PLAN 8: Brain size matters. Evaluate the evidence regarding this statement./
How can studying the environmental constraints of an animal help us understand the organization of its brain?
INTRO: It is clear that within different animals there are variations of brain size- there have been many perspectives on whether brain size matters and this will be further explored within this essay.
PARA 1: FORAGING AND DIET
The evolutionary perspective has a key role in explaining the debate in whether brain size matters.
Evolution= process by which the inherited traits of a population of inter breeding individuals changes through successive generations over time.
FORAGING AND DIET
In primates, rodent, rabbit etc. fruit eating species have larger brains than species with other types of diet e.g. leaf eaters.
Larger brains may reflect evolution favoring cognitive abilities underpinning exploration because fruit is more patchily and less predictably distributed - frugivores have larger home ranges and brain size also correlates with home range size.
In one study the scientists believe orangutans confined to part of Borneo where food supplies are frequently depleted may have evolved through the process of natural selection comparatively smaller brains than orangutans inhabiting the more bounteous Sumatra.
Thus supporting the statement that brain size matters.
PARA 2: RELATIVE SIZE OF BRAIN STRUCTURES
Differential increases in the size of area - some areas may relate to specializations in sense organs and correlate with collection, storage, retrieval of food.
Behavioral adaptations have been related to differences in relative sizes of certain brain structures. For example some species of bats find their way and locate prey by hearing- it was found the auditory center is much larger in bats that depend on hearing. It has also been found that birds that store bits of food for later use have a larger hippocampus relative to the fore brain and to body weight compared to birds than don’t store food.
Neocortex volume relative to total brain volume in primates.
PARA 3: SOCIAL GROUP SIZE
Social group size is a strong predictor of neocortex size-larger brains may be selected for, because they confer greater reproductive fitness when functioning in a group increased social acuity; keep track of social rank, ability to manipulate others within group and deceit etc.
However, often lifestyle correlates with diet and is best if we can find evidence from different taxonomic groups (classification of organisms into hierarchy of grouping).
PARA 4: SIZE MATTERS
Size may play a role in innovative behavior, tool use and social learning. Species with larger brains (relative to body size) may be better able to establish themselves in a novel environment.
E.g. partridges have smaller brains and attempt to introduce it to novel environment (for hunting) were less successful. Barn owls have larger brains and attempt to introduce it to the novel environment (for pest control) have been more successful.
HOWEVER, Calvin (2005) said even though our brains are triple the size of our primitive ancestors, history suggests the growth had nothing to do with becoming smarter. Ancient man went through two periods where brain mass increased, yet during these times toolmaking techniques did not improve!
Homo sapiens were walking around in Africa 200,000 years ago with a brain size of ours, little happened in terms of
