Human Evolution and Diversity Flashcards
Australopithecus (SG)
-Smaller body & brain size
-“Southern apes”
-First bipeds (but not efficient)
-Very sexually dimorphic
-Vegetarian
Early Homo habilis (SG)
-East and south Africa
-Larger brain
-Started making stone tools
-Smaller jaws and teeth because they became opportunistic meat eaters
Middle Homo erectus (SG)
-“upright” efficiently!
-First to leave Africa
-Increased body and brain size
-Longer childhood period to allow for brain growth
-Stone tools
-True hunters- more meat reliant- more energy for brain growth
-Were around for 2 million years which is longer than any other homo
Later Homo sapiens (SG)
-Evolved outside of Africa
-Increased brain size
-Sothern & eastern Africa
-Advanced tools, hunting, diverse diet
-fire mastery
-Changes in: locomotion, behavior, social organization, culture
Gene Flow and Human Migration (SG)
-Erectus left Africa and adapted to different climates
-Erectus evolved into Neanderthals in Europe and Denisovans in Siberia
-Sapiens interbred with Neanderthals and Denisovans
Neanderthal SNPs
-1-4% of genome of Europeans and middle eastern peoples is Neanderthal
-Over 135,000 genes identified but only 1400 tested
-For each SNP an individual can carry 0, 1, or 2 variant copies but usually only carry a small subset of the genes
-Avg 23 and me customer carries 267
General Trends of Hominin Evolution (SG)
Increased: body size, brain size, bipedalism, socialization, meat reliance, tools/art/culture
Decreased dentition size
human variation
-Multiple migrations across the globe into varying habitats caused differing selective pressures and genetic drift
-Society and culture differences changing biology
human diversity (SG)
-Population specific differences important to understanding evolution of diseases and human adaptations
-Yet treatments should be based on individuals not groups/ethnicities/races
Genetic examples of cladal adaptations (SG)
- Tibetans- altitude- O2 delivery- EPAS1
- east Asians- temp- sweat glands- EDAR
- sub-Saharan Africans- malaria- sickle cell- beta globulin
- Inuit/Siberian- high fat diet- fatty acid oxidation- CPT1A
- middle east/Europe/Africa- milk consumption- lactase persistence- LCT
Habitual Bipedalism
- advantages
-Efficiently foraging in a cooling climate
oFood scarcity
oTraveling farther to get food
oEasier to forage on two feet b/c hands are free to grab
o Predator avoidance b/c can see farther
o Postural adaptation
-Bipedalism is energy efficient
o Fewer calories consumed to walk longer as compared to knuckle walkers
o Humans walk 4x more than chimps with same energy expenditure
o Not as efficient at running as chimps
o early hominins may have been slightly more efficient than chimps
-Bipedalism set the stage for tool making which has contributed to higher protein diet which in turn provided necessary energy for brain growth
-Each generation needed to improve reproductive and survival skills – traveling further to hunt/forage
Bipedalism Anatomy changes from chimp to sapiens (SG)
-Feet: facing forwards b/c thumb would get in way of walking
-Knees are close together to be more efficient with energy to move forwards
-Pelvis: more bowl shaped to hold organs
-Pelvic inlet: smaller because we need a narrow stance, so we don’t waddle which is more energy efficient to not waddle
-Shorter and less robust arms for carrying objects and tool making
-Shorter phalanges for precision grip
- spine: S shaped to support the weight of whole body
- legs: bipedal now to walk long distances and grab shit
Bipedalism and Knee adaptations
- quadrupeds
- bipedal
- Quadrupedal:
o Straight knees make it energetically expensive to stand for extended periods but more efficient for walking
o Chimps have to throw his weight over the supporting limb when walking on 2 feet - Bipedal:
o Pelvis is wide
o Knees are closer to the midline so feet are under our center of gravity which is energetically favorable because we don’t need to move our weight from one side to the other like chimps waddle
o Can keep balance standing on one foot
o Knees can lock to support body weight
Bipedalism and Back adaptations
- 4 limbs
- 2 limbs
- Body weight distributed on 4 limbs
o Have C-shaped spine
o convex thoracic region
o narrow and long pelvis on the back of the animal because doesn’t hold organs - body weight all on 2 limbs
o S shape spine because
1. 2 additional curvatures to develop spring like effects to deal with body weight
2. Larger lower vertebrae for support
o Broader and bowl-shaped pelvis for organs
o Increased pressure on lumbar vertebrae & intervertebral discs increases susceptibility to prolapsed/herniated discs, nerve damage, back pain (especially in pregnant women) (SG)
Bipedalism and foot adaptations
-Enlarges heel for support
-Loss of opposable hallux
-Shorter toes for locomotion
-Hallux in line with other toes to increase push off
-No longer used for grasping but optimize locomotion
-Arch to absorb shock and act
