Homo sapiens

This is the complete introductory guide to the evolutionary path of Modern Man. Where we came from and how we got here by examining the fossil evidence.   
Homo sapiens means ‘wise man’.  In the scientific classification system species are commonly identified by two names (binomial nomenclature). The first name is the genus and the second is the species (the first word is always capitalized, the second is not) hence; Homo sapiens.  The time period for Homo sapiens is 300,000 to 350,000 years BCE (before the common era) to present.

Homo sapiens skull illustration

Since the dawn of the digital age many great breakthroughs have been made in our understanding of human evolution.  The Human Genome Project is one example.  Studying DNA and mitochondrial DNA has been invaluable. 

However, having said that it is not without controversy.  Going old school by the meticulous study of fossil remains and the overall knowledge bank accumulated by paleoanthropologists in the field has given rise to several differences of opinion with certain aspects of the digital breakthroughs.

I am really not going to get into that to any extent.  This essay is an overview that touches on all the available diagnostic tools and presents what I believe is a coherent look at human evolution.  I hope to explain some of the principles of evolution and how they apply to Homo sapiens.  I am also going to present the fossil evidence that has been discovered giving us a clearer picture of where humans came from.

A Timeline Overview 

It can take a long time for one species to evolve into another species.  I don’t see it as a straight line going up but more like stair steps.

Some evolutionary steps are bigger than others and some last longer before it jumps forward again but there has been a continual evolving movement to more advanced forms.  This is pretty much how for example Australopithecus africanus evolved into Homo erectus.  At some point along the timeline a population group of A. africanus had changed so much that the changed population group could no longer successfully breed with the group it had changed from and hence a new species had evolved.  I’ll be going over this in greater detail soon but first let’s talk about the measurement of time itself.

The Nomenclature Of Time

It can be somewhat confusing when talking about time periods because there is a different nomenclature for geological time and anthropological time.  As you might expect anthropological time is only concerned with man while geological time applies to the entire 4.5 billion year history of earth as defined by major geological or paleontological events.  Since I am only concerned with human evolution I am only going to talk about the timeline in reference to that.

Geological Time

Geological time is divided up into eons, eras, periods, and epochs.  Eons being the largest block of time, then an era, then a period, then an epoch.  We are currently in the Phanerozoic eon, the Cenozoic era which is divided into three periods, the older being the Paleogene which started 66 million years ago, then the Neogene 23 million years ago, then the current period is Quaternary (kwuh-tur-nuh-ree) starting at 1.8 million years ago with two epochs.

As far as human evolution goes it started in the Neogene period of the Cenozoic era during the last epoch of that period known as the Pliocene which is 5.3 to 1.8 million years ago.

The Quaternary period that follows the Neogene is divided into two epochs, the Pleistocene and the Holocene.  The Pleistocene starts at 1.8 million years ago and runs to 13,000 years ago to the start of the Holocene.

At 13,000 years ago or the start of the Holocene, Homo sapiens where the only Homo species left alive.  So this means that as far as human evolution goes we are only concerned with the Pliocene and the Pleistocene geological time epochs.

Here is a chart of the geological time of the earth.

Anthropological Time

Then there are the Anthropological Time Periods which have their own nomenclature.  In the study of man there are two broad categories of time for man, Prehistory (no written records) and Recorded History.   Prehistory has three ages.  The first age is the Paleolithic or Stone Age from 3.3 million years to 12,000 years BCE. The second age is the Mesolithic and the dates vary depending on the area of the world but roughly 12,000 to 7,000 years ago. The third is the Neolithic Age, again it is defined more by cultural traits than a specific time period but typically 9,000 to 3,000 years ago.  Recorded History starts about 3,500 BCE or 5,500 years ago.

I am only going to be referencing the Paleolithic as that is where early man takes shape. The Paleolithic is divided into three parts. The oldest being the Lower Paleolithic from 3.3 million years to 300,000 years BCE, then the Middle Paleolithic from 300,000 to 50,000 years BCE, then the Upper Paleolithic from 50,000 to 10,000 years BCE.

The Stone Age or the Paleolithic got its name because this is the age where early man started to make and use stone tools.  It is generally considered that the early the Homo species made and used stone tools but there is also evidence that Australopithecines began to use stone implements and so the Lower Paleolithic starts about 3.3 million years ago when early man began making and using stone tools.

Here is a time chart of the Anthropological time periods with some of the early man species that lived during each period.

anthropological time chart

Most, if not all, of the evolution of man takes place in the Lower and Middle Paleolithic where during that time period of 3.3 million years to 50,000 years ago man evolved from the Australopithecines to Homo sapiens.  The Australopithecines with the physiological adaptation of the ‘foramen magnum’ position at the base of the skull (thereby allowing upright walking) started the path towards modern man.

The reason I wanted to talk about the two different nomenclatures is in case you hear or read a discussion about human evolution and one side is talking about the Pliocene or Pleistocene and the other side is talking about the Paleolithic and you are thinking well which is it.  It’s both.   Sometimes they are used interchangeably but mostly people and charts and all that will use the geological terms. That is just the way it is.  You will read and hear mostly Pliocene and Pleistocene but when you run into the term Paleolithic you can now understand what that term is and how it fits in.

As far I am concerned I am just going to make reference to time by using how many years ago something happened and an example would be when talking about say Homo erectus I will say their time span is from 1.9 million BCE to 70,000 years ago.  The BCE refers to ‘before the common ear”.  Sometimes you will read 1.9 ma or Ma, which means million years ago.  I have seen mya for million years ago.  Another one is YBP, meaning ‘years before present’ or just BP meaning ‘before present’.  Personally I like BCE.  The term CE refers to the ‘common era’.  Using CE and BCE is a secular way of saying BC – AD, you just have to think of it like that.

The Dawn Of A New Epoch

You might be sitting there thinking that all these time periods we’ve just been talking about are so long that who knows when the next one will begin.  Well funny you should think that.  The International Union of Geological Sciences (IUGS), is the professional organization in charge of defining the various times on the geochronological scale and it is now under pressure to name a new time epoch.  Many scientists consider the Holocene to have ended and a new epoch to have started.  They call it the Anthropocene. 

Anthropo meaning ‘man’ says the new epoch is the age of man.  But what exactly does that mean and when did it start.   Geological time is defined by major geological or paleontological events.  An example of a paleontological event would be the start of the Paleogene period 66 million years ago when the non- avian dinosaurs went extinct.  It was an event that caused a momentous world shift. 

The main argument for establishing a new epoch is that even as you read this a new world shift has already taken place.  The impact of man is undeniable and it has left a permanent mark on the earth and changed it in many ways.

The Holocene has ended and the Anthropocene has begun.  If you want to put a date on the beginning of the Anthropocene, the general consensus seems to be the time period of the Industrial Revolution or roughly from about 1750 to 2000 give or take.  That is the time when human activity has undeniably started to change the earth.

It’s pretty interesting when you see the time charts of the different eras, periods and epochs going back 4.5 billion years and then you think wow, we are right now living in an age that will in the future be known as the start of a new epoch, the Anthropocene.  If that doesn’t give you goose bumps, well then… you are pretty normal but still you have to admit it’s cool.

The final chart I am going to show you is a geological time chart only showing the four time epochs of man.  When you are reading about human evolution in the media this is mostly the time nomenclature used unless the written piece comes from the world of anthropology and even then you will see these references.

Part One,     Part Two,    Part Three,   Part Four