Compendium Review Chapter 22

I. Origin of Life
II. Biological Evolution
III. Classification of Humans
IV. Evolution of Hominids
V. Evolution of Humans

I. Origin of Life
A. Fundamental Principle of Biology: All living things are made of cells and every cell comes from a preexisting cell.
1a. Chemical Evolution: A slow increase in the complexity of chemicals. (Mader 468)
B. To understand evolution, we must appreciate deep time- time stretching beyond what is easy to intuitively grasp.
1b. Toilet paper analogy—if a roll of toilet paper is Earth history, humans reside in the shreds at the end of the very last sheet. (Frolich PowerPoint Slide 4)
(Insert Key Events of History of Life picture / Frolich PowerPoint Slide 5)
C. The Primitive Earth:
1c. Sun and Planets: Probably formed from aggregates of dust particles and debris,taking approx. 10-billion years.
- 4.6 billion years ago: solar system in place.
2c. First atmosphere was probably formed by gases escaping from volcanoes. Therefore, the primitive atmosphere would have been made up of mostly water vapor, nitrogen, and carbon dioxide, along with small amounts of hydrogen and carbon monoxide. (Free oxygen was scarce, if any.)
- Earth was extremely hot, and as it cooled, it formed dense clouds.
- Water vapor condensed to liquid water, and rain began to fall. = Oceans. (Mader 468)
- How do we know? Existing ancient rocks. (Frolich PowerPoint Slide 6)
D. Small Organic Molecules:
1d. Rain washed gases into oceans.
- The great deal of energy present (ie volcanoes, lightning, ultraviolet radiation, etc.) made the primitive gases react with one another and produce small organic compounds, such as nucleotides and amino acids.
- Experiment conducted by Stanley Miller confirms this theory. (Mader 468-469)
(Insert Stanley Miller picture / fig.cox.miami.edu / http://fig.cox.miami.edu/~cmallery/150/life)
(Insert Stanly Miller Experiment picture / Frolich PowerPoint Slide 7)
E. Macromolecules: Newly formed small organic molecules probably joined to produce organic macromolecules.
1e. RNA- first hypothesis: The only macromolecule needed to progress toward formation of the first cell was RNA (ribonucleic acid). It is possible that, then, RNA could have carried out the processes of life commonly associated today with DNA.
2e. Protein-first hypothesis: Amino acids join together when exposed to dry heat. This theory suggests that amino acids collected in shallow puddles, and the heat of the sun caused to to form proteinoids (small polypeptides) that have some catalytic properties. When returned to water, they form microspheres, sturctues that are made of only protein but have mnay of the properties of a cell.
F. The Protocell: Can carry on metablism but not reproduce.
- Could have come about by a lipd that was made available to microspheres, the two tend to associate, and produce a pipid-protein membrane.
- Protocell could have used the abundant small organic molecules in the ocean as food.
- Protocell was most likely a heterotroph: organism that takes in preformed food.
- Also would have been a fementer, since there was no free oxygen. (Mader 469)
(Insert Early Earth picture / Frolich PowerPoint Slide 6)
G. The True Cell: How did the first cell acquire both DNA and enzymatic proteins?
1g. RNA-first Hypothesis: First cell had RNA genes that, similar to mRNA, could have specified protein synthesis. Some of these proteins would have been enzymes. One of these enzymes may have used RNA as a template to form DNA, and replication would have then proceeded normally.
2g. Protein-first Hypothesis: Some of the proteins in the protocell would have evolved the enzymatic ability to synthesize DNA from nucleotides in the ocean. DNA would have then gone on to specify protein synthesis, and the cell could have acquired all its enzymes, inlcuding those that replicate DNA. (Mader 468-469)
II. Biological Evolution
A. Since the first true cells were the simplest of life cells, they must have been prokaryotic cells, lacking a nucleus.
- Eukaryotic cells, which have nuclei, evolved from these first cells.
- Multi-cellular organisms and other kingdoms evolved, like fungi and plants.
B. Biological Evolution: The process by which a species changes throughout time. Two important aspects:
- Descent from a common ancestor, which explains what all living things have a commno chemistry and cellular structure.
- Adaptation to the environment, which enables an organism to survive and reproduce in its environment. (Explains diversity of life.)
C. Common Descent: Life forms change over time and from place to place.
1c. Charles Darwin: English naturlaist who first formulated the teory of evolution based on his travels at the age of 22.
- Gathered evidence to support the idea of common descent, based in fossil, anatomical, and biogeographical data. (Mader 470)
(Insert Charles Darwin picture /www.paracompusa.com / http://www.paracompusa.com/SmartScience/Popa/Vol4-2.html)
D. Evidence for Historical Fact of Evolution
1d. Fossil record
–Most rocks contain fossils (in sedimentary rock). (Frolich PowerPoint Slide 8) Best evidence because they are the actual remains of species that lived on Earth at least 10000 years ago and up to billions of years ago. Includes trails, footprints, burrows, casts, preserved droppings, bone, impressions, and insects trapped in tree resin.
- Paleontologists: Find and remove fossils from strata.
- Fossil Record: History of life recorded by fossils.
(Mader 470)
–Long-term change in biological communities. (Frolich PowerPoint Slide 8)
- In general, life progressed from the simple to the complex: Unicellular prokaryotes, unicellular eukaryotes, multicellular eukaryotes, fishes, terrestial plants, animals. On land, nonflowering plants, flowering plants, amphibians, reptiles (including dinosaurs), birds, etc. (Mader 471)
(Insert picture of Ambulocetus / http://www.flickr.com/ / http://www.flickr.com/photos/68509222@N00/384835318/)
2d. Transitional Fossils: Those that have characteristics of two different groups: origin of mammals, origin of birds.
- Anatomical similarities.
- Shared embryological features.
- Shared biochemical and genetic features.
(Insert Evidence for Historical Fact of Evolution picture / Frolich PowerPoint Slide 8)
(Frolich PowerPoint Slide 8)
E. Different Types of Evidence Support the Hypothesis that Organisms are Related Through Common Descent.
1e. Biogeographical Evidence: Biogeography: The study of the distribution of plants and animals in different places throughout the world.
- Life forms evolved in a particular locale and then spread out, which provides for a variety of plants and animals where geography separates continents, islands, or seas.
- Ex. Rabbits were not found in S. America, though the geography was suited for them, because they evolved somewhere else and could not reach S. America.
2e. Anatomical Evidence: Common Descent allows for the explanation for anatomical similarities among organisms.
- Ex. Forelimbs are used by birds, whales, horses, lizards, and monkeys, for different purposes.
- These are Homologous Structures: similar in structure anatomically because they are inherited from a common ancestor.
- Analogous Structures: Serve the same function, but are not constructed similarly, nor do they share a common ancestry.
- Ex. Wings of birds and insects, the jointed appendages of a lobster, and humans are analogous structures.
- Vestigal Structures: Anatomical features that are fully developed in one group of organisms, but are reduced and may have no function in similar groups.
- Ex. Ancestors of whales walked on land. "Modern" whales have a vestigial pelvic girdle and legs, but are completely aquatic. These are also explained by Common Descent. Traces of evolutionary history.
3e. Biochemical Evidence: Almost all living organisms use the same basic biochemical molecules, including DNA, ATP, etc.
- Therefore, humans share a large number of genes with much simpler organisms. Life's vast diversity has come about by only a slight difference in the regulation of genes.
F. Intelligent Design:
- Evolutionary theory has been supported by repeated scientific experiments and observations.
- Intelligent Design argues that the diversity of life could never have arisen without the involvement of an "intelligent agent". Faith-based, not science-based.
G. Natural Selection: Mechanism for adaptation.
- Adaptation: A species becomes suited to its environment.
- Critical Elements of Natural Selection are as follows:
* Variation: Individual members of a species vary in physical characteristics. Physical variations can be passed from generation to generation.
* Competition for Limited Resources: The number in each generation usually stays about the same: resources are limited and competition for resources reults in unequal reporduction among members of a population.
* Adaptation: Members of a population with advantageous traits capture more resources and are more likely to reproduce and pass on those traits. Over time, the environment "selects" for the better-adapted traits. Therefore, each subsequent generation includes more individuals that are adapted in the same way to the environment.
- Accounts for great diversity of life. (Mader 474)
III. Classification of Humans
A. Biologists classify organisms according to their evolutionary relatedness.
1a. Binomial Name: Each organism has a name that gives its genus and species.
- Organisms in the same domain have general characteristics in common.
- Those in the same genus have very specific characteristics in common.
B. DNA Data and Human Evolution: DNA data is being relied on more heavily today to trace the history of life.
1b. 1970s: Carl Woese reports that on the basis of rRNA data, there are three domains of life and the archaea are more closely related to eukaryotes than to bacteria. Animals are more closely related to fungi than plants. (Mader 475)
(Insert Three Domain System of Classification picture / kilby.sac.on.ca / http://kilby.sac.on.ca/faculty/dgalajda/oacbiology/domains__cladistics.htm)
C. Humans Are Primates
- Our closest living relatives are monkeys and apes (anthropoids).
- We share a common ancestor, most recently with apes, farther into deep time with monkeys and even farther in with lemurs and tarsurs (prosimians).
- The living species are not our actual ancestors—we need the fossil record to see them.
(Frolich PowerPoint Slide 9)
- Primates have mobile limbs (w/ five digits each, opposable thumb); grasping hands; a flattened face; binocular vision (including cones); a large, complex brain; and a reduced reproductive rate.
- All traits shared with humans.
D. Comparing Human Skeleton to the Chimpanzee Skeleton
1d. The genomes of humans and chimpanzees are 99% identical.
- 1% difference: Humans, not chimps, are adapted for an upright stance. (Mader 476-477)
(Insert Human / Chimpanzee Skeletons pictures / http://www.flickr.com/ / http://www.flickr.com/photos/mindfuldocumentation/71000531/)
(Insert Evolution of Primates picture / Frolich PowerPoint Slide 9)
IV. Evolution of Hominids
A. Evolutionary Tree: A working hypothesis of the past history of a group of organisms. (See Evolution of Primates picture.)
B. The First Hominids: Hominid refers to our branch of the evolutionary tree.
- Lineage: Any two lines of descent.
- Each lineage throughout time accumulates genetic changes, which lead to RNA and protein changes.
- Molecular data suggest that hominids split from the ape line of descent about 7 mya.
C. Hominid Features: Anatomical features are used to determine if a fossil is a hominid.
- Bipedal posture: Walking on two feet.
- Shape of the face: Flatter, more pronounced chin.
- Teeth are generally smaller and less specialized.
- Brain size.
D. Earliest Fossil Hominids
- Odest fossil: Sahelanthropus tchadensis, dated 7 mya, found in Chad, central Africa. Only found a skull.
- Orrorin tugenensis: dated 6 mya, found in eastern Africa. Limb anatomy suggests bipedal posture.
- Ardipithecus kadabba: dated between 5.8-5.2 mya.
E. Evolution of Australopithecines: Beginning of hominid line of descent.
- Group of species that evolved and diversified in Africa.
- Some were slender, some were powerful.
- Fed on soft fruits and leaves, some of the more "robust" fed on a more fibrous diet.
- First was unearthed in Southern Africa. (Australopithecus africanus)
- Walked upright. Proportions of limbs were apelike.
- Relatively large brain.
- A. afarensis: Lucy. Dated at 3.18 mya, she stood upright and walked bipedally.
Ape-like above waist (small brain) and humanlike below the waist (walked erect). Proves human characteristics did not evolve all at one time. = Mosaic evolution.
V. Evolution of Humans
A.Fossils are assigned to the genus Homo if the following criteria are met:
- Brain size is 600 cm3 or greater.
- The jaw and teeth resemble those of humans.
- Tool use is evident.
B. Early Homo: Homo habilis "handy man": Dated between 2.0 and 1.9 mya.
- May be ancestral to early humans due to larger brain size, smaller cheek teeth, possibility of speech, and indication of tool use. May have been the beginnings of society and culture, if they hunted and ate together.
(Insert Homo Habilis picture / primatas.no.sapo.pt / http://primatas.no.sapo.pt/homem.htm)
C. Homo Erectus: Fossils found in Africa, Asia, and Europe. Dated between 1.9 and 0.3 mya.
- First H. erectus to be unearthed was in 1891, by Eugene Dubois.
- Several different species are included in this group, although all are similar in appearance.
- Compared with H. habilis, H. erectus had a larger brain and a flatter face. Nose projected, much taller. Were erect, with striding gait. Skeleton still showed some australopithecine features. Believed to have migrated from Africa into Asia and Europe.
- First hominid to use fire, and fashioned more advanced tools than early Homos.
- Believed to have used "home bases".
- Language and culture.
(Insert Homo Erectus picture / www.forcesitaly.org / http://www.forcesitaly.org/italy/immagini?M=D)
D. Evolution of Modern Humans
1d. Most accept the idea that Homo sapiens (modern humans) evolved from H. erectus. (Mader 482-484)
- Ability to interbreed.
- Little anatomical difference among populations.
- Little biochemical difference among populations.
- DNA and protein analysis show recent single common ancestor within 1 million years, perhaps only 200,000 years ago. (Frolich PowerPoint Slide 11)
2d. Multiregional Continuity Hypothesis: Belief that Homo sapiens evolved in several different locations. (ie. Asia, Africa, and Europe.)
3d. Others argue that it is unlikely that evolution would have produced essentially the same result in these different places. They suggest the following theory:
4d. Out-of-Africa Hypothesis: Proposes that H. sapiens evolved from H. erectus only in Africa, and thereafter migrated to Europe and Asia about 100000 years BP. This hypothesis suggests that we are more genetically similar than the other hypothesis, and this is the more accepted hyposthesis of the two.
E. Neandertals:
- First Neandertal discovered in Neander Valley, Germany, approx. 200000 years BP.
- Massive brow ridges, and their nose, jaws and teeth protruded far forward. Low forehead, lower jaw lacked a chin. Brain was slightly larger than modern humans. Heavily muscled. Lived in Europe and Asia during the lst ice age.
- Culturally advanced. May have built houses when not living in caves. Manufactured a variety of stone tools, including spear points. Hunted bears, woolly mammoths, rhinos, etc. Used and controlled fire. Buried their dead w/ flowers. may have even had a religion. Capable of thinking symbolically. (Mader 485)
(Insert Neanderthal and Modern Human Skulls Comparison picture / Frolich PowerPoint Slide 13)
F. Cro-Magnons: Oldest fossils to be designated Homo sapiens.
- Named after fossil location in France.
- Believed to be the modern humans who entered Asia and Europe from Africa 100000 years BP.
- Thoroughly modern appearance.
- Did not interbreed with Neanderthals, but seemed to coexist.
- Made advanced stone tools, including compound tools.
- May have been first to throw spears, and were accomplished hunters.
- Culture included art.
(Insert Cro-Magnon Skull picture / www.skadi.net / http://www.skadi.net/forum/showthread.php?t=11043)
G. Human Variation
1g. Widely distributed about the globe. Different ethnicities.
- Could be due to environmental adaptations. (ie dark and light skin)
- Bergmann's rule: animals in colder regions have a bulkier body build.
- Allen's rule: Animals in colder regions have shorter limbs, digits, and ears, to help regulate body temperature.