 Geographical isolation- part of the population is isolated (usually physical barrier eg. River/mountains)  Phenotypes that are advantageous in one environment may not be advantageous in another. (phenotype- characteristics of an organism resulting from alleles Gradually the frequency of alleles in the two populations becomes different. The development of a new species. When different populations evolve in different ways.

 Reproductive isolation- eventually two populations become so genetically different that they cannot interbreed. (E.g.. Different courtship style/ mating season different time of year)  New species is formed  Darwin’s Finches

1. Think of a species. 2. How could two populations become geographically isolated? 3. What phenotypes might be advantageous in each location? 4. How might the populations become reproductively isolated?

preserved remains of a living organism

Fossilization is a rare event. Different types of fossil form under different conditions and environments. Fossilized remains only form in the absence of microbes, which need food, oxygen, water and warmth. ambermud ash/mud ice and frozen soil

 Carbon dating  Potassium-argon dating  Stratigraphy

Organic materials Radioactive carbon C 14 Present in carbon dioxide C 14 taken in by plants C 14 eaten by animals (levels remain fairly constant until the organism dies) C 14 has a half life of about 5700 years Usually used to date samples less than 50,000 years old After 30 years there is only about 3% of C 14 left in the sample

Potassium-40 ( 40 K) Argon-40 ( 40 Ar) Calcium-40 ( 40 Ca) Decays at a known rate The half life of ( 40 K) is approx 1.25billion years Can work out the age of the sample by finding out how much ( 40 Ar) it contains Useful to date volcanic rocks as significant amounts of 40 K

 Generally new rock forms on top of old rock so usually older fossils are found low down.  Volcanic layers either side of fossils can be dated to estimate the age of the fossil.  However, earthquakes, fault lines, eruptions can bend and tilt rock layers.  Layers can also be washed out of layers - The study of layers in rock Stratigraphy

250million years old 2 billion years old

Objectives:  How do we tell from fossils that an animal was bipedal  How can we estimate the size of an animals brain?  How do we tell what an animals diet was?

 Hominid – member of the family Hominidae  Includes: Humans, Gorillas, Apes and Chimpanzees  It was thought that humans were the only living Hominids but biochemical evidence shows close similarities between us and the great apes.  Humans and apes share a common ancestor 5-7million years ago

 Soft parts of organisms decay.  Brains fit snugly into skull.  To find the size of the brain we find the volume inside the skull  CRANIAL CAPACITY

Thick enamel – hard foods like nuts and seeds Thin enamel – soft foods like fruits MICROWEAR- hard foods leave more scratches than softer foods Large jaws have bigger and stronger muscles – can eat tough fibrous foods Apes have large canine teeth used to display aggression not just eating meat – cannot tell you about diet Hominids have smaller canines to allow for chewing

 Australopithecines  Homo hablis  Homo erectus  Neandethals  Homo sapiens  Ramapithecus

 Make a presentation about your hominid.  Will present to the rest of the group who will take notes.

You need to include: 1. The dates the species lived 2. Location 3. What they looked like 4. Features of skull and teeth 5. Lifestyle 6. Use of tools or fire 7. Culture

Australopithecus Homo erectus Homo hablis Homo neanterthalensis Homo sapiens Physical characteristics.... Posture Cranial capacity Diet Tools Culture How