Lecture Outline - Chapter 22

22.1 Evidence for Evolution (p. 456)
	1.	Fossils Show the History of Life (p. 456, Fig. 22.1)
		a.	Fossils show gradual change over certain lineages and a general increase in complexity over time, supporting evolutionary theory.
		b.	The age of fossils can be determined using isotopes.
		c.	The fossil record traces the history of life on earth.
	2.	Comparative Biochemical Evidence (p. 457)
		a.	Nearly all organisms on earth use the same biochemical molecules (DNA, ATP), all use the same triplet code for amino acids, and many share similar gene sequences. 
		b.	The degree of relatedness between organisms is reflected in the similarity of their DNA base sequences.
	3.	Comparative Anatomical Evidence (p. 457, Figs. 22.2, 22.3)
		a.	Many diverse organisms show anatomical similarities, such as vertebrate forelimbs. 
		b.	Similar structures that were inherited from a common ancestor are called homologous structures.
		c.	The unity of plan seen in all vertebrates is evident in their common stages of embryological development.
		d.	Vestigial structures are anatomical features that served a purpose in an ancestor but no longer have a function.
	4.	Biogeographical Evidence (p. 458, Fig. 22.4)
		a.	Biogeography is the study of the distribution of plants and animals throughout the world. 
		b.	At one time, the major continents were joined in one landmass that eventually broke apart into the continents of today. Areas that show biological similarities with one another were joined in more recent history. Those that show great differences in organisms were separated early on, leading to separate lines of evolution in different areas.
22.2 The Evolutionary Process (p. 459)
	1.	Charles Darwin's theory of evolution through natural selection was based on the ideas that follow.
	2.	Variations Come First (p. 459)
		Individuals within a population vary in physical characteristics, and these variations can be inherited.
	3.	Struggle for Existence (p. 459)
		More individuals are produced each generation than can survive and reproduce.
	4.	Survival of the Fittest (p. 459)
		Individuals within the population that are better adapted to conditions at the time are more likely to reproduce.
	5.	Adaptation to the Environment (p. 459, Fig. 22.5)
		As a result of evolution, many different species form, each adapted to a specific set of environmental characteristics.
22.3 Organic Evolution (p. 460)
	1.	Origin of Life (p. 460, Fig. 22.6)
		a.	The sun and planets formed from aggregates of dust and debris 4.6 billion years ago.
		b.	The primitive atmosphere on earth was produced by outgassing from the earth's interior and contained very little free oxygen.
		c.	Small Organic Molecules Evolve (p. 460)
			As the earth cooled, clouds of water vapor condensed and rained down on the earth, bringing with them atmospheric gases. Energy from lightning and volcanic heat triggered the gases to react, producing simple organic compounds. 
		d.	Macromolecules Evolve and Interact (p. 460)
			i.	Small molecules reacted and formed larger ones, and RNA likely formed. RNA can act both as a substrate and an enzyme, which supports this RNA-first hypothesis.
			ii.	The protein-first hypothesis suggests that dry heat, such as on a rocky shore, caused proteins to form from amino acids. This led to DNA genes, which today need protein enzymes for replication.
		e.	A Protocell Evolves (p. 460)
			A protocell with a lipid-protein membrane must have evolved first. It might have contained RNA, which served both as genetic material and as enzymes. Small organic molecules would have served as food for this heterotroph.
		f.	A Self-Replication System Evolves (p. 460)
			i.	If the first cell had RNA genes, they could have directed protein synthesis. A reverse transcriptase would have produced DNA, and DNA genes arose.
			ii.	If the cell began with proteins, they could function as enzymes, guiding the synthesis of nucleotides, and eventually, nucleic acids. It seems unlikely that a molecule as complex as RNA could arise on its own.
	2.	Evolution and Classification of Living Things (p. 462, Fig. 22.7, Table 22.1)
		a.	Taxonomy is the branch of biology dedicated to naming, classifying, and describing living creatures. Categories used for classification include kingdom, phylum, class, order, family, genus, and species.
		b.	Organisms are named using their genus and species, a binomial system of classification.
		c.	Classification represents evolutionary relationships between organisms. Organisms today are grouped into five kingdoms.
22.4 Modern Humans Evolve (p. 463)
	1.	Primates Live in Trees (p. 463, Fig. 22.8)
		a.	Humans evolved from primates, most of which live in trees. Primates have an opposable thumb, a shortened snout, stereoscopic vision, extended parental care of offspring, and an emphasis on learned behavior during a lengthy juvenile dependency period.
		b.	Humans are most closely related to the apes. Chimpanzees are our closest relatives.
		c.	Humans can be distinguished from apes by posture, locomotion, dental features, and various other traits.
	2.	Hominids Walk Erect (p. 463)
		a.	The hominid line led directly to modern humans and began with the australopithecines of 4.4 million years ago (MYA) to 1 MYA. Australopithecus afarensis, or "Lucy," was small but walked upright and had a heavy jaw and smaller brain than modern humans. Several species of hominids may have existed 2 MYA, descending from Lucy's species.
		b.	Homo habilis Made Tools (p. 464, Fig. 22.9)
			i.	Homo habilis ("handy man") made stone tools. Stone flakes were used to clean hides and remove meat from bones. Speech was likely in this group, 	which also probably possessed attributes of culture and cooperation.
			ii.	Brain size, posture, and dentition cause H. habilis to be classified as a Homo.
		c.	Homo erectus Traveled (p. 464)
			Homo erectus had an even larger brain and traveled extensively throughout Europe, Africa, and Asia. It probably first appeared in Africa. It was the first hominid to use fire and to make axes and cleavers. It was a good hunter. Evidence indicates the use of "home bases" and social interaction. Language and culture were likely.
		d.	Modern Humans Originate (p. 464, Fig. 22.10)
			i.	The out-of-Africa hypothesis suggests that Homo sapiens arose in Africa and then migrated to other areas of the world about 100,000 years ago. Modern humans may have interbred with H. erectus, whose traits eventually disappeared.
			ii.	The Neanderthals (H. sapiens neanderthalensis) from 200,000 years ago had massive brow ridges and protruding facial features, and were, perhaps, an archaic H. sapiens. They were heavily muscled and had larger brains than modern humans. They were culturally advanced and buried their dead with flowers, indicating a possible religion.
			iii.	Cro-Magnons (H. sapiens sapiens), from 100,000 years ago, had a modern appearance, were accomplished hunters, and likely caused the extinction of many large mammals. They painted and sculpted, and lived in small groups.
	3.	We Are One Species (p. 466, Fig. 22.11)
		All humans on earth today belong to one species, Homo sapiens sapiens, even though racial differences occur. Such phenotypic differences like skin color are most likely due to climatic differences in the areas where each race arose. Differences in stature could reflect climatic temperature differences.