Lecture 2 (25/07/16) Learning Outcomes To be able to explain the three adaptive trends which are characteristic of all primates. To be able to describe the range and major characteristics and give examples of the major groups of primates the prosimians, the New and Old World monkeys, the apes and humans. To be able to draw a simple evolutionary/phylogenetic tree of primates including a timeas. To use scientific nomenclature for naming of primates. To gain an understanding of primate origins. Joints Classifications of Joints Fibrous, cartilaginous, synovial. Types of Synovial Joints: These are the most moveable joints. Ball and socket. Hinge. Saddle. Ellipsoid. Pivot. Gliding. Types of Joints Fibrous joint: Immovable/Partly movable. E.g. Cranial sutures can be slightly moveable in a young child, but become immovable later on as they fuse together.
Cartilaginous Joint: Tiny bit of movement. E.g. vertebral bodies Joints between vertebral bodies; Long bone containing epiphyseal plates (where bones grow from). Synovial Joint: Freely moveable. Different components of synovial joint can be observed in the picture above. NB: Collateral ligaments can occur on both sides of the joint, which supports the joint (since it s a ligament). Types of Synovial Joints E.g. Shoulder joint + Hip joints are both ball and socket joints. Lots of movement around the joint. E.g. Elbow joint = hinge joint. Movement is like a hinge (back and forth). Shoulder Joint
Ball and Socket (Example of Synovial Joint). Diagram above represents a coronal section (frontal plane) through the shoulder joint. Types of Synovial Joints E.g. Base of the thumb = saddle joint. Gliding joint = bones slide across one another. Base of the fingers = ellipsoid joint. Similar to a ball and socket joint, but with less movement. Neck = pivot joint. Red = first vertebra; white = projection of the second vertebra. This allows us to rotate our head. NB: Vertebra is an irregular bone found in the spinal column. Why concentrate on chimpanzees? We concentrate on chimpanzees because they are most closely related to humans. Most closely related to chimpanzees then gorillas, orang-utans, gibbons etc.
Humans, apes and old world monkeys have a common ancestor. Old world monkeys come from Africa and Europe. New world monkeys come from North and South America. Humans are more similar to old world monkeys than new. Anthropoids include things like monkeys, apes and humans. Prosimians are also primates, but they have much more primitive features than the anthropoids. Lecture Outline 1. Characteristics of Primates. 2. Classification of Primates. 3. Evolutionary/phylogenetic trees. 4. Primate origins. Characteristics of Primates There is no single feature to describe primates. Instead, we look at three adaptive trends found in primates: A. Adaptation to living in trees (arboreal). B. Maintenance of dietary variation. E.g. cows only eat grass, but humans eat a wide variety of food. C. Large amounts of parental care invested in a small number of offspring. Important in the development of the brain. A. Adaptations to living in trees (Arboreal) (a) Nails instead of claws: Advantage is large, flat, sensitive tactile pad which requires a flat nail. This is important in navigating the environment. (b) Free mobility of digits: Long and prehensile (capable of grasping) digits. Opposability of finger and toes (in some). Precision grip and power grip.
Primates have varying degrees of these grips. Humans have the best and most powerful precision and power grips of all primates. (c) Generalised/primitive limb structure: E.g. retention of a clavicle (collarbone) and rotation of shoulder. Clavicle is important for the rotation of the shoulder. Can help with hanging on trees. E.g. rotation of the wrist, radius and ulna makes the forearm very flexible. (d) Visual adaptations: When the eye sockets face forward, this allows for great abilities in a 3D world. Eye sockets face forward = good 3D vision = beneficial for things like leaping from branch to branch, where it is important to estimate distances between branches. Primates/Humans also have good discrimination and colour vision. Posterior of eye sockets are bounded by a postorbital bar thought to protect the eye from distortion from movement of muscles on side of skull.
(e) Reduction of sense of smell: Use of touch to examine (except for loris and lemur) rather than smell. Reduction in size of snout (except for baboons). Reduction in sense of smell caused reduction in size of snout. (f) Trunk uprightness: A preadaptation to bipedalism (movement using two rear limbs/legs)? B. Maintenance of Dietary Variation (a) Retention of different types of teeth: Incisors, canines, premolars, molars. Variety of teeth allows for unspecialised diet (both meat and vegetables). Teeth used to grasp and manipulate the environment. Only pigs and bears have similar teeth to humans, both of which have unspecialised diets. (b) Reduction in number of teeth.
Primitive mammals viewed at the top, and more modern mammals viewed towards the bottom. Teeth can be viewed to be less like canines. Human teeth do not appear to be as varied as other anthropoids and prosimians due to shorter canines. Humans have two incisors, a canine, two premolars and three molars in one quadrant of the mouth. C. Large amounts of parental care invested in a very small number of offspring More parental care = parents can teach more = offspring learn more and therefore chance of survival is higher. Complex and expanded brain especially in visual and association areas.