Human uniqueness: cognitive evolution

Question 1

Evidence of no interbreeding H. sapiens and archaic H. sapiens like Neanderthals?

Answer 1

1. no increased morphological similarities between Neanderthals and Europeans, Asians and Erectus.
2. genetics: all subbranches of h. sapiens closely related, came from the same African bottleneck.
3. Neanderthal DNA is different from Anatomically Modern Humans.

Question 2

What are some of the features that make humans unique

Answer 2

1. bipedalism
2. creation of complex tools
3. productive, abstract language
4. social learning, the learning niche: production trumphs consumption late in life
5. large EQ
6. life history: long life, slow development, monogamous pairs that have large parental investment
7. diet: high quality, difficult to obtain food, eg meat and cooking

Question 3

What is the allometric line?

Answer 3

The curve which represents the relationship between body size and brain size for mammals.
Brain size is NOT proportional to body size, it actually develops slower than body size.
This is why the allometric line is a log versus log function because brain size = C * body size^k and k < 1

Question 4

What are several ways in which energetic constraints of brain expansion were lifted?

Answer 4

1. shift from leaves to fruit eating
2. meat eating
3. cooking
4. cooperative breeding
5. alloparental care
6. smaller gut

Question 5

What is the ecological hypothesis

Answer 5

There is a selective pressure related to the change in diet. Eg frugivores need to monitor availability of food supply, need a large mental map to navigate food sources, and there is extractive foraging.

Question 6

When will the brain evolve?

Answer 6

When benefit (selective pressure) is higher than cost (energy constraints lifted)

Question 7

What is social brain hypothesis

Answer 7

Maintaining social relationships requires devoted brain mechanisms, living in groups is adaptive but requires social cognition to deal with issues. Like coordinating behaviours with others, defusing conflicts. Ecological problems can then be solved socially rather than individually. Also looks at pair bonds: in monogamous bonds, the animal has to avoid getting stuck with bad partner.
Related is also the correlation between group size and brain size.

Question 8

What is cultural intelligence hypothesis?

Answer 8

Not general intelligence, but social cognition is better in humans compared to chimps and orang utans. This enables humans to make use of social learning: at a young age, they learn the tools of their culture, like language and maths, which bootstraps the learning of many more complex skills later in life.

Question 9

How was tools as a selective pressure disproven?

Answer 9

1. most rapid brain growth between 1.5 and 0.3 MA (H. erectus), while during this period, not that much better tools were created.
2. Last 0.3 MA, the technological advance is immense, yet there is barely brain expansion.

Question 10

What is the Machiavellan intelligence hypothesis

Answer 10

Large brains have evolved via intense social interaction like in SBH. But, this hypothesis says it is the ability to use other persons as tools (manipulating to meet your own goals) while maintaing social cohesion is what’s important to have selective advantage. Involved is deception and alliance formation.

Question 11

According to the recent study using computational models, which of the hypotheses of selective pressure are the most likely? How much is their relative influence?

Answer 11

1. Ecological challenges are the biggest factor that drives brain expansion (60%)
2. Furthermore, 30% is cooperation challenges, 10% is competition challenges. This is less than they expected. (This part can be seen as the SBH/Machiavellan hypotheses)
3. In order to correctly predict adult brian size, a rapid brain development was needed. A possible explanation for how this could have happened lies in the Cultural Intelligence hypothesis.

Question 12

How are phylogenetic trees built?

Answer 12

1. phenotypic similarity
   
   • homology vs convergent evolution
   • apomorphy (new traits)
2. DNA

The principle of parsimony should be followed: fewest nodes

Question 13

How can you see in a phylogenetic trees which species are most related to each other?

Answer 13

What is important is how recently they diverged.
For example: the species that humans most recently diverged with (presense of intenral node) is chimpanzees. The humans+chimps diverged from the orang utans further back than they diverged with the gorillas, so they are more related to gorillas. The more recently they share a common ancestor, the more related they are: this is why bonobos are more closely related to humans than they are to gorillas.