Human Evolution - Biological Flashcards
What is biological evolution?
The change in the genetic makeup of a species over time
Humans belong to what group along with apes and monkey etc
Primates
Describe some common features of primates
Binocular vision
Large eyes
Prehensile digits
Nails not claws etc
Define the term Hominid
Group of primates that includes humans (bipedal apes) and the great apes (orangutans, gorillas and chimpanzees)
Define the term cranial
Refers to the cranium/head
Identify cranial differences between the great apes and humans
For each feature, describe how they are different and explain why in relation to locomotion and/or diet
Position of the foramen magnum Size of the zygomatic arch Size of jaw Size of molars Presence of diastema Sexual dimorphism with reference to canines Size of cranium Size of brow ridges Nuchal crest szie Sagittal crest size
How do humans and the great apes differ in their locomotion?
Humans are bipedal and great apes are quadrupedal
How do humans and great apes differ in their diet?
Humans are omnivorous and great apes predominantly herbivorous
Great apes and humans had a common ancestor some 7 million ago approximately that live where?
In the trees - this explain why many of our features are linked to an arboreal lifestyle (life in trees)
Explain the sequence of events that lead to evolution of humans as a sub-group of primates
About 5-6 million years ago, the climate of Africa became cooler and drier. This lead to a reduction in the forest cover and an increase in woody grassland/savannah. This increased competition for food, territories etc in the forest. Our common ancestor left the trees and began life on the ground to exploit new resources.
Once our common ancestor had began life on the ground, outline the advantages of being bipedal in this new lifestyle
Being able to see predators and potential prey over the top of the grass
More energy efficient when travelling over long distances so can hunt for longer
Less surface area exposed to the sun but more surface area exposed to the cooling breeze for thermoregulation
Frees up hands to carry young, make tools or carry food from kill sites to a safer place
Outline any disadvantages of being bipedal
Slower over short distances compared to quadrupedalism
Puts greater stress on the body since it is carrying the whole weight of the body on two limbs e.g. varicose veins
Name the genus for main early group of humans
Australopithicenes
Outline the main cranial trends seen from the early Australopithicenes through the early Homos and finally to Homo sapiens. Think why they occurred.
Nuchal and sagittal crests became reduced
Foramen magnum became centrally located
Jaw, zygomatic arch, teeth all became smaller
Diastema gone and no sexual dimorphism with reference to teeth
Increase in cranial size
Reduction in eye brows
Outline the main post-cranial trends seen from the early Australopithicenes through the early Homos and finally to Homo sapiens. Think why they occurred.
Increase in leg length and therefore height
Decrease in arm length
Reduction in body hair
Increase in valgus angle and size of femur condyles
Increase in length and diameter of femur
Increase in foot arch
Big toe in line
Fingers became straighter and more divergent thumb
Pelvis became shorter and broader
Rib cage flattened
