November 24, 2004

Human Nature Part 1: A Brief History of Life 

One of the major points of disagreement between the "Conservatives" and "Liberals" seems to be about the very essence of the human nature. Are we "noble savages", perverted to evil by capitalism? Or are we complex beings, with an equal capacity of committing acts of unspeakable evil and shining good? Is it true that the Whites are genetically oppressors of women and every "coloured person"? Or is it that any race or ethnic group can become oppressor of another, in certain cirmcustances?

In order to use facts to shed some light on these issues, we must remember that humans did not come out of the blue, but have a rather long evolutive history behind them.
So, let's tell this story - briefly.

According to this timetable, the first living organisms, anaerobic bacteria, appeared on Earth roughly 3.5 billion of years ago. 3500 million of years ago, keep it in mind. Actually, those organisms were quite different from today's bacteria, and they have their own domain: Archaea.
For a couple of billion years, bacteria and Archaea expanded in population, but without significant evolution. 1.8 billion years ago, Eukaryotes appeared as fossils. Without going into too many details, we humans are eukaryotes, like all other anymals - this means that we share the same basic biochemistry and molecular biology.

Oxygen concentration in the atmosphere started to increase, due to the action of photosyntethic organisms, and while this oxygen made life impossible for many bacteria and archaea, it led to the explosion of eukaryotic lifeforms (remember, competition and survival of the fittest).

The first animals appeared something like 650 million years ago. Most of the major groups of animals living today first appeared in the fossils of Cambrian period, from 540 to 490 million years ago. During this period, the ancestors of all of the known animal groups appeared, plus strange animals, whose fossils can be found in the Burgess Shale and subsequently became extinct. Large predator arthropods died off, but the small, just-appeared vertebrates survived. Anyway, the following period was the Ordovician which ended 443 million years ago - with a mass extinction that wiped out the majority of marine invertebrates and a significant part of all animals.

Plants and animals moved on land only later, during the Silurian period, but we have to wait until the Devonian to see land-living vertebrates; these animals expanded during the Carboniferous, together with giant plants which remains originated the deposits of coal.
Later on, 248 million years ago, another catastrophe struck the Earth: most of the marine lifeforms, and many of the terrestrial one became extinct. The causes of this extinction are not completely clear, but it is known that 90-95% of the marine species become extinct.
This event also marks the end of the Paleozoic Era.

However, the Permian extinction opened the door for the explosion of vertebrates and the Age of Dinosaurs, which lasted until 65 million years ago. During this age, certain reptiles slowly evolved towards birds, while mammals occupied a secondary role. But when even the dinosaurs become extinct 65 million years ago (almost surely because one or more sizable meteors or comets impacted with Earth), new groups were ready to seize the chance and prosper. And thus ends the Mesozoic Era.

All the modern animals appeared during the subsequent Paleocene Epoch, and evolved steadily in time, having to face only the occasional ice age and no more catastrophic extinctions. We humans are technically Homo Sapiens (Sapiens), and besides minor differences like colour of skin, eyes and hair, and a few small physiological variations, all belong to the same species, and there is absolutely no scientific ground to consider any race superior to any other.

Homo Sapiens is a primate, and descends from the early primates which appeared around 60 millio years ago. Proto-simians, mammals which began to keep a more erect posture, date back to 55 million years ago. Evolution went on and on, and finally the line leading to Homo Sapiens and chimpanzees separated from the line of gorillas 9 million years ago. Another ramification occurred 3 million years later, and the line of the chimpanzees separated from the early hominids.

Homo Sapiens reached his final form during the Pleistocene (some set the moment at 40 000 years ago), and by 11 000 years ago, humans lived on most of the world.
Apparently, humans started to congregate in cities some 6000 - 7000 years ago, while the first social organizations similar to the modern ones are about 3000 years old.

So, let's get mathematic now:

First life forms: 3.5 billion years ago.

Age of Vertebrates: from 240 million years ago.
(240 000 000 / 3 500 000 000) * 100 = ~7% of the total time of life on Earth.

Age of Primates - from 60 million years ago: 1.7%

Age of Hominides - from 6 million years ago: 0.17%

Not much, eh? Actually, we are just the blink of an eye compared to the incredibily long history of our planet. This also mean that, from a genetical and evolutive point of view, homo sapiens is still very close to chimpanzees, which are by all means animals. Actually, we share something like 98% of the genome with chimpanzees. And a lot of similarities with even the most archaic animals, like crocodiles.
We are also very different from the animals, sure: we have an incredibly complicated and powerful brain, reason and feelings, and a structured speech, and the rare capability of representing concepts with abstract sounds and symbols (writing, drawing, diagrams). But this is just another layer, in my opinion.
All the underlying layers, the biochemistry, the cell organization, the organs, the structure of the brain, is not really different from those animals that live without morals and ethics, but only obeying to the amoral and rigidly utilitarian laws of nature.

The question then is: how does all this affect our behaviour? Are we something entirely different, or just another species of of animals?


Post a Comment

This page is powered by Blogger. Isn't yours?