SHARE
A reconstruction of Homo naledi’s head by paleoartist John Gurche, who spent some 700 hours recreating the head from bone scans Pic by: John Gurche and Mark Thiessen Source: National Geographic.

We…humans have existed for only a tiny fraction of the Earth’s history. Dinosaurs walked Earth between 230 and 65 million years ago. The oldest known humanlike fossil has been dated at 6 million years old.Evolution explains the way all living things evolved over billions of  years from a single common ancestor. This concept is often illustrated by the so-called tree of life. Every branch on the tree represents a species (A form of a living thing). The fork separating one species from another represents the common ancestor that each pair of species shared. So ultimately, all life is interconnected, but any two species may be separated by millions or even billions of years of evolution.

Ardipithecus ramidus, one of the oldest hominids that lived in Africa more than four million years ago |  Illustration by Arturo Asensio  | Source: sci-news.com/othersciences
Ardipithecus ramidus, one of the oldest hominids that lived in Africa more than four million years ago | Illustration by Arturo Asensio | Source: sci-news.com/othersciences

Age of apes
Most scientists believe our common ancestor existed 5 to 8 million years ago. Then two species broke off into separate paths, one ultimately evolving into gorillas and chimps, the other evolving into early humans called ‘hominids’. In the millions of years that followed, at least a dozen different species of humanlike creatures have existed, reflected in the fossil discoveries. In fact, the fossil record does not represent a complete straight line of ancestry at all; many of these early hominids left no descendants and simply died out. Still others are most likely direct ancestors of modern humans.

This common ancestor diverged over time to form many different species of hominid, only one of which survived to become modern humans. All the rest of the hominids, including early humans, became extinct. During the evolution of human beings, many features gave individuals advantages that offered them a better chance of survival, including the ability to stand upright, so predators and prey could be seen more easily and having a larger brain, providing the ability to plan ahead, work together, and eventually speak.

The fossil record provides a fairly good outline of human evolutionary history. The Oldest hominid fossils called ‘Ardipithecus’ recovered from sediments in the Middle Awash Valley of Ethiopia dated to between 5.2 and 5.8 million years ago. Later, an African apelike species named as ‘Australopithecus’ evolved probably around 4 million years ago with two skeletal characteristics that set it apart from apes: small canine teeth (the teeth on either side of the four front teeth) compared to the long canines found in almost all other primates, and, most importantly, walking on two legs. The name australopithecine means “southern ape,” in reference to South Africa where the first known fossils were found. Many more Australopith fossils have been found in the Great Rift Valley in eastern Africa, in countries including Ethiopia, Tanzania, Kenya, and Chad.

The very early years of the transition from ape to human, from 6 million to 4 million years ago, is poorly documented in the fossil record, but those fossils that have been discovered document the most primitive combinations of ape and human features.

Where we stand in the ‘tree of life’?                         Source: bbc.co.uk/schools
Where we stand in the ‘tree of life’? Source: bbc.co.uk/schools

A hot topic
After many more fossil excavations, scientists have discovered 30 types of varieties of early to modern hominid types that are divied in to five major groups according to their characteristics; Ardipithecus, Australopithecus, Paranthropus, Kenyanthropus and Homo. The modern human… we are placed under the category of ‘Homo’ naming ‘Homo sapiens sapiens’. The news from the very recently discovered fossilized member of  the human family ‘Homo naledi’ came out to the society in September 2015.

It has been discovered in 2013 and scientists were studying the fossil for years to identify and to place it where it belongs in the hominid timeline. Scientists still do not know the total number of hominid species that existed, because new fossils are discovered every decade, the story of human evolution becomes clearer all the time.

 From australopithecus to humans today

ancestors (4)