How Long Have Humans Been on Earth

The human species is only one among those existing on Earth, and like all known forms of life is subject to the laws of evolution. This implies that man appeared at some time in the past as a result of progressive adaptive changes that generate new evolutionary lines and lead to the disappearance of others. The question about the antiquity of our ancestry and its origin does not have a simple answer. What we know about the hominization process that has led us to be what we are, is based on a long and tortuous path of discoveries and hypotheses spread over time. The science that studies this is paleontology, however, in recent decades new disciplines such as genetics, among others, have been very useful in tracking the origin of humanity.

It is estimated that the evolutionary branch that leads to modern man, separated from chimpanzees between 5 and 7 million years ago. Between this moment and about 4 million years ago appeared the ability to move upright, a fundamental fact in the process of hominization. The first bipedal hominids that certainly had an upright locomotion are the Australopithecus (Australopithecus), this species appeared and prosperous with great success in the wooded savannas of the east of the African continent 4 million years ago, and some specimens have preserved skeletons in very good condition It disappeared 2.5 million years ago, perhaps due to the desertification of the savanna, however, this genus radiates in at least 5 different species scattered from Ethiopia and Chad to South Africa. The environmental pressure originated two large groups of Australopithecines, vegetarians specialized in hard products of little nutritional value, and carnivores, which resulted in the first individuals of the genus Homo.


The first representatives of the genus Homo were the Homo rudolfensis that lived from 2.4 to 1.9 million years ago, with a cranial volume of 750 cm³, and Homo habilis that appeared 2.5 million years ago and became extinct 1, Four. The habilis gave way to Homo ergaster, who with a cranial capacity of about 880 cm³ and an age of 2 to 1 million years, was the first ancestor of the man who left Africa. Out of this continent I evolved towards Homo erectus in the Far East, and Homo ancestor in Europe. It is curious that the technology developed to carve the stone by Homo ergaster was superior to that used by its Asian and European descendants. To explain this, it is speculated that its development may have occurred after the migrations.


With a somewhat confused origin, later in Europe appeared the Homo heidelbergensis, which lived from 500,000 to 250,000 years ago, and which seems to be the ancestor of the Neandertals (Homo neanderthalensis). In Africa, the Homo rhodesiensis occurred in parallel, giving rise to the Cro-Magnon Man or Homo sapiens of today.


Everything indicates that the anatomically modern man, has its origin in a preexisting human population of about 200,000 years ago located in East Africa on the Omo River. This conclusion is supported by the genetic analysis of mitochondrial DNA, as well as by paleontological records. The fossils belonging to this population are known as the Men of Kibish, and are considered the oldest remains of Homo sapiens. They correspond to a population apparently of few individuals, in comparison with the archaic humans scattered throughout the Ancient World. The evolutionary success of this small group was such that it displaced the rest of the whole Earth. The last humans not belonging to the genus Homo sapiens were the Neandertals, they became extinct 29,000 years ago in the current Andalusia. It was therefore the last species of the genus Homo that coexisted in time and space with modern man, probable cause of its extinction.