Lecture 27/28 Human Evolution Flashcards
Scopes Monkey trial (2)
-In 1925 John Scopes was convicted of violating a state law prohibiting the teaching of evolution
-In 1995 Alabama education board ruled that all textbooks must carry the disclaimer that evolution is a theory not a fact
Humans and extant apes (3)
-Scientists UNIVERSALLY agree that humans belong to the same clade as apes
-Clade includes gibbons, orangutans, gorillas, and chimps
-Most agree that within this clade of great apes, humans lie within a smaller clade, the African great apes
-This means that the exclusion of humans from the great apes
synapomorphies distinguishing apes from other primates (6)
-not tail
-Erect posture
-Flexible hips and ankles
-Arm and shoulder structure
-Flexible thumb and wrist
-Large brain
Genus Homo (Humans) (2)
-There are 6-8 Homo species recognized
-there is some debate whether some of these are distinct species or regional variants of each other
Homo Habilis (4)
-Existed 2.4 -1.4 MYA
-Made tools
-More primitive cranium
-Lived in trees rather than being bipedal
Homo Erectus (6)
-1.8 MY -700,000 years ago
-First HOMO outside of Africa (migrated 1.4 MYA)
-Famously known as the “peking Man”
-First human to truly walk upright thanks to the evolution of locking knees
-May have used fires to cook their meat
-Were polymerous as males were much larger than females
African fossils challenge human evo theory (3)
-Fossils found in 2000 in Kenya challenge the traditional “Straight line of human evolutions from the knuckle dragging ape to briefcase carrying man”
-Evidence shows that H. Habilis and H. Erectus lived side-by-side for at least half a million years
-they probably didn’t interact as habilis was more vegetarian and erectus was more meat focused
Homo Antecessor (2)
-980,000 - 780,000 years ago
-Possible common ancestor of humans and Neanderthals
Homo Ergaster (2)
-Sometimes considered to be a non-asian variant of homo erectus rather than a sperate species
-Was around before homo erectus, (around 2.5 - 1.7 MYA) but that could be because they were the homo erectus before migrating to Asia
Homo Heidelbergensis (3)
- 800,000 - 300,000 years ago
-aka the heidelberg man
-also called homo rhodesiensis
homo neanderthalensis (2)
-250,000 -24,000 years ago
-mtDNA suggested no significant gene flow between humans and Neanderthals but nuclear genome suggests interbreeding.
Denisovans (4)
- Cousins of neanderthals but do not yet have assigned species name
-DNA extracted from broken finger bone and wisdom tooth complete sequence of genome, which showed that people from New Guinea have 4.8% Denisovan DNA
-inbred with modern humans
-While Neanderthals spread westward Denisovans spread eastward
Homo floresiensis (4)
-100,000 - 80,000 years ago
-Discovered on Indonesian island of Flores in 2003
-were about 1m tall with the brain the size of a chimps hence the nickname “hobbits”
-undecided whether or not they are their own species or a stunted form of humans , but evidence points to them being their own species
Three models of the origin of homo Sapiens
1) african replacement
2) hybridization and asssimilation
3) multiregional evolution
African Replacement Model (3)
Believes that:
-Modern humans evolved in Africa around 250,000 - 200,000 years ago and began migrating out of Africa about 70,000 -50,000 years ago
-Eventually, Homo sapiens completely replaced all existing homo species in Europe and Asia
Hybridization and Assimilation Model
-Basically just the African replacement model but with occasional hybridization between modern and archaic humans as they moved into new lands
Multiregional model (2)
-Believes that homo sapiens evolved as one interconnected species in Africa Asia and Europe
-Gradual transformation in each location from archaic to modern humans through combination of migration and mating
Testing the three models (4)
- Homo Sapiens are monophyletic which contradicts the multiregional model
-Greater genetic diversity is found in african regions of Homo Sapiens, with other regions have subset of these alleles
-Genetic difference among regions is small, indicating divergence from another species then migration
-In all, most evidence supports the out of africa model
Current model - Leaky replacement (4)
-Modern humans evolved in Africa around 200,000 years ago (speciation)
-they began migrating around 50-70,000 years ago, eventually replacing existing homo species in Europe and Asia (migration)
-There were many times that our migrations failed
-there were many times where we breaded with other homos
