Harry Williams, Historical Geology 1

HISTORICAL GEOLOGY HUMAN ORIGINS

Primate CharacteristicsMany primate characteristics developed in response to a life in the trees and then a life on the open prairie, as forests were replaced by grasslands in the Miocene epoch. Some of those characteristics are:5 digitsopposable thumbgrasping handnon-specialized teethcomplex vocal capabilityclosely-spaced eyes }smaller snout } STEREOVISIONflatter face }color visionThe order PRIMATES is divided into 2 suborders; the more primitive PROSIMIANS ("pre-monkeys"), which lack some of the characteristics above (e.g. stereovision), and the more advanced ANTHROPOIDS (including modern monkeys, apes and man), which have more of these characteristics.

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The classification scheme is based on grouping together primates with similar features into progressively narrower subdivisions (basic taxonomy) i.e.Order (e.g. Primates) = collection of similar subordersSuborder (e.g. Anthropoidea) = collection of similar superfamiliesSuperfamily (e.g. Hominoidea) = collection of similar familiesFamily (e.g. Hominidae) = collection of similar generaSubfamily (e.g. Hominin) = (smaller) collection of similar generaGenus (e.g. Homo – Latin for human) = collection of similar speciesSpecies (e.g. sapiens) = collection of similar individuals One of the families that developed from the anthropoids -HOMINIDAE - consisted of primates with distinctive, Human-like features. A subfamily – Hominins - included Homo sapiens, the species of "modern Man“, but other species and genera belong to this subfamily...

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The Emergence of HomininsThis part of the world has been called "the cradle of Man", because it's here that the Hominins that were modern Man's ancestors are believed to have developed. Many fossil Hominin bones, dating back to the Pliocene (about 3-4 mybp) have been found in this area. These primates were basically transitional between apes and man, and were given the Genus name "Australopithecus" (meaning southern ape-man). Several species were discovered, including Australopithecus africanus in South Africa.

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The oldest Hominin bones have been found in Chad, dating back to about 7 million yrbp. These are the oldest Hominin fossils known and suggest that Hominins developed between 6 and 7 million yrbp. The most famous Hominin, discovered in 1974 at Hadar by Donald Johanson, is the most complete Hominin skeleton yet found. "Lucy" as the individual was informally named, has the scientific name Australopithecus afarensis and is about 3.5 million years old. These primitive ancestors of modern humans were short (about 3.5-4.5 feet), upright (but feet turned out), chinless, had a brow ridge and a small brain (600-700 c.c) (not human). Ardipithecus ~4.4 million, seems transitional between apes and man (could walk on grasping feet; not human; brain only 300 cc).

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The transition from Australopithecines to hominins of the genus Homo is not marked by great anatomical differences, however there is some evidence of stone tool use by the latter.

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The first humans - Homo rudolfensis (right) and Homo ergaster were roaming the African plains about 2.5 million yrbp. Why did Homo evolve from Australopithecus? Probably the change to a drier cooler climate and increase in grasslands -> improved bipedalism, greater intelligence (larger brain) and greater use of stone tools.

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Homo erectusOne of the descendents of the Australopithecus line was

Homo erectus, who appeared about 1.8 mybp and was the first Hominin to migrate out of Africa to Eurasia. Homo erectus was widespread in Africa and Asia by 1 mybp. Some of the differences from Australopithecus = taller, excellent walker (feet did not turn out) and, ESPECIALLY, a larger brain (775-1300 c.c. - modern Man = 1200-1500 c.c.). This larger brain was reflected in a greater use of tools, and maybe the development of FIRE and hunting in bands (the evidence is inconclusive). The heavy brow ridge and chinless jaw remained and distinguished Homo erectus from Homo sapiens. Homo erectus is best remembered as the stage of BRAIN ENLARGEMENT.

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Homo sapiens neanderthalensis"Neanderthal Man", named after the Neander Valley in Germany, was the first species of modern Man (Homo sapiens), appearing about 125,000 yrbp. The Neanderthal may be considered a "subspecies" of Modern Man - having many similarities, but also a few differences e.g. they were shorter, had the brow ridge and chinless jaw. However, the rest of their skeleton was the very similar to modern Man's and their brains were as large as ours. The Neanderthals had a complex culture, including a belief in "an afterlife”. Neanderthal Modern Human

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Neanderthals were skilled in the use of fire and tools. They commonly lived in caves for shelter from the harsh ice age climate.

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Homo sapiens sapiens"Cro-magnon Man" appeared between 50,000 and 35,000 yrbp, competing with the Neanderthals and causing them to become extinct by about 34,000 yrbp. The Cro-magnons were essentially the same as modern Man and we descended directly from them. They developed culture even further, including cave paintings in Europe. Cro-magnons spread all over the old world, and then, during the last glaciation crossed the Bering Strait land bridge into the "New World" - North America. Originally these Humans were hunter/gathers, but by about 10-15 000 yrbp they developed agriculture, built cities and invented writing. The era of "recorded history" had began.

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Early Man In The AmericasJust when Man moved into North America is still not certain. Debatable evidence =30,000 year old flint tools in California.28,000 year old roasted mammoth bones in California.24,000 year old fire pits in Nevada.23,000 year old obsidian blade in Mexico.More sound evidence =18,620-15,680 year old skull in California.13,000-11,500 year old bone needle in Washington State.spear points 13,000-11,000 years old in New Mexico.11,000-9,000 year old flint tools in New Mexico.The oldest known Human remains from South America are dated at 12 600 yrbp.