2. Definitions - evolution: Darwin defined this term as "descent with modification." This is the change in a lineage of populations between generations. In general terms, biological evolution is the process of change by which new species develop from pre-existing species over time. In genetic terms, evolution can be defined as any change in the frequency of alleles in populations of organisms from generation to generation.
- bipedalism: Of hominids, walking upright on two hind legs; more generally, using two legs for locomotion.
- hominids: Members of the Hominidae family, which includes only modern humans and their ancestors since the human lineage split from the apes.
- fossils: Most commonly, an organism, a physical part of an organism, or an imprint of an organism that has been preserved from ancient times in rock, amber, or by some other means. New techniques have also revealed the existence of cellular and molecular fossils.
2. Understanding the video
1. Global understanding
– After listening: circle the words you actually heard with a pen: human – species - ancestors – evolve.
What did it reveal? It was from a creature that walked upright (a Hominid). / Hadar became one of the most significant Hominid sites in the world.
1. Watch the video and write down information about this discovery.
Global understanding: circumstances
- Time of day: about 12 o’clock - Temperature (F°): 110 degrees - Type of fossil: part of an elbow Detailed understanding: the discovery
- Living group: Hominid - Gender: female - Size: small - Age: 3.2 million years old - Nickname: Lucy (because of the Beatles’ song) - Species: Australopithecus afarensis (Southern ape from Hafar)
2. Portrait: watch the video and describe Lucy in your own words.
Lucy must have looked partly manlike, partly ape-like. On this picture, she resembles a chimp and yet we cannot classify her as an ape.
3. Conclusion: pick out the expressions showing how important the discovery was.
Although older fossils have been found, Lucy remains the benchmark by which all other human ancestor fossil discoveries are judged. She was the woman that stood up and the woman that shook up the human family tree.
Part b: Anatomy
- The common ancestor
1. Watch the video and fill in the chart below.
Charles Darwin ( naturalist)
Humans and African apes must have shared a common ancestor.
Our closest living relative is the African chimpanzee.
Anatomical and molecular studies. Our two species share about 98% of the same genes.
2. Right or wrong? If you think it is wrong, justify by quoting the video.
- Humans evolved from chimpanzees.
W, Our close relationship with chimps does not mean we evolved from chimpanzees.
- Chimpanzees evolved from humans.
W, Our close relationship with chimps does not mean that they evolved from us either.
- Millions of years ago, humans and apes had a common ancestor.
- The older ancestors are, the more ape-like they look.
Much drier and colder. Open woodlands replaced forests.
Adaptation of apes to this environment
Apes had grasping toes and joint mobility in their arms and shoulders made them successful in this environment
One species adapted to this new environment: our common ancestor.
Part c: Walking tall
1. Re-order the sentences in chronological order.
 A volcano erupted in Tanzania.
 Everything was covered by ashes.
 The rain turned the ash into a kind of natural cement.
 Animals left tracks on the soil.
 Two hominids left tracks on the soil.
2. Watch the video and describe what the hominids left on the ground.
They left footprints that were discovered one million years later by a team of palaeoanthropologists.
What do we call these pieces of evidence now? Circle the correct answer: the Laetoli footprints.
3. Bipedalism - List the information defining bipedalism.
Bipedalism is one of the defining characteristics of being a hominid.
- Toes: Observe the two different toes and describe the difference between a human toe and a chimp toe in one sentence.
Unlike chimps that have a diverted big toe, the human big toe is in line with the other toes.
- Listen again and explain the reason for such a difference: what is an ape toe supposed to do? What does a human toe help us do?
Chimp toes are adapted to grasp, whereas human toes help to propel the body forward.