BIOE 109
Summer 2009
Lecture 13- Part II
Human evolution
Human evolution
• humans are classified within the superfamily
Hominoidea (with gibbons, orangutans, gorillas and
chimpanzees).
Human evolution
• humans are classified within the superfamily
Hominoidea (with gibbons, orangutans, gorillas and
chimpanzees).
Human evolution
• humans are classified within the superfamily
Hominoidea (with gibbons, orangutans, gorillas and
chimpanzees).
Similarity between human and
chimpanzee genomes
Comparison of the human and
chimpanzee genomes
Comparison of the human and
chimpanzee genomes
• the genome of “Clint” was published September 1,
2005.
Comparison of the human and
chimpanzee genomes
• the genome of “Clint” was published September 1,
2005.
• mean nucleotide divergence between humans and
chimps was 1.06%.
Comparison of the human and
chimpanzee genomes
• the genome of “Clint” was published September 1,
2005.
• mean nucleotide divergence between humans and
chimps was 1.06%.
• differ by 1 chromosomal fusion (human chromo. 2) and
at least 9 pericentric inversions.
The evolution of human chromosome 2
Comparison of the human and
chimpanzee genomes
• the genome of “Clint” was published September 1,
2005.
• mean nucleotide divergence between humans and
chimps was 1.06%.
• differ by 1 chromosomal fusion (human chrom. 2) and
at least 9 pericentric inversions.
• 13,454 human and chimp genes with unambiguous
homology were aligned.
Comparison of the human and
chimpanzee genomes
• the genome of “Clint” was published September 1,
2005.
• mean nucleotide divergence between humans and
chimps was 1.06%.
• differ by 1 chromosomal fusion (human chrom. 2) and
at least 9 pericentric inversions.
• 13,454 human and chimp genes with unambiguous
homology were aligned.
• 29% of all proteins compared were identical!
The primate fossil record
The primate fossil record
• primates first appear in the late Cretaceous (about 70
MYA).
The primate fossil record
• primates first appear in the late Cretaceous (about 70
MYA).
• the first anthropoid ape fossil dates to Algeria (50
MYA).
The primate fossil record
• primates first appear in the late Cretaceous (about 70
MYA).
• the first anthropoid ape fossil dates to Algeria (50
MYA).
• small anthropoid apes found in Egypt (30 MYA) and
Kenya (25 MYA).
The primate fossil record
• primates first appear in the late Cretaceous (about 70
MYA).
• the first anthropoid ape fossil dates to Algeria (50
MYA).
• small anthropoid apes found in Egypt (30 MYA) and
Kenya (25 MYA).
• another gap to 15 MYA when several small hominids
roaming N. Africa.
The primate fossil record
• primates first appear in the late Cretaceous (about 70
MYA).
• the first anthropoid ape fossil dates to Algeria (50
MYA).
• small anthropoid apes found in Egypt (30 MYA) and
Kenya (25 MYA).
• another gap to 15 MYA when several small hominids
roaming N. Africa.
• very few fossils from 6 to 14 MYA!
Evolution of Homo sapiens
These 3.6-million-year-old footprints from Laetoli, Tanzania were made
by a pair of individuals who walked side-by-side through fresh ash
from a volcanic eruption.
Evolution of Homo sapiens
5
4
Ardipithecus ramidus (4.4 – 4.2 MYA)
Australopithecus anamensis (4.2 – 3.9 MYA)
A. afarensis (“Lucy”, 3.9 – 3.0 MYA)
Time
(MYA)
3
A. africanus (2.8 – 2.4 MYA)
2
Homo habilis (2.5 – 1.6 MYA)
H. ergaster (1.8 – 1.5 MYA)
1
0
H. erectus (1.2 – 0.4 MYA)
H. heidelbergensis (0.6 – 0.2 MYA)
H. sapiens (0.15 MYA)
Features of early hominid evolution
Features of early hominid evolution
1. Exact path of descent unknown
Features of early hominid evolution
1. Exact path of descent unknown
• more hominid species continue to be discovered.
Features of early hominid evolution
1. Exact path of descent unknown
• more hominid species continue to be discovered.
Features of early hominid evolution
1. Exact path of descent unknown
• more hominid species continue to be discovered.
2. Evolution was continuous and gradual
Features of early hominid evolution
1. Exact path of descent unknown
• more hominid species continue to be discovered.
2. Evolution was continuous and gradual
• no sudden “jumps” in size or cranial capacity
observed.
Features of early hominid evolution
1. Exact path of descent unknown
• more hominid species continue to be discovered.
2. Evolution was continuous and gradual
• no sudden “jumps” in size or cranial capacity
observed.
• cranial capacity increased from 600-800 cm3 to 12001400 cm3 over past 2 MY.
Gradual evolution of human cranial capacity
Features of early hominid evolution
3. Many hominid species co-existed in Africa
Features of early hominid evolution
3. Many hominid species co-existed in Africa
• notably the “robust” Australopithecines.
Diversity of fossil hominid species in Africa
Neanderthals – not in my family tree!
Neanderthals!
• Homo sapiens neanderthalensis lived in western
Europe 400,000 to 30,000 years ago.
Neanderthals!
• Homo sapiens neanderthalensis lived in western
Europe 400,000 to 30,000 years ago.
• average height was about 5’4’’ but weighed about 20
lbs more than H. sapiens sapiens (due to extra
muscle).
Neanderthals!
• Homo sapiens neanderthalensis lived in western
Europe 400,000 to 30,000 years ago.
• average height was about 5’4’’ but weighed about 20
lbs more than H. sapiens sapiens (due to extra
muscle).
• in 1997, Neanderthal mtDNA was amplified and
sequenced (360 bp).
Neanderthals!
• Homo sapiens neanderthalensis lived in western
Europe 400,000 to 30,000 years ago.
• average height was about 5’4’’ but weighed about 20
lbs more than H. sapiens sapiens (due to extra
muscle).
• in 1997, Neanderthal mtDNA was amplified and
sequenced (360 bp).
• recently, 1 million bp of Neanderthal DNA has been
sequenced (and the full genome is on the way…).
Conclusions:
Conclusions:
1. Neanderthals diverged from the modern human
lineage ~600,000 – 800,00 years ago.
Conclusions:
1. Neanderthals diverged from the modern human
lineage ~600,000 – 800,00 years ago.
2. Little evidence of any introgression of Neanderthal
DNA into modern humans.
Conclusions:
1. Neanderthals diverged from the modern human
lineage ~600,000 – 800,00 years ago.
2. Little evidence of any introgression of Neanderthal
DNA into modern humans.
3. Effective population size ~3,000 (compared to
13,000 for early modern humans).
…….. The last refuge
The evolution of anatomically modern
humans
The evolution of anatomically modern
humans
The evolution of anatomically modern
humans
Predictions of the African Replacement
model
Predictions of the African Replacement
model
1. Ancestral alleles should trace to Africa.
Predictions of the African Replacement
model
1. Ancestral alleles should trace to Africa.
2. Appearance of modern humans should be
recent (< 200,000 years).
Predictions of the African Replacement
model
1. Ancestral alleles should trace to Africa.
2. Appearance of modern humans should be
recent (< 200,000 years).
3. Genetic diversity should be greatest in Africa.
Predictions of the African Replacement
model
1. Ancestral alleles should trace to Africa.
2. Appearance of modern humans should be
recent (< 200,000 years).
3. Genetic diversity should be greatest in Africa.
• all three predictions have been confirmed.
Predictions of the African Replacement
model
1. Ancestral alleles should trace to Africa.
2. Appearance of modern humans should be
recent (< 200,000 years).
3. Genetic diversity should be greatest in Africa.
• all three predictions have been confirmed.
•“mitochondrial Eve” and “Y-chromosome Adam” lived in
Africa about 150,000 and 60,000 years ago,
respectively!
Complete mtDNA genomes from 53 humans
Recent evidence refuting the African
replacement hypothesis
Recent evidence refuting the African
replacement hypothesis
• in 2005 Alan Templeton reconstructed the history of
human populations by analyzing 25 gene trees.
Recent evidence refuting the African
replacement hypothesis
• in 2005 Alan Templeton reconstructed the history of
human populations by analyzing 25 gene trees.
• his analysis rejects the complete replacement
hypothesis with a probability equal to 10-17!
Recent evidence refuting the African
replacement hypothesis
• in 2005 Alan Templeton reconstructed the history of
human populations by analyzing 25 gene trees.
• his analysis rejects the complete replacement
hypothesis with a probability equal to 10-17!
• he detected three waves of migration out of Africa.
“Out of Africa again and again”
Based on genetic markers
Conclusions
1. Evolution is the foundation of all
biology!
Conclusions
1. Evolution is the foundation of all
biology!
2. Evolution is relevant!
Conclusions
1. Evolution is the foundation of all
biology!
2. Evolution is relevant!
• in health and medicine…
Conclusions
1. Evolution is the foundation of all
biology!
2. Evolution is relevant!
• in health and medicine…
• in agriculture and natural resources…
Conclusions
1. Evolution is the foundation of all
biology!
2. Evolution is relevant!
• in health and medicine…
• in agriculture and natural resources…
• in environmental and conservation issues…
Conclusions
1. Evolution is the foundation of all
biology!
2. Evolution is relevant!
• in health and medicine…
• in agriculture and natural resources…
• in environmental and conservation issues…
• in understanding nature and humanity…
Conclusions
3. Natural selection rules!
Conclusions
3. Natural selection rules!
… but can’t do it all.
Conclusions
3. Natural selection rules!
… but can’t do it all.
• can’t simultaneously maximize all components of
fitness…
Conclusions
3. Natural selection rules!
… but can’t do it all.
• can’t simultaneously maximize all components of
fitness…
• can’t control neutral evolution…
Conclusions
3. Natural selection rules!
… but can’t do it all.
• can’t simultaneously maximize all components of
fitness…
• can’t control neutral evolution…
• can’t direct adaptive evolution in small
populations…
Conclusions
3. Natural selection rules!
… but can’t do it all.
• can’t simultaneously maximize all components of
fitness…
• can’t control neutral evolution…
• can’t direct adaptive evolution in small
populations…
• can’t stop aging and death…()
Objectives for the course
Objectives for the course
1. To foster an approach that may be called
“evolutionary” or “population” thinking.
Objectives for the course
1. To foster an approach that may be called
“evolutionary” or “population” thinking.
• distinguishes between “proximate” and “ultimate”
questions.
Objectives for the course
1. To foster an approach that may be called
“evolutionary” or “population” thinking.
• distinguishes between “proximate” and “ultimate”
questions.
• focuses on the importance of genetic variation in
natural populations.
Objectives for the course
2. To foster an understanding of organisms
in the context of their evolutionary histories.
Objectives for the course
2. To foster an understanding of organisms
in the context of their evolutionary histories.
• necessitates an expansion of perspective to
include deep time scales.
Objectives for the course
2. To foster an understanding of organisms
in the context of their evolutionary histories.
• necessitates an expansion of perspective to
include deep time scales.
• most characters are “inherited” from ancestral
species.
Objectives for the course
3. To realize the potential and limits of
evolutionary change within species.
Objectives for the course
3. To realize the potential and limits of
evolutionary change within species.
• evolution is a “tinkerer” not an engineer.
Objectives for the course
3. To realize the potential and limits of
evolutionary change within species.
• evolution is a “tinkerer” not an engineer.
4. To dispel any preconceived idea that
evolution has any ultimate goal in mind.
The final exam
The final exam
• Time: 6pm- 8pm (2 hours)
• Cover lectures 8 (The adaptationist program) through
13 (Human evolution).
Part 1. Multiple choice. 20 questions, 2 points each,
40 points total.
Part 2. Distinctions. Answer 5 out of 6, 4 points each,
20 points total
Part 3. Short answers. 8-10 questions, 2-5 points each,
40 points total.
EXTRA Credit questions!!