the Burgess deposit also contains at least a dozen organisms that do not belong to any modern phylum (sponges, coelenterates, annelids, mollusks, arthropods, echinoderms, chordates), each of which could be unique representatives of a new phylum; as well as 20-30 arthropods that cannot be placed in any modern group.

The Tardigrade family appears. They were discovered in 1773 by the pastor Johann August Ephraim Goeze. Over 1,150 species have since been discovered. They are microscopic animals with segmented bodies and eight legs. They are extremophiles: they can live in extreme environmental conditions, such as temperatures just above absolute zero (0K) or much higher than the boiling point of water, pressures from zero to several times the pressure at the bottom of the ocean, doses of ionizing radiation several times greater than those that would kill a human, and they can survive the vacuum of space. They can go without food for more than 10 years and become dehydrated at up to 3% of their water content. They are 0.5 mm long when adult. And they are a species that dates back 530 million years. They are found everywhere, from the Himalayas to the ocean trenches, and there are 25,000 of them per liter of water. Earth is the planet of the Tardigrades…

Earth’s fourth eon: Phanerozoic (indicates life forms visible to the naked eye). Pangea fragments into the current continents. An explosion of living species occurs: archaea, bacteria, protists, chromists, fungi, animals and plants, viruses (an outsider…), and finally, at the pinnacle of evolution: cats (and us to change the sand).

Cambrian (Paleozoic period, Primary era)

A period called Nama by biologist Ben Waggoner. A profusion of small tunnels can be seen in the mud on the seafloor. This period is also called Wormworld. An example is Cloudina.

Presumed first appearance of the sense of sight in the terrestrial animal world.

Scientists still debate the causes of the Cambrian explosion, but the most widely accepted theory is that oxygen in Earth’s atmosphere began slowly increasing around 550 million years ago. Oxygen provided a much more efficient way to metabolize food, giving animals more energy to mobilize and hunt prey. The emergence of predators kicked off these escalating arms races, and then we essentially witnessed an explosion of different ways of doing business. Among the most bizarre: priapulids (penis worms): worms that turned their mouths inside out, revealing a throat lined with hairy teeth. These worms, also known as cactus worms, are mostly extinct today, but were widespread during the Cambrian. The fossilized worm found in the Grand Canyon (which was then closer to the equator and therefore had a tropical climate) represents a previously unknown species. Due to its relatively large size—about 10 centimeters—and distinctive teeth, it has been named Kraytdraco spectatus, after the fictional krayt dragon from the Star Wars universe. This particular penis worm appears to have had a gradient of hundreds of branched teeth, used to scoop food into an extensible mouth.

period called the White Sea by biologist Ben Waggoner. The animals on the seabed are still without fins or legs, but there is evidence that they could move, even though their habitat is still two-dimensional: the seabed. Examples include the following species: Kinderella, Helminthoidichnites, and Spriggina. There are also the first examples of predation. And oxygen levels continue to rise.

Thousands of species of trilobites thrive on the ocean floor: they are the first invertebrates with an exoskeleton

Vendian Glaciation

First invertebrate life forms with shells (early Paleozoic)

Earth’s magnetic field nearly collapsed completely 591 million years ago, and this change, paradoxically, may have played a key role in the emergence of complex life, new research has found. The study, published in the journal Communications Earth & Environment on May 2, 2024, found that Earth’s magnetic field, created deep within the Earth between its liquid mantle and solid core, was significantly weaker than its current strength for at least 26 million years. The discovery of the prolonged weakening of Earth’s magnetic field also helped solve a long-standing geological mystery about when Earth’s solid inner core formed. This time span aligns with a period known as the Ediacaran, when the very first complex animals emerged on the seafloor as the oxygen content of the atmosphere and ocean increased. These strange animals barely resembled life today: soft fans, tubes, and donuts, and discs like Dickinsonia, which grew up to 1.4 meters in size, and the snail-like Kimberella. Before then, life was largely unicellular and microscopic. Researchers believe that a weak magnetic field may have led to increased oxygen in the atmosphere, allowing the evolution of early, complex life. “The magnetosphere shields Earth from the solar wind, thus maintaining Earth’s atmosphere. Therefore, a weaker magnetosphere means that lighter gases such as hydrogen would be lost from Earth’s atmosphere.” This combination raises the question of whether increased hydrogen ion loss in a reduced magnetic field contributed to oxygenation, ultimately allowing the diversification of the macroscopic and mobile animals of the Ediacaran fauna. Hydrogen, in fact, can escape into space through thermal and non-thermal mechanisms, resulting in net oxygenation of the atmosphere.

Last common ancestor between cephalopods and Homo sapiens. Studies highlighted and conducted by Peter Godfrey Smith point to a complex intelligence in the modern octopus, and likely even self-awareness. This poses a dilemma: either self-awareness evolved independently at least two or three times (us, octopuses, crabs, etc.), or it evolved only once, but long ago, before the emergence of cephalopods. The last common ancestor between cephalopods and Homo sapiens dates back 600 million years. The octopus’s nervous system is very different from ours, essentially having a central brain (with two hemispheres and no corpus callosum connecting them above) and eight large groups of neurons distributed across each tentacle. It’s unknown how the interaction between these 8+1 “brains” works, but one hypothesis is that there are different circumstances where different modalities are used (independence of the tentacles or central control of the brain in the octopus’s “head”). Octopuses also possess some characteristics found in other species (including Homo sapiens), such as REM sleep.

Ancient origin of the eyes: jellyfish already have a light-sensing organ. It’s a nervous organ under the umbrella, with light-sensitive cells that enable contractions and movement.

A period called Avalon by biologist Ben Waggoner. It is characterized by flat, two-dimensional life forms on the seafloor.

Cryogenian Glaciation

Trezona Formation, Australia. First fossil evidence of organisms that may be the first animals: a type of sea sponge.

The oceans are starting to dry up: the water released into the atmosphere by volcanoes in the form of water vapor is no longer equal to the water seeping into the subsurface and the mantle, especially through continental faults: the planet is cooling due to the decrease in internal radioactivity.

Early protozoa (unicellular invertebrate organisms)

Possible episode of “snowball earth” (Sturtian) i.e. a terrible ice age in which the oceans freeze up to the tropics; life probably survives in limited oases such as the Caribbean, the Red Sea, the Persian Gulf, the Eastern Mediterranean, the Amazon, Central Africa, Indonesia, Northern Australia

Various episodes of terrible ice ages (with ice even in the tropics at sea level) followed by terrible periods of greenhouse effect of volcanic origin with consequent global warming

The supercontinent Rodinia splits up

Evidence of dramatic polar migration perhaps due to massive volcanic events

First evidence (found in May 2019 in Canada) of fungi with complex filamentous structure

The first multicellular organisms. These were, at first, algae.

Even before sight, two things fundamental to life on Earth arise: sexuality and death. The advantage of death and sexuality, which are in fact linked, is that each pair of living beings, after reproducing sexually, generates one or more different beings (which enables the evolution of species). Subsequently, after sexual reproduction, the living being dies, leaving no copies of itself, leaving space and natural resources for the next generation. Death therefore represents a great advantage for evolution.

On Earth, with the advent of oxygen, brought by the proliferation of life, the number of mineral species increased from 1500 to 4500.

Some (microbial) life on Earth evolves sexual reproduction for the first time, and consequently, genes that cause aging and thus death.

proto-eukaryote engulfs a bacterium, or the bacterium enters the proto-eukaryote via a flagellum. The bacterium will become what we call a mitochondrion. A phenomenon of endosymbiosis or parasitism, therefore. It is now accepted that mitochondria and chloroplasts originated in eukaryotic cells as a result of a symbiosis (i.e., coexistence between different species that benefits both) between two ancestral “prokaryotic” organisms. It is believed that one of the two “ate” (or entered into) the other but was then unable to digest it (or escape), and therefore this second organism began to live inside the first. Over time, this coexistence would have been maintained and strengthened, until the symbiotic organism fully integrated with its host, giving rise to an organelle called the mitochondrion. There’s a wealth of evidence supporting this theory, linked to a series of similarities between mitochondria and bacteria, which we’ll discuss later. The same may have subsequently been true for chloroplasts.

massive asteroid, at least 10 km in diameter, impacted what is now South Africa. Vredefort Crater is the largest meteor crater on Earth. It is located in the South African province of Free State and contains the town of Vredefort. The site is also known as Vredefort Dome or Vredefort Impact Site. The crater has a diameter of approximately 300 km, larger than Sudbury Basin (250 km) and Chicxulub (170 km).

Oxygen begins to spread across planet Earth. Oxygen is the element that ruins the others, encrusting their pure surface with a layer of chaos and decay. At the same time, it enormously enriches the planet’s abundance and diversity of compounds and minerals, thus greatly increasing life’s diversity. Life, and civilization itself, from a chemical perspective, can be thought of as an organized resistance to oxidation. Here and there, we manage to stem the tide and even turn it back a little, by stripping metals from their ores, planting forests, extinguishing fires, but never for long on a geological scale. Oxidation accompanies the march of time and the inevitable triumph of entropy. Oxygen gives life, but in doing so, it makes death closer and more inevitable. It is the single most important cause of aging and age-related diseases.

The Huronian glaciation; this was a glaciation of enormous duration and proportions, isolated in time; it was followed by a billion years of torrid climate.

On Earth, thanks to the abundant presence of water and the formation of granite, 1000 types of minerals are formed.

On planets like Mercury (dry) the variety of minerals is around 300, while on planets like Mars (wet) it is around 420.

Formation of unmetamorphosed sedimentary rocks (i.e. not altered by violent heat and pressure) in Africa and Australia, where in 1977 and 1983 AD both stromatolites (mats of sediment bound by bacteria and blue-green algae) and true cells were found by Knoll and Barghoorn and by Walter.

From the collision and union of different cratons (outcrops of light granite perhaps also formed thanks to microorganisms) the first super-continent was formed: Vaalbara; the cratons are also called Archaean cratons (protocontinents) for example the Kaapvaal craton (South Africa) and the Pilbara craton (Western Australia) remained.

Most of the lunar seas are formed

End of the Noachian Epoch on Mars, beginning of the Hesperian Epoch

Single-celled life on Earth.

The number of minerals and compounds on planet Earth expands from about 250 to several thousand, thanks to plate tectonics, volcanism, and the abundant water that creates granite. Then, the advent of oxygen (released by life forms like plants) will further expand the number of compounds and minerals to about 4,500. And life expands this diversity beyond 5,000. The advent of human technology will further expand this number.

First evidence of rock solidification

4.35 billion years ago, the Moon underwent a remelting event due to the orbital evolution of its orbit. During its passage through the Laplace plane transition, the Moon experienced widespread heating and tidal melting, sufficient to restore the formation ages of most lunar samples, while retaining a previous crystallized form of rare zircons formed earlier. This would explain the diverse lunar samples brought back to Earth by the Apollo missions.