11. Human Changes Over Time Flashcards
List the characteristics that make a mammal.
A variety of teeth
One single lower jawbone attached directly to the skull
Three bones in their middle ear
Various amounts of hair or fur on their bodies throughout their lifetime
Mammary glands that produce milk
To be classed as mammal the organism only needs 1 of these
List the characteristics that all primates share.
Prehensile or grasping hand
Opposable thumb(s)
Flat finger nails instead of claws and sensitive tips of digits
Large, forward facing eyes.
Large brain volume in comparison to body size
To be classed as a primate the organism only needs 1 of these
List the characteristics that hominoids share.
No tails and semi-erect moving posture (knuckle walkers)
To be classed as a hominoid the organism only needs 1 of these
List the characteristics of hominin skeletons
Smaller arm length to leg length ratio (shorter arms in comparison to legs)
Bowl like pelvis (shallow wide pelvis)
Angled femur
Arched foot
S shaped spine
Toes in a line (no opposable toes)
State the morphological changes in hominins related to bipedalism
Humans have shorter arms in comparison to leg length than other primates and hominoids.
Our pelvis has become more bowl like than our ancestors
Human femurs have angled inwards to offer more support when walking.
Loss of opposable thumb on foot (toes all in a line)
S shaped of the spine
Describe the location of the foramen magnum in Homo sapiens.
The foramen magnum is more centralised on the base of the skull in Homo sapiens this means that the head is better balanced allowing for bipedalism
State the advantages of bipedalism
It saved energy so enabled them to walk greater distances and migrate
Allowed hands to remain free for carrying and manipulating objects such as tools.
Enabled greater vision to scan for predators.
List the evidence that supports the interbreeding between Homo neanderthalensis and Homo sapiens
Existed at the same time.
1–4% of the human genome (non-African populations) is identical to DNA found in Neanderthals.
State the evidence that supports Homo denisova as a new species
Nuclear DNA from the bone was found to be very closely related to Neanderthals, but different enough to be a new distinct species, termed Homo denisova, or Denisovans.
What is the evidence that supports interbreeding between Denisovans and Homo sapiens
Melanesian Homo sapiens share 4–6% of their DNA with Denisovans, but that other human populations do not.
State the evidence that supports Homo luzonensis as a new species
The fragments of fossils showed a new combination of features that were different from the combination of features found in other species in the genus Homo. Therefore, the specimens were believed to warrant their classification as belonging to a new species which was named Homo luzonensis.
State one peice of evidence that suggests Homo sapiens evolved in Africa
there is the greatest genetic variation in African mt.DNA (as mutations accumulate over time)
List the characteristics of hominin skulls
Centralised foramen magnum
Lesser brow ridge
More uniform teeth – more parabolic jaw
Larger brain case
State why analysis of mitochondrial DNA may be a better choice over nuclear DNA
Predictable rate of mutation due to no crossing over
A cell has many copies of mitochondria
State why analysis of nuclear DNA may be a better choice over mt. DNA
Gives a picture of the whole genome instead of one chromosome
Gives a picture of what was inherited from both parents instead of just the maternal line
