Human Evolution Flashcards
Biological Evolution
Change in allele frequencies over time.
Cultural Evolution
Change in knowledge - the transmission of ideas.
Bipedalism
Walking habitually on two legs.
Advantages of Bipedalism
Being taller (see further to look for food and predators)
Thermoregulation (being upright means less surface area for sun to hit plus more air to circulate, allowing better cooling)
Sexual display (possibly allowing sex organs to be displayed allowing reproductive success)
Energy saving (although walking on two legs isn’t faster than four, it is slightly more energy efficient, especially over long distances)
Foramen Magnum in Bipedalism
Hole in base of skull where the neck where the spine enters has become more centralised, allowing the skull to balance in line above body/feet.
Saggital Crest in Bipedalism
Saggital crest (along the top of the skull), which serves as an attachment for masseter (chewing) muscles is usually absent.
Nuchal Crest in Bipedalism
Nuchal muscles (located at the back of the skull and keep the skull upright, where neck muscles attach) is much smaller and is further down - less muscles are needed for head to be held above body and facing forward.
Zygomatic Arch in Bipedalism
Zygomatic arches do not flare out to accomodate for larger masseter muscles, means face is narrower as opposed to wider.
Brow Ridge in Bipedalism
Trend towards no brow ridge.
Valgus Angle
Head of femur (hip joint) is wider than knees, femur is thus angled inwards (valgus angle). Quadrupeds don’t have a valgus angle.
Endocranial
Increased brain size - 1400cc as opposed to 400cc.
Fully opposable thumb
Thumb is longer and more mobile than quadrupeds. Increased dexterity in thumb joints and ligaments.
Cerebellum
Increased specialisation of the cerebellum: finer muscle coordination and balance.
Cerebrum
Increased specialisation of the cerebrum: complex processing, problem solving.
Broccas Area
Increased specialisation of the broccas area: sound sequencing and production.
