Modern Homo sapiens

The first fossil skeletons bearing a distinct resemblance to modern humans were discovered in caves in southwestern France. The fossils are about 35,000 years old. Older fossils of the same type have been found elsewhere in Europe, as well as in Africa, Asia, and even Australia. These early modern humans are referred to as Cro-Magnons, names for the cave where they were originally discovered. Cro-Magnons had a cranial capacity equal to that of modern humans, 1400 cubic centimeters. They are distinguished from Neanderthals by their high forehead and lack of protruding brow ridge and teeth, taller than Neanderthals; they stood about 1.8 m tall.

The oldest truly modern H. sapiens fossils yet found are about 100,000 years old and were found in Africa. Modern H. sapiens probably coexisted with the Neanderthals for about 70,000 years and with H. erectus for more than 50,000 years. As the Neanderthals declined, modern humans became more efficient hunters and home builders, and their tools became distinctly more sophisticated.

Cro-Magnon remains have been found with reindeer bones in certain areas of southern Europe. What does this fact suggest about the diet of Cro-Magnons and the environment in which they lived?

Source: http://shafali.wordpress.com/2009/12/30/caricature-cartoon-drawing-perceptions-neanderthals-homosapiens/

Spread of Modern Humans

All modern humans belong to a single species, Homo sapiens. There are phenotypic differences, such as skin color, associated with people living in different regions. However, all H. sapiens are genetically similar enough to produce offspring together. How did these different phenotypes arise?

Multiregional Evolution

Some anthropologists propose that modern humans evolved in parallel all over Earth from different populations of Homo erectus. For this process to result in a single species of modern humans, as actually exists, constant gene flow between the different populations would be necessary. Without exchanges of genes during the transition from H. erectus to H. sapiens, the different populations would tend to speciate into separate groups, in response to local environmental pressures.

If the multiregional hypothesis is correct, it would suggest that regional differences in phenotype have been developing for well over a million years. Some investigators claim that Asian fossils of Homo erectus show the high cheek bones seen in modern Homo sapiens living in Asia.

Out of Africa

The more widely supported hypothesis, the recent-African-Origin hypothesis, states that modern Homo sapiens originated in Africa only about 100,000 to 200,000 years ago and then, like Homo erectus before them, left Africa. They colonized the world, displacing and causing the extinction of Homo erectus and early Homo sapiens, such as the Neanderthals.

The recent-African-origin hypothesis gets much of its support from studies of the genes found in the mitochondria. Because mitochondria reproduce asexually, their genes are not subject to the mixing caused by gene flow and meiosis. In humans were one large population dating back to over a million years ago, we should find human mitochondria that show a million years of accumulated mutational differences. Instead, most human mitochondria have very similar genes. The period of time needed for mitochondria to accumulate the differences actually seen is only 100,000 to 200,000 years-far short of a million years. Because all humans mitochondria are so similar, supporters of this hypothesis infer that all modern humans came from one small group in Africa a fairly short time ago- 100,000 or 200,000 years ago.

According to the existing fossil evidence, Neanderthals dies out about 30,000 years ago. Some anthropologists hypothesize that the Neanderthals were killed off by Cro-Magnons. Others hypothesize that the two groups interbred. What evidence would you look for to evaluate these two hypotheses?

Source: http://www.harunyahya.com/definitivereply07.php

Characteristics of Humans

Bipedalism, the ability to walk primarily on two legs, is a uniquely human trait among mammals. The cup-shaped human pelvis supports the internal organs during upright walking. The human spine has two curves, resulting n an S shape that allows for upright posture.

In the human foot, the toes are much shorter than those of apes and are aligned with each other. Because humans are the only primates that have this foot structure, we can infer that the shape of the human foot is a specific adaptation to bipedalism.
The enlargement of the brain in humans has resulted in a more vertical face than that found in apes. Among other differences, the larger human brain has extensive areas devoted to the production and understanding of speech. Apes have homologous areas in their brains that are important in the production of sounds used in communication, and apes can also be taught to mimic certain forms of sign language. However, apes living in the wild have not developed any complex, flexible set of signals that can compare to those that make up the languages in humans.

How might the acquisition of language account for the very fast cultural and intellectual development that has occurred in the evolution of humans?

Source: http://angila34.blogspot.com/2007_07_01_archive.html

Welcome :)

Welcome to the human evolution blog. This is dedicated for grade 12 students. I hope you will enjoy it.