Chapter 4: Human biological evolution

Question 1

Great rift valley

Answer 1

Ethiopia, Kenya, Tanzania
where very high populations of human remains have been found

Question 2

Fossil

Answer 2

in anthropology, describes any preserved early human remains no matter their condition

Question 3

Fossil record

Answer 3

can be used to describe human evolution based on data of human remains, or it could simply mean the assemblage of bones collected

Question 4

Taphonomy

Answer 4

the study of what happens to organic remains after death
Through this, anthropologists can identify the natural and cultural processes that may have acted upon the assemblage

Question 5

Human Osteology

Answer 5

the study of the human skeleton
used by paleoanthropologists who need to identify very small bone fragments as human as opposed to other kinds of animals
They also use it to identify the age of an individual who died and their gender

Question 6

Lumpers vs. Splitters taxonomic debate

Answer 6

Lumpers tend to assume there is considerable variability within genera and species and therefore have relatively few taxonomic categories for the several millions of years of human evolution
Splitters assume that there is relatively little variability in genera and species and recognize that there are many different genera and species over the millions of years

Question 7

Widely used dating techniques

Answer 7

Potassium argon dating, Radiocarbon dating, Dating by association

Question 8

Potassium argon dating

Answer 8

• the best technique to identify the age of sites over 200,000 years old
• When volcanic sediment is hot there is potassium but no argon, as the sediments begin to cool, potassium turns to argon and we know its rate of change, dates are then able to be identified by a sample in a lab
• Usually applied in paleoanthropology by dating the volcanic sediments below and above the biological or cultural human remains

Question 9

Radiocarbon dating (C14)

Answer 9

• The best technique for determining the antiquity of sites less than 50,000 years old
• All living things contain C14, at the instant of death, carbon 14 begins to decay at a known rate using this, with lab analysis the date at which the organism died can be inferred

Question 10

Dating by association

Answer 10

Used when there are no volcanic sediments or organic remains to date
If 2 things are found in the same stratigraphic layer, and the antiquity of one object is known, then the other object is likely the same age

Question 11

Characteristics that define Hominins from other Hominoids

Answer 11

primary: bipedalism
secondary: teeth and features of the skull, larger brain, tool use, dental arcade is usually parabolic (rows of teeth widen going back), tend to have smaller canines then apes, tend to have thicker root enamel and reduced prognathism

Question 12

Hypotheses for why bipedalism occured

Answer 12

• carrying model (food, children, rocks, sticks)
• effective heat management (heat dissipation)
• greater endurance (energy efficiency)
• increasing height (for vision, more food and display)
• walking in trees

Question 13

Skeletal changes accommodating bipedalism

Answer 13

• Repositioning of foramen ovale so that it is balanced on the spine
• Changes to vertebral column (adding curves)
• Changes to pelvis (widening, basin-shaped, stabilizing weight distribution)
• Lengthening of the femur (increased stride length)
• Modification to knee (allowing full knee extension and locking in place)
• Angling of femur inward
• Changes in the foot

Question 14

3 contenders for who the first hominins were

Answer 14

Sahelanthropus, Orrorin, Ardipithecus

Question 15

Prognathic

Answer 15

extension or bulging out of the lower jaw

Question 16

Trends in human biological evolution

Answer 16

proficiency in bipedalism, size and shape of skull, decreased prognathism, smaller teeth, loss of body hair, differences in skin tone depending on environment