We have done two topics in this: sexual selection and brain size. I'll just give you some beginning noises that you can pick out of and will hopefully get you going..
- Size of males generally larger. (Clutton-Brock & Harvey, 1977) - variation in body-size dimorphism is due to intra-sexual competition.
- Humans are the only great ape with enlarged breasts outside of lactation - sexual selection ornamentation rather than serving any function.
- Here's a list of primate brain sizes: H. s. sapiens [1300cm3], H. s. idaltu [1450cm3], H. heidelbergensis [1200cm3], H. neanderthalensis [1400cm3], H. ergaster [800cm3], Ausralopithecus [500cm3], Common chimpanzee [400cm3]
As you can see, there has been a gradual increase then a slight dip to sapiens, showing that we must have reached our limit for maximum brain size. The intelligence has increased as brain size goes up. You can compare brain size to other animals to, and compare specific parts of the brain (neocortex does a lot of high order functioning).
- Comparison of precocial (small litters of developed and social)and altricial (large litters of poorly developed non-social) species. Humans are secondarily altricial when primates are generally precocial.
General principle of Comparativism is that by comparing extinct or extant species, we can learn about the evolutionary history of traits, and about unique features of a species
(Original post by hayley6391)
i've currently written about Operant and classical conditioning and then attachment would this be right?
have you got any info on brain size you could send i dont really understand all of what you've put
Sorry I'll try and write something a bit clearer. Might still be unreadable, but I'll have a go xD
The brain size of extinct species can be measured using an endocast (pouring latex rubber into cranial cavity of fossil skull), which shows what the absolute brain size should have been (absolute rather than relative - the exact size it was).
The figures by themselves mean very little (consider how females have lower brain sizes than males, but have equivalent IQs). However, an evolutionary trend can be seen. By comparing the increasing brain sizes of our extinct ancestors, we can gather that brain size was very quickly selected for, so must have had a huge benefit. Comparative psychology then tries to answer why it is that we have this rare trait of high intelligence. Note that comparative psychology is wanting to know the evolutionary history and about unique features - in this case, it's the evolutionary history of our brain, and the unique feature of high intelligence.
We can also compare brain sizes to extant (living) animals, although absolute brain size doesn't work so well. Sperm male has a brain of 8000cm^3 - does that mean sperm whales are very much more intelligent than a chimpanzee of 300cm^3? No. We can use relative brain comparisons here - such as a brain weight to body weight ratio. Human brains are 3.1 times as big as one would expect for an average primate of our body size.