Human Brain Evolution, Neuropsychology, and Comparative Research

What order do lemurs, tarsiers, monkeys, apes, and humans belong to?

The primate order

What is a cladogram?

A simple branching chart that shows the relative time sequence of the origin of closely related groups of animals.

What is a notable characteristic of primates?

Primates have colour vision.

What distinguishes apes from other primates?

Apes have no tails and can raise their arms to brachiate.

How many infants do female primates usually produce per pregnancy?

One infant.

How do humans compare to other primates in terms of height?

Humans are relatively tall compared to other primates.

What significant changes in human anatomy have facilitated tool use?

Changes in hand structure

How much has the human brain increased in size compared to ancestral species?

Increased to more than three times in volume.

What does the Encephalization Quotient (EQ) measure?

It compares brain size to body size to estimate relative brain size.

What does a higher EQ indicate about an animal?

It indicates a larger than expected brain mass relative to body size.

Which species has the highest EQ?

Modern humans.

How many neurons do modern humans have?

Around 86 billion neurons.

What is a significant finding regarding neuronal density in high EQ animals?

The density of neurons in the cortex is quite low compared to humans.

What major tectonic event occurred around 8 million years ago?

The formation of the Great Rift Valley.

How did the Great Rift Valley affect ape evolution?

It led to the evolution of bipedal hominins in the drier eastern region.

What adaptation did Homo habilis develop in response to environmental changes?

Scavenging from dead animals in herds on the open grasslands.

What skills did Homo erectus develop around one million years ago?

Hunting skills and producing superior tools for killing, skinning, and butchering animals.

What unique contribution to human brain development is mentioned?

Food cooking.

What challenge do primates with abundant neurons face?

They pay a high metabolic cost for energy consumed by neurons.

What is the significance of the adaptability of Homo sapiens?

It has allowed modern humans to populate almost every climatic region on Earth.

How did diet influence brain evolution in early hominins?

A fried diet supported more neurons, creating a need for more foraging time.

What role did fire play in the evolution of Homo erectus?

Fire allowed for cooking, which predigests food and maximizes calorific gain, reducing foraging time.

What is the Radiator Hypothesis proposed by Dena Falk?

It suggests that an effective cooling system for the brain, akin to a car's radiator, is necessary for increasing brain size.

Why is brain cooling important?

Metabolic activity generates heat, and the brain risks overheating under extreme conditions.

What anatomical feature in early human skulls suggests enhanced cooling?

Holes in the skull through which cranial blood vessels pass indicate a widely-dispersed blood flow to the brain.

What are the three primary lines of inquiry in comparative neuropsychology?

1. Understanding basic brain mechanisms, 2. Designing animal models of neurological disorders, 3. Describing evolutionary and genetic influences on brain development.

How do neuropsychologists study basic brain mechanisms?

They conduct cross-species comparisons, such as studying vision across different species.

What is the significance of the Pax6 gene?

It is implicated in eye development across all sighted animals, including humans.

What are homeobox genes?

DNA sequences that govern protein encoding for body development, influencing segmentation in both fruit flies and humans.

Why are animal models important for studying disorders like Parkinson's disease?

They help researchers reproduce disorders, manipulate variables, and formulate treatments before applying them to humans.

What are the three goals of research related to Parkinson's disease?

1. Prevent it, 2. Slow its progression, 3. Treat symptoms as they progress.

What are the three Rs in animal research ethics?

1. Replacement, 2. Reduction, 3. Refinement.

What does phenotypic plasticity refer to?

An organism's ability to change its phenotype based on environmental conditions.

What is epigenetics?

Mechanisms through which the environment influences gene expression by turning genes on or off.

What is gene methylation?

A process where a methyl group attaches to a nucleotide base in DNA, affecting gene expression.

How does methylation affect gene expression?

It can increase or decrease gene expression, influencing protein development.

What is the relationship between genotype and phenotype?

Genotype is the genetic makeup, while phenotype is the observable traits resulting from that genotype.

What is the concordance rate for diseases in identical twins?

Concordance rates range from 30%-60%, suggesting environmental factors also play a significant role.

How can behaviors influence phenotype?

Behaviors and environmental exposures can lead to observable changes in traits, such as muscle growth from exercise.

Two main ways we use to measure EQ (relative brain size)

Compare the size of the brain to the size of the body and to measure the amount of neurons in the brain