Human Evolution Flashcards
Primate Characteristics
- Thick brow ridge
- Limb length (suited to tree dwelling and quadrupedal movement)
- Hand and foot anatomy
- Tail Anatomy
Primate Common Hominin Characteristics
- Superior intelligence
- often complex social behaviour
- highly developed problem solving ability
Hominoid Characteristics
- No tail
- Larger body size
- More complex brain
Hominoids
subgroup of primates that include all of the apes, as well as a smaller subgroup, Hominini, that includes humans
Hominoid Common Hominin Characteristics
- social behaviour
- superior intelligence
Hominin Characteristics
eg. Australopithecus, homo
- Bipedal with modified feet, thigh bone, pelvis and spine (located on forearm magnum)
- Large cerebral cortex
- reduced canines
- prominent nose and chin, reduced eye ridges
- body hair short/reduced to assist cooling
- highly sensitive skin
- complex social behaviour
Causes of change in structure
- moving from predominantly living in trees to living on land
- walking upright and running to hunt prey
- brain development
- technological development and using tools to help survival
Skull Structure
- brow ridge reduced in modern humans
- slope of forehead more vertical to accomodate frontal lobes of brain
- teeth and jaw become smaller
- volume becomes larger (larger brain size)
Technological Evolution
As brain size increased, as has the ability to develop technology
- tools and weapons (jaw and teeth become smaller)
- ability to create fire
- building
- making clothing (amount of body hair decreased)
Cultural Evolution
refers to any form of learned behaviour, such as how to make a tool, to learning a social rule. Knowledge is passed through generations.
- communication (development of languages allows knowledge and ideas to be passed)
- Art (cave drawings)
- Rituals (belongings found with bored remains)
- Learning to play musical instruments (bone instruments)
Human evolutionary tree-fossil evidence
originally based on structural comparisons between species and fossil evidence of cultural and technological evolution
- gradual increase in brain size and cognitive ability-decrease in tooth size
- use of fire
- evidence of symbol use and ceremonies
Human evolutionary tree- genomic evidence
- comparative genomics have become an important investigative tool in determining human evolution pathways.
- provided evidence of the existence of a new human group, Denisovans (interbreeding may have occurred between modern humans and homo Denisovans)
- provide evidence that modern humans and homo neanderthalenis interbred
DNA sequences (closely-related)
Over course of millions of years mutations will accumulate within segment of DNA.
- greater number of differences between comparable base sequences = more time has passed since two species diverged
- more similar the bases = more closely-related the two species
Amino Acid Sequences (distantly-related)
Typically used to compare distantly-related species.
- have slowest rate of change due to codon degeneracy
- more differences in amino acid sequences between species = longer since shared common ancestor
DNA Hybridisation
- separated into single strands with sufficient heat (90) the mixed together
- if two strands from different species share similar sequence they will hybridise (anneal together to form double strand)
- amount of heat required to seperate hybrid molecule indicates similarity (more heat = more hydrogen bonds = more similar)
Phylogenetic Tress
diagram that depicts the lines of evolutionary descent of different species, organisms or genes from common ancestor
- Root (initial ancestor)
- Nodes (hypothetical common ancestor, gives rise to 2+ daughter taxa)
- Outgroup (most distantly-related)
- Clades (common ancestor, node and all connected branches)
BMP4 (Darwin’s Finches)2
Evolution of different beak shapes and lengths that allowed different species to feed on different food sources.
- BMP4 (beak width and depth)
- CaM (beak length)
BMP4 (Cichlids in African Lakes)
evolved to have different jaw shapes that allow different feeding locations and methods, reducing competition for food, allowing survival.
- determined by time of expression, level of expression, location of expression of BMP4 gene during embryonic development
- High levels (biting, short robust jaws, small closely spaced teeth)
- Low (suction feeders, elongated jaws, large comb teeth)
