Primate Classification: Evolution & Traits

Primates in Nature: Introduction

• Primates make up an order of mammals adapted to life in trees, which is reflected in their complex characteristics.

Methods of Classification

• Parallel evolution occurs when the same trait evolves separately in closely related species, not from a common ancestor, illustrated by finches in different regions developing similar structures independently.
• Convergent evolution involves independent evolution of similar adaptations along distinct evolutionary lines, seen in wings of bats, insects, and birds.

Homologous vs. Analogous Traits

• Homologous traits are physical features in two species that share a similar structure, regardless of function, such as arms and legs having one upper and two lower bones.
• Analogous traits involve physical features in two species with similar functions but different structures, exemplified by bird and insect wings that both enable flight.

Primitive and Derived Traits

• Primitive traits stay unchanged from an ancestral state; the five digits in the hand and foot show traits inherited from earlier vertebrate ancestors.
• Derived traits have been changed from an ancestral state, as seen in the even toes of Artiodactyls and odd toes of Perissodactyls, along with modern horses having one digit, while ancestors of horses had three or five.

Approaches to Classification

• Phenetics form biological classifications based on overall physical similarities, ex: overall genetic distance.
• Cladistics classifies organisms by evolutionary relationships to form biological classifications; derived vs primitive characteristics (shared-derived traits).

Vertebrate Characteristics

• Humans are in the phylum Chordata, all animals with a spinal cord and a notochord at some point in development.
• A notochord is a flexible internal rod along the back of an animal.
• Humans are in the sub-phylum Vertebrata, with backbones and bilateral symmetry.
• Bilateral symmetry involves left and right sides mirroring each other.
• Vertebrae covers the internal spinal cord and enlarged nerve tissue at the end of the cord (brain).
• Most vertebrates show similar limb structures - one upper and two lower bones, and five digits.
• Humans are in the Class Mammalia, and are vertebrates

Mammal Characteristics

• First mammals emerged ~200 million years ago.
• Mammals typically give birth to live offspring instead of laying eggs; only monotremes like platypus lay eggs.
• Marsupials, such as kangaroos, give birth to extremely premature fetuses that stay in a pouch.

Placental Mammals

• Humans are placental mammals, and share the subclass feature of a placenta.
• A placenta is a temporary organ that provides the fetus with oxygen and food and helps filter out harmful substances.
• It aids offspring by assuring suitable nutrition and requires energy from the mother to maintain its function, which limits offspring amounts.

Mammalian Characteristics

• Mammary glands are an exclusive characteristic, and they provide milk with immunities to newborn infants, whose nourishment requires a lot of maternal energy.
• Parental care includes prenatal and postnatal care of offspring by the parents in mammals (higher than in reptiles).
• K-selected species make few offspring while maximizing survival chances; this is exemplified by primates.
• r-selected species make many offspring and provide little care; it is mostly exemplified by fish, frogs, and inserts.

Human Reproduction and Child Care

• Great Apes (chimpanzees, gorillas, orangutans, and gibbons) delay becoming pregnant until offspring mature (about 5 years for chimps) before birthing.
• Humans bear offspring every year and do not wait till the offspring is mature (~15 years).
• While possessing more offspring in the same amount of time as Great Apes, parental care measures are uncompromised.

Temperature Regulation

• Mammals are homeothermic, capable of maintaining a constant body temperature under most conditions.
• Reptiles are cold-blooded, being unable to maintain a constant body temperature, unlike mammals.
• Various methods can maintain mammalian temperature, including fur insulation plus vasoconstriction and vasodilation, respectively decreasing/increasing blood flow to the body's extremities.
• Constriction reduces heat loss, while dilation increases heat loss.
• Maintaining body heat involves ingesting much food to create surplus energy which is also achieved through sweating.
• To manage temperature, humans utilize clothing, fire, A/C and technology.

Teeth

• Modern reptile teeth are uniform, grow throughout life; solely possess the function to hold and kill prey.
• Mammalian teeth show types that occur in two sets over their lifespan: deciduous (baby) teeth, and permanent set.
• Human baby teeth start to be shed at age 6 and continues till age 18 or 20.

Teeth Types

• Incisors = flat teeth are used for cutting, slicing, and gnawing food.
• Canines = teeth located behind the incisors are usually used to puncture.
• Premolars = teeth used for crushing and grinding food.
• Molars = teeth furthest back are used for crushing and grinding food.

Dental Formulae

• I = number of incisors, C = number of canines, PM = number of premolars, M = number of molars in 1/2 of the upper or lower jaw (due to mirror image).
• The dental formula is I, C, PM, M.
• Humans possess a dental pattern - 2-1-2-3.
• The upper formula could be 2-1-2-3 and the lower might be 2-1-2-2, displaying two less teeth in the lower jaw.

Diet and Teeth

• Diet is related to warm-bloodedness in mammals which requires more food compared to cold blooded, and possesses a wider range of their diet.
• Due to mammalian teeth wearing out over time, circumventing wear involves dental hygiene to manage any cost.

Skeletal Structure

• The limbs of four-legged mammals slope down shoulders and hips (tucked under the body), unlike reptile limbs that stretch from their body sides.
• Having their legs under the body helps mammals better support their weight.
• By contrast, humans differently rely on two limbs for movement.

Behavior

• All vertebrate brains have a related structure, even as they vary in size and proportions.
• All vertebrates have a hindbrain, midbrain, and forebrain.
• The hindbrain is associated with reflexive behaviors, bearing/balance, and control of autonomous functions like autonomic functions (breathing).
• It is composed of the medulla, pons, and cerebellum.

Medulla Oblongata

• Nerve impulses from the medulla regulate breathing rhythmically through diaphragm/ intercostal muscle stimulation.
• The medulla regulates the diameter of blood vessels and contains mu receptors that opiates bind to.
• This mu interaction of the opiates accounts for breathing supression and swift, fatal results for the destruction of the medulla.

Pons

• The pons serves as a relay station between the Cerebral cortex and the cerebellum.
• Nerve impulses from eyes, ears, and touch receptors are sent to the cerebellum.
• Regulatory reflexes of the breathing system are regulated by the pons.
• The reticular formation goes through the central hindbrain (extending in midbrain) and has sensory input from upper brain regions, which passes back up to the thalamus.
• It also drives arousal, vomiting, and sleep.

Cerebellum

• The cerebellum consists of deeply convoluted hemispheres totaling 10% of he brain's weight.
• Motor coordination is its greatest function of understanding.
• Those who incur damage to their cerebellum can perceive the world but move jerky and noncoordinated.
• So, the cerebellum appears to be skilled in learning implicit motor skills (unconscious habits, and how to do things).

Midbrain

• Visions, motor skills, auditory and visual processing are controlled in the midbrain region.
• The reticular formation collects input from higher brain center and passes it on to motor neurons as the the substantia nigra aids “smooth" out body movements:.
• The substantia's damage leads to Parkinson's diseases, while the dopamine-packed ventral tegmental area (VTA) creates synapses in the forebrain.
• Related to binding with amphetamines/cocaine, the VTA provides pleasure along with addiction and other qualities.

Sensory Information/Voluntary Movements (Forebrain)

• The forebrain is made up of two large cerebral hemispheres.
• Smell is spared when every other sensory input is passed via here.
• The Lateral Geniculate Nucleus serves as a relay center with visual pathway and optic data pre-processing.
• The Autonomic nervous system and pituitary gland are controlled in the hypothalamus, which includes hormone production.
• Disrupted hypothalamus regulation of temperature (and blood) causes bodily death while causing activity across sleep and emotion.
• The posterior lobe of the Pituitary receives Anti Diuretic Hormone and oxytocin, releasing them from the hypothalamus.

Brain Comparison

• The Reptiles have a largely midbrain and hind brain as they rely heavily on hearing and vision
• The Mammals' enlarged greatly forebrain makes them primarily responsible them for for coordination and sensory information.
• Aforebrain region's cells, especially for memories, learning, and intelligenc, are located in the cerebrum,
• More neutral brain connections occur in more convoluted cerebrums, with the Cerebrum is its largest portions.

Limbs/Grasping

• Five Digits on each foot/hand represents a Mammalian, primitive characteristic.
• While this may is only single one digit remains in horse's modern digit., mammals feature (derived trait)
• A Prehensile (grasping) ability characterizes a primate body plan.
• Primates have Prehensile feet, but Humans do not possess good hand ability.

Arboreal Environments

• Ground terrestrial and Tree arboreal settings exist
• Initially Arboreal, primates started evolving and moving before many transformed to environments classified as (terrestrial).

Digits

• Primate Digrits appear specifically designed to help the wrap around specific Tree and Expanded Tactile Pads such as the thumb are common.
• Tactile adaptations such as nails evolved to safe end-digit sensitive in nerve function.
• A unique adaptation for hand is that primates will make use use the body sections to move specific food food the mouths.

Genrealized/Specialized strucutres

• The Generalized strucutre supports an organisms wide ranging environment, along side limbs that provide flexibility.
• Special limbs with allow limbs have bones adapt environment to more specific uses such as horse's powerful limbs suited to running.

Vision and Stero

• Bincocular stereo. Provides for binoculuar depth perception in primate.
• Sterophonic Color/light, the Sterioscopic ability to produce color are unique features, that require processing of image on brain. It has evolved for unique to detect features contrast such those jungle/forest.
• In addition traits for both mate show indicate Nocturnal to not much colors as required.
• Most of primates' behavior and intelligence have been shown for large sizes

Suborers/Features

• Most primapes possess large brains, relative in the brain sizes such high mental acuity for enhanced sensory
• Primate are classified in two groups called anthropides or prosimisans.
  • Prosimii differ differ as lacking various features like color and olfactory traits often not found anthropoids.
• Primisian groups, have evolved more features compared primates but relative small body more at night.
• And vertical/leap high small dimensions those time during diurnal.
• The types are
  • Asain african lorrises for for smell or no smell as they have small noses. More limited species with no smell
• Lemurs have diverse groups. Small noses.

Leumaiformes

— Lemurs: from Lemuroidea vs orises

• All the Africa and Eurasia lemurs in lemuriphormes group have not

• All possess all other similar, while tarsiffomris do. While most do

• Homin are more more, complex structures and better in vision during ,and is a of ,with the American new world primates ,with and Old Apes/Homini

  • The Classifications ->Hap dry vs strerp nose, or to dry nose with no tails

The features are Monkeys: (apes and home). tail and ,and and ,for to the. humans legs/arms