Humans as Primates - Primate Evolution

What are phylogenetic trees?

A diagram which shows the evolutionary relationship between a number of organisms derived by a common ancestor.

how to properly write binomial system

Homo sapiens The genus is captalised while the species is not. It is underlined.

What is primates

primate is a taxonomic order which classifies humans, apes, monkeys and some other related animals

What are the characteristics of Primates

Characteristics and Trends of Brain in Primates as go from low to high order

Characteristic	Trend
Size	Increasing size of brain relative to size of body
Convolutions	Gradual increase in the number of folds in the surface of the cerebrum
Cerebral Cortex	Cerebral cortex making up an increasingly large proportion of the brain (higher functions)
Frontal lobe	Has greatest enlargement in surface area, compared with other apes (responsible for higher functioning: thinking, reasoning, planning & processing)

Dental characteristics and trends in primates:

• Dental arcade - the shape of the tooth row - evolved differently. Humans - parabolic shape. Apes - U pattern.

• Diastema - a gap in a row of teeth, usually referring to gap next to canine teeth in primates. Allows teeth to interlock. Not present in modern humans.

• for humans, trend towards smaller molars & decrease in robustness of teeth.

differences in head in general between humans and lower order primates

apes have prominent brow ridges whereas humans have reduced brow ridges

Characteristics and Trends of sight and smell in Primates as go from low to high order

Characteristic	Trend
Eyes	Increasing efficiency in vision Eyes becoming gradually more forward facing, to give stereoscopic vision
Eye Socket	Eyes gradually becoming enclosed in a protective bony socket
Visual area of brain	Increasing proportion of the cerebrum devoted to vision
Smell	Sense of smell reduced with gradual reduction in length of the snout

Trends of mobility of digits in primates

Characteristic	Trend
Mobility	Increasing mobility & ability to move digits independently of one another
Opposability	First digit opposable & increasing length results in increased effectiveness of opposability
Claws/nails	Primitive primates retain claws on some digits; higher primates have nails on all digits

Types of grips:

• Precision grip: one of the hallmarks of human beings, but is not unique to humans. Amount of contact between index finger & thumb is unique and enables humans to handle small or delicate objects effectively

  •Such as used for holding a pencil or needle when sewing.

• Power grip - happens when thumb & fingers apply force against the palm

features that allow for brachiation (arm swinging in monkeys) - NOT IN TEST

• shoulders - short/reduced clavicle, high shoulder blades, mobile shoulder joint

• arms - longer arms/smaller arm to leg ratio, flexible elbow joint

• hands - long, curved fingers, short thumbs, robust but flexible wrist joint

How:
- adapted for swinging in trees

• hands adapted to grasp branches

• provide strength to support the weight of the hominin in trees

• creates energy efficent pattern of movement