 Nebula- a cloud of gas and dust in space.  Ribozyme- RNA molecules that can catalyze specific chemical reactions.  Cyanobacteria- bacteria that can carry out photosynthesis.  Endosymbiosis- a relationship in which one organism lives within the body of another, and both benefit from the relationship.  Primate- a category of mammals with flexible hands and feet, forward-looking eyes and enlarged brains relative to body size.

 Prosimians-oldest living primate group that includes mostly small, nocturnal primates such as lemurs.  Anthropoid-humanlike primate  Hominid-primate that walks upright, has long lower limbs, thumbs that oppose the other 4 fingers, and a relatively large brain.  Bipedal-animal that walks on two legs.

 What theories have you heard about how the Earth and the solar system were created?

 Scientists agree on 2 things about the origin of Earth: ◦ Earth is billions of years old ◦ The conditions of the early planet and its atmosphere were very different from those of today.  Most widely accepted theory is that the solar system was made by a condensing nebula.

 Evidence says the sun formed 4.6 billion years ago  Material from nebula came together because of gravity  Leftovers started circling the sun  Over millions of years repeated collisions built up and made the planets.

 700 million years Earth was hot and violent.  Asteroids, meteorites, and comets hit the planet releasing large amounts of heat  Heat kept earth in a molten state.  Materials separated into Earth’s layers

 Hydrogen, Carbon monoxide, and nitrogen were released and formed the atmosphere.  billion years ago Earth started to cool  Solar Radiation and lightning produced energy for reactions  Continents began to form  Water condensed and rain fell to create bodies of water  Presence of water helped create life

 2 hypotheses on how life started on Earth: ◦ Miller-Urey Experiment ◦ Meteorite Hypothesis  1953 Miller and Urey designed an experiment based on the idea that an input of energy from lightning led to the formation of organic and inorganic molecules present in the Earth’s atmosphere. ◦ Passed electricity through gases and the result was organic matter

 Meteorite that landed in Australia in 1969 showed evidence of organic matter.  90 amino acids were identified, 19 of those are found on Earth.  This means that it’s possible that amino acids could have been around when Earth formed, or they got here when Earth was being hit by meteorites and asteroids.

 2 major hypotheses on how Cells came to exist: ◦ Iron-sulfide bubbles hypothesis ◦ Lipid membrane hypothesis  1990s-William Martin and Michael Russell proposed that the iron sulfide mixing with the ocean water created chimneys that stored biological molecules acting as a cell membrane. When the right things came together the first organic cell membranes formed.

 Lipid Membrane Hypothesis says that lipid molecules spontaneously form membrane- closed spheres called liposomes.  1992 Morrowitz tested the idea that liposomes formed double layered membranes.  They could then form many organic molecules.  This could have been the primitive start to the first cell

 Another theory is that RNA was the first genetic material around on early Earth.  Two scientists in the 1980s discovered that RNA could catalyze reactions.  Ribozymes can speed up their own replication and synthesis.  RNA can do everything on it’s own.  Membranes may have formed around RNA as a form of natural selection.

 What do you think happens when we put water and organisms that go through photosynthesis together?

 Single-celled organisms changed the surface of the Earth by leaving behind minerals.  They also changed the atmosphere by producing oxygen.  3.5 billion years ago photosynthetic life arrived. Also the age of the oldest known fossils.  These are marine cyanobacteria. They are prokaryotic.

 Some live in colonies and make stromatolites.  Stromatolites are a mix of sediment and cyanobacteria.  They have fossils that are 3.5 billion years old, but some are still communities.  The cyanobacteria produce oxygen as a byproduct of photosynthesis.

 Eukaryotic organisms evolved 1.5 billion years ago.  Started as single celled and eventually became multicellular.  1970s Lynn Margulis found evidence to support endosymbiosis.  This theory says that early mitochondria and chloroplasts were once on their own and then were taken up by larger prokaryotes.  This was a beneficial relationship because the smaller organelles produced things the larger cell needed to funtion.

 First prokaryotes and eukaryotes could only reproduce asexually.  Only a few of the ones that reproduce asexually today have ancient asexual origins.  Asexual reproduction leaves us with very little genetic variation.  Sexual reproduction may have resulted in an increase in the rate of evolution by natural selection.  May have been the first step in the evolution of multicellular life.

 What living primate is the closest relative to our species?

 Common ancestor of all primate more than likely arose before the mass extinction 65 million years ago.  Primates have arms that can move around a shoulder joint freely, and opposable thumbs.  Also share strong molecular similarities.

 Primates breaks down into 2 subgroups: ◦ Prosimians ◦ Anthropoids  Prosimians are the oldest of the 2 groups and is mainly nocturnal like sugar gliders, lemurs, lorises, and tarsiers.  Tarsiers are living fossils because they haven’t changed much in 40 million years.

 Anthropoids are further divided into New World monkeys, Old world monkeys, and hominoids.  New World monkeys all live in trees and have tails that allow them to grab on to branches.  Old World monkeys can go in trees, but mainly hangs out on the ground. They have larger brains and can manipulate objects better.

 Hominoids is further divided into lesser apes, great apes (gorillas, chimps, orangutans), and the hominids.  Hominids can walk upright, have opposable thumbs, and relatively large brains.  Hominids include all species in human history.

 Many hypotheses exist for how Hominids evolved.  The first trait before larger brains and tool use to come about was walking upright on 2 legs.  Changes in skeletal anatomy were needed for this to happen

 2 major groups of Hominids: ◦ The genus Homo ◦ The genus Australopithecus  Australopithecus was a very successful genus that lived around 3-4 million years ago.  The brain was about as large as a modern day chimpanzee’s brain, but had very human like limbs.

 Earliest member of Homo was Homo habilis ◦ A.K.A. the handy man because of the tools normally found with them. ◦ Lived million years ago ◦ Brains closest to modern humans  Homo neanderthalensis ◦ Lived from 200, ,000 years ago Europe and the Middle East ◦ May have coexisted with Homo Sapiens

 Homo Sapiens aka Modern Humans arrived on the scene about 100,000 years ago in Ethiopia.  Has not stopped evolving  Human evolution is influenced by culture. ◦ Tools and their sophistication over time is an example of culture.

 Human evolution would not have advanced the way it did without a change in brain size and skull size.  Studies have shown that the genes for brain and structure of the skull evolved much faster in hominids than in any other primates.  This proves that the rapid evolution of brain size was a strong selective advantage for the hominids.