Evidence for Evolution

Fossils Pentadactyl limb Embryology Biochemistry Classification

Fossils Remains of organisms found in sedimentary rock Tissues have been turned into minerals by means of pressure and temperature Older fossils are usually found deeper in the sedimentary rocks

(Parts of) Organisms are covered by sediment, fossilise and are found Organisms living in water are fossilised more often

Fossilised skeleton of a mammoth

Fossilised fronts (leaves) of a fern

Fossilised human foot printFossilised dinosaur foot print

Pentadactyl limb design

Competition in the seas and changing climates may have forced fishlike animals to adapt to living on land Swim bladders turned into lungs and fins into limbs

Fish

The body plan changed slowly The end result was a pentadactyl vertebrate, an Amphibian

Amphibians

Amphibians developed into Reptiles

Reptiles into Birds

And Mammals

The pentadactyl limb continued to develop The early horse was the size of a dog. The animal lived in the Dense tropical forests and needed The four-toed foot for support on the soft soils. When the climate changed forests disappeared and the “horses” adapted. They lost toes and the bones in the remaining finger became longer. A hoof protected the tip against damage. The horses had to be taller to see over the tall grass and able to run faster. The present-day horse is four times taller than its ancester.

Embryology In the 19th century, Haeckel suggested that Embryology also supports the theory of evolution. Later however, it was discovered that he had manipulated his findings and diagrams

Haeckel’s hypothesis was that all Vertebrate animals undergo evolutionary steps when they develop from a fertlised egg cell into a fully developed foetus. He saw the above investigation as proof of his hypothesis. Scientists now only support parts of his idea.

Haeckel is also famous for his art work on marine animals. Below diagrams of Coelenterates, jelly fish and sea anemones

Biochemistry The use of DNA, aerobic respiration and photosynthesis and many chemical recations are universal, used by many organisms

Classification shows the relationship between organisms and how they may have developed out of eachother

Theory of evolution

A young Darwin travelled to South America and gathered a large number of species. After his return to England, he continued studying these specimen And he did several experiments on artificial selection of plants and Animals In 1859 Darwin published his theory of evolution: Survival of the Fittest In his book: “On the Origin of Species”

Darwin stated three rather obvious facts: - Species produce more offspring than needed for the continuation of the species - Offspring is not identical (variation) - There is not enough food/space for all individuals produced (survival of the fittest)

Species produce more offspring than needed for the continuation of the species

Offspring is not identical (variation)

-There is not enough food/space for all individuals produced -(survival of the fittest)

Evolution based upon selection of the best variation in the offspring

Small variations won’t make a difference. The bigger de difference however the more effect on the success of the individual

Small differences changed the size and shape the beak of the ancester This happened in response to changes in the environment (availability of And competition for food). Some birds remained general feeders others specialised

Speciation Mutation Variation Selection Speciation Evolution

Mutation

Variation (Lamarck)

Variation (Darwin)

Natural Selection

Sexual Selection

Speciation

Evolution