lec 34- human history Flashcards
what is the DNA difference between chimps and humans?
1.2% DNA difference, 98.8% similiar
1.2% = 35 million base pairs difference
when did homo sapiens emerge?
300,000 years ago in Africa from an archaic human ancestor
what was the ancestor of homo sapiens, neanderthals, and denisovans?
homo heidelbergensis, derived from homo erectus
what are archaic or parallel humans?
hominins close to homo sapiens in many anatomical and cultural features, but different enough to be recognized as parallel humans
what are the two best known parallel humans?
- homo heidelbergensis: brain size of 1200 cc and sophisticated tool making activity, living in Africa and Europe about 600,000-400,000 years ago, and may be ancestral to both neanderthals and modern humans
- neanderthals (homo neanderthalensis): with brain as large as modern (1400 cc), and advanced but still simple stone tool-making ability, first appeared 400,000 years ago, and likely exchanged genes with other archaic humans
where was homo heidelbergensis found and what are its characteristics?
-discovered in Heidelberg Germany from a jaw
-has been found in Europe and Africa
-has heavy brow ridges, but flat, human face
where did neanderthals come from and what are there characteristics?
-evolved in Europe and western Asia
-have robust skeleton and large brains
-larger muscles, thicker bones, with shorter arms and legs than modern humans
what do neanderthal artifacts reveal?
-sophisticated behaviour and tool use
-body ornaments, manufactured tools, and burial of dead all suggest intelligence and social complexity
did humans and neanderthals interbreed?
yes
what is the third archaic hominin species?
denisovans
how do they know denisovans are a different archaic hominin?
ancient DNA analysis of a finger bone from a denisova cave indicates a different hominin still lived with other archaic humans until 40,000 ya
does denisovan DNA still exist?
yes in Australasian regions
did denisovans and homo sapiens interbreed?
yes
what defines modern humans?
-large complex brains
-language/complex speech and sociality
-menopause and offspring rearing
what is linked with highly developed speech abilities in humans?
-increasing size and density of nerve fibers in a part of the brain
-the arcuate fasciculus enhances speech abilities
when did colonization of the rest of the continents begin for humans?
120,000 years ago
what was the last continent which as colonized?
north and south America
when did the first humans arrive in America?
20,000 years ago
what is the origin of the indigenous people?
Asian ancestry, came from Siberia and crossed land bridge connecting it to Alaska
how did the neanderthals and denisovans disappear?
-from competition, fully disappeared 28,000 years ago with only humans being alive
-competed for the same niches and humans were more successful
who are the cro magnon and what were their characteristics?
-early modern humans who lived in rock shelters in France
-had complex cultures, including art, complex tools, adaptability, advanced hunting, and food gathering abilities, and no doubt language that mad complex societal groups possible
did the cro-magnon live during the neanderthals and denisovans?
yes
what is the likely location of hybridization between homo sapiens and neanderthals?
the middle east
how do we know humans experience genetic drift and bottlenecks when expanding away from Africa?
genetic diversity decreases when going away from africa, America has low heterozygosity
are all humans one species?
yes
what is the future for humanity?
-biological evolution will take place at a slow rate, as we will have to adapt to the swiftly changing environments
-brains will get smaller over time to save energy loss
what is evolution simplified?
genetic variation (mutations, recombination) –> selection/drift –> evolutionary change (populations altered genetically by differential reproduction
