Weeks 9-10 Flashcards
Definition of fossil?
Organic matter in an organism that has died and has slowly been replaced by inorganic compounds
What can a fossil tell us about past life?
What an organism looked like, ate, when it lived, and what kind of environment it lived in
What are the most common types of fossils available for understanding human evolution?
Hard parts of an organism like teeth and bones
Definition of relative dating techniques?
Methods of dating that provide us with assessments of a fossil’s age relative to other fossils
Definition of chronometric dating techniques?
Methods of dating that provide a specific age of a fossil based either on an analysis of a piece of the fossil itself or analysis of the rocks surrounding the fossil
Relative dating technique example
Stratigraphy- the study of the layers of the earth
Chronometric dating technique example
Dendrochronology- the study of tree rings
What is the arboreal hypothesis?
Because early primate ancestors were arboreal, they developed a cluster of traits, such as specializing in herbivorous foods and a leaping/clinging type of locomotion
What is the visual adaptation hypothesis?
The cluster of primate traits arose as a result of the visual nature of primate insect predation. Accurate 3-D vision, grasping hands and feet, and nails rather than claws would seem to be adaptations that fit well for an active, nocturnal, arboreal insect predator
During which geological epoch (and how many million years ago) did the first true primates appear in the fossil record?
Eocene epoch- 53-35 mya
During which geological epoch (and how many million years ago) did the first anthropoid primates appear in the fossil record?
Oligocene period- 35-23 mya
During which geological epoch (and how many million years ago) did the first hominoids appear in the fossil record?
Miocene epoch- 22-5 mya
Why is it rarely possible to clearly identify which fossils represent direct ancestors of primates living today?
Each of the Eocene primate lineages exhibit all the primitive traits we would expect to find in a primate ancestor, so it is difficult to determine which one it is without more fossils to show the evolution from one of those lineages to primates today
What are hominins?
Hominins are humans and all their ancestors/relatives after the split with any other ape lineage
What shared derived traits characterize the hominins? (5)
- Modifications in the pelvic girdle and lower limbs that make them capable of effective bipedal locomotion,
- Changes in the upper arm and vertebral column indicate that weight is borne by the legs,
- Smaller canine teeth,
- Forward-placed foramen magnum,
- No shearing complex
What features of the fossils suggest that A. afarensis locomotion was different from modern human locomotion (even though both walk upright)?
Long arms and curved phalanges suggest it used both terrestrial and arboreal environments, walking bipedally on the ground and moving with all four limbs through the trees
What kinds of habitats did A. afarensis live in?
Primarily mixed savanna and woodland environments 4-3 mya; rich in grasses, shrubs, root and tuber plants, and fruiting/nonfruiting trees; temperatures varied across the year but were never as cool as those of the temperate world today; rainfall was about 20-32 in. per year with the possibility of a dry season(s)
What was A. afarensis diet like?
Fruits, leaves, nuts or grains, and a variety of tubers and roots; insects, birds’ eggs, small mammals, reptiles, scavenge remains of carnivore kills
Is it reasonable to argue that A. afarensis is a possible tool user? Why or why not?
Yes. It may have used sticks and grasses to forage for insects and may have used stones to crack nuts. All hominids use tools of some sort, so it is very likely that tool use is a primitive characteristic shared by a recent common ancestor of modern primates that was an ancestor of A. afarensis as well
What are some of the different hypotheses proposed to explain how bipedal locomotion was favored by natural selection? (7)
- Beneficial for carrying objects
- Beneficial for hunting
- Derived from a foraging pattern favoring upright reaching
- Beneficial for long-distance walking or running
- Beneficial for visual surveillance
- Beneficial in thermoregulation
- Male provisioning & female infant carrying resulted in bipedality
Whiten et al. argue that chimpanzees have culture. What do they mean by this?
Groups of chimpanzees have social traditions that are not purely biological or genetic in origin but rather reflect a set of learned and socially transmitted behaviors.
What is the evidence for chimpanzee culture?
Greeting gestures, tool use patterns (using stones to crack nuts; termite fishing)
How do you think chimpanzee culture differs from human culture?
Humans use complex forms of culture and language, allowing us to construct fantastical ideas and images in our minds, share them with one another, and turn them into reality
How do you think chimpanzee culture differs from the culture of the earliest hominin stone toolmakers?
Chimpanzees did not create tools, but simply manipulated stones, leaves, etc. to use as tools
