Human Evolution Flashcards
What are the 6 reasons why humans are vulnerable to diseases?
- pathogens evolve faster than hosts
- natural selection lags behind environmental change
- trade offs make it nearly impossible for natural selection to solve certain biology problems
- species evolution history puts constraints on potential changes from natural selection
- some traits increase reproductive fitness at cost of increasing vulnerability to disease
- what may appear to be a disease may really be an adaptation
Natural selection in the pathogens favors mutations that allow 2 things. What are they?
- Pathogens to use host’s resources to copy themselves more efficiently
- pathogens to invade the immune system effectively
When a new infection starts, the immune system learns to recognize key ____ of pathogens and produce ___ that latch onto them
key molecular features, produce antibodies
What are the 3 reasons for rapid selection in pathogens?
- huge capability to reproduce
- high mutation rate of many pathogens –> lateral gene transfer for viruses & bacteria
- huge amount of genetic variation available
What is virulence?
ability of pathogen to cause disease
Virulence is driven by pathogen’s use of _____ to replicate.
Host’s resources
What determines the overall fitness of pathogens?
- reproduction within a host
2. transmission to other hosts
What can cause pathogens to fail to reproduce and spread?
If a pathogen is too virulent and kills the host, the pathogen fails to spread to new hosts, which decreases its fitness
What is one way that pathogens are prevented from moving from one host to another?
improving hygiene
Define resistance.
Capacity of pathogens to defend against antibiotics or other drugs
As long as bacteria are exposed to sublethal doses of the antibiotic… (complete the sentence about what happens to resistant strains of the bacteria)
…resistant strains outcompete susceptible ones and resistant genotypes spread
What is a strategy to defeat the constant evolution of bacteria?
Give different antibiotics to different patients to slow down the transmission of bacteria between them
What are homologous structures that humans have with primates?
feet and skulls, coccyx and tails
Mass extinctions of non-avian dinosaurs triggered adaptive radiation of ___.
placental mammals
The oldest primate fossils date back ___ years.
55 million years
Apes and hominines are more closely related to… Old World or New World monkeys?
Old World monkeys
What are the closest living relatives to humans?
Chimps & bonobos
What are hominins?
Humans as well as all species more closely related to humans than chimps; humans are the only surviving members of the group; includes humans and all extinct species branching from human lineage after splitting from last common ancestor w/chimps
Why are the precise relationships among hominins being debated?
Some species are known only from a single fossil, not even a whole skeleton; there is extensive homoplasy & some features repeatedly emerge and disappear
What are key traits in humans that evolved over time?
big brains, bipedalism, tool use
The virulence of a pathogen is influenced by what two agents of selection?
selection for within host replication & selection for between host transmission
What are some consequences of antibiotic resistance?
- Greatly increased morbidity and mortality in humans
- Use of ineffective antibiotics delays or prolongs treatment
- No antibiotics available for some infections
- Greater health care costs
- Prolonged hospital stays
- Expensive ‘last ditch’ prescriptions
- Expensive isolation treatments
- Higher risk to health professionals
What are features that have changed in humans from primate origins?
reduced prognathism (protruding jaw), brain size
What are unique features of the Homo habilis?
- Orthognathic
- ECV - 770 cc
- Very large cheek teeth
- evidence of tool use, butchery
- australopithicene descendant
What are unique features of the Homo ergaster?
- “working man” - used advanced tools
- fire use
- tall (6’3”)
- larger brain (850cc), small cheek teeth
Homo ergaster is the first hominid to have what five features?
- Big brain (800-900 cc)
- Orthognathic
- Small cheek teeth
- Modern stature / limb proportions
- No evidence of climbing adaptations
