HE - unique adaptations of genus Homo
Study these flashcardsFree · spaced repetition · iPhone, Android, Mac & web
All cards
1
4 options for defining the genus Homo
"I know it when I see it"
Morphology
Adaptive package
Integrated biological definition
Morphology
Adaptive package
Integrated biological definition
2
"I know it when I see it" - who supported this Homo definition?
Linnaeus
3
Morphology - who supported this Homo definition?
Leakey et al
4
Image occlusion: name the hidden labels
5
Adaptive zones - who supported this Homo definition?
Wood and Collard 1999
6
What did Wood and Collard suggest?
Members of Homo should occupy a single adaptive zone
7
What are the 2 crtieria for occupying a single adaptive zone?
Monophyletic group - as is the case for all other genera (has to contain common ancestor and all its descendants)
Same adaptive strategies - way that they survive and reproduce should be similar
Same adaptive strategies - way that they survive and reproduce should be similar
8
What is the integrated approach to defining Homo?
Suggests variability selection hypothesis important in understaning the origins of Homo
9
Outline how variability selection hypothesis shaped hominin evolution
Potts 1998
Origins of Homo lie in adapting to unpredictable environments
Such traits evolved in Australopithecus and onwards
Origins of Homo lie in adapting to unpredictable environments
Such traits evolved in Australopithecus and onwards
10
Define life history
Pattern of survival and reproduction events during the life of an organism
11
7 factors life history includes
Birth
Weaning
Growth rates
Age at first reproduction
Interbirth intervals
Sensecence
Death
Weaning
Growth rates
Age at first reproduction
Interbirth intervals
Sensecence
Death
12
What did Wells and Stock suggest and when?
2007
Unique life history of Homo is key to success of the genus
Unique life history of Homo is key to success of the genus
13
Human life history in comparison to other great apes
High rate of survival
Live longer
Start reproducing later
Shorter interbirth intervals
Live longer
Start reproducing later
Shorter interbirth intervals
14
Image occlusion: name the hidden labels
15
What does body mass correlate with?
Life history traits - gestation length, age at first weaning, first reproduction, interbirth interval, lifespan
16
What did Will et al find and when?
2017
Rapid increase in body size in early Homo
Modern human body size appears with Homo erectus
Rapid increase in body size in early Homo
Modern human body size appears with Homo erectus
17
Image occlusion: name the hidden labels
18
State 2 types of dental structure
Retzius lines
Cross-striations
Cross-striations
19
Outline Retzius lines
Growth lines in tooth enamel
Formed in regular intervals (6-12 days)
Forms perikymate (ridges) on external surface
Formed in regular intervals (6-12 days)
Forms perikymate (ridges) on external surface
20
Outline cross-striations
Formed daily
21
Evidence of systematic disturbances in dental microstructure
Darker Retzius lines
Neonatal line = darkest band (stress of being born)
Neonatal line = darkest band (stress of being born)
22
Image occlusion: name the hidden labels
23
Homo erectus sample age estimates
Height: ~1.6m
Weight: ~50kg
Modern human body proportions and size
Skeletal age: ~14y
Dental eruption age: ~11-12y
Dental microstructure age: ~8y
Weight: ~50kg
Modern human body proportions and size
Skeletal age: ~14y
Dental eruption age: ~11-12y
Dental microstructure age: ~8y
24
How does brain growth relate to life history?
Large brain = slow life history
25
Describe brain growth in Australopithecus afarensis
Slow
Lower end of modern humans
Grew just as aslowly as modern humans despite ape-sized brain
Lower end of modern humans
Grew just as aslowly as modern humans despite ape-sized brain
26
Define culture
Process involving social transmittance of behaviour among peers and between generations
27
2 factors which culture may impact
Tools
Language
Language
28
4 kinds of evidence found for tool use/making in the fossil record
29
What did Harmand et al find and when?
2015
Stone tools from Kenya ~3.3 Ma
Stone tools from Kenya ~3.3 Ma
30
What did McPherron et al find and when?
2010
Oldest cut marked bones in Ethiopia ~3.4 Ma
Oldest cut marked bones in Ethiopia ~3.4 Ma
31
Outline the expensive tissue hypothesis
Guts and brain metabolically costly
Takes a lot of energy to digest plant matter
Higher quality diet (meat) requires smaller gut
Frees energy for larger brain
Trade off between gut and brain size
Takes a lot of energy to digest plant matter
Higher quality diet (meat) requires smaller gut
Frees energy for larger brain
Trade off between gut and brain size
32
Describe the feedback loop in the expensive tissue hypothesis
More energy
Bigger brain
More foraging strategies
Increases technological ability
More energy...
Bigger brain
More foraging strategies
Increases technological ability
More energy...
33
What did Putt et al find and when?
2017
fMRI
Tools made by early and late Homo use different parts of the brain
Brain regions used to create simplest tools very similar between humans and chimps
Suggests ape-like brain sufficient to make simple tools
More complex tools not possible due to lack of motor skills to make them (eg. precision gripping)
fMRI
Tools made by early and late Homo use different parts of the brain
Brain regions used to create simplest tools very similar between humans and chimps
Suggests ape-like brain sufficient to make simple tools
More complex tools not possible due to lack of motor skills to make them (eg. precision gripping)
34
Image occlusion: name the hidden labels
35
Image occlusion: name the hidden labels
36
Other than Homo sapien which other Homo also has Broca's area
Homo erectus
Broca's area in this hominin is chimp-like
Broca's area in this hominin is chimp-like
37
What are fossil endocasts?
Brain leaves imprints on inside of skull
38
What attaches to the hyoid bone?
Tongue
39
Difference between modern human and chimp hyoid bone
Chimp = bulla - creates by laryngeal air sac
Allows louder vocalisations
Allows louder vocalisations
40
How does the hyoid bone in Australopithecus afarensis compare to modern humans?
Possible bulla (air sac) as found in chimps, not humans
41
How does the hyoid bone in Neanderthals compare to modern humans?
Similar to modern humans
42
Outline FOXP2
Highly derived gene compared to other mammals
Found in Homo sapiens
FOXP2 mutation = apraxia - difficulty in producing sequences of sounds, syllables and words
Neanderthals share derived Homo sapiens version of FOXP2
Found in Homo sapiens
FOXP2 mutation = apraxia - difficulty in producing sequences of sounds, syllables and words
Neanderthals share derived Homo sapiens version of FOXP2
43
What is a limitation of using genes to explain the evolution of speech?
Very difficult to link genes to funtion
44
What is considered one of the most distinctive features of the genus Homo?
Modern human-like dental development
45
What does dental development correlate with?
Brain size
Age at first reproduction
Lifespan
Age at first reproduction
Lifespan
46
Describe modern human enamel growth
Slow trajectory
47
Describe tooth formation rates in australopiths and H. erectus
Shorter compared to modern humans
Modern human dental development seems to have emerged late into human evolution
Modern human dental development seems to have emerged late into human evolution
48
Which species do not show slow trajectory of enamel development?
Apes
Australopiths
Fossils attributed to H. habilis, H. rudolfensis, H. erecuts
Australopiths
Fossils attributed to H. habilis, H. rudolfensis, H. erecuts
49
Outline the difference between hominin and modern African ape enamel
Hominin = thick enamel
Modern African apes = thin enamel
Modern African apes = thin enamel
50
Compare and contrast the dental development between modern humans and H. erectus
Key events in tooth growth identical
BUT underlying growth process in enamel differs
BUT underlying growth process in enamel differs
51
What can the slow trajectory of enamel growth be regarded as being associated with?
Regarded as a life history trait associated with prolonged growth period of modern humans
52
In which hominin species is there the first evidence of a shift in enamel growth rates?
Larger brained Neanderthals
Modern humans
Modern humans