lecture 6 - Brain Evolution Flashcards
(40 cards)
what did Charles Darwin propose?
Evolution- natural selection, selectional pressures and adaptations.
what must you have for successful evolution?
Extinction.
how many known species are there?
2 million.
what creates variation?
Mutations- unfavourable mutations are selected out and adaptive mutations are favoured then spread through the population.
Define Homology.
Physical resembelence based on common ancestory.
Give an example of Homology.
All mammalian forlimbs have commonly inherited characteristics.
what is convergent evolution?
were 2 different species living in the same environment can produce the same characteristics, as selectional pressures are so similar to each other.
give an example of convergent evolution.
A tuna fish and a dolphin resemble each other because they have evolved for efficient swimming. Even though a Tuna is a fish and a dolphin is a mammal.
what is an analogous feature?
similarity of function although the structures of interest may look different. e.g. human hand and elephants trunk.
how many years ago did humans evolve?
4-6million years ago.
what is the FOXP2 gene?
the first gene relevant to the human ability to develop language.
The gene that enables us to speak- making humans unique.
A gene thought to be critically involved in vocal behaviour across species.
what is the FoxP2 gene?
this is the mutation gene of FOXP2 that is involved in vocal behaviour.
did Neandertals have the human variant of the FOXP2 gene?
yes
what is the aim of the Neandertals Genome Project?
to characterise the DNA from fossils that are understood to be Neandertal in origin. To see if they too were capable of speech and language.
what did Krause et al (2007) give evidence/support for in his experiment?
Neandertals are capable of speech/language as 46 DNA samples from 22 bones from 46000 were extracted and found to have the SAME mutations as humans today.
how does the human brain compare with other species?
we have a large cranial capacity - space inside skull filled with the brain.
what is the advantage of studying cranial capacity?
because it can also be applied to the fossilied remains of extinct species.
what is linked to larger brain size?
mammals-tend to have larger brains as they eat food that are harder to find e.g ripe fruit.
what did Jerison (1973) think about brain size?
normal for brains to get bigger if humans get bigger- not that surprising after all?
what is the Encephalisation Quotient?
A measure of brain size relative to body size.
EQ = A/E
(ratio of species actual brain size to the expected given its body weight).
how many times larger is the human brain than a hypothetical primate of the same body size?
3.
what part of the brain has evolved more rapidly than other brain areas?
Cerebral Cortex - interesting as it develops later in life.
what does Jerison think about brain size and cognitive capacity?
they must be RELATED.
what does Holloway suggest?
evolutionary change takes place due to brain reorganisation NOT just the expansion of the same areas. Human brains are different in comparison to other primates.
