Week 11
No description yet. This curated deck is ready for daily study.
Card preview (24)
Where you place humans on the tree of life?
Primate phylogeny -> numerous derived characteristics Clearly most related to great apes (hominidae)
When did the branch leading to humans split off of tree of life?
Consensus from many independent gene sequences Human most related to chimps Molecular clock - separation 5.4 mya
What are the Homini?
Humans, extinct ancestors and related races/species
How many taxonomic groups within great apes?
Within the great apes (Hominidae) – four taxonomic groups (tribes) Orangutans, gorillas, chimpanzees and humans.
What is an overview of the oldest hominins?
Oldest – Sahelanthropus tchadensis Discovered in Chad, central Africa – ca 5-6 Mya
What are examples of other hominin forms?
Homo Habilis Homo erectus Homo heidelbergensis
What is an overview of the hominini despersal?
Homo genus range expansion out of Africa approx 1.8 MYA Homo erectus like forms (archaics) spread across the world Resolving between these species remains controversial
What was an overview of the different forms between the different forms around the world?
Recent evidence suggest that different forms were members of a single species H. erectus - a very successful species – surviving 1.8 million years Modern humans – only very recent
What makes us human?
Use of complex tool industry is the definition of humans (homo) Increased cognitive abilities - brain size H. erectus developed tool and cultural technologies Advances may have lead to expansion of Homo species across the globe 1.8 Mya
What are potential key drivers for human cognitive abilities?
Feedback loops caused by tool use and/or social interactions between species
What is the evolution of bipedalism?
Footprints - Australopithecus afarensis - 3.3 Mya Seen in upright bipedal, free striding gait – well developed arch to the foot
Why did bipedalism evolve?
Frees the hands for fine manipulations Greater stamina for long distance travel More effective hunting Improved ability to carry food
What is the evolution between bipedalism and human habitats?
Many theories link bipedalism to living in a savanna – where A. afarensis lived but prior to this A. anamensis (4mya) – thought to be bipedal - existed in dry woodland
What are the differences between humans and other great apes?
Gorillas, Chimps, n = 24 chromosome pairs After split from chimps, 2 chromosomes fused (12 and 13) Humans n = 23
What is the genetic differences between humans and other great apes?
1% if focus on coding sequences in genome 5% all regions (incl insertions and deletions)
Which genes make us human?
80 genes in chimps – disabled in humans Functional differences in genes related to sensory perception, immune defence, spermatogenesis
In key organs what are the differences between human and chimp compared to rhesus monkey?
Blood human and chimp equidistant to rhesus Liver human slightly more diverged than chimp Brain human massively diverged compared to chimp
Where did humans evolve?
Generally agreed – evolved in east Africa But Henn et al 2011 PNAS. >500,000 markers – indicates S. African origin?
What are the two origins of modern humans?
Out of Africa Multi-regional evolution
What is an overview of out of Africa theory?
Emerged recently in Africa – spread and replaced archaics
What is an overview of multi-regional evolution theory?
Hominin populations - evolved in situ into modern homo populations – with gene flow between Implies ancestral forms = not biological spp
Which theory for the human evolution was correct?
Fossil evidence could not refute multi-regional evolution hypothesis Genetic/genomic evidence indicates there was recent expansion & replacement by H. sapiens Out of Africa theory
Did non-African archaics contribute to the gene pool of modern humans that expanded into each region?
2% Neanderthal DNA in non-African Humans 4-6% Denisovan DNA in Melanesian humans
What is an overview of the Origin of Humans?
Humans – demographically young species From east or south Africa – ca. 100,000 years ago Recent expansion - with small sequential colonisation events