Human evolution Flashcards
q
What class are humans, and what are the characteristics of that class
Mammalia,
1.Fur or hair
2.Milk producing mammary glands
3.three bones in the middle ear
4.teeth compromising of incisors ,canines,molars and premolars
5.Lower jaw made of a single bone.
What are order are humans, and what are the characterisitics of it
Primates
1.Body features
2.Skull features
3.Functional features
What super family does humans classify into, and what are its characteristics
HominOIDS
1. Lack of tail
2. Shorter spine
3. Broader ribcage and pelvis to help them sit upright
4. Y5 molar pattern
5. Larger and more complex brain
6. Typically longer amrs than legs EXCEPT HUMANS
7. Distinctive molar teeth in lower jaw.
What tribe is homo sapiens from, and what are its characteristics
Hominins
1. Bipedalism
2. Communication and formation of complex social groups
What are the body features of a primate
- A flexible skeleton, with arm that can rotate in the shoulder socket to allow to reach behind their body
- Prehensile hands/feet that can grasp objects and have 5 fingers/toes in each limb
- Large number of sensitive touch receptors in fingers
What are the skull feautes
1.Binocular vision due to possessing large,front facing eyes that give 3d vision making depth of perception possible.
2.Larger cranium for their body size
3.Relatively long gestation periods to accomodate for brain development
( gestation means how long u been preggy for)
What are functional features
Strong social mammals that live in groups
Hominins include homo sapiens and all of our extinct ancestors that could walk in a bipedal locomotion? True or false
True
What does bipedalism mean
A form locomotion where it involves using only two legs for walking upright
What is evidence of bipedalism in a hominin?
- Centralised foramen magnum
- Bowl shaped pelvis
- S shaped spine
- Broader ripcage
- Increased carrying angle of the femur
Overtime what happened to Hominins brain size over time and what happened cause of it
Increased in brain size which resulting in higher cognitive processes that developed
Speech
Complex emotions
High order desicion making
Abstract thinking and planning
Does the biggest brain in primates mean the smartest?
No, neanderthals had bigger brains than humans but we predcit they used it for superior vision and thermorgulation whereas humans instead evolved extensive networks to promote socialisation.
Due to the brain size increased what happened to the brain that resulted in higher cognitive function
The CEBRUM became more folded which increased SA and** increased in neural connections.**
What are the cons of having a larger brain and link it to the mortalityu and dietary requirments
When a brain is larger, that means more mutations occured resulting in a high morphological change, this is energy costing , therefore high morality rates and a higher dietary requirements.
What are the cons of having a larger brain and link it to the mortality and dietary requirments
Having a larger brain means higher cognitive abilities, which meanst they had lower predator vunerbilities, more group caring, better cooking production. This meant lower mortality and lower dietary requirements.
List the structural changes in the skull over time in hominins
1.More centrralised foramagnum
2.Lessing of the brow ridge
3.Shrinking of the saggital crest
4.Flattening of the face
5.More domed skull
6.Smaller teeth
7.Less of a protruding chin
What is the foramen magnum and what happened over time
The hole in the base of the skull through where the spinal cord passes.
It became more central as hominins became more upright, maintaining balance of the head.
What is the saggital crest and what does having a big one mean and what happened for it to reduce
Saggital crest is present on the top of the skull running lengtwise along the midline where Jaw muscles attach.
Having a bigg saggital crest would mean large muscles can attach and increase jaw strength (they ate a lot of meat) .
In humans, saggital crest reduced as brain size increased and teeth became smaller. ( as we started cooking food)
What is brow ridge
Crest of the bone situated on the frontal bone of the skull.
Why did the face get flatter over time?
AS the envviorment got more drier and homo sapiens developed tools and relyed more on them to break and cut foods. The jaws and teeth became less demanding and therefore the face became more delicate, flatter look. Allowing for more complex communication and expression of emotion.
Why the skull became more domed?
To faccilaitate the increased brain size
Whats a feature that primates possed to order to live an arboreal lifestyle?
aboreal means living in trees
3D colour vision
High rotational movement in the hip and shoulders
Some posses tailsTails
Why the teeth became smaller?
Tool reliance meant no need for big teeth and jaw, this increased evolutionary pressure to spend less energy making large teeth.
