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Human Evolution

Mammal Characteristics

• Produce milk for young• Hair• Differentiated teeth• Embryos develop inside and gain nutrients

from the mother (placentals)

Primates

• Order of animals in class Mammalia• 3 main groups: lemurs, tarsiers, and

anthropoids (monkeys, apes and humans)

Primate Characteristics• Open shoulder structure• Legs and feet designed to bear majority of the

individual’s weight

• Well developed fingers• Fingernails and Toenails (not claws)• Opposable thumbs

Continued• Hip and shoulder joints allow a wide range of

motion• Eyes directed forwards– Binocular vision = both eyes view the same objects

simultaneously with slightly different angles

• Large and complex brains• Omnivorous• One offspring at a time

What makes humans unique from other primates?

• Larger and more complex brain• Capable of language• Completely bipedal• Hands are better adapted for precise movement• Manufacture and use complex tools

Where did we come from?• Homo sapiens = only species of human that still

exists– 20 extinct species that are more closely related to

humans than chimps (hominims)

• Fossil records help us study our ancestors– Focus on pelvis, backbone, skull, jaws and teeth

• Molecular comparisons determine relatedness– Chimpanzees = closest living relative

Relatives• Hominids– Bipedal, human-like animals that belong to the same family

as modern humans– Appeared approx. 4 million years ago– 2 genera – Homo and Australopithecus (Lucy)– 2.5 million years ago hominids began to use tools– 1.5 million years ago hominids became more widely

distributed throughout the world (Homo erectus)– 160,000 years ago = early modern humans eventually lead to

Homo sapiens– Current debate over modern human lineage

• Not a linear progression but a branching phylogeny