PREHISTORIC HUMANS

On December 27, 1831, a Cambridge University student named Charles Darwin set sail from England to begin on a five-year mapping expedition around the coastline of South America. Before the end of the journey, Darwin would conclude that all modern day organisms---including humans---had evolved from lower life forms. This contradicted the 19^th Century belief that God had made all of Creation in a single day, as described in the Old Testament book of Genesis. Darwin was hesitant to make his conclusions public.

In 1859 Darwin finally published On the Origin of Species, which laid the groundwork for his Theory of Evolution. (He completed an original draft of the book in 1842; but he kept the manuscript in a desk drawer for sixteen years!) He followed the Origin of Species with The Descent of Man in 1871. The latter book argued that human beings and apes were descended from a common ancestor.

Modern humans are known by the scientific name homo sapiens. The genus homo first appeared about 2 to 2.5 million years ago. (Genus means “groups” in Latin. A genus is a group of related species.) Homo sapiens, or “thinking man,” was not the only species within the homo genus, although homo sapiens is the only member of this group that survives today.

In 1856, three years before Darwin published The Origin of Species, a humanlike fossil was discovered in the Neander valley of Germany. This species, Homo neanderthalensis, or Neanderthal Man. Neanderthals, like modern humans, were fully bipedal. Their brains were somewhat larger than the brains of Homo sapiens, although anatomically different. Neanderthals were, on average, stronger than modern humans. They were short (about 5’6”); and fossil evidence indicates that many of them suffered from severe arthritis.

Neanderthals inhabited Europe and Western Asia. They first appeared about 230,300 years ago; and the last Neanderthal likely died about 28,000 years ago. Neanderthals are thought to have coexisted with Homo sapiens for about 10,000 years. Competition with Homo sapiens is thought to have accelerated the Neanderthal’s demise, Some scholars have even suggested that the Neanderthals were the target of the world’s first genocide.

In any event, Neanderthals were technologically inferior to the Homo sapiens. Neanderthals did possess basic spears and other crude weapons, but they did not have projectile weapons that enabled them to safely kill from a disadvantage. This would have put them at a severe disadvantage vis-à-vis the Homo sapiens, but in competition for food, and in any instances of direct combat.

DNA research indicates that Neanderthals are not the ancestors of modern man. Scientists classify them as a separate species. Not only are Neanderthal gene sequences significantly different, but fundamental physical differences (such as skull shape) make it unlikely that there are any direct lines between them and modern humans.

Culturally, there are a number of similarities between Neanderthals and the basic elements of what we recognize as human culture. Neanderthals constructed shelters and controlled fire. They skinned animals and cooked their meat. They also grasped the concept of death. Neanderthals buried their dead, often with ceremonial items like animal bones and ochre.

Could romance have occasionally blossomed between H. neanderthalensis and H. sapiens ? We aren’t completely certain; the question of whether or not Neanderthals and early Homo sapiens interbred remains a mystery. However, there is evidence to indicate that such unions did in fact take place. Skeletons have been found in Europe that appear to combine the physical characteristics of both species. This has has an interesting implication: if the Neantherthal and Homo sapiens did interbreed in some instances, then some of us may have a distant Neanderthal ancestor.

The first Homo habilus (“handy man”) fossils were found in Tanzania by Louis Leakey in 1964. Although H. habilus is a direct ancestor of H. sapiens, this early hominid would stand out at the neighborhood picnic. H. habilus had disproportionately long arms (by our standards); and a gorilla-like facial structure. Its brain was less than half the size of the modern human brain. H. habilus was also short; the average specimen stood about 4’3” tall.

Homo habilus likely could not control fire, use language, or formulate abstract concepts. They did not bury their dead. H. habilus did have some basic tools, but these were more often used for stripping flesh from carrion than for actual hunting. H. habilus occupied a lower rung of the food chain than its descendents. The “handy man” was a favorite meal of the Dinofelis, a predatory cat similar to the sabertooth.

Homo erectus, another direct ancestor of modern man, lived in Europe, Asia, and Africa from 1.5 million to 1 million years ago. At an average height of 5’10” tall, Homo erectus was about the same height as modern man. H. erectus also looked more like us; its face was less sloping and less simian in appearance. Famous H. erectus fossil specimens include the “Java Man,” discovered in 1891, and the “Peking Man,” discovered in 1927.

The notion that “we are all related” has become a cliché. However, scientists do in fact believe that the entire human race was descended from a single woman, who lived somewhere in East Africa around 150,000 years ago. This early hominid female, dubbed “Mitochondrial Eve” or “African Eve” is thought to be the source of all surviving human DNA.

In contrast to the Eve of the Old Testament, Mitochondrial Eve was not the only female of her species alive in her time. Her status of the mother of modern humanity arises from the unbroken line of daughters that she produced. All members of the human race are thought to be related to Mitochondrial Eve through their respective maternal lines.

A mitochondrion is a cell organ, or organelle, that belongs to all eukaryotic cells (cells of complex organisms). A mitocondrion contains DNA, known as mitochondrial DNA.