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Transcript of HUMAN EVOLUTION
Evidence to Support the theory of Evolution
remains of animals and plants found in sedimentary rock deposits give us an indisputable record of past changes through vast periods of time.
his evidence attests to the fact that there has been a tremendous variety of living things.
Their existence confirms that species are not fixed but can evolve into other species over time.
homologous and analogous structures
Homologous structures are similar structures that serve a similar purpose and share a common evolutionary origin.
An example of a homologous structure include the legs of a horse and a donkey.
Analogous structures are similar structures that also serve a similar purpose, but they do not share an evolutionary origin.
An example of analogous structure includes the wings of an insect and a bat.
Biochemistry is the study of the basic chemistry and processes that occur in cells. The biochemistry of all living things on Earth is incredibly similar, showing that all of Earth’s organisms share a common ancestry.
Cladistics is a method of hypothesizing relationships among organisms — in other words, a method of reconstructing evolutionary trees.
The basis of a cladistic analysis is data on the characters, or traits, of the organisms in which we are interested. These characters could be anatomical and physiological characteristics, behaviors, or genetic sequences.
There are three basic assumptions in cladistics:
1. Change in characteristics occurs in lineages over time.
2. Any group of organisms is related by descent from a common ancestor.
3. There is a bifurcating, or branching, pattern of lineage-splitting.
infertile & acidic
rain has washed away many nutrients
decomposition is rapid due to lack of sunlight
very diverse in plants & animals
more than 1/2 the world's plant & animal species
70% of the plants are trees
ex. of vegetation (plants): orchids, bromeliads, vines, ferns
ex. of fauna: birds, bats, small mammals, insects
Pale-Throated Three-Toed Sloth
Strangler Figs (AKA Banyan Trees)
The History and Development (evolution) of the Theory of Evolution
Challenged Darwin's theory of Spontaneous Generation
Spontaneous Generation-theory that earliest bacteria formed from non-living matter
His experiments to find where bacteria came from, disproved this idea and showed life could only come from life(bio genesis)
had his own ideas how species changed over time and came up with Speciation-the process by which new species are formed from old ones
Influenced his grandson (Charles Darwin) and shared his findings with him
The history and development of the theory of evolution
The Evidence to support the theory of Evolution
Speciation and Human Evolution
Biomes:Environmental influences on Evolution
Fig. 1 illustrates modern taxonomic groups and their ancestors
The Rise of
Homo Sapiens Sapiens
Human evolution is the process of change by which people originated from apelike ancestors.
The rise of humans from chimpanzees 4-6 million years ago was influenced by mutations to DNA sequences that play roles in turning genes on and off.
The Rise of Homo Sapiens Sapiens
The history and development of the theory of evolution (Kat and Stef)
Strawberry Poison Dart Frog
The evidence to support the theory of evolution (Evelyn)
Speciation and human evolution (Hanna and Sam)
Biomes: Environment influencing forces of evolution (Maressa)
Fig 2 depicts a transcription factor binding to a model of DNA enabling the controlling and expression of genes which contributed to human evolution.
Fact: They are related to armadillos & anteaters
This Presentation Includes...
Fact: The vibrant colors warns predators that they are poisonous
Speciation and Human Evolution
Fact: the fruit of this tree is part of up to 70% of the animals diet
The Human Journey:Migration Roots
Fact: the trunks of this tree can be up to 16 feet around
Tropical Rainforest Biome
ex. Amazon basin of South America, Congo basin, other lowland regions in Africa
elevation of about 3000 feet
only covers about 6% of Earth's total surface
Tropic of Cancer
Tropic of Capricorn
only 2 seasons: wet & dry
about 125-660cm of rainfall yearly
(compared to about 92cm of precipitation here in Ontario yearly)
warm all year-round
humidity of about 77-88%
200 000-250 000BP
Migrations in Oceania
Migrations of Homo Sapiens
Europe: 40 000BP
Siberia: 40 000BP
12 000-30 000BP
BP = Years before Present
The Genographic Project
The Genographic Project is an ambitious attempt to answer fundamental questions about where we originated and how we came to populate the Earth by analyzing our DNA
“The greatest history book ever written is the one hidden in our DNA.”
—Dr. Spencer Wells
This map illustrates their findings on the human journey...
Archeologists believe that humans first appeared in Eastern Africa
Later, modern humans began to explore environments outside their African homeland
Modern humans began to inhabit Southwest Asia, Afroeurasia and to Australia and the Americas.
DNA suggests that humans departed from Africa by an easterly route
They would have had an abundant and nutritious diet of edible plants, fish, and seafood
Humans began to occupy the cold lands of Russia and Ukraine. From there, they migrated into the even icier environments of Siberia.
100 000 BP
Australia: 60 000BP
100,000 BP, Homo sapiens had already learned to live in places, such as deserts and dense forests, that no earlier hominids had occupied.
Humans accumulated more new ways of dealing with their environment and preserving what they knew
Communities that made a living by hunting and gathering food, made their way eastward across Eurasia
They moved around the rim of the Arabian Sea to India, and eventually from there around the Bay of Bengal to Southeast Asia and China.
They also learned to be very efficient hunters (plant foods were scarce, had to learn how to hunt huge animals such as mammoths).
Some humans crossed the Bering Strait from eastern Siberia into the Americas.
Once in the Western Hemisphere, they spread from northern Canada to the southern end of South America within one or two thousand years.
1 300-1 500BP
13 000-15 000BP
Population increased by "extensification," (increasing the number of communities and the area of settlement across the world without increasing the size of each community).
After 200 000years of traveling...
At one point, climates shifted and Africa became dry and population dropped (humans were endangered)
Examples of vestigial structures on the Human body
Now the appendix in humans seems to be a depository for bacteria that is used in the colon to aid digestion and absorption
It is there because humans were believed to once have had tails and live in trees
These tails were eliminated because they were a disadvantage- leading for humans to still have a place for a tail
Populations of the same or similar species occupying separate ranges making it impossible for the species to breed
Species that live in the same areas but are restricted from interbreeding
Perpetual change is the theory that states the world and organisms are constantly changing.
Common descent means that all organisms are related, and share a common ancestor.
Multiplication of species means new species are born from old species in a constant process resulting in more diversity.
Gradualism is essential to evolution of organisms and it means that evolution occurs in slow incremental changes over long periods of time.
Natural selection means that nature will select favorable traits of an organism that fit their environment at that time. Selects against the weaker adaptations so those best adapted are more likely to survive and reproduce.
Humans originated in Eastern Africa 200 000BP
The Tropical Rainforest Biome
Jean Baptist de Lamark(1744-1829)
proposed humans evolved from a lower species through adaptations over time
came up with vestigial organs(idea if organism/structure wasn't needed, it would evolve to shrivel and go away over a large number of years
helped with Darwin's idea of Natural Selection
Grew up a Christian so church always influenced his beliefs and perception- found it difficult because many of his findings contradicted his beliefs
came up with evolution theory-published in "The Orgins of Species"
theory heavily based on role of natural selection,(and others- Perpetual change, Common Descent, Multiplication of Species, Gradualism)
Flaws in theory:
4 animals and 2 plants theory, variation with species is a result of environment and conditions,and theory of "Pangenesis"- gemmules are reason traits are passed throughout generations
- found very bio diverse islands despite seemingly inhospitable conditions
Species on islands evolved differently from South America because of different location, climate, and its remoteness
helped him develop his theory of evolution
different islands= different variations of species
ie. Finches where food was on trees had shorter beaks, and Finches where food was in hollow trees evolved to have long beaks
Creationists(believe God created earth and everything on it, out of nothing) disapproved and denied his theory
Difficult to have support because many couldn't believe in evolution unless they sacrificed some of their own beliefs
2 Main Types:
Principles of Geology
-first to propose that process of formation of earth was very slow and also supported notion that earth older then biblical estimation
-Developed theory of Uniformitarianism originally formed by Hutton
-His theory helped support Darwin's theory on gradual evolution because of its time frame
Hutton challenged Earth's estimated age of 6000 years and the idea that it wasn't changing
Discovered the "great geological cycle"
Developed Uniformitariaism theory- idea geological forces are at work in the present and have a big impact, although they can't be seen
His theory gave Darwin the knowledge that earth was older than was estimated- fossils uncovered could be thousands of years old
Radioisotope: A version of a chemical element that has an unstable nucleus and emits radiation during its decay to a stable form.
The absolute age of a fossil is determined by dating the fossil with radioactive isotopes(radioisotope).
Through travel noticed that even though geographic areas were the same, each had unique wildlife that was similar to other areas
Hypothesized all wildlife was related in some way and their environments made them change
Influenced Darwin's ideas of how earth originated and Natural Selection
1st to assert that bio geography=evidence for evolution
New Discoveries Since Darwin:
Mendel's work with pea plants- lead him to discover after crossbreeding the plants, certain traits showed up in the next generations
August Weismann- found the importance of DNA to heredity and came up with germ cell theory(inheritance only happens because of germ cells ie. egg and sperm)
Walter Sutton- chromosomes carry the inheritance characteristics
1943- DNA is shown to be genetic material
With the passage of time, organisms change and diverge from their common ancestor to form new species.
The following evidence for evolution demonstrates the concept of the common ancestor.
DNA,RNA,the genetic code, and protein synthesis are similar in all organisms.
The greater the genetic and molecular similarity between species, the closer their common ancestor.
For example, humans and chimpanzees have 98% of their genes in common.
Has helped create the diversity we see present in modern day plants and animals.
The Earth's continents were once, a large super continent called Pangaea that split into two smaller ones known as Gondwana and Laurasia.
The separation and collision of the continents has not only created valleys and mountain ranges, but it has also brought species together and apart again, consequently letting natural selection take over and lead to the animals we see today.
Directional and Sexual Selection
Directional selection is a type of natural selection that favors one extreme phenotype over the mean or other extreme. This phenomenon is usually seen in environments that have changed over time. Changes in weather, climate, or food availability lead to directional selection.
Sexual selection is a term that means that an individual of a species specifically selects a mate based on certain characteristics. Sexual selection impacts natural selection because the choosing of the traits will enhance the number of alleles(alternative form of a gene) of a given type or weaken the number of alleles of a different trait based on the preferences of the individuals who are mating.
Embryology is the study of embryos. An embryo is an unborn(or unhatched) animal or human young in its earliest phases.
Embryos of much different kind of animals: mammals, birds, reptiles, fish, etc all look very similar, and it's often difficult to tell them apart. For example fish embryos and human embryos both have gill slits.
This shows that animals are similar, and that they develop similarly, implying that they are related ; have common ancestors, and that they started out the same , gradually evolving different traits, but the basic plan for a creature's beginnings remains the same.
"What Darwin Never Knew" Video Summary
Explains how Darwin's theory of evolution works.
Answering the questions that Darwin could not about his own theory.
Gave background information about Darwin and how he came up with his theory of evolution at the Galapagos Islands, examining iguanas, tortoises and finches.
Darwin's study on embryos and how he discovered gills on human embryos.
Explained Darwin's theory of Natural Selection, how nature is brutal and animals adapt to survive to the environment.
Discussed Darwin's Variations theory.
Darwin's publication of "The Origins of Species".
DNA - G,A,T,C, DNA does not stay the same, mutation generates variation(ex the Knock Mouse).
Human Genome Project, humans have 23,000 genes.
More about Embryology("embryos are the platform for diversity").
Study on fruit flies, discovered "switches"they are not genes, they do not make cartilage, muscle, etc, but instead turn on and off the genes that do.
Why whales and Manatees have leg bones (homologous structures)
Theory of Humans evolving from a fish, Darwin did not know the answer.
Transitional fossils, Neil Shubin and his crew dug up a fish with a flat head and long snout(signature of a fish that pushed itself on land) called Tiktaalik.
Theory was that Tiktaalik pushed itself on land to escape predators in the water, and that all four legged creatures descended from Tiktaalik., and because of changes to an ancient set of genes we are here.
What makes us human?DNA, chimps and humans share 99% of DNA, but our brain differs from theirs and that's because in that 1%, a mutation in our jaw creates space to let our brains expand into adulthood.
Small differences in DNA can make an enourmous change.
http://www.medterms.com/script/main/art.asp?articlekey=5188 http://bioweb.cs.earlham.edu/9-12/evolution/ http://anthro.palomar.edu/evolve/evolve_3.htm http://sandburgevolution.wikispaces.com/Homologous+vs.+Analogous+Structures http://www.dummies.com/how-to/content/what-evidence-supports-the-theory-of-evolution.html http://biotechnologyclass.blogspot.ca/2010/04/how-does-comparative-biochemistry.html http://evolution.berkeley.edu/evolibrary/article/phylogenetics_05 http://www.studymode.com/essays/Impact-Of-Continental-Drift-On-Evolution-333409.html http://evolution.about.com/od/NaturalSelection/g/Types-Of-Natural-Selection-Directional-Selection.htm http://evolution.about.com/od/Terms-O-Z/g/Sexual-Selection.htm http://necsi.edu/projects/evolution/evidence/embryos/evidence_embryo.html