REVILLE COLUMN: The science of biology proposes that humankind is descended from an ape-like ancestor. Archaeologists have unearthed fossilised remains of major intermediate forms along the recent evolutionary line that led to modern humans, but much remains to be discovered about how we came to be human.
I will discuss the physical evolution of man in this article and cultural and ethical evolution in my next two articles. You will find it helpful to read each article in the light of the preceding articles.
Human evolution is well outlined in Isaac Asimov's New Guide to Science (Penguin, 1984). The 17th century Irish Archbishop James Ussher dated the creation of the universe and the origin of humankind precisely to the year 4004 BC. It is reasonably definite historically that Saul, first King of the Israelis, was enthroned about 1025 BC. Ussher took this date and worked back through the chronology of the bible to conclude that humanity is no older than a few thousand years.
Prior to the 18th century nothing was known about the everyday life of ancient times before 1000 BC - written records in known languages didn't deal with earlier times. In 1738, the cities of Pompeii and Herculaneum, buried by the eruption of Vesuvius in 79 AD, began to be excavated. Historians became conscious of what could be discovered by digging, and archaeology got properly started.
Archaeologists divide cultural history into three major periods - the Stone Age, the Bronze Age and the Iron Age. What we normally refer to as "civilisation" seems to have begun about 10,000 years ago in the Near East when humans first turned from hunting to agriculture, started a settled way of life, learned to domesticate animals, invented new tools and pottery, and so on. Although this easily predated the reported biblical date of creation, humanity was already old as this stage.
The 19th century French archaeologist Eduouard Lartet, among others, discovered evidence of the great antiquity of tool-making humans. He found a mammoth tooth on which some early human had scratched a good drawing of a mammoth from the living model. The mammoth, a type of hairy elephant, became extinct well before the start of the New Stone Age.
A recent finding in Ethiopia suggests that the first hominid, a member of a subdivision of the primate family whose only living representative is modern man, emerged about seven million years ago. The find, by French archaeologist Michael Brunet, was reported in the science journal Nature in July, 2002.
Until recent times, the earliest human ancestor to diverge from apes, seen in the fossil record, was Australopithecus afarensis. In the early 1970s a famous female skeleton of this species, nicknamed Lucy, was unearthed in central Ethiopia.
Lucy lived between three and four million years ago. She was less than four feet tall, walked on two legs, had long arms, massive jaws and a small brain (450cc). About three million years ago, Lucy's kind diverged into two lines of descent, one of which, a million years later, gave rise to the genus Homo. The first Homo, Homo habilis, meaning "handyman", lived between two and 1.5 million years ago.
Homo habilis was still of small physique but had a larger brain case (700cc) than Lucy. About 1.5 million years ago, Homo habilis evolved into the large-brained (850cc) Homo erectus.
Homo erectus was probably the first hominid to migrate from Africa. Fossils of archaic Homo sapiens, the first human subspecies, have been found in Europe, Asia and Africa. It is assumed that these early people descended from Homo erectus in various parts of the world simultaneously. The brain of modern humans is about 1,400cc.
Homo erectus was eventually succeeded world-wide by the modern subspecies Homo sapiens sapiens, whose oldest fossil remains, found in Africa, are about 120,000 years old - 80,000 years older than any found in Europe or Asia. This, together with other archaeological evidence, suggests that modern humans developed from a single isolated population of archaic Homo sapiens in Africa and then spread out all over the world.
The earliest fossil remains of Neanderthals are over 200,000 years old, but Neanderthal man eventually became extinct (by 30,000 years ago), perhaps wiped out by neighbouring and competing groups of Homo erectus. The systematic elimination of competing groups has been observed in present day chimpanzees.
William Reville is associate professor of biochemistry and director of microscopy at UCC