9 Human Evolution Flashcards
Which species of ape are closely related to humans? Identify 3 features that differ between humans and other apes.
Chimpanzees and Bonobos
3 Features:
- Bipedalism - humans are the only apes that walk upright on 2 legs
- Brain size - humans have larger brains
- Hands modified for fine hand grasping
Approximate date for the event “Divergence of human and chimpanzee lineages”. What continent did this occur on?
- 6-8mya
- East Africa
Approximate date for the event “Origin of Homo Sapiens”. What continent did this occur on?
- 200,000 years ago
- Spread from Africa to other parts of the world
Define Hominin. Explain that hominins branched into many species and that as a result, for most of hominin history, there were multiple species of hominins alive at the same time
- Hominin: a group composed by species regarded as human, directly ancestral to humans or very closely related to humans
About 20 other knkown species, all died out except modern humans (homosapiens). Multiple different hominin species lived at the same time in the same place
Describe the major changes in each of these characters during the evolution of humans
from the human/chimp common ancestor. For each change, be able to classify it as
having happened early or late in the evolution of hominins:
* Larger brain
* Flatter, more delicate face
* Shorter canine teeth
* Smaller molars
* More restricted range of motion in shoulders (less arboreal)
* Bipedal (walking on two legs)
* Changes in foot shape (adaptations for bipedal walking)
- Larger brain (LATE)
- Flatter, more delicate face (EARLY)
- Shorter canine teeth (EARLY)
- Smaller molars (LATE)
- More restricted range of motion in shoulders (less arboreal) (LATE)
- Bipedal (walking on two legs) (EARLY)
- Changes in foot shape (adaptations for bipedal walking) (EARLY)
Sketch a phylogenetic tree showing the relationship between H. heidelbergensis, H.
neanderthalensis, and H. sapiens. (No dates needed on the tree.)
Image is downloaded in files
Describe the geographic range of Homo Neanderthalensis
- Lived in Europe to southwestern and central Asia (not Africa)
- Direct ancestors of modern day humans interbred with Neanderthals in Europe and Asia (Middle East)
List some of the technological achievements (fire, tools, art, etc.) of early H. sapiens (modern humans).
- Advanced stone tools
- language
- bone and ivory tools
- elaborate shelters
Describe how migration and gene flow have affected human genetic and phenotypic
variation over time
A mesh of many populations migrating back and forth across the world led to interbreeding. As a result, genetic variation increased
Use genetic and phenotypic evidence to explain why human racial groups are not
biological categories.
Specifically:
a. Provide evidence that human phenotypic variation is continuous rather than
divided into distinct racial categories.
b. Provide evidence that human genetic variation is continuous and does not
correspond well to racial categories.
a) Supported by the fact that traits like skin color, hair texture, and facial features vary along a gradient rather than being sharply divided into distinct racial categories. This continuous variation is influenced by factors like geography and mixed ancestry, resulting in a spectrum of traits rather than discrete categories
b) Supported by the fact that genetic diversity is greater within populations than between racial groups. There’s no specific genetic markers that are unique to any particular racial group, further indicating the lack of clear genetic boundaries between them.
Provide evidence that racial groups are socially/culturally defined.
Race itself does not contribute to genetic variation of a population. What contributes to genetic variation is gene flow that can be influenced by historical events such as migration, colonization, and social structures
Explain how essentialist thinking can be misleading when thinking about race in
humans.
Essentialism can be misleading when thinking about race in humans because it can lead us to think that there are clear boundaries between races. In reality, human genetic variation is continuous and overlapping,.
Describe some of the historical origins of “scientific” racism.
Louis Agassiz illustrated pictures people of different races comparing them to animals and drew pictures that were inaccurate. Linnaeus classified and ranked different races. They created racial groups to justify colonialism and slavery.
