What affect do you think a global flood could have on sedimentation rates?
A tree typically grows one ring each year. Thus, if you cut a tree down and count the tree rings, you can determine how old the tree is. If there are 123 rings, the tree is, most likely, 123 years old. Counting tree rings is a good method for determining the age of a tree, but how does that help determine the age of artifacts in archaeology? Well, the first thing that you have to realize is that the appearance of a tree ring depends on several environmental factors for the year in which the ring was formed. The length of the growing season, the amount of rain, the average temperature, and several other factors all play a role in determining how wide and dark the ring being grown that year will be. As you look at a tree's rings, then, you will see patterns of wide rings, thin rings, dark rings and light rings. Those patterns are a result of the weather patterns that occurred in the tree's environment over its lifetime. Okay, fine, but how does that help an archaeologist? Well, since the weather in a given region affects the appearance of tree rings, archaeologists studying a certain region can cut down an old tree that is still alive. They can then look for distinct patterns of tree rings that correspond to several years of a given weather pattern for that region. Counting from the outside of the tree to the start of this special pattern will then tell archaeologists how many years ago that weather pattern occurred. Archaeologists find several such patterns and catalog them as master tree ring patterns for that region of the world. So, when an archaeologist discovers a log that was once used to build a home or something like that, he or she can look at the rings in the log and try to find one of those master tree ring patterns. If the archaeologist finds one, then he or she knows how many years ago the ring patterned formed, because that has already been determined. Since the archaeologist knows when that ring pattern was formed, he or she can then count the remaining rings on the tree that was discovered and determine when that tree was cut down. That will tell the archaeologist how long ago the people who cut down the tree were alive, and that will determine the age of the artifacts left by those people. Archaeologists have cataloged master tree rings patterns which have allowed them to date certain artifacts to as far back as 6600 B.C. Now before I go any further, I have to point out something that is very important. You must pay close attention here:
Before 1970 , taxonomists classified all forms of life into two kingdoms: Animalia and Plantae (based on Linneaus ). Bacteria, fungi, and photosynthetic protists (as they were discovered) were considered plants, and the protozoa were classified as animals. In 1969, Robort H. Whittaker proposed a five-kingdom classification scheme. Whittaker identified two kingdoms of primarily unicellular microorganisms based on whether they showed prokaryotic or eukaryotic cellular organization. The kingdom Monera consists of generally single prokaryotic cells, whereas the kingdom Protista consists of generally single eukaryotic cells. All of the organisms in the remaining three kingdoms (Plantae, Fungi and Animalia) are eukaryotic, and most of them are multicellular. Carl Woese introduced a sixth kingdom in 1990 , and a restructuring called the "Tree of Life" consisting of three domains. The cell structure of "extremophiles" (Archaea) is so different from that of prokaryotic and eukaryotic cells, he argued, that they should occupy their own kingdom.
Can we figure out the blanks? The American Kestrel (Falco sparverius) Turdus migratorius (common robin)
Could be evidence for descent with modification Could be evidence for a single intelligent “creator”
Do similar embryological forms show common ancestry or a common designer? Ludwig Rutimeyer, a professor of zoology and comparative anatomy, at the University of Basel, reviewed Haeckel's work and Haeckel's mistakes were brought to the attention of the professors at Jena (Rutimeyer 1868). Charged with fraud by five professors and convicted by a university court at Jena, he agreed that a small percentage of his embryonic drawings were forgeries. Haeckel alleged he was merely filling in and reconstructing the missing links when the evidence was thin. During the trial, Haeckel confessed that he had altered his drawings, but excused himself by saying: “I should feel utterly condemned and annihilated by the admission, were it not that hundreds of the best observers and biologists lie under the same charge. The great majority of all morphological, anatomical, histological, and embryological diagrams are not true to nature, but are more or less doctored, schematized and reconstructed”.
Case Study: Developmental Homologies In 1868, a scientist named Ernst Haeckel published drawings of early vertebrate embryos which he manipulated to look more similar than they actually were. This was because he held preconceived views about evolution. Haeckel’s drawings were eventually recognized as fraudulent, but they are still found in some biology textbooks as good evidence for common ancestry. Haeckel’s ideas continue to spread misconceptions today. In humans at one month, there are throat pouches in the skin near the neck. These are sometimes labeled as ‘gillslits’, suggestive of a fish ancestry. In fish, these pouches do develop into gills. But in humans and other organisms, the middle ear canals develop from the second pouch, and the parathyroid and thymus glands come from the third and fourth. These labels are therefore quite biased. Other common misconceptions include the idea that a human embryo has a ‘yolk sac’ like a chicken and a ‘tail’ like a primate. These parts have now been identified as the blood-forming sac and the coccyx : an important point of muscle attachment necessary for our upright posture.
Other examples: camera eye of the vertebrate and the cephalopod (squid & octopus): walking limbs of insects and vertebrates cranium of vertebrates and exoskeletal head shield of insects fusiform shape of fish and cetaceans (whales & dolphins)
Darwin didn’t know about DNA – it hadn’t been invented yet. Most people of his time believed that things you learned and experienced during your lifetime could be inherited by your offspring. Darwin believed there had to be a system to pass down physical traits and he was right. Since Watson & Crick discovered how nucleic acids transfer genetic material in 1953, a whole new field of genetics has exploded into the realm of science .
Before 1970, taxonomists classified all forms of life into two kingdoms: Animalia and Plantae. Bacteria, fungi, and photosynthetic protists were considered plants, and the protozoa were classified as animals. In 1969, Robort H. Whittaker proposed a five-kingdom classification scheme that is widely used today, and which we follow in this text. Whittaker identified two kingdoms of primarily unicellular microorganisms based on whether they showed prokaryotic or eukaryotic cellular organization. The kingdom Monera consists of generally single prokaryotic cells, whereas the kingdom Protista consists of generally single eukaryotic cells. All of the organisms in the remaining three kingdoms (Plantae, Fungi and Animalia) are eukaryotic, and most of them are multicellular. They may be classified further on the basis of their way of acquiring nutrients. Members of the kingdom Plantae photosynthesize, and members of the kingdom Fungi secrete enzymes outside their bodies and then absorb the externally digested nutrients. In contrast, members of the kingdom Animalia ingest their food and then digest it, either within an internal cavity or within individual cells. Recently, a sixth kingdom has been proposed. Many microbiologists argue that the cell structure of the Archaea is so different from that of prokaryotic and eukaryotic cells that they should occupy their own kingdom. Following the fashion, this text adopts the updated six-kingdom classification system (Fig. 1.1). 6 Kingdom Classification System Kingdom Eubacteria: true bacteria (formerly in kingdom monera) Kingdom Archebacteria: extremophiles (formerly in kingdom monera) Kingdom Protista (same)
Formerly part of the kingdom monera Microbiologists who study bacteria determined that the DNA of these are much different from other, true bacteria Most Archaea live in extreme conditions (very hot, acidic/basic, sulfurous, etc)
Formerly a part of the kingdom monera Name means “true bacteria” These are the kind of bacteria likely to make us sick, live in our gut to help us digest food, or be used in the making of cheese Bacilli Streptococcus Staphylococcus Dicoccus Spirilla
Contains all of the eukaryotes (organisms with a nucleus in their cells) Protista Fungi Plantae Animalia
Includes All Protists: Eukaryotic Unicellular Animal-Like Protists (protozoans) Pseudopods, Ciliates, Flagellates Examples: Amoeba, Paramecia, Giardia Plant-Like Protists (autotrophic) Euglenoids, Dinoflagellates, Diatoms, Green/Red/Brown Algae Fungus-Like Protists Examples: Water molds, slime molds
All eukaryotic, multicellular, heterotrophic, sessile organisms Includes: molds, mushrooms, rusts, lichens Mycorrhizal associations allow plants to absorb more water and nutrients from the soil
All eukaryotic, multicellular, autotrophic, sessile organisms Produce their own food from sunlight and carbon dioxide Common Phyla: Bryophyta (mosses) Pteridophyta (ferns) Coniferophyta (conifers, like pine trees) Angiospermophyta (angiosperms, like flowering plants
All eukaryotic, multicellular, heterotrophic, motile (most) organisms Common Phyla: Porifera (sponges, corral) Cnidaria & Ctenophora (jellyfish and similar animals) Platyhelmenthes (flat worms, tapeworms) Nematoda (small unsegmented worms)
Used to help identify unknown specimen Work by asking yes or no questions whose answers lead the reader to the correct taxa for the organism
Origins of Life Patterns of Evolution - Classification -
Phyletic Gradualism (Uniformitarianism) Sedimentation rates we commonly see today are very slow (centimeters/year) • Assuming those rates have been constant throughout Earth’s history, it would take millions of years for the sedimentary layers we see at locations such as the Grand Canyon to form
Phyletic Discontinuity (Catastrophism) Catastrophic events (volcanoes, floods, etc.) cause rapid, widespread sedimentation and dramatic changes to the geologic record • Mt. St. Helens displaced huge amounts of dirt, rock and snow, carving a mini grand canyon and leaving over 50 feet of sediment deposited across the valley within a matter of minutes
Punctuated Equilibrium Slow sedimentation rates and evolutionary changes "punctuated" (interrupted) by events that facilitate rapid bursts of evolution • Mass extinctions • Explains "Cambrian Explosion" Sudden appearance of new species (fossils) • Explains lack of transitional fossils
Fossil Dating Methods Stratigraphy • Age of rock layers and the fossils within are interpreted with the belief that younger fossils are deposited on top of older fossils (superposition) Radioisotope Dating • Decay of unstable elements used to measure elapsed time (assumes known original amount, constant rate of decay, and lack of contamination) Molecular Clocks • Measurable rates of mutation used to compare DNA of organisms and estimate time between evolved ancestors
Classification & Phylogeny Classification • the process of describing, naming, and grouping things based on their similarities • grouped organisms are easier to study Taxonomy • scientific study of how living things are classified Phylogeny • the evolutionary history of a organisms as depicted in a "family tree"
Systems of Classification Carolus Linnaeus (1750s) • grouped organisms based on observable features (long before evolution was proposed) • system used for over 250 years • devised naming system for organisms Binomial Nomenclature 2 part naming system using Latin words Genus species (i.e. Felis concolor) Phylogenetic Classification 1707-1778 • Retains Linnaean system for the most part • Species with similar hypothesized evolutionary histories are grouped more closely together • Based on DNA similarities more than physical appearance • Evolution of species is presupposed
Levels of Classification There are 7 levels of classification. Remember: King Philip Came Over For Good SoupKingdom broadest levelPhylumClassOrderFamilyGenusSpecies most specific
Binomial Nomenclature two-name system of naming • Genus is 1st name (upper case); species is 2nd name (lower case
Phylogenetic Tree Classification based on : • Morphology (similar physical structures) • Fossil record • Embryological patterns of development • Genetic similarities (DNA)
Cladograms A phylogenetic tree is based on a grouping/sorting similar organisms into groups called clades. This is a relatively new system of grouping incorporating the same derived characteristics to represent evolutionary relationships. • Organisms within a group are descended from a common ancestor • There is a branching pattern (splits in two where changes occur) • Change in characteristics occur in lineages over time
Homologous Characteristics A structure found in different species, but derived from a common ancestral structure. • The structure may or may not be used for the same function in the species in which it occurs. Examples: • skeletal structure of vertebrate limbs • embryonic similarities • similarities in DNA, RNA, & their proteins
Embryonic Homologues Turtle Structures that have different mature forms but develop from the same embryonic Primitive Fish tissues Alligator Limbs are structurally similar but have different functions Recent developments in biochemistry show "similarity does not imply a genetic relationship" Mammal
Analogous Structures Similar in function, but NOT derived from a common ancestral structure Examples: • wings of birds & bats • walking limbs of insects & vertebrates • eyes of a horse and an octopus • human skull and beetles head shield exoskeleton Bones are homologous structures, but wings are only analogous.
Inherited Traits Neo-Darwinism incorporates the similarities of genetics between species as evidence of evolution Other scientists look at genetic code and see the complexity and efficiency of information transfer as evidence for an intelligent “designer”
Six Kingdoms Archaebacteria Eubacteria Protists Fungi Plants Animals First true cells are thought to have arisen from aquatic, anaerobic, "protocells" EUBACTERIAARCHAEBACTERIA 6
Domain (or Kingdom) Archaea Formerly part of the Monera kingdom Bacteria that live in extreme conditions: • hot • acidic • sulfuric • deep • cold
Domain (or Kingdom) Eubacteria Formerly part of the Monera kingdom "True Bacteria" • make us sick • live in our intestines • make cheese Different shapes • Bacilli (rod-shape) • Strep/Staphylococcus (round chains/clusters) • Spirilla (stringy spirals)
Domain Eukaryota Includes all eukaryotic organisms Includes 4 kingdoms: • Protista • Fungi • Plants • Animals
ke Kingdom Protista a l-Li s)A nim zoan to(pro Eukaryotic (have nucleus) Paramecium Giardia Amoeba Single-celled Fungus- P l Like a n Water Mold Slime Mold t - L i Euglena Dinoflagellates Green Algae Brown Algae Diatom k e
Dichotomous Keys1a. Organism has 4 legs Go to # 21b. Organism has more than 4 legs Go to # 202a. Organism has a tail Go to # 32b. Organism has no tail Go to # 353a. Organism has stripes Bengal Tiger3b. Organism has no stripes African Lion