Human evolution in africa Essay
Evolution In Africa
Humans, as we consider ourselves, evolved in Africa. Not entirely, but from early primates to our present state. Many people dispute this fact, despite astounding evidence supporting the theory, for various reasons. Showing all the genetic, paleological, and geological proof, I find it very hard indeed to contradict the evidence.
True, humans didn’t evolve entirely in Africa. As a matter of fact the first known ancestors of humans where found in North America, in the Utah Valley. These animals where nothing more than a shrew in the shadow of the dinosaurs. However, with the event that killed the dinosaurs, they where finally allowed to reproduce and spread. At this time, according to isotope dating, the world was averaging 4 times warmer than it now is. As time went on, the small mammal had spread throughout Eurasia. All of Eurasia then was covered in tropical forests. Primates evolved in what is now the Indian Subcontinent.
From their placement in India, then still lowland, primates spread throughout the world once more. Some returned to North America, only to be wiped out by rodents already living there. Others spread to Europe and the Middle East.
By this time, Africa had just split from marsupial overrun Gondwanaland. About a million years later it reached the Middle East, and primates moved in. By now the world had cooled enough that the primates in Europe had been decimated to near extinction. They also migrated south, for the Mediterranean Sea was at that time dry lowland. Now almost all of the primates left in the world were in Africa, and the only marsupial that wasn’t wiped out was the opossum.Primates and large cats now ruled, with rodents scarce, which meant that the primates had to adapt to keep from becoming lunch. In light of this, natural selection shows only those primates with larger bodies and higher intelligence survived.
The once rodent sized primates, lemurs, now only exist in Madagascar, which had separated from Africa in the early Eocene Epoch, and where there were no predators to be found. In most of Africa, however, the primates got larger. They shifted evolutionary gears to start becoming apes and hominids.
The first apes to evolve, Afropithecus was very small by ape standards. They were dumb tree swingers, but it was by their appearance that we owe our existence, along with chimps, gorillas, and orangutans. These apes, despite their stupidity, were very successful and spread back to India once more. Then deserts began to form in the Middle East, and isolated those apes in Africa from their cousins in India. The Indian apes evolved into 2 species, although only one is alive today: the orangutan.
In Africa, these apes also evolved into 2 species: proto-chimps and proto-gorillas. The proto-gorilla was then isolated in high mountain areas, which forced it to become a herbivore. It also became larger than its fellow apes to contend with the cold temperatures of its environment. The gorilla, hence, came to be what it is today, with 3 subspecies (Gorilla gorilla gorilla, Gorilla gorilla graueri, and Gorilla gorilla beringei) according to the area in which they live (Cameroon-Gabon Refuge, and Central Forest Refuge, respectively).
Kenyapithecus, the common ancestor of proto-chimps and proto-gorillas, was a “knuckle walker”, which explains why both present day species tend to knuckle walk, but what explains why humans are bipedal if our closest relatives are quadrupeds?
The answer lies in the fact that we evolved when the savannas of Africa were just beginning to form on the east of the Western Rift Valley. It is hypothesized that it was the formation of the Western Rift Valley that separated our ancestors from that of the common chimpanzee. So while the west stayed heavily covered in tropical forest, the east started drastically changing. Our ancestors had to adapt to live in a clearer surrounding. To cross flat plains, it is wasteful of energy to use a knuckle walk posture. So, our ancestor, at that time Australopithecus, had to become bipedal to conserve that energy that was no longer needed to climb trees and cross uneven terrain.
About 3 million years ago, the Mediterranean Sea dried up. As our ancestors began reproducing and spreading, some of them were forced out of Africa into Europe once more. These, however, were far more successful than their ancestors were. Who we know as the Neanderthals were the descendants of this population that was forced out of Africa. Our own ancestors, however, remained in Africa.
From the evolutionary data records, we see that the first “modern” humans finally appeared about 1,600,000 years ago. They were still very primitive, nomadic hunter-gatherers, but they used tools and began forming a complex culture.
As I have shown: humans evolved in Africa. Not entirely, but from early primates to our present state. Although many people dispute this fact, for various reasons, I think it is most certainly fact. Showing all the genetic, paleological, and geological proof, I find it very hard indeed to contradict the evidence.