Primate Morphological Traits Allometry of Brain and Body Size.
-
Upload
brenda-perry -
Category
Documents
-
view
215 -
download
1
Transcript of Primate Morphological Traits Allometry of Brain and Body Size.
![Page 1: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/1.jpg)
Primate Morphological Traits
Allometry of Brain and Body Size
![Page 2: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/2.jpg)
Us and Them
• No single trait differentiates primates from other animals
![Page 3: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/3.jpg)
2 Features that Stand Out1. Larger brains, with variation within2. Greater dexterity and mobility than other
animals, with variation within
![Page 4: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/4.jpg)
Brains• Neocortex is larger– Cognitive abilities– Reasoning– Consciousness– 50-80% of total brain volume
Neocortex in blue, from: http://www.nibb.ac.jp/brish/Gallery/cortexE.html
![Page 5: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/5.jpg)
Why develop a bigger brain?
• Typically, morphological traits are a function of ecological adaptation, tied to the:– Need for food– Need to mate to reproduce– Need to diminish predation and other threats
![Page 6: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/6.jpg)
“Social Brain Hypothesis” Robin Dunbar, 1988
• Larger brains correlate with more social primates
• Larger brains = larger social groups
http://www.nature.com/neuro/journal/v5/n3/fig_tab/nn0302-190_F1.html
Colored areas: frontal cortices
![Page 7: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/7.jpg)
Competition or Cooperation
• Allies in social groups ensure access to resources and protection…
but…• Neocortex size is also correlated with tactical
deception
![Page 8: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/8.jpg)
Competition or Cooperation• Tactical deception: acts or behaviors that
deliberately mislead others; a form of Machiavellian intelligence– Machiavellian or
Social Intelligence Hypothesis(read particularly the last few paragraphs)
– Machiavelli defined
Rhesus macaques; from: http://scienceblogs.com/zooillogix/Langurs%20Fighting.jpg
![Page 9: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/9.jpg)
Competition or Cooperation• Others argue in favor of expedience– Primates have the ability to adjust competitive
and cooperative behaviors as needed
• Larger neocortex: cooperation stimulates reward centers located in this part of the brain
Bonobos; from: http://www.primates.com/bonobos/wild-bonobos.jpg
![Page 10: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/10.jpg)
Memory• A larger neocortex has ecological advantages• Memory: remembering where food is
located, how to extract food
![Page 11: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/11.jpg)
Allometry• 2 traits can be related in 2 ways:– Isometrically: 2 variables increase or decrease in
direct proportion to one another– Allometrically: 2 variables increase or decrease at
different rates• e.g., hominid brain size relative to body size beginning
around 2-3 mya
![Page 12: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/12.jpg)
Body Allometry: Diet
• Basal Metabolic Rate: BMR– Rate at which energy is used to maintain bodily
functions at rest
![Page 13: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/13.jpg)
Allometry: Body and Brain• BMR (and brain size):
allometrically related to body weight– Greater weight = lower metabolism
= eating more lower energy foods (e.g., gorillas are folivores, top photo)
– Lesser weight = higher metabolism = eating more high energy foods (e.g., chimps favor fruit (bottom photo), nuts)
![Page 14: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/14.jpg)
Allometry: Body and Brain
• Gorillas: larger bodied, smaller brain• Chimpanzees: smaller bodied, larger brain• Brains: require high amounts of energy to run– 2% of body weight– 20% of energy to run
![Page 15: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/15.jpg)
Why bigger or smaller brains?
• Metabolic rates might constrain brain sizeOr
• Skills needed to find high energy foods might result in selection for bigger brains
![Page 16: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/16.jpg)
Jarman/Bell Principle
• Originally explained antelope behavior, but applies to primates…
• Relationship between body size, metabolic rate, and food quality
Nutrient requirement
Nutrient requirementBody weight
Large animal Large (abundant foods)
Small(poor quality foods)
Small animal Small (rare foods) Large(high quality foods)
![Page 17: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/17.jpg)
Life Histories• Larger brains relate to extended life histories• Social consequences?– Long infant dependency allows for more time to
develop socially
Far right: collared lemursNear right: macaques
![Page 18: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/18.jpg)
Life Histories
• Presocial: animals well-developed at birth• Altricial: animals under-developed at birth;
long dependency (see Table 2.1 page 43)
![Page 19: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/19.jpg)
Jarman/Bell Principle and Sexual Dimorphism
• Body size and physical differences between the sexes
• Within the same species, when compared to females, larger males:– Require more time to develop– Have a greater dietary intake– Spend different amounts of time eating– May eat different types of foods
![Page 20: Primate Morphological Traits Allometry of Brain and Body Size.](https://reader035.fdocuments.us/reader035/viewer/2022062717/56649e5d5503460f94b56d04/html5/thumbnails/20.jpg)
The End
Next topic: More primate morphological traits