Evolution

Fossil Record - direct evidence of evolution Comparative Anatomy - Shared features Embryology - shows shared features amongst young Biogeography - closely related organism are usually found in close proximity

Proposes humans originated in Africa and that we are all descendants of a group around 60,000-100,000 years ago. Evidence: Oldest fossils found in Africa whilst outer fossils are younger, all humans share a maternal ancestor called Mitochondrial Eve (150-200k y.a)

Radiometric Dating (Measures decay of radioactive isotopes in rocks to determine their age) Stratigraphy (Older rocks found on top) OLdest rocks are 4.5b years old, and fossil record shows gradual progression of life forms from simpler to complex against a timeline of Earth’s lifespan.

Appearance: 1-1.5m tall, bipedal but in trees, brain larger than apes but smaller than human, human like teeth Fossil History: 3.9-2.9m y.a., East Africa, “Lucy” found in 1974 Ethiopia

Gradual change in genetic makeup of a population over many generations leading to the development of new species. Driven by genetic variation, natural selection, and genetic drift.

Divergent: 2 or more species that share a common ancestor evolve different traits or characteristics Convergent: Unrelated species evolve similar traits or characteristics

Differences among individuals within a species. Can be genetic, environmental, or due to just random chance.

Differences in the genetic code of individuals within a population

Random changes in gene frequencies within a population - can lead to new traits or loss of existing ones.

The majority of weight over one point (centre of gravity)

Hyracotherium: 3-toed and lived in forest environments while likely eating leaves and twigs. Forests –> Grasslands - adaptation of longer legs, toes fused to form a single hood that made running more efficient on plains Size increased to escape predators and access food easier Skull became longer and teeth flattened

Similarities: Primates, opposable thumbs, 5 fingers 5 toes, shoulder joints Differences: Humans are bipedal but apes walk on all fours Humans have a shorter pelvis and s-shaped spine, apes have a longer and narrower pelvis with a c-shaped spine. Humans have a flatter face with smaller jaw and teeth whereas apes have a larger jaw with more pronounced canines.

Process by which organisms with advantageous traits are able to survive and reproduce to pass their trait onto their offsprings.

• Advantaged organisms survive whilst disadvantaged die out • Advantaged reproduce • Offspring receives trait • As more offspring are made and the disadvantaged die out the frequency of the advantageous trait increases

Traits that have evolved to become well-suited to a particular environment

Characteristics of an offspring that have been inherited or passed on from the parents

Where individuals with certain phenotypes survive due to the underlying genotypes that provide an advantageous trait for a particular environment.

Light-coloured before i.revolution, dark-coloured afterwards the variation in colour shows diversity, the darker moth adaptation helped the moths to survive as it helped them camouflage, and as light-coloured moths died out, the dark-coloured moths would reproduce, leading to the frequency of the trait to increase over time.

Genetic variations such as mutations or inherited traits. Exposure causes non-resistant individuals to die, survivors reproduce and offspring have the trait

A scientific explanation for how life on Earth has changed over time. IT suggests all living things are related to each other, and that they have evolved from a common ancestor.

Found on the Galapagos Islands (Volcanic Islands in Pacific Ocean off the coast of Africa). This supported the theory as each island contained birds with different beaks, depending on the food source available. Birds with beaks not suited to environments died out, and birds with beaks suited survived and reproduced.

A group of organisms that share common characteristics and are able to interbreed to produce offspring.

The process by which new species arise from a common ancestor. 4 types: Allopatric: populations are geographically separated Sympatric: Species evolve in same location but are reproductively separate Perpatric/Parapatric: Invovled speciation where populations are partially isolated or in close but distinct environments.

Variation: Differences due to genetic mutations in a population Isolation: Population divides into 2 or more that are unable to interbreed. Geographic - Physical barriers Reproductive - Differences in mating barriers Ecological - Occupy different habitats or niches Selection: Acts on variation within each population favouring traits that aid in survival and reproduction.