CHAPTER 23

Human Evolution

23-1  The Evolution of Life
The formation of organic molecules from inorganic molecules is chemical evolution. 
The theory of chemical evolution is supported by several convincing experiments.
Some scientists believe that the chemical building blocks for life arose from outer space.
The earliest cells were probably aggregations of polymers that acquired nutrients directly from the environment
     Eukaryotes probably arose by endosymbiotic evolution
     Eukaryotes gave rise to multicellular organisms

23-2  How Evolution Works 
Genetic variation is the raw material of evolution. 
Natural selection is a process by which organisms become better adapted to their environment. 
Natural selection ensures that the fittest organisms in a population survive and reproduce. 
 
23-3  The Evidence Supporting Evolution 
The fossil record yields some of the best supporting evidence for evolution. 
Common anatomical features in different species support the theory of evolution. 
The common biochemical makeup of organisms also supports the theory of evolution. 
     Studies of common developmental patterns support the theory of evolution. 
Experimental evidence supports the theory of evolution by natural selection. 
     The study of biogeography helps explain evolution.

23-4  Early Primate Evolution
Primates evolved from an insect-eating mammal
The fossil evidence of primate evolution is limited, making it difficult to determine the exact progression of early human ancestors.

23-5  Evolution of Australopithecines
The earliest hominids were members of the genus Australopithecus

23-6  Evolution of the Genus Homo
The first truly humanlike organisms were called Homo habilis.
Homo habilis gave rise to Homo erectus.
Modern humans belong to Homo sapiens.
Human races result from variations caused by geographic separation.

23-7  Health and Homeostasis
Evolution has resulted in the presence of many homeostatic mechanisms.