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We Are More Than Animals

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There is no evidence that Home sapiens will evolve into new species or split into subspecies any time soon. That means we could consider the history of humanity as the history of Homo sapiens with two conditions. First, we should put all biological evolution before genus Homo appearance aside. Secondly, we should exclude other non-Sapiens humans from Sapiens history. Let us look briefly into the biological evolution path, which ended up with Homo sapiens.

Thinking, probably, about the history of humanity – Image credit: https://commons.wikimedia.org/wiki/File:In_Thought_…_(3020466221).jpg;

Classified to Be Not Secret

There are multiple ways to slice and dice the biological evolution on Earth. In this post, we look at a scientific classification/taxonomy of living and lived subjects and see how to get to the place occupied by Homo sapiens

This is a hierarchical classification. As of now, it includes eight categories: Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species. The broadest category is Domain. Every species belongs to some specific category at every hierarchical level. We, Homo sapiens, is not an exception. It is easy to find out where we belong in this classification.

Every species included in a specific category share few main features with all other species in the same category. The totality of those features is different from the set of main features in another particular category. This is how we differentiate to which category a certain species belongs.

Humans Do Not Evolve from Bacteria

We know that humans are animals. Could we understand more about our place in taxonomy? Let us first look at where animals belong on a level of Domains.

Phylogenetic tree
Phylogenetic tree. Image credit: https://en.wikipedia.org/wiki/File:Phylogenetic_tree.svg

In this high-level categories’ description Animals are at the top right corner.

Animals are Eukaryotes. Consequently, humans are Eukaryotes. And, by the way, we did not evolve from bacteria.

Chronology of Evolution, Which Led to Sapiens

The broader is the category – the earlier some species from that category appeared on Earth. There is the chronology of the appearance of the first species for particular categories in the top-to-bottom hierarchies’ ladder.  This chronology will tell us the timeline of biological evolution down to specific species.  We are interested, of course, in Homo sapiens.

Members of CategoryFirst Appearance,
Mln Years Ago
Name of CategoryType of CategorySource
Animals800AnimaliaKingdom[1]
Chordate541ChordataPhylum[2]
Mammals178MammaliaClass[3]
Primates85 – 55PrimatesOrder[4]
Hominids (Great Apes)5.8HominidaeFamily[5]
Homo2.1 – 2.8HomoGenus[6]
Categories, to which Homo Sapiens belongs

The first animal species emerged on Earth around 800 million years ago.

Animal specie
Example of Animal specie. Image credit: Image by Pera Detlic from Pixabay

There are problems with each of the methods, which are used to reconstruct the history of life on Earth. The dates in the timeline are approximate. We will use 3.8 billion years ago as an approximate date when life first appears on Earth. That means it took an evolution around 3 billion years to produce the first animals. You could see from the table above that since 800 million years ago things sped up in Animalis kingdom. As we already know, humans are Animals.

Good to Be in Chordata Phylum

A level of classification or taxonomic rank below kingdom and above class is called a phylum. There are about 35 different phyla in the kingdom of animals. Humans belong to the Chordata phylum. Specifically, all chordates species, which possess a backbone, were put by scholars into the subphylum Vertebrata

Shark
Example of the subphylum Vertebrata specie. Image credit: Image by Christel SAGNIEZ from Pixabay

Humans are Chordates. Humans are Vertebrates.

We now approach a classification level, where terms are more familiar not only to biologists but to the general public too.

Vertebrates include several different groups. One of those groups is Tetrapods. This group, in turn, consists of amphibians, reptiles, birds, and mammals. Humans are Tetrapods.

Class Of 178 Million Years Ago

The closer a particular category is to nowadays – the more data is available. Also, more methods of species identification and differentiation have appeared. That is the good news and the bad news. The good news is that we got more precision in species identification. The bad news is that it leads to more disagreements between researchers. Right now, there is no universally accepted classification system for mammals.

There are many features, which characterize mammals. I will point out just one feature – the presence of the neocortex region in the brain. It is known that the neocortex is involved “in higher functions such as sensory perception, generation of motor commands, spatial reasoning, conscious thought, and in humans, language”. Humans are Mammals.

Squirrel
Example of Mammal specie with the neocortex. Image credit: Image by Oldiefan from Pixabay

More Social Networks Since 70 Million Years Ago

A level of classification or taxonomic rank below Class and above Family is called an Order. There are 19 orders of mammals

Humans belong to the Primates Order. There are some disagreements among researchers about main primate features. I will point out just one feature. “Within primates, there is a tendency towards . . . an increasing reliance on sight and increasingly complex social behavior“.

          Humans are Primates. Primates include such groups as Apes, Monkeys, and Prosimians (tarsiers, lemurs, lorises, and allies). Humans are Apes.

Of Course, Humans Are Big Apes

We are down to the sacramental question – did humans descend from monkeys? The verdict is clear if we look at the taxonomy of Primates Order.

Humans are Apes. Humans are Great Apes. Humans are not Monkeys and are not Monkeys descendants. However, some time ago Monkeys and Apes had one common ancestor. That ladder goes all way back to the first appearance of life on Earth.

It is well known that out of 9 species in the Hominids (Great Apes) family of primates only one genus survived – the genus Homo

And, of course, we know that from genus Homo only one species survived – Homo sapiens.

What Our Biology Tells Us

We have a certainty now about who we, Homo sapiens, are biologically.

We are Eukaryotes. We are Animals. We are Chordates. We are Vertebrates. We are Tetrapods. We are Mammals. We are Primates. We are Apes. We are Great Apes. We are humans (members of the genus Homo). We are Homo Sapiens.

How fast the biological evolution from first Eukaryotes to first Homo sapiens proceeded in time?

The Pace of Evolution to Us, Sapiens

Let us skip the first billions-years-long stage of evolution from the first life to the first animals. Then we could draw a figure from the data in the table at the beginning of this post.

Stages of biological evolution
Duration of stages of biological evolution on a way to Homo Sapiens, Million years

We see that the typical duration of the evolution stages down from Animalia category is in low millions to hundreds-of-millions years.

A new category addition is a sign of increased biological diversity. Yet, there is no linear dependency here. A significant increase in the duration of the evolutionary stage from the Animals-to-Chordate stage to the Chordate-to-Mammals stage is a clear indication of the non-linearity of biological evolution.

In this post, we briefly looked at an evolution, which led to Homo sapiens appearance on Earth. However, for simplification purposes, we omitted important events in biological life on Earth – an extinction of species. We will look at it in the next blog post.

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By victortorvich

I'm a scientist and a writer. My upcoming book is “Subsurface History of Humanity”.

5 replies on “We Are More Than Animals”

The interesting thing about tracing our evolutionary lineage, is it shows just how improbable we are. Life may have a high probability of arising under the right conditions. But the further down the phylogenetic tree we go, the more improbable things become. It took billions of years for complex life to develop, and required a number of environmental developments, like rising oxygen levels in the atmosphere.

In that light, a civilization producing intelligence, a combination of intelligence and dexterity with which to manipulate the environment, seems like a profoundly unlikely event.

That probability should not be that small for a whole Universe if there are an infinite number of galaxies, stars, and planets. However, the Fermi paradox is not solved yet. Among all those emerged and emerging intelligent lifes in the Universe the life on some planet should be the first (if we count from Big Band). One theory is that the intelligent life on planet Earth is the first one. The probability of that to happen will go back to a very small number.

Definitely it doesn’t imply we’re alone in the universe. But it might imply the nearest other civilization is very far away. We might well be the earliest in our region.

An interesting question is, once the first evolves, and assuming it’s possible for them to affect other biospheres in their region, will any other civilizations be able to evolve?

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