EVOLUTION
,
,EVOLUTION
• Throughout this module dates will be shortened as follows
• 4.5 billion years ago - 4.5 bya
• 3 million years ago - 3 mya
A little of what was learnt in Grade 10 ...
Before you start this module, it is vital to remember what you learnt in grade 10.
• The universe started 13.7 bya because of the Big Bang - the most widely accepted current theory of the
universe's origin.
• © Did you know that all the hydrogen the earth has today came from that occasion, since then no more
hydrogen has been made. · Therefore, we contain molecules that are 13.7 million years old.
• The earth is very, very old - so old that it is difficult to imagine: 4 550 million (4.6 billion) years old.
• Earth's crust has been built up in layers over millions of years. The layers have been successively laid
down either by water (sedimentary rocks) or by volcanic activity (volcanic rocks). Each layer is therefore
of a different age, oldest layers at the bottom.
, EVOLUTION
• Dating of fossils - relative dating and radiometric dating (absolute dating) can determine the age of a
rock layer, and therefore the age of fossils embedded in that rock.
• At least five mass extinctions have occurred, with many species becoming extinct; 250 mya 90 percent
of life disappeared; 65 mya dinosaurs disappeared.
By studying fossils one:
• learns about ancient forms, e.g. trilobites, and the appearance and extinction of organisms, from individual
species to whole taxonomic groups, e.g. the dinosaurs.
• understands that life-forms changed and gradually became more similar to present-day life-forms.
• gains evidence to support the idea that species change, i.e. have undergone evolution.
• South Africa is very rich in fossils with
• some important finds, for example:
• earliest organisms (3.5 bya), stromatolites (fossilised Cyanobacteria) - Barberton in Mpumalanga
• primitive land plants, e.g. a fern, Glossopteris - KwaZulu Natal
• coelacanth, - a fish group ancestral to amphibians
• mammal-like reptiles - a bridge between reptiles and mammals - Karoo
• humankind's earliest direct ancestors, Australopithecus africanus and Homo erqaster - Sterkfontein Caves at the
Cradle of Mankind
,
,EVOLUTION
• Throughout this module dates will be shortened as follows
• 4.5 billion years ago - 4.5 bya
• 3 million years ago - 3 mya
A little of what was learnt in Grade 10 ...
Before you start this module, it is vital to remember what you learnt in grade 10.
• The universe started 13.7 bya because of the Big Bang - the most widely accepted current theory of the
universe's origin.
• © Did you know that all the hydrogen the earth has today came from that occasion, since then no more
hydrogen has been made. · Therefore, we contain molecules that are 13.7 million years old.
• The earth is very, very old - so old that it is difficult to imagine: 4 550 million (4.6 billion) years old.
• Earth's crust has been built up in layers over millions of years. The layers have been successively laid
down either by water (sedimentary rocks) or by volcanic activity (volcanic rocks). Each layer is therefore
of a different age, oldest layers at the bottom.
, EVOLUTION
• Dating of fossils - relative dating and radiometric dating (absolute dating) can determine the age of a
rock layer, and therefore the age of fossils embedded in that rock.
• At least five mass extinctions have occurred, with many species becoming extinct; 250 mya 90 percent
of life disappeared; 65 mya dinosaurs disappeared.
By studying fossils one:
• learns about ancient forms, e.g. trilobites, and the appearance and extinction of organisms, from individual
species to whole taxonomic groups, e.g. the dinosaurs.
• understands that life-forms changed and gradually became more similar to present-day life-forms.
• gains evidence to support the idea that species change, i.e. have undergone evolution.
• South Africa is very rich in fossils with
• some important finds, for example:
• earliest organisms (3.5 bya), stromatolites (fossilised Cyanobacteria) - Barberton in Mpumalanga
• primitive land plants, e.g. a fern, Glossopteris - KwaZulu Natal
• coelacanth, - a fish group ancestral to amphibians
• mammal-like reptiles - a bridge between reptiles and mammals - Karoo
• humankind's earliest direct ancestors, Australopithecus africanus and Homo erqaster - Sterkfontein Caves at the
Cradle of Mankind
