Biological Anthropology: Human Origins and Biological Diversity

The Anthropological Context

Definition: Primates are mammals that include modern humans.
Characteristics:
- Five digits on hands and feet.
- Opposable thumbs.
- Highly reliant on vision.
- Extended development period.
- Large brains.
- Primarily arboreal and diurnal.
- Highly social (live in groups).
Genetic Similarity: Nearly 99% genetic similarity between humans and chimpanzees.

Prosimii (Prosimians):
- Lorises
- Lemurs
- Tarsiers
Anthropoidea (Simians):
- Platyrrhinii (New World Monkey):
  - Ceboidea (marmosets, tamarins, howler, spider monkey, capuchins)
- Catarrhinii (Old World Monkey):
  - Cercopithecoidea (macaques, langurs, baboons)
  - Hominoidea (apes and humans):
    - Lesser Apes (gibbons)
    - Greater Apes (gorilla, chimps, orangutan)
    - Humans (Homo sapiens)

Catarrhini
- Cercopithecoidae
  - Baboon
- Hominoidea
  - Hylobatoidae
    - Gibbon
  - Hominidae
    - Pongidae
      - Orangutan
    - Homininae
      - Gorillinae
        Gorilla
      - Panini
        Chimpanzee
      - Hominini
        Human
Timeline:
- 30 million years ago: Hominoidae
- 20 million years ago: Hominidae
- 10 million years ago: Homininae

Definition: The change of a species, population, or culture.
Activation: Often activated by environmental change.
- Shift in earth’s axis (wobble)
- Natural disasters (volcanoes, earthquakes, floods, etc.)
- Ice Ages (cold and dry)
Mechanism: Occurs because of the genetic and physical variability and malleability of our species.

Definition: Organisms best adapted to a particular environment are more successful reproductively than those who are not.
Outcome: Leads to the favorability of particular traits among a species.
Other Evolutionary Forces: Genetic drift (chance), gene flow (migration/mixing), and mutation (random change) are also important.

Australopithecus anamensis:
- 4.2 million years ago, Kenya
Australopithecus afarensis:
- 3.8 – 3.0 million years ago, Tanzania & Ethiopia
- Fossil: Lucy - Dinkenesh (“Thou Art Wonderful”)
- Found in Hadar in the Afar Region of Ethiopia
- Lived 3 million years ago (77 pounds, 430 cm3 CC)
  - CC stands for Cranial Capacity, a measure of brain volume.
Australopithecus africanus:
- 3.0 – 2.5? million years ago, South Africa (79 pounds, 490 cm3 CC)

Other Australopithicines (not directly related to humans):
- A. garhi (Ethiopia)
- A. boisei
- A. robustus (South Africa, Tanzania)

Characteristics:
- Smaller teeth than Australopithicines
- Larger brains: A. afarensis (430 cm3), Chimpanzees (390 cm3 CC), Gorillas (500 cm3 CC), early Homo greater than 600 cm3 CC
- More tool use and hunting than Australopithicines
Species:
1. Homo habilis:
  - 2.4 to 1.7 million years ago, E. Africa, no weight provided, 660 cm3 CC
2. Homo erectus:
  - 1.7 million years ago to 300,000 years ago, Africa, Asia, and Europe, no weight provided, 900 cm3 CC
3. Homo sapiens sapiens:
  - 300,000 years ago, world wide by 12,000 BP, 132 pounds, 1350 cm3 CC
  - Also referred to as anatomically modern Homo sapiens sapiens (AMHs).

We are not considered descendants of Homo sapiens neanderthalensis or Denisovans.
They were one of many forms of archaic Homo sapiens (AHS).
One became us.
Although Neanderthals were physically larger than AMHs they were eventually wiped out by AMHs.

Description: Some modern humans moved out of Africa around 100,000 years ago and populated the rest of the world, replacing pre-modern human forms such as H. erectus and Neanderthals.
Conclusions:
1. We are all descended from a single population who lived in Sub-Saharan Africa lived around 300,000 B.P.
2. We have two branches in our evolutionary tree: one remained in Africa, while the other moved out no later than 135,000 B.P. (~100,000 B.P.)
3. The greatest genetic variation occurs within the African branch.
4. This means the African branch is the oldest branch or source population of anatomically modern humans.
5. This model is supported by the fossil record and research from molecular anthropology (mitochondrial DNA) Haplogroups

Explanation: The physical or biological differences among humans are due to our ancestors’ biological and cultural adaptations to the environment (e.g., skin color, lactose intolerance, etc.).
Genetic Similarity: Although differences do exist, we are more than 99.9% the same genetically.

The darker the skin, the more melanin.
Melanin provides greater protection from ultraviolet radiation from the sun and thus the more protection from sunburn or skin cancer.
Those that live closer to the equator have darker skin tones than those that live further away from the equator.
The lighter the skin, the greater the ability to absorb more ultraviolet radiation from the sun and manufacture of vitamin D.
Lighter skin decreases the chances of developing rickets- a vitamin D deficiency.

A scale used to classify skin color, ranging from 1-30+.

Phototype	Sun's action on the skin	Pigment characteristics
I	Easily get burnt, never get tanned, redden	Red-haired people, with freckles, belonging to the Celtic race
II	Easily get burnt, do not get tanned very much	Fair-haired people
III	Fairly get burnt, gradually get tanned	Dark-haired people
IV	Do not get burnt very much, always get tanned very well	Latin people
V	Rarely get burnt, are always tanned	Arabic, Asian people
VI	Very rarely get burnt, have a large amount of melanin	Black people

Body Build:
- (Allen’s rule): larger protruding body parts (limbs) in tropical climates; rationale, more efficient heat dissipation
Body Size:
- (Bergman’s rule): bigger bodies in colder environments because they conserve heat better than slender bodies

Thompson’s rule: longer noses cold weather adaptation; longer noses have more blood vessels to warm up the cold air breathed in by a person

Definition: The inability of humans to produce the lactase enzyme to digest dairy products (lactose)
Infants are tolerant but some people develop this as they become children and adults
Prevalence:
- 19% of European Americans, 58-67% of Native Americans, 70-77% of African Americans, and 95-100% Asian Americans have this trait.
This varies among groups due to cultural differences.
e.g., cattle herders regardless of background tend to have a lower frequency of lactase deficiency than non-cattle herders