Humans Flashcards
What are the key features of the modern human skull
Humans have smaller face (than Neanderthal) and relative orthagnathic, face underneath skull with vertical forehead and globular skull – tall skull to length of skull
No contiuous SO torus
Have mental eminence
When was the human most recent ancestor
Many hominin fossils date from 400-200kya so will be contemporaneous with sapiens ancestor but none show distinctive features of sapiens
When was there a shift in human technology
Major dichotomy between Middle Palaeolithic (Mousterian Mode 3 lithics,
Neanderthal) and Upper Palaeolithic (Mode 4/5 lithics, modern humans) behaviour
What are the key features of the multiregional model
1 – time-depth : ~ 2 million years of an evolutionary trend towards sapiens
2 – parallelisms : similar selective pressures (throughout the 2 million years) in different regions of the world, leading to single evolutionary trend
3 – gene flow : besides the parallelisms, 2 million years of isolation would lead to speciation, so gene flow (at rate and frequency x) throughout the whole world would be necessary to maintain all regional populations as part of a single evolving species
4 – chronological synchrony : since gene flow has to have taken place to maintain the species’
genetic unity, it must have also acted as a homogenising force ; therefore, the changes
observed in one region of the world should be soon observed in all regions.
5 – regionality precedes humanity …
What is the mtDNA that showed multiregionalism is wrong
First mtDNA study of human variation showed
that:
All modern humans are genetically closely related to each other
The last common ancestor of all humans lived recently
That the root of the modern human genetic tree is in Africa
Cann et al. (1987) Nature
How do “CONTINUITY TRAITS” and difference in selective pressures refute multiregionalism
Use other mammals to refute multiregionalism
“continuity traits”: unique features shared by recent East
Asians and Chinese H erectus, and recent Australians
and Javanese H erectus
Different regional impact of climate change: regional
hominin populations under different selective pressures
Of the ~30 regional characteristic Asiatic traits, only 10 actually occurred in the stated regions
this type of multiregional evolution has never been observed in mammals apart from maybe the Javanese rhino
How does sapiens morphology refute multiregionalism
All modern humans are morphologically more closely related to each other than to any non‐modern hominin population, independently of which part of the world
How did Gagneux et al. (1999) disprove multiregionalism
The ancestral African population was extremely small:
FST = µ 2Ne ‐ ancestral effective population of 15,000‐10,000 people
genetic bottleneck
What is chronological synchrony
gene flow maintaining the species’ genetic unity, thus acting as a homogenising force spreading the changes that emerge in one region to the rest of the world
What showed that different hominins chronologically NOT synchronous, refuting multiregionalism
• Modern human fossils from Skhul and Qafzeh, Isral
• Discovered in the 1930s
• Several individuals
• Modern human anatomy, but very robust and Middle
Palaeolithic tools
• Originally thought of as “transitional” Neanderthal‐modern
• Re‐dated in the 1980s and 1990s: shown to pre‐date some of
the Neanderthals (Amud, Kebara) in the Middle East
When were the earliest modern humans
Earliest modern humans in Africa, 200,000+ years ago
Why do the Denisovans help refute multiregionalism
Neanderthals/Denisovans and modern humans are sister clades, with a common ancestor in the Middle Pleistocene
The earliest record of modern human morphology and complex behaviours is in Africa, much earlier than anywhere else in the world
What are the key rebuttals to multiregionalism
Neanderthal & Denisovan DNA
different hominins chronologically NOT synchronous
Shared H. sapiens morphology and small ancestral population size
absence of “CONTINUITY TRAITS” and difference in selective pressures
mtDNA
Give Fossil ancestral “candidates” in Africa for most recent human ancestor
Give the ages in kya
Morocco: Jebel Irhoud ~315
South Africa:
Florisbad ~280
naledi ~260
East Africa:
Kabwe (Zambia) ~300
Eliye Springs (Kenya) ~360
Ndutu (Tanzania) >400
What has changed in the evolutionary geography of Homo sapiens
- Time
• ~300,000/200,000 years ago to the present - Space
• from Africa to worldwide - Demography
• from 10,000‐30,000 people to > 7,000,000,000
Describe the theory of African multiregionalism for human origins
Requires extremely large estimates of ancestral effective population size as it
incorporates ancestral lineages across sub‐groups
- Limited pan‐African population structure
- Inconsistent with range of estimates of Ne (9,000‐30,000)
• If Ne reflects ~10% of census size, the maximum estimate (32,500) =1.4
individuals/100 km2
lowest recorded: Dobe !Kung ~6.6 x 100 km2; Hadza ~30 x 100 km2 - no HG communities are as sparse as necessary DEMOGRAPHICALLY UNLIKELY INCONSISTENT WITH HOMININ DIVERSITY IN AFRICA 400‐200 Ka
What are the features of the single origin range expansion with local extinctions model of human diversity
• Genetic variation should decline with distance from one source African population [1] • Most genetic lineages should originate from a single ancestral African population (despite incomplete lineage sorting which would lead to some basal lineages elsewhere) [1] • Predicts large expansion within Africa prior to out of Africa Consistent with range of estimates of Ne (9,000‐30,000) and KhoeSan as the most divergent human population with largest Ne [2‐5] DEMOGRAPHICALLY LIKELY
What are the features of the single origin range expansion with regional persistence model of human diversity
• Clinal patterns of genetic diversity and coalescence from a single African source [1]
• Complex phylogeography, with deep coalescent events in regions outside the
source (reflecting gene flow)
• Consistent with recent findings that ~10%
divergent ancestry in W Africa [2,3] and the
deeply divergent Y‐chromosome lineage in
W Africa (tMRCA ~250,000 yrs; 4]
DEMOGRAPHICALLY LIKELY, BUT NEEDS MORE
DATA
What are the features of the archaic hominin admixture in Africa model of human diversity
• Predicts “archaic” African hominin
admixture into living populations [1] – not
yet identified, but there are genomic
outlying regions in Africa [2,3] with very old
coalescent ages (~1 Ma in pygmies – 3)
suggesting deep population structure
Consistent with the age of H naledi, for example
But poor fit between demographic
models and interpretation of
“introgressed” segments
NEEDS MORE DATA
- What is the Mode 3 hypothesis? What is the recent genetic evidence for it?
Humans and neanderthals doing similar technology unless it happened before split Neanderthal mtDNA closer to modern humans than Denisovans – dispersal of humans out of Africa 300-400kya and mixed with neanderthals and gave them Y chromosomes (both male and female admixture) making them closer to us than we are to DEN
Further mixing 200kya during a green sahara event – recurrent mixing of western Eurasians and modern humans
Where does the idea of African multiregionalism stem from
the presence of regional geographic variation in the African archaeological record by 300kya, the morphological diversity of the African fossil record between 300 and 100kya, and the presence of modern, derived morphological features in divergent regions of Africa
Together, these findings inspired the hypothesis that populations across Africa were all connected to each other. This model states that migration across the continent is more parsimonious than independent convergence of anatomical features and archaeological innovations
Explain the Single Origin Range Expansion with Local Extinctions
Many near modern human populations exist in Africa since 200kya
Modern humans originated from a single population in Africa (south or east) that expanded and outcompeted other groups of near modern humans, or expands into regions left empty by these other groups going extinct due to external factors.
How does the Single Origin Range Expansion with Regional Persistence differ from the Single Origin Range Expansion with Local Extinctions model
Again gives importance to a single population in a specific area of Africa, but allows for gene flow between this group and other near modern human groups
Explain African multiregional theory
Modern humans originate from a pan-African population
Describe Archaic Hominin Admixture in Africa model of human origins
Modern humans evolved in parallel with other hominin species (eg naledi) and there is gene flow between species
When are the earliest modern human fossils from
from Ethiopia, 200 – 160 Kya –
derived universal traits of
Homo sapiens, but very
different from each other
How big was the ancestral human population
~ 10,000‐15,000 people
Is the Kabwe fossil modern human
No
Very different to modern humans – synchronicity (300kya) – closer to mid-Pleistocene hominins
Tall, pronounced SO torus, bregmatic eminence, enormous face
Is the Florisbad fossil modern human
Very similar to modern humans but not got full package of traits
275kya
When is naledi from
250kya - v primitive hominin
What is one of the first modern human skulls
from Monokibish, 200kya
chin
high globular skull
What is the importance of Skhull
Modern features
Already out of Africa
125-100kya
Describe the quantification of human’s globular head
• A quantitative measure of the globular modern human head
• Genetic association of values of this “index of endocranial
shape” amongst Neanderthal introgressed genomic fragments in the genomes of 4468 Europeans
• Key SNPs correlations associated with reduced globularity
• Correlated SNPs: affect neural expression of 2 genes linked to neurogenesis and myelination
Gunz (2018)
What actually is a human, from a palaeontological perspective? Which features are autapomorphies? (6)
Large brained hominin
Tall and narrow
globular cranium
reduced cranial superstructures
small faced under vault
mental eminence
Which human populations are likely to have been the earliest to diverge
Khoisan groups in southern Africa:
The most genetically differentiated living
human population, followed by the Hadza (TZ) and the Pygmies (Mbuti, Efe, etc)
What is the paradox of the modern human LHS
Relatively higher energy budget and reproductive output than apes (“fast”)
Long juvenile period and lifespan (“slow”)
Homo sapiens evolved a unique life‐history amongst all hominins, probably driven by hypothalamic output from the brain - indicated by Retzius Periodicity
What is a way to assess regulation of LHS pace
Retzius Periodicity (RP): number of days between the deposition of successive long‐period growth lines in teeth (striae of Retzius in tooth enamel)
histological manifestation of a neuroendocrine biorhythm (Havers‐Halberg oscillation)
closely related to body mass and BMR, role in regulating pace of life‐history in mammals
How does the LHS of other Homo vs sapiens differ, considering energetics, ecology, and behaviour?
other Homo: large size, encephalised, fast growth
• Energetically very demanding – diet shift, carnivory
• Ecologically effective – early independence, predator risk minimisation
• Socially and behaviourally challenging – likely increase role of social cohesion, provisioning, innovative
solutions (cooking?)
Homo sapiens: large size, encephalised, slow growth
- Energetically efficient – budgeted development through longer ontogeny
- Ecologically challenging – longer dependence on mother, big risk of predation
• Socially and behaviourally very demanding – provisioning of mothers with dependent children, social
cohesion and belonging, major pressure on technological solutions, increased dependence on learning
social norms and skills, increased importance of social memory
Where are Mode 3 and 4 technologies found
Mode 4: Only seen in parts of Eurasia
NOT in Australia
Mode 3: seen in Neanderthals and first modern humans in Africa
What happens between 300-400 Ka?
Environmental change extreme aridity
Turnover in fauna – perhaps because of humans becoming a mega-predator
– middle stone age
What is modern human behaviour
All living humans have ‘modern behaviour’
‐ Complex cognition symbolism, abstraction
‐ Complex behaviour, altruism, cooperation, teaching, etc.
‐ Complex societies, kinship/non‐kinship
networks, shared heritage, norms
‐ Cumulative culture
Why do advanced stone tools suggest increased cognition
- Production of a core implies pre-preparation so that when struck a particularly shaped flake will come away – level of abstraction (also seen in N)
What is the importance of ochre
Symbolism – neanderthals liked shells of particular colours – also in human s
Ochre processing workshop in Qafzeh, Israel, 93kya
Found a lump of ochre with pestle still inside it
Ochre also used as mastek fro hafting artefacts onto handles – may be practical not symbolic
But pervasive presence of red ochre particularly (not seen in N) suggests they were choosing a particular colour scheme
How do early human ornaments compare to those of Neanderthals
N has only 1 case of necklace
Many cases in humans from 100kya onwards – why?? – form of singalling personal and group identity (cf football t-shirt – display of support; married woman with ring etc)
How long ago can art be seen
Blombos, South Africa
Middle Stone Age layers
~70,000 yrs
– deep intentional zigzag engraving – aesthetic or communication – major change in symbolism
Lion-man (40kya) -> clear display of abstraction/ imagination
Give examples of the emergence of more complex behaviour in the Middle Stone Age
Pinnacle Point, South Africa, 164kya: evidence for early use of marine resources (shellfish) and production of microliths (Marean et al. 2007)
Ethiopia, 160 kyr: evidence
of mortuary behaviour. White et al (2003)
Qafzeh 11 burial, Israel,
120 kry: complex
burial/grave goods
Increased distance travelled for raw material before 300kya – trade?
Grass bedding at back of cave – 200kya
Different ways to make necklaces look by changing string
What is the importance of the Herto child
160kya – polished skull from being passed around
had associated antlers
also Adult at Herto – cut marks - defleshed
Why is modern human technology different
Humans are characterized by changing culturally very quickly
Stone tools lasted 1.5My – cf. technology now
Humans are characterized by changing culturally very quickly. Can we see this in the record
South Africa HP culture (Howiesons Poort, mid stone age tradition, see Jacobs 2008 paper) lasted only 5ky – came, succeed, then disappeared
What is the importance of cumulative culture
social networks increase efficiency of knowledge transfer – investment in friendship from early childhood – these friendships are more important predictors of shared knowledge than family ties – peer group is important aspect for cumulative culture
Multi-level sociality increases rate of social evolution – high mobility between camps – lots of knowledge transfer despite low population density
Our slow LHS requires specific social structures for interdependence on other people and communities – evolution of modern behaviour evolved so will not suddenly appear as a package in the record
(Migliano et al. 2017)
Give the dates for the following transition events in sapiens’ history
The Holocene Filter Structuring Dispersals Expansion Origins
The Holocene Filter (15 – 0 Ka) Structuring (45 – 25 Ka) Dispersals (70 – 50 Ka) Expansion (130 – 100 Ka) Origins (240 – 200 Ka)
When did Expansion occur in human history
What were the associated climatic events
130-100kya
135‐128 Ka: climatic shift from hyper‐glacial to very warm conditions (Green Sahara) • 128‐72 Ka: long and complex interglacial, MIS5
What are the associated modern human fossils found during sapiens’ expansion
Modern human fossils bsaically found across Africa & the Levant (from Israel to Sudan to South Africa):
Singa, Sudan (133 Ka)
Mumba, TZ (130‐109 Ka)
Aduma, Ethiopia (105‐79 Ka)
Klasies River Mouth, South Africa (115‐60 Ka)
Skhul & Qafzeh, Israel (130‐90 Ka)
What were the Skhul fossils originally interpreted as
modern human‐Neanderthal hybrids, more recent than Neanderthals in the Levant
1987: Dated to 80‐130,000 yrs (ESR, TL), older than the Levantine Neanderthals
What was the first key sapiens dispersal OoA
130-80kya
130‐80 Ka: modern humans in the Levant (Skhul & Qafzeh) but reached as far as Australia
=> Archaeological evidence: Fuyan cave – teeth of modern humans 80kya;
Madjedbebe Rockshelter in Australia - stone tool technology from middle stone age of Africa
70‐50 Ka: Neanderthals in the Levant
(Kebara, Shanidar, Amud, Dederiyah)
Why do genetics suggest the sapiens dispersal OoA 130kya was only small (2)
Neanderthal born in last 100ky has modern human genes in genome from population who dispersed before most modern Eurasians – grew up Neanderthal – if humans assimilated into Neanderthals that suggests it was not a major movement out of Africa
Genetic tree of humans very skewed – most people come from an explosion of diversity that occurred very recently – very few people can trace their ancestry back to the root of the tree (all in africa – hunter gatherers – Khcesan from southern Africa, and Sandawe)
Are all click languages related?
No
– not closely related – very distant in fact – relics from time of hunter gatherers in Africa before the expansion of farmers and pastoralists – early modern humans used clicks?
Hunter gatherers would have encountered archaic hominins and these would have been assimilated into human community
When do most people share a LCA from
What was this period marked by, population-wise?
80-70kya
marked by population contractions and regionalization within Africa, so we do not know where this ancestral population lived
When was the main sapiens dispersal OoA
When did this dispersal reach Australia
Was there any admixture
70-50kya
by 50kya
The dispersal involved admixture with both DEN and N in Eurasia, and possibly with archaic human populations in West Africa.
this is mostly from mtDNA research as there are v few fossils
How do tools reveal the expansion and contraction of sapiens in Africa
tech in one area differs from the others – ochre and shell beads in Morocco and south Africa BUT then in south Africa we see the Stillbay (shift in tech) while in North africa we see Aterian tanged points – regionalization 100-70kya
When was there a megadrought in East Africa in last 150kya
East Africa had a megadrought between 135-75kya – asynchronous with higher latitudes
