Download Evidences for Evolution

Evidences for Evolution
The earth is about 4,600 million (or 4.6 billion) years old. The first signs of
life appeared about 3,800 million years ago.
We can see evidence of evolution all around us. We can observe: Similarites in all living things that suggest descent from a common
ancestor
 Differences between living things in the same family that suggest
change over time (evolution)
1. Fossils – the remains of living things, found in sedimentary rocks, are
simpler the older (deeper) they are. Fossil species are similar to but
differ from today’s species. The evolution of many modern day species
can be traced very fully e.g. elephant, horse. New fossil types mark a
change in the environment. Transitional forms link past and present.
2. Biogeography – the study of the distribution of species shows animals
on islands resemble species from the nearest mainland.
3. Comparative Anatomy – comparing body structures of different
species shows homology (similar construction due to a common
ancestor). E.g. pentadactyl limb of mammals and birds. Vestigial
organs show remnants of once useful parts e.g. kiwi’s wing.
4. Comparative Embryology –shows related animals (e.g. vertebrates)
often have similar stages in their embryonic development.
5. Molecular Biology – All species share a common genetic code,
suggesting all forms of life are related to some extent through
branching evolution from the earliest organisms. Similarity in DNA
sequences and amino acid sequences in proteins such as cytochrome
and haemoglobin also suggest common ancestry.
6. Artificial Selection – As farmers selected the best plants and animals
to breed from they have changed their form over time, getting bigger
and better suited to the environment they are living in.
7. Contemporary Examples – evolution of antibiotic-resistant bacteria,
DDT-resistant insects, mutants of HIV resistant to new drugs etc.
Evolution is not a theory, it is a fact.
Evolutionary theory is about the mechanism by which this change occurs.