Ch. 18 Evolutionary Trends of Hominids Flashcards
what is the ranks of primate tribe
Hominidae (Hominids) (humans, orang, gorillas, chimps) >
Homininae (Hominines)(gorillas, chimps, humans) >
Hominini (hominins) (humans)
define adaption
any characteristic that helps an organism survive and reproduce in its natural environment
what are the 8 adaptions for erect posture
o Position of foramen magnum, curvature of spinal column, jaw, the pelvis, the carrying angle, the knee, the foot, center of gravity
what is the difference in position of foramen magnum between humans and apes
Humans
Located centrally underneath skull
apes= back
why did foreman magnum change position
(During evolution) FM gradually moved forward until skull is able to balance on top of vertebral column
what is the difference in neck muscles between humans and apes
Humans- Weight of skull is borne by vertebral column so large neck muscles not required
apes- Needs large neck muscles to hold head in position
what is the difference in curvature of spine between humans and apes
o Apes: C shaped
o Humans: Double curvature= S shape (contributes to upright stance)
what is a feature of the human spine, lumbar vertareb
- Humans developed: Vertebrae in lower, lumbar, region (small of back) = wedged shaped from front to back= forming forward- jutting curve
what are three things that the lumbar curve provide
o improves body balance in upright position
o enables head to balance on top of neck
o cervical curve in neck= brings vertebral column directly under center of gravity of skull
what is the difference in jaw between humans and apes
- Apes= Protruding Jaw
- Human= flatter facial profile
why did jaw reduce and become flatter (what did it allow)
o Change Important in allowing skull to balance on top of spine, because weight in front of foramen magnum is approx.. equal to weight behind
o // balance achieved with minimum muscular effort
what is the difference in pelvis between humans and apes
- pelvis in humans= broader + shorter from top to bottom than in apes
what does the bowl shape pelvis allow
supports abdominal organs while standing erect + females to support developing fetus during pregnancy
what does broad hip bones allow space for
- Broad hip bones= space for attachment of large buttocks muscles= which move the legs and keep upper body erect
why does the femur converge inward
Because pelvis= broad= hip sockets wide apart