case 7 Flashcards
What is the culture brain hypothesis?
learning from others and transmitting culture
What is apomorphy?
a new derived trait.
What is the principle of parsimony?
The simplest tree having the lowest number of steps (evolutionary changes) is accepted.
Looking at DNA which is the humans most related to of the great apes?
Chimpanzees.
When looking at coevolution a number of weird traits happens with human. Give examples
Weird traits
- Language : we can talk about abstract stuff very easily
- Diet : we can eat everything
- Long childhood
- Cooperation
- Tool use.
what do you need to take in consideration when seeing a large brain (why a large brain does not immediately means more intelligent).
1) correct for body size 2) different brain structures, processes.
Explain a little bit about the human brain.
Explanation;
- Weight of the brain is about 1,3 kg
- 86 billion neurons
- Cerebral cortex: 16 neurons
Call some differences between chimpanzees and humans?
Differences due to:
- Single nucleotide alterations: 1,23 of human DNA
- Larger deletions/insertions covering 3% of human DNA
- Chromosomal inversions and translocation even larger proportion
Majority happens in the non-coding part of the DNA!
- Most differences reflect random genetic drift
- Minority of functionally important changes.
Biggest difference is because of epigenetics.
- (point mutation) give some more info on FOXP2
Chimpanzee and human version of FOXP2 differ by two amino acid substitutions (the protein consist out of 715 amino acids).
- It is an transcription factor.
- It is the language gene
(duplication in coding regions) Give some more information on SRGAP2
copy number variation (CNV): sections of the genome are repeated, and the number of repeats varies Compared to chimpanzee, human genome has increased copy number of SRGAP2
Primates.
o Ancestral copy: SRGAP2A
o SRGAP2A promotes synapse maturation
o Maturation (synapse size, synaptic
density) complete at P21
Human
o Human specific (truncated) duplicates: SRGAP2B and SRGAP2C
o Binding of SRGAP2C to SRGAP2A inhibits all functions of SRGAP2A
o Maturation much slower, much longer period of synaptic plasticity
and increased synaptic density
(point mutation in non-coding regions) give some more information on HAR.
Human accelerated regions (HAR):
- 49 segments of human genome that are conserved through vertebrate evolution but strikingly different in humans
- Named according to their degree of difference between human and chimpanzee
- 96% of it maps on non-coding DNA
HAR1 shows largest degree of human-chimpanzee difference
* Overlaps with long non-coding RNA genes (HAR1A and HAR1B)
* Highly expressed in neocortex of developing brain, but exact function unknown
Give some information on the metabolically expensive of the human brain.
the human brain consumes 25% of our energy: metabolically expensive
No correlation between metabolic rate and relative brain size across mammals.
Metabolic requirements of large brains are offset by a corresponding reduction of the gut.
What is ecological hypothesis?
Selective pressure due to change in diet. Fruit eating animals had to look for there food (need to monitor the availability) therefore the need a mental map to navigate. And you need to peel or crack something before you can eat it. A lot of different task.
- What is the social brain/ machiacellian hypothesis?
- Similar ideas:
Large brains have evolved via intense social interaction/ competition
Machiavellian intelligence hypothesis is a bit more limited/ specific
than the social brain hypothesis. Difference is that Machiavellian intelligence hypothesis The ability to use other individuals as tools.
* Manipulating the social environment in
order to meet preconceived goals
* Deception (groom as a means to steal food)
* Alliance formation (grooming predicts
future support
And the social brain hypothesis : Large brain of primates reflects the computational demands of the complex social systems that characterize the order
ARHGAP11B gene
found only in humans and a few related species, is thought to have played a key role in the rapid expansion of the neocortex, the part of the brain involved in higher cognitive functions like language and problem-solving. Increased brain folding (gyrification) is associated with higher intelligence, largely because it allows for more cortical surface area, which facilitates more neurons and synaptic connections. This enhanced capacity for neural communication supports the complex cognitive functions that underlie intelligence. However, brain folding is just one factor among many that contribute to cognitive abilities, and other elements such as neural efficiency, white matter connectivity, and synaptic plasticity also play crucial role
