gradualism versus punctuated equilibrium
phyletic transformation vs cladogenesis (types of speciation)
basics of microevolution
Moths, mice, finches
the specific resources used by a species (how a species ‘makes its living’)
Describe adaptive radiation using lemurs as an example
- The relatively rapid expansion and diversification of life forms into new ecological niches
- ex:lemurs: Lemur separation/Madagascar/ only live in Madagascar/ Two factors: Species has to have adaptive potential Some species are more adaptable than others and Adaptive opportunities
- change accumulates gradually in evolving species
- Many intermediate forms over a long time – you can see the progression
- long periods of no change punctuated by rapid events of change
- Much less intermediary forms or fossils; less available or known ‘missing links’
- Possibly due to extreme climate change
- Fewer intermediate forms b/c of (relatively) shorter time span
what do genes code for?
specific amino acids
what is biocultural evolution? give example
The mutual, interactive evolution of human biology and culture; the concept that biology makes culture possible and that developing culture further influences the direction of biological evolution
- Example: Sickle cell anemia
- H. erectus Biolcultural evolution
- Culture offered non-biological solutions Clothing, fire, shelter, better tools
- Created more diverse adaptive variation· Left Africa for first time
- genetic diff. between a newly separated pop. and parant group
- Gene pool will be different
- movement of genes from one population to another.
- movement of genes from one population to another brings chages in allele proportions
Change in genetic makeup of group caused by random phenomena, not genetic selection
- Survival does not equal success - Reproduction = SUCCESS!
- Process is not foolproof; extinction is the norm
members of the same species
ability to pass along genes through offspring
- response to environmental conditions
- Selection does not create variation…it acts on it
- With population isolation, get new species, but it takes time!(and doesn’t happen very often)
group consisting of modern human beings and immediate ancestors (after split with chimps)
hominin classificatory breakdown
- Hominoidea superfamily
- Hominidae family
- Homininae subfamily
- Hominin tribe
where are hominin fossils found?
- Great Rift Valley: east side of Africa
- Exposed beds: result of tectonic activity and erosion; researchers look in strata deposits for fossils
- volcanic activity ash fall promotes fossilization and preservation of fossils
how do we date hominin remains?
- relative dating
- absolute dating
- Potassium - Argon Dating
- Fission Track Dating
- Cross Dating
How did bipedalism affect the skeletal system?
- Head placement over feet which has to do with the placement of the....
- Foramen magnum directly under skull (where spinal column goes into skull, in apes FM comes in at angle)
- Pelvis is bowl shaped Supports internal organs
- Legs longer than arms
- Feet: arch acts as a shock absorber; Feet is not perfect features; We evolved to run
- Spinal curvature acts as shock absorber to support bipedalism
how does brain size vary in terms of general hominin evolution (think relative versus absolute size)?
- Relates to cognition
- Capacity for culture
- Chimp brains (350-400cc)
- Early Hominins (450cc)
- Modern humans (1370cc)
Bipedalism, Canine Reduction, Tool use ….are these things related?
Bipedalism came and it freed up hands to make tools; Brain got larger in the process
- Sherwood Washburn said that quadrupedal proto-homin increased tool use which led to reduction in canines because of weapon use becuase they werent being used as much all this stimulated bipedalism and the creastion of more tool use.
- example of biocultural evolution
Who was Ardipithecus and how has the discovery of this species changed the current view of the hominin/chimpanzee divergence 6 – 7 mya?
What implications does this genus have for understanding hominin emergence (i.e. environment in which it lived)?
- Female known as "Ardi" dates to 4.4 MYA
- found in 1998 in Ethiopia in Awash River
- first hominin/bipedal creature found with opposable toes on feet also has long arms
- has human like characteristics: foramen magnum under skull, reduced canines, limited sexual dimorphism
- Also has ape like characteristics: omnivorous forest diet, began evolution in the forest, not grassland
why do our femurs angle in?
balance our weight over our knees
Characterize the Australopithecines; although still quite robust, what traits make them more gracile than those species classified in the genus Paranthropus
- 1: more efficient bipeds
- 2: dentition changed - Thicker enamel, larger molar, Reduced canines
- Limited brain development
- 3 million years + without significant change 2-1.5 mya start seeing homo habilis and increased brain size
- Knee that locks straight HINT Bipedalismo Disadvantages: slowo Advantages: energy efficient; walking; good view; carry things; efficient cooling; freed hands (tool use) 60% less heat from the sun = bodies are staying a lot cooler
Which australopithecine do some researchers think is most likely to be our direct ancestor and why?
Why were the Paranthropus species considered so robust (triats) and why do we think they were this way – what was their diet and why do we think so? Why do most researchers think they became extinct?
when do H. habilis and H. rudolfensis show up?
What are Oldowan tools and what is the debate about whether the Oldowan tool makers were primarily hunters or scavengers (lecture, text, presentation, film).
When did this H. erectus show up in different parts of the Old World?
how does the Sahara Pump hypothesis explain the timing of H. erectus geographic dispersion?
o Refugia – small isolated grasslands, forest area during glacial periodo Then warmer and grasslands expand to cover most of continent Forest and grasslands expansive during the interglacial periodso Facilitated migration over areas for food resources Desert expansive during glacial periods (all the water is tied up in the glaciers to the north)· Important sites – all looking for missing links
major cultural development is associated with Homo erectus that may explain why hominin dentition began to decrease in size?
Why does Alan Walker think Homo erectus could not speak like we do (know specifics of his argument as discussed in class)?
alan walker brocas area etc
What are the characteristics of Homo sapiens neandertalensis? What kind of evidence do we have for the Neandertals?
the dispersal of AMHS:
replacement model and its evidence
- associated with Christopher Singer
- idea that we came out of Africa and replaced everyone else and that no interbreeding took place
- idea that Homo erectus populations in Africa gave rise to AMHS in Africa
- Then, AMHS migrated to Europe and Asia, replacing h. erectus and Neandertals populations in Europe and Asia
- Humancentric model because it places us by ourselves and that we outcompete these other hominins
fossil evidence: Oldest AMHS fossils in Africa. It fits because its Consistent with African Genesis.
mDNA: AMHS populations have most genetic diversity; should be the oldest most ancient ones. mDNA diversity is a result of mutations; oldest population should have most mutations otherwise it would not be diverse and has been evolving longer.
The Dispersal of AMHS:
regional continuity model and its evidence
- associated with Milford Wolpoff
- AMHS evolved at the same time in major regions of the old world (Africa, Europe, and Asia)
- Some gene flow between populations would be needed
- Mix with AMHS (coming out of Africa), and AMHS derived from European Neandertals and asian h. erectus populations
- Problem if this model were true: is that not a lot of gene flow back to Africa
- No evidence there was migration back to Africa because you cant get populations remixing in Africa without gene flow
Characterize the Upper Paleolithic
What important events happened during this period regarding culture and dispersal of AMHS?
- 40,000 - 10,000 bp
- Last major period of the fourth glacial advance
- Considerable climate change
- population increased happen
- more human dispersal, which means more sites, and larger groups
- subsistence base broadens becuase large animals die off due to climate change
What might the cave art murals have meant to Upper Paleolithic AMHS?
- demonstrate that men, women, and children were in the caves and involved in the painting process
- Possibly ritual in nature; analogous to modern church or houses of worship; symbolic significance based upon the context of what was found (empirical evidence)
- caves had no domestic materials, possible ritual areas
What are the four major stone tool traditions
What periods do the successive traditions date to, which hominin species are they associated with (or do we think they were associated with), and what are the technological advancements associated with each one?
- (1) Oldowan, chopper(s) - 2.5 – 1 mya - australopithecus
- (2) Archeulean (handaxe) - 1.5 mya Earlier form - Abbevillian - H. erectus
- (3) Mousterian, 125,000 – 40,000 bp
- Levallois technique (turtle back core) - Archaic H. sapiens (Neanderthals)
- (4) Blade Technology – AMHS - can be fashioned into mountable projectile points for arrows or the atlatl
Why are stone tools so important to paleoanthropologists/archaeologists, especially for understanding the biocultural emergence of Homo sapiens?
- Stone tools preserve, are inorganic, and are recoverable
- Bits of material culture can be reconstructed in order to say something about their behavior
How do the successive traditions reflect the evolutionary emergence of humans?
- There was probably other perishable material cultural items, but we have no proof, since they do not preserve
- 2.5mya does not necessary mark the start of culture; they were probably using perishable tools prior to 2.5 mya
Be able to solve a simple Hardy-Weinberg equilibrium problem (always remember to start with the number representing the homozygous recessive segment of a sampled population) and a Punnett Square problem. Review the review material on this subject for exam 1 (the sample questions should prepare you for this part of the final exam).