The genetic data

Where do we come from?
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Paleoanthropology
– All the bones
– All the lineages
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Archaeology
– Tools and artefacts
•
The radiological dating revolution
– The physicist changing the picture
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The genetic data
– Sequencing of mt-DNA and the Y-chromosome
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The origin and evolution of languages
– The relationship between languages
The ”dating revolution”
Homo species in the Middle East
Qafzeh 120k
Skhul 110k
Tabun 135k
Kebara 60k
H. neanderthalensis
H. sapiens
Amud 50k
The origin of modern man
Different models
Multiregional model
Neanderthals
Java man
Klasiere
European
Aboriginals
Africans
Out of Africa
Archaic and new populations does not mix
New populations replace the old.
Multi regional
model
“Out of Africa”
Hvor finner vi DNA ?
Cellekjerne
m/DNA
Mitokondrier
m/DNA
En vellykket symbiose for en stund siden 
Maternal mitochondria
Kromosomer
To kopier av hvert kromosom - en fra far og en fra mor
Ved celledeling kopieres de og kondenseres (metafase)
Metafasekromosomer kan sees i lysmikroskop
Undersøkelser basert på nukleært DNA (n-DNA)
.
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n-DNA vil bli ‘‘stokket om’’ ved formering (meiosen)
– De fleste gener er diploide.
– Dette kompliserer analysen.
• Har kraftfulle DNA-sekvenseringsteknikker nå
•
Somatiske kromosomer.
– Sekvensering av gener.
•
Kjønnskromosomer
– X-kromosomet likt med somatiske kromosomer.
– Y-kromosom er paternelt
– Deler av Y-kromosomet blir ikke ”stokket” om under meiosen
• Arves ”uskadd” fra far til sønn
•
Proteiner kan og sekvenseres
– Kan finne proteinrester fra svært gamle ”fossil”
– Deler av T. Rex collagen er sekvensert
Data from mitochondrial-DNA (mt-DNA)
mt-DNA accumulates mutation 5-10 times faster
than nuclear-DNA.
A 1.1kb control region can be used
as a molecular clock
Compare mt-DNA in different populations in the
world thought to be representative for the
indigenous population
Results of the mtDNA sequencing
Chimpanzee
!Kung
Homo
Ca 5Myr
ca 125-165 Kyr
Rest of the world
The !Kung
South African bushmen
Isolated hunter/gatherer society
The “click” language (Khoisan)
Meet our common ancestors
Bushmen, Hottentots.
Click language: !Kung
(Xhosa is also a Click language)
Y-chromosome
• Paternal inheritance
• Most of the Y-chromosome does not
recombine during meiosis
– genes are inherited intact from father to
son
• The paternal molecular clock
Y-chromosome
• Very few Y-lineages on the earth
– The Y-chromosome shows surprisingly
little variance
• Y-chromosome variants are not
equally distributed throughout the
world
– 1-3 variants locally
Y-chromosome data
The oldest chromosomes are African
Common paternal ancestor 150 Kyears ago
Mitochondria and
Y-chromosomes gives
the same picture
The old data also suggested an
African origin
The spread of Homo Sp.
The old ones
Separation of different groups of H. sapiens
120 k
100k
70k
50k
30k
20k
10k
Kyears
Africans
Non- Africans
S.E. Asians
Aboriginals
Caucasians
N.E. Asians/Amerinds
N.E. Asians
Amerinds
N.Amerinds
C./S.Amerinds
Neanderthals
Spread of Homo sapiens
H. Sapiens migration took place
under the last ice age
Land bridges 18 000 year ago
Minimum number of non-related women
giving rise to the present populations
On the brink of extinction
• Approx 70 Kyears ago there were
nearly no H. sapiens left.
• ” a genetic bottleneck”
• Contributed to the low genetic variation
in H. sapiens?
– Less than in a family group of chimps
• If were cattle, the vets would worry
Did women and men migrate at a similar rate?
• Mitochondria lineages are dispersed
• Y-chromosome lineages are local
• Women migrated more and over longer
distances
• After the emergence of farming
– Boys stayed on the farm
– Girls married someone from another farm
Strong opposition
• The ”Out of Africa” hypothesis was met
with strong opposition from most
paleoanthropologists
• It did not fit with the picture painted with
bones and sculls
• This field is also flavoured with good
old Victorian Eurocentrism
Why all this controversy ?
• Science does not exist in a vacuum–
interacts with the society particular in
• Paleoanthropology /anthropology
• Archaeology
• History
• These disciplines are strongly influenced
by strong personalities
Why all this controversy ?
• These disciplines address issues which
for many people has a moral value
– What is a human being?
– When did humans appear?
– Creation versus evolution?
– What about races ?
• and if..which race came first .. and
second..and..?
Why all this controversy ?
• Paleoanthropology
– When did humans appear?
• What is a human being?
– This is a discipline which has it’s roots in a
British Eurocentric conservative culture
– Agenda:
• Establish a clear distinction between man and
beasts
• Find the scientific basis for the “obvious” superiority
of the white man
Why all this controversy ?
• Biology/Molecular biology
– When did humans appear?
• Look for genes that are characteristic for humans?
– A discipline with it’s roots in liberal (almost anarchistic)
culture in the 60-70 ties
• Techniques available to “everybody”
• Expects to find evidence for continuous
development from primates to hominids
Why all this controversy ?
• Where did H. sapiens come from ?
– Paleoanthropology:
• Simultaneous development in many regions of the
world
– (The origin of the white man ?)
– Molecular biology
• It would have been nice if all of us came form Africa

– that would give the racists something to think about
Why all this controversy ?
• African..?? not me.. no way
– Races –white man – black man
• Christian fundamentalist versus science
– Creation or evolution ?
• Darwinism is not a problem for most of the Christian
churches, Jews, Muslims, Buddhist of Hindus.. or..
• Old versus New
– Paleoanthropology versus Genetics
• A lot of strong emotions
– It’s not for the fainthearted
The controversy
• Was (is) two strong camps
• Out of Africa - Multiregional
• All scientific findings had to fit in one of the models
• Findings that could not be interpreted as a strong support for
one of the theories where “under-communicated “
• The middle ground wasn’t a nice place to be
– Things have improved.. Possible to report findings
that does not fit either theory..later..
Let’s look at Europe
Early migrations of H. sapiens
Let’s look at Europe
Europe is a political construction,
not a naturally defined region
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Basque
Celts
Icelandic
Danes
Swedes
Norwegians
Finns
Saami
• Basque
• Celts
• Galicians
The last of the first?
Finns
Two immigrations
Two Y-chromosome lineages
Nearly no males at a point
Language influence
from the Saami?
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Danes
Swedes
Norwegians
Icelandic
• Saami
Controversies
• Europe
– The Neanderthals - The origin of the Europeans?
• Asia
– Everyone from Africa?
• What about the aboriginals in Australia
– Maybe some Homo erectus genes there?
• Americas
– Who came first and from where and when?
– Before or after the Clovis culture?
Europe:
All Europeans from Neanderthals?
•
Paleoanthropologists:
– Many Europeans got a
features in the lower
jaw-bone which similar
to the Neanderthals jaw
bone
•
Geneticists
– Genetic split 700
Kyears ago
Neanderthal - hybrids ?
• Skeletal remains have been found that have
features that can be interpreted as being from
Sapiens/Neanderthal hybrids.
– Hybrids or just normal variation?
• Advanced morphometric analysis suggests
that it is just normal variation in H. sapiens
– ..well even more recent data a bit later..
Asia
•
H. erectus lived in Asia for a long period
•
Local lineages different from H. neanderthalensis and the Peking man
– Regional development ?
•
Archaic population had a “flat” scull (face)
– as many modern Asians have today
•
H. sapiens migrating out of Africa had a scull similar to Africans and
Caucasians have today
•
New finding support “Out of Africa”
– Asian features was developing about 20 Kyears ago
–
..Even newer findings later 
Asian Y-chromosomes comes for Africa
Australia
The aboriginals came to Australia about 50 Kyears ago.
Two distinct different scull types today: robust and gracile.
Ngandong ?
Micro evolution ?
Gracile
Robust
The Australian controversy
Gracile or robust scull
Ngandong
The Americas
When and where?
The Americas
When and where?
”Out of Africa”
• The genetic evidence is consistent:
– All humans living on the earth now stems
from a little group of humans migrating out
of Africa 100-200 thousand years ago
– Very little genetic variation in the human
population
• Less than in an average family group of
chimpanzee.
• …but….
The saga of the neanderthals
Neanderthal
father and son
Neanderthal profile
Neanderthal executive
The Neanderthals were
strong and sturdy
Brain volume
Homo species in the Middle East
Qafzeh 120k
Skhul 110k
Tabun 135k
Kebara 60k
H. neanderthalensis
H. sapiens
Amud 50k
We were not alone
Neanderthals performed
ritual burials
Ritual burials
Qafzeh (Middle-East) 100 K years ago
H. Sapiens and H. Neanderthalensis had similar cultures
The Neanderthals had a vocal apparatus similar to
ours
but did they talk…?
Distinct cultures
Neanderthals
behaved humanely
Non–productive
individuals were taken care of
Why did the Neanderthals disappear?
•
H. neanderthalensis larger, stronger and a bigger brain
•
H. sapiens and H. neanderthalensis had similar cultures for
millennia
•
H. sapiens developed better tools
– H. neanderthalensis seem to be able to learn and adapt
•
H sapiens developed it’s unique culture, but that happened long
after the Neanderthals were extinct.
• Language and communication ?
H. Sapiens obviously has a culture with
rituals, mythical characters and religion
Why did the Neanderthals disappear?
• Victims of global warming…?
The world of Neanderthals
The world of Neanderthals
Repeatedly large
variations in flora
and fauna
H. sapiens
adapted better
that
H. neanderthalensis..?
Sequencing of the Neanderthalgenome
• Large parts of the Neanderthal genome
sequenced (several individuals)
• Sequence data also from a separate
group (The Denisovans)
DNA-sequence data from
different groups
Sequencing of the Neanderthal-genome
• Non-Africans have ~ 5% of their
genome from Neanderthals (?)
– Africans < 0,2%
• Did some of the Neanderthal genes
give the offspring an advantage?
– HLA-gene variants and the ability to fight
infection that was prevalent in Europe(?)
Current hypothesis
..the case of a toe in Siberia..
Current hypothesis
Our ancestors ?
A. afarensis
H. habilis og H. ergaster ca 1,5 - 2 Myr
Homo erectus
H. Erectus stayed i Asia
From 1,8 Myear until 100 Kyear
ago (30 Kyear?)
Zhoukoudian
Then came the Hobbit
H. Floresiensis
H. Floresiensis
Homo florensis
• Mini Homo erectus?
– ” miniaturization - The island effect” ?
• Homo sapiens with a genetic defect?
– microcephaly ?
• Separate linage
– Migrated from Africa to Asia prior to H. erectus?
• cranium, jaw, teeth, feet
• Not decided
Hominid lineages
a myriad of traits….?
The Lice tells
• Lice and other parasites adapt to their
host(s)
• Phylogenetic trees can also be constructed
for parasites
– Can be compared to the genetic tree for the
host(s)
– and what is known concerning culture and
contact between populations
The Lice tells
Very close contact between
Sapiens and Erectus ;-)
Human phenotypes
• Small genetic changes can result in
very different phenotypes
– Example . Skin colour
Natural variation of skin colur in humans
Strong correlate with the local intensity of UV-light
Skin colour
• Effects of UV-light:
– Skin damage
• cell death
• Cancer
– Stimulation of
melanocytes via
melanocyte
stimulation
hormone
– ): production of
pigments
• sunscreen
Effects of UV-light
good and bad
• Good
• Bad
• Synthesis of Vitamin-D
• Breakdown of Folic
acid
– Ca2+ uptake
– CH3-donor in
metabolism
Skin tone in humans
• Balance between need for:
– Vitamin-D and Folic Acid
• To reduce skin tone:
– Mutate the receptors for melanocyte
stimulating hormone 
• Pale skinned humans have mutations in the
receptor for melanocyte stimulating hormone
Summary
•
Africa seems to be the cradle of hominids
– many migrations out of Africa
• and some back to Africa
•
!Kung- Khoisan (and possibly two additional groups) are most likely our
common ancestors.
•
ALL members of the present population of humans roots back to a small
band of individuals migrating out of Africa 100-150 Kyears ago
– we were nearly extinct – genetic bottleneck
•
It is remarkably little genetic variation in the human population
– If we were cattle, dogs or horses, the vets would worry
– Non-Africans have acquired Neanderthal genes (~ 5% of the genome)