Hominid Evolution & Classification

Chapter 16

Hominid Skulls

Subject A = ChimpanzeeSubjects J-L = Neanderthal (70,000 to 45,000 years ago)Subject M = Cro Magnon (30,000 years ago)Subject N = Modern Man

Human ClassificationDomain: EUKARYAKingdom: ANIMALIAPhyla: CHORDATASubphyla: VERTEBRATAClass: MAMMALIASubclass: EUTHERIAOrder: PRIMATASuborder: ARTHROPOIDEA Family: HOMINIDAEGenus: HOMOSpecies: SAPIENS

Humans are members of an order of mammals: primates.

Primates first appeared about 65 million years ago.

The first primates lived in trees, and we have inherited some of their characteristics.

Characteristics of Primates

o Highly diverse group with the following general features in common

o Manual dexterity: an opposable first digito Senses:

• Binocular vision (eyes on the front of the face allowing for overlapping fields of vision)

• Color vision (if diurnal) and black/white vision (if nocturnal)

• More brain power devoted to vision than smello Locomotion: flexible bodies that allow for easy

movemento Complex brain and behaviors: problem-solving,

socializing, and communicatingo Reproductive rate: fewer offspring; single births

Other PrimatesGreat Apes

ChimpanzeesHumans

Male orangutanFemale orangutan

OrangutansGorillas

Suborder: Arthropoidea

Arthropodoidea: all non-monkey primates

Genetically speaking, humans are most closely related to apes.o These primates lack tails and

have forelimbs longer than their hind limbs

Domain: EUKARYAKingdom: ANIMALIAPhyla: CHORDATASubphyla: VERTEBRATAClass: MAMMALIASubclass: EUTHERIAOrder: PRIMATASuborder: ARTHROPOIDEA Family: HOMINIDAEGenus: HOMOSpecies: SAPIENS

Chromosome Analysis We share more than

97% of our genes with chimpanzees.

Our behavior also has some similarities.o Chimpanzees make

and use simple tools.o They seem to have a

sense of self.

Primate Evolution Cladogram

Domain: EUKARYAKingdom: ANIMALIAPhyla: CHORDATASubphyla: VERTEBRATAClass: MAMMALIASubclass: EUTHERIAOrder: PRIMATASuborder: ARTHROPOIDEA Family: HOMINIDAEGenus: HOMOSpecies: SAPIENS

Hominid Evolution

The human branch of the primate tree is only a few million years old. Apes and hominids diverged from a common

ape-like ancestor between 8 and 5 million years ago.

Hominid Characteristics

• Big brain with more complexity in areas responsible for reasoning

• Thinner face with smaller teeth

• Long thumbs and flexible wrists

• Bipedal (upright walkers):• Shorter arms• Restructured pelvic and

foot bones• Hole for spinal cord at the

base of the skeleton rather than the back

Genus: Homo Continued structural

changes:o Larger brainso Thinner faceso Smaller teeth

Significant advances:o Used toolso Hunted and gathered foodo Used fireo Built shelters o Developed culture and

communication

Domain: EUKARYAKingdom: ANIMALIAPhyla: CHORDATASubphyla: VERTEBRATAClass: MAMMALIASubclass: EUTHERIAOrder: PRIMATASuborder: ARTHROPOIDEA Family: HOMINIDAEGenus: HOMOSpecies: SAPIENS

Species: sapiens Binomial classification: use the genus and

species names to refer to an organism Homo sapiens (modern human) appeared in

Ethiopia about 195,000 years ago.

200,000 years ago,

many species of the Homo

genus were

present.

Out of Africa Hypothesis (1988)

200,000 years ago, many species of the Homo genus were present.

30,000 years ago, only homo sapiens remained.

WHAT HAPPENED TO THE OTHER SPECIES?

1988 Out of Africa Hypothesis: modern humans evolved in Africa and then migrated to other parts of the world.

Out of Africa Hypothesis (1988)

In the 1990s, scientists learned about mitochondrial DNA.o Mitochondrial DNA is a smaller fragment of DNA found in the

mitochondria of eukaryotes. Only 37 genes are located on human mitochondrial DNA. All of these genes are related to mitochondria function.

o Mitochondrial DNA is ONLY inherited from mothers as sperm mitochondria are destroyed by the egg after fertilization.

Mitochondrial DNA changes very little over time. It takes many years for mutations to occur.o Remember molecular clocks? The more mutations…the

longer the species has existed. Scientists have studied mitochondrial DNA from humans all

over the earth. They found that people in Ethiopia have the most mutations in their mitochondrial DNA.

Therefore, humans likely originated in Ethiopia from a “Mitochondrial Eve.”

Migration of Descendants of Mitochondrial Eve

Final Overview of Family Hominidae Evolution

Mill

ions

of y

ears

ago

Australopithecusanamensis

Ardipithecusramidus

Ardipithecusramidus kadabba

Orrorin tugenesis

Australopithecusafarensis

Australopithecusafricanus

Australopithecusrobustus

Australopithecusboisei

Homoergaster

Homohabilis

Homoerectus

Homoneanderthalensis

Homosapiens

?