We often think of the human race as young but new archaeological discoveries suggest that our species may be much older than we thought. Scientists estimate that we arose around 200,000 years ago but new evidence suggests that humans evolved significantly earlier than that. One of the first big changes that the human race underwent was an upright walk this allowed our ancestors to travel from forests into grasslands.
Another major change was the ability to build complex tools in the Middle Stone Age a group of humans developed finely crafted flaked points and spear shafts. These were the basis of projectile points which made it possible to hunt elusive prey they also changed how humans interacted with ecosystems.
Another important change in the human lineage was the development of a brain. The ape-like Sahelanthropus started the transition six million years ago but it wasn’t until modern humans appeared that they were able to think and develop complex tools modern humans became a single species.
Scientists still debate how old the human lineage really is recent studies from Papua New Guinea suggest that a species called the Denisovans interbred with modern humans as recently as 15,000 years ago. Even though there aren’t any recognizable fossils from this time researchers say that there was a genetic legacy left behind. Some Asian people have inherited between 3 and 5 percent of their DNA from these early humans.
While the earliest human remains dated to less than 200,000 years ago many more recent finds reveal an early migration to Africa. A 100,000 year old jawbone from Zhirendong for example retains some archaic traits while retaining modern ones. Similarly a skull fragment found in southern Greece known as the Apidima skull may be the earliest modern human fossil discovered outside of Africa.
There aren’t any definitive answers to the questions of how old our species is but new evidence from Morocco shows that it began to take shape around 300,000 years ago at the same time the world population was about 80 births per 1000 people a year that would make for a very high birth rate. But it would also mean that our species has undergone rapid evolution.
The speed of the process of human evolution is attributed to a variety of factors including the adoption of a novel diet and the introduction of tamed fields. The team emphasized that this speed is a function of environmental conditions rather than any specific biological mechanism.
Another study estimated that the human lineage has been evolving since at least 80,000 years ago which is as far back as radiocarbon dating can go. Some researchers say this isn’t enough evidence other anthropologists suspect the human lineage dates back even further.
To find out how old our species is researchers have used a variety of techniques some have used a molecular clock to estimate how long it takes for genomes to evolve. Others have assumed that mutation rates were constant throughout the past.