Human change over time Flashcards
Characteristics of mammals
a group of animals that are characterised by the presence of fur or hair and milk-producing mammary glands
- Fur or hair over their body surface
- Milk producing mammary glands
- A lower jaw made of a single bone
Characteristics of primates
a group of mammals with opposable thumbs, flat nails and binocular vision
- Hands with an opposable thumb, which can grasp tree limbs and food and manipulate small objects
- Nails, rather than claws, that expose the fingertips, which are sensitive to touch
- Three-dimensional vision, which allows depth perception and judgement of distance
- Very small litters, usually only one offspring at a time, which allows intensive and extended parental care.
- Large brains relative to their body
- Social
- Fully rotating shoulder sockets
Characteristics of hominoids
a superfamily of primates that lack a prehensile tail, including apes and humans
- The absence of a tail
- Distinctive molar teeth in the lower jaw with five cusps
- Relatively long upper limbs
- Wider chest
- Shoulder joints that permit the arms to be rotated
- Larger and more complex brains (that allow for greater intelligence, problem-solving and communication).
Characteristics of hominins
refers to the modern human species and our extinct close relatives that could walk with bipedal locomotion.
- Bipedalism - can walk erect on their hind legs in a sustained fashion (upright stance)
- Forelimb shorter than hind limbs, thumb opposable, not big toe
- Shape of spine S shaped
- Brains extremely large relative to rest of the body
- Gestation period is unusually long (40 weeks)
- Highly evolved communication system
- Position of the foramen magnum central on the skull
Characteristics of hominins
refers to the modern human species and our extinct close relatives that could walk with bipedal locomotion.
- Bipedalism - can walk erect on their hind legs in a sustained fashion (upright stance)
- Tail absent, forelimb shorter than hind limbs, thumb opposable, not big toe, nails flattened, nostrils close together, opening forward and downward
- Shape of spine S shaped
- Brains extremely large relative to rest of the body
- Gestation period is unusually long (40 weeks)
- Highly evolved communication system
- Position of the foramen magnum central on the skull
mtDNA
- Comes from the maternal lineage, so no recombination occurs
- Has a higher mutation rate because it does not have repair mechanisms
- Most of the plasmid is constant. D loop is region highly susceptible to mutation - mutates faster than section of nuclear DNA
- cannot provide interbreeding between another species
Whole genome DNA
- Both the maternal and paternal lineages due to recombination
- Allows for larger amounts of DNA to be sequenced
- Lower mutation rate because it has repair mechanisms
- Provides evidence of interbreeding with another species
Migration of modern human population around the world
The traditional ‘Out of Africa’ hypothesis suggests that all Homo sapiens evolved in Africa and then began to migrate out through North Africa about 60 000 years ago.
The updated out of Africa theory states…
- First wave out of Africa was Homo Erectus (some stayed)
- The ones that stayed evolved into Homo heidelbergensis → In Asia and Europe, Homo heidelbergensis gave rise to Homo neanderthals and Homo denisovans
- Homo heidelbergensis that stayed in Africa evolved into Homo sapiens about 300 000 years ago
- Homo Sapiens left Africa and everything else became extinct
The Multiregional Hypothesis
- The ‘multiregional’ hypothesis suggests that modern humans evolved independently in many regions of the world – Africa, Europe, Eurasia and South-East Asia. According to the ‘regional continuity’ hypothesis, widely separated human populations in Africa, Europe and Asia have been exchanging genes for at least a million years.
- This differs from the ‘Out of Africa’ hypothesis, which states that the evolution of Homo sapiens occurred in Africa, rather than in multiple regions worldwide.
