The document discusses three hypotheses for the evolution of the human brain: the epiphenomenal hypothesis which argues that brain size increases led to mental states but did not causally impact behavior; the ecological hypothesis which proposes that environmental conditions constrained brain evolution to better adapt to consuming leaves or fruits; and the social brain hypothesis, though not described in detail. The epiphenomenal hypothesis views behavior as solely caused by neural impulses and muscles, independent of mental states. The ecological hypothesis suggests fruit-eating animals evolved larger brains than leaf-eating animals to process resources.

1. The evolution of human brain:-

2. Three hypothesis:-
*Epiphenomenal
*Ecological
*Social brain hypothesis

3. Epiphenomenal hypothesis:-
*Brain is evolved due to increase in size. Mental states exist in relation to
some material happenings, but causally are completely irrelevant. Behaviour
is caused by muscles that contract upon receiving neural impulses, and neural
impulses are generated by input from other neurons or from sense organs.

4. In general, materialist theories are those subscribing to the
statement that mental events can have no effective action on the brain
events in World 1— that World 1 is closed to any conceivable outside
influence such as is postulated in dualist-interactionism. The term
LIAISON is used for both intention and perception, particularly in
voluntary movement.

5. Ecological Hypothesis:-
*Environmental conditions bounds the brain for
evolution. Here to be considered two types of
consumers-
Folivorous- Leaf consumers.
Frugivorous- Fruit consumers.
*Fruit consumers are more likely to be having more
developed brain in terms of (a) Overall size of brain,
(b) Relative size & (c) Brain’s tendency to use
resources.