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When was the common ancestor with a living relative for chimps and humans?
7.6 million years ago
What are some transitions from the common ancestor that has happened in the past 6-7 million years?
change to bipedalism, change in brain size
walking on two legs
When was Australopithecus Afarensis alive and what are its features
- 3.8-3 mya
- like "Lucy"
- similar to apes - face
- canine teeth
- cranial capacity - 375-500 cc
- hands and arms were intermediate
- clear evidence of bipedalism- evidence for not just an ape
What evidence showed that Lucy was bipedal?
- Foramen magnum- hole that connects skull to backbone- moved back away from the back of the skull (in between humans and apes)
- Pelvis was shorter and broader than apes
- The angle of the femur is not 90 degrees like in apes- but more like humans
- Footprint fossils in volcanic ash- product of two legged walk
When did Australopithecus Africanus like and what were it's traits?
- 3.3-2.3 mya
- Similar to Australopithecus Afarensis
- clearly bipedal
- Cranial capacity- 430-500 cc
- Canines smaller than Afar.
- Skull shape between afar. and homo sapiens
- Jaw is more parabolic (ape=rectangular)
What is the debate over Australopithecus Africanus?
- Where it fits into our family tree
- 1. Afar > Africanus> Homo
- 2. Afar>>>>(>africanus)>> homo - side branch
When was Homo Habilis living and waht are its traits?
- 2.5 mya
- many similarities to Australopithecus - body size and face structure
- Bigger Brains- 560- 700 cc
- qualitatively different- stone tools- first species (Oldowan technology)
Why is the Homo Habilis a confusing species?
- Some anthropologists classify this species as Australopithecus Habilis because it may be transitional (doesnt fit into any genus)
- Some anthropolgists split this species into two- homo habilis and homo rudolfensis
- Stone tools - first associated with homo habilis or rudolfensis
- crack open bones to get nutrient rich bone marrow - increase diet
When was homo erectus alive and what are it's traits?
- 1.8 mya to 300,000 years ago
- includes java man and peking man
- first hominids to migrate out of Africa into Europe and Asia - tool making ability and brains
- legs are longer than Australopithecus
- arm:leg ratio close to humans
- jaw was more jutting, molars larger, and thicker brow ridge
- longer childhood
- cranial capacity 750-1225 cc
- more advanced technology- achevlean technology
Why is Homo Eretus causing confusion?
Some anthropologists split fossils into two species - homo erectus and homo ergaster
same as homo erectus but eastern african fossils while Homo erectus is found on three continents
Whats special about Homo erectus's childhood?
- use teeth to determine childhood length= marks left on teeth for how long he grew
- longer childhood than Australopithecus but not as long as homo sapiens
- its a period of learning
- Two faced cutting hand axes
- Evidence of fire- reason species moved to colder climates
- increasing range of edible stuff- if you cook things you can eat them
When were the homo heidelbergensis alive and what are its traits?
- 700,000 years ago- evolved from homo erectus
- Skeletons are similar to homo sapiens from neck down
- Brain size is up to 1200 cc
- new technologies- Mousterian technology
- Some called the older fossils of heidelbergensis - homo antecessor
older fossils of heidelbergensis - same thing
- Featured "Lavallois technique" - creation of multi-faced stone core
- -strike core at edge and you get a sharp scraper
- takes lots of foresight- hard
When were Homo Neanderthalansis alive and what are its traits?
- AKA Neanderthals
- 200,000-30,000 years ago
- evolved from heidelbergensis
- brains were as big as modern homo sapiens (1350-1400 cc) with a sloping forehead and bun shaped in the back
- bodies were adapted to cold climates- short and squat and more muscular
- Mousterian technology
- apparent disappearance
Whey did the homo neaderthalansis apparently disappear?
- No fossils found younger than 25,000-30,000 years
- Eliminated by competition with homo sapiens
- Interbred with European homo sapiens- hydridized
- Most evidence supports competition
- genetic evidence- some interbreding. but not much
When were Homo Sapiens alive and what are their traits?
- oldest fossils are in Ethiopia - 125,000-150,000 years ago
- Look like modern humans - technology is the only difference between modern homo sapiens and older homo sapiens
- Cranial capacity 1350-1400 cc
- Little change in 100,000 to 150,000 years
When did homo sapiens start to make changes in technology? and what happened after?
- Around 60,000 years ago the major changes in tools and technology
- They moved from Africa to the rest of the world even to the americas by 30,000-15,000 years ago
What is the mechanism for helping to prove Evolution?
same thing as reproduction
What was part 1 of the mechanisms- aka Excess Fecundity?
More offspring produced by a given species that can survive to reproduce than can be supported by a given environment
Who was Malthus and what did he believe?
- He was an economist who worried about excess humans - the population would exceed the food supply
- Darwin said this is true, but not all survive to be able to reproduce- over time about one - two offspring reproduce per parent
What is part 2 of Natural Selection aka Variation in Population?
- If you look at the individuals of a given species they will vary in anatomy, physiology and behavior - not all identical
- Two main sources of variation - Sexual reproduction and mutations
How does Sexual reproduction produce variation in population?
- It takes genes from two individuals and mixes them together and combines them with a huge number of possible combinations
- product of chromosome sorting in meiosis
- You have 64 trillion possible combinations in the offspring
How do mutations create variations in populations?
- produce something new- new base sequence
- occurs "randomly" not something taht occurs for a specific purpose - cant predict what mutation will occur or if i will be good or bad
- Some are beneficial - improve proteins, create new proteins, change a way the gene is regulated
- Some mutations can be passed down if in the sex chromosomes
- Most genetic changes are more likely to produce huge changes
What is a Gene Duplication event?
- an event that creates extra copies of genes
- Ex: Vertebrates have extra copies of hox genes- 4 sets - one copy does the original job and the other are free to mutate without losing any information - one copy doing job
- could result in creation of new genes, creation of new regulatory switches in non cody regulatory parts of the sequence
Explain how Hox Genes and development of vertebrae mutations can make big differences.
There are 4-5 different types of vertebrae - during development when and where hox genes are turned on/off determines what kind of vertebrae they have
Explain Hox c6.
- One of the ten types of hox genes
- Vertebrae forward of where hox c6 is on will develop into cervical- neck vertebrae
- Any thing behind the point where hox c6 is on develop into thoracic vertebrae
- where ever its on- you get ribs
Explain Fox P2
- Involved in the development of the brain - broca's area- essential for speech and a role in grammar and written language
- just one gene involved in making this area
- codes for protein - transcription factor that controls other genes that build Broca's
- found in wide range of species
- only two differences between mouse and chimp and only two more different changes between humans and chimps - over millions of years - suggest something favors two changes in human line
holding on to youth
What is the difference between chimps and human brains?
- Main difference is due to the rate of growth of brain after birth
- -Chimps brinas doubles to 350 cc and stops at age 3
- -Humans are born with 425 cc and continues to grow at a rate that it was growing in the womb- "Neotenous" - holding to youth- fetal growth rate
- Roughly tripple brain size to 1400cc stopping at age 5-6
What is Step 3 of evolution aka "superior traits"?
- Animals with superior traits survive
- Non random processs-
What a superior feature?
a feature that gives an advantage over other features at obtaining necessary resources
What is stabilizing selection?
- selecting against extreme genotypes and phenotypes and favoring ones that are close to the mean value
- mean value ones are best adapted and most fit
- stable- doesnt move much
What is Directional Selection?
- Selects against the mean and favors those at the one extreme end of the range
- has to go one direction only!
What is artificial selection?
- When humans have acted as a selective agent favoring certain traits
- Ex: dog breeds
What is Disruptive selection?
- Selects against the mean and can favor either end of the range - at the same time
- if they stay separated- they could eventually become two separate species
What can happen with cells mutate?
- it can gain the ability to make key nutrients - make a vitamin that wasnt there before
- Cells can gain the ability to use a previously unusable nutrient - such as nylon
- Cells become resistant to antibiotics - could be a mutation from before- or could happen during
How do viruses attach to cells?
How does your immune system help to defeat viruses?
- the first time your infected it takes a while to fight it - which makes you sick because it takes time
- Remembers the shape- but viruses could change
- Immune system responds more rapidly the second time
- Vaccinations insert the virus into your body- to show the immune system what shape it has
- Natural selection favors mutations in viruses which means its more likely for them to change shape to infect you
Why can you get the flu over and over again?
- Because there are many different mutant strains
- Natural selection favors mutants because it has an advantage over older strains
- Ex: Spanish Flu 1918
Why is HIV hard to get rid of?
because the immune system attacks the first attack but the virus stays in your body and evolves to change its shape which makes it similar to a new infection
Who is David Lack and what did he study?
- a british guy studied the galapagos island with the finches with the beaks in 1940s
- found that species with the same beak size did not co-exist because there was competition over seeds
- Small bodies were good at small seeds and large bodies were good at larger seeds - everything but the mean - disruptive
- But was only there for a short time so didnt see changes happen
Who are Peter and Rosemary Grant and why are they important?
- in 1970s they went to Galapagos Islands
- they studied the beak sizes- during drought and wet seasons
- Big beaks were favored in dry seasons because very little small seeds
- small beaks and bodies were favored in wet seasons because they didnt have to eat as much and smaller seed
What is Speciation?
- the process of forming new separate and distinct populations
- natural selection is an important part of the process but its not the only force in the creation of new species
Why is Anagenesis speciation?
- aka Phyletic evolution
- a single population changes over time until the change is significant to produce a new "chrono-species" separated in time from the old original ancestral species-
- creates single newer species
What is Cladogenesis speciation?
- aka Cladistic evolution
- new species are derived from sub-population of an existing species
- "branching" or "bushy" patterns
What is reproductive isolation?
a barrier isolates one closely related population from another creating two sub-population
What is allopatric speciation?
A single population is divided into two or more sub-populations by geographic barriers such as mountains, rivers and oceans
What is sampling error and what does it have affect on?
- when allopatric speciation occurs its unlikely that the two samples will have the same frequencies of alleles as the original group
- theres a high probability that uncommon alleses will be completely absent in the new population or be of high frequency
What is the founder effect?
- when sub-populations are quite different in allele frequency from the initial population
- speciation is most rapid in small isolated populations
What is an incipient species and what is it made from?
The species created when a barrier separates populations and mutations change the population making a new species over time
What happens if the barrier is removed quickly? or not removed for millions of years?
- if removed two quickly they will interbred and become the same population again
- but if millions of years goes by and the incipient species changes enough, they will not interbred and stay separate
What are mechanisms that can maintain reproductive isolation after speciation?
- Differences in reproductive parts- animals with hard exoskeletons
- Differences in mating rituals or times- like songs
- physically separated from each other by specialized habitat needs
- If the hybrids are not fit they will not be produced
Hawaii creates what types of different things and why?
- Different fruit fly species
- because the islands prevent them from flying from one to another
- different plants that are the same species just adapted to different habitats-
What are some reasons for higher speciation rates?
- The appalachian mountains existed for millions of years without interruption creating time for animals to evolve
- the mountains have great geological and topographic diversity
- Climate differences force animals to adapt to specific climates
What is Macroevolution? and microevolution? and why are they disliked?
- Large scale changes over longer periods of time creating new higher taxa and new complex strcutures
- Smaller scale changes over short periods of time
- some people thing microevolution doesnt prove macroevolution but it does because it uses the same mechanisms
What is Functional Continuity?
a particular structure evolves by slight improvements with the structure continues to perform the same function
What is Functional Shift?
modifications are initially favored because they improve ability to do something different from what the structure will do eventually- could end up with new function
How does the reptile ear and jaw bones evolve into the mammal ear?
- The reptiles jaw bones (quadrate and articular) formed the old joint. the Dentary bone extended up and back into the skull until the new joint formed (squamosal)
- Because they were redundant structures- the one joint was free to evolve into the mammal ear
- it was a functional shift because it used to be use for chewing and hearing (dual use) but not its for hearing