Human Evo Midterm

Science

Relies on empirical evidence and testing, ideas change over time as new evidence emerges

Religion

Relies on trust and faith, ideas change very slowly

Indigenous Knowledge Systems

Based on empirical observations of environments, passed down, also called ethnoscience

Scientific method

Make observation, identify problem, formulate hypothesis, design experiment, collect, organize, and analyze data, draw conclusion

Scientific Theory

Proposed explanation based on wide variety of observations and experimental results, explains why something happens

Scientific Law

Explains what happens in nature under certain conditions

Fossils

Traces of animals, decomposition must be slow enough for organic material to be replaced by minerals, only in specific environments

Biostratigraphy and index fossils

Sediments that were deposited far apart but contain the same index fossil species are interpreted to represent the same period

Tephrostratigraphy

Volcanic eruptions dated through studying layers of tephra, has a chemical composition unique to each eruption

Paleomagnatism

Sequence of reversals of magnetic north and south can be used to date sedmiments containing magnetically charged particles

Fluorine, Uranium, Nitrogen dating

Asseses amount of elements in the groundwater that has been incorporated during fossilization, only useful for bones found at the same location

Uranium series dating

Limestone and other materials contaning calcium carbonate, between 10,000 and 500,000 years old, only used on materials with strong stratigraphic sequences

Electron spin resonance

Measures amount of energy released from bones and teeth, 60,000 to 2 million years old, less accurate than TL

Fission Track Dating

Glass, mica crystals, meteors, fissioning of uranium when heated to high temperatures, between 10,000 and 20 million years ago

Obsidian Hydration analysis

Based on amount of water absorbed at flake edge, up to 100,000 years old, depends on humidity and temperature

Amino acid racemization

when an organism dies certain amino acids racemize from L to D forms at a steady rate until there are are an equal number of L and D, organic materials up to 100,000 years old, temperature impacts rate of racemization

Taxonomy

Establishes the rules of classification based on physical similarities that reflect evolutionary descent

Charles Linnaeus

Swedish naturalist, attempted to classify all animals and plants by looking for common features, created taxonomy

Genus

Group of members more closely related to each other than to species from other genus, share broad adaptive zone, should all share derived characteristics not seen in other genera

Catastrophism

Series of violent short lived, large scale catastrophic events lead to creation of geological features and extinction of animals, Baron Georges Cuvier

Lamarkism

Characteristics aquired over an individuals life can be passed on to offspring through repeated action or will

Darwinism

In all organisms there is variation, more individuals are produced than can survive, if a variation provides advantage for survival that trait will be passed on to a greater number of offspring, leading to overall increase in the trait over generations

Natural selection

Can only occur where there is variation, acts on traits that affect reproduction, consistent selective pressures will result in certain traits better fit for survival and will be passed on

Differential Reproductive Sucess

Individuals that posess beneficial traits or variation are more likely to survive in that environment and produce offspring with those traits

How evolution works

Population encounters selective pressures, over time may become distinct species descended from a common ancestor

Law of Segregation

Traits are inherited as discrete units, two genes for each trait, at time of sex cell production the 2 genes segregate so offspring only get one gene from each parent

Gene

Segement of a chromosome responsible for expressing a specific characteristic, a sequence of DNA nucleotides on a chromosomal segment that is responsible for making a functional protein

Locus

Location for a specific gene on a chromosome

Law of Dominance

Traits expressed in the presence of another allele are dominant, hidden traits are recessive, for an recessive allele to be expressed there must be two copies of the allele

Law of Independent Assortment

Genes controlling different traits are inherited independently of one another in a process called random assortment

Homozygous

Two copies of the same allele are present

Heterozygous

Two different alleles at a locus

Epigenetics

Study of how behaviors and environment can cause changes that effect how genes work

Epigenetic modification

Chemical processes that change how tightly or loosley regions of DNA are packaged, can turn genes on or off, environmental factors can trigger them, reversable

Modern Evolutionary theory

Two stage process, the production and redistribution of variation and natural selection where inherited differences affect their ability to reproduce successfully

Evolution

Change in allele frequencies from one generation to the next, allele frequencies and indicators of the genetic makeup of an interbreeding group of individuals

Mutation

Molecular change in the DNA code, a mutation produces alleles that can be acted on by natural selection, most mutations are neutral or advantageous but some are disadvantageous

Genetic Drift

Allele frequencies increase or decrease in a population by chance over time, alleles may be added to a population due to random factors, alleles may be lost in a population due to random adverse events

Founder effect

Occurs when only a small number of individuals from a larger population are involved in producing the next generation

Gene Flow

Exchange of genes between members of the same species

Adaptation

Environmental changes mean selection pressures change, allele frequencies change for adaptation

Microevolution

Short term changes in allele frequencies

Macroevolution

Large scale evolutionary processes above the species level, usually takes longer and involves species, geological history, principles of classification and modes of evolutionary change

Analogy

Structures that are similar in organisms without shared ancestry and evolved independently to serve the same purpose

Homology

Structures that are shared by species based on descent from a common ancestor

Ancestral traits

Traits shared by organisms due to inheritance from a distant ancestor

Derived traits

Traits that are modifications of ancestral traits

Shared derived traits

Modified traits that are shared by two different groups of organisms

Unique derived traits

Modified triats that are unique to one group

Evolutionary systematics

Traaditional approach in which presumed ancestors and descendants are traced in time by analysis of homologous characters, phylogenetic tree

Cladistics

Attempts to make rigorous evolutionary interpretations based solely on analysis of certain types of homologous charaters

Species

Reproductively isolated groups of organism that produce viable offspring

Speciation

Macroevolutionary processes by which a new species evolves from an earlier species due to isolation

Allopatric Speciation

Requires complete reproductive isolation within a population leading to a new species that is geographically seperated from the ancestral population

Parapatric Speciation

Only partial reproductive isolation is required, ranges of populations may be overlapping creating a hybrid zone

Sources of contention for variations in fossils

Individual variations, age related changes, sexual dimorphism

Splitters

Divide organisms into numerous, smaller groups, emphasize the differences between organisms and often interpret differences as substantial variation between species, claim speciation occured more frequently

Lumpers

Group organisms into a few, large groups, emphasize the similarities between organism and interpret differences as minor variations within the group, assume speciation was less common

Phyletic Gradualism

Traditional view of evolution that emphasized that change accumulates gradually in evolving lineages

Punctuated Equilibrium

New perspective that claims evolutionary change proceeds through long periods of statis, punctuated by rapid period of change, started by Stephen Jay Gould and Niles Edlredge

Epiphysis

Ends of bone

Diaphysis

Shaft of bone

Function of bone

Support muscles and soft tissue, protects vital organs, facilitates movement, reservoirs of important minerals, create new cells for the blood in the medullary cavity

Ligaments

Bands of dense and fibrous connective tissue that link bone ends together in and around joints, key to joint function

Cartilage

More flexible than bone but stiffer than muscle, gives structure to the larynx and nose, acts as a cushion between bones

Axial skeleton

Center of the entire body, where things originate from, skull, rib cage, spine

Appendicular skeleton

Limbs, and everything attached to the axial skeleton

K/T extintion event

Cretaceous-Tertiary extinction event, ~65 mya, end of the age of dinosaurs, start of the age of mammals, dramatic shift in environment

Mammalian Adaptive Radiation

Less predators after the extinction of dinosaurs and many other animals, mammals were able to spread out and occupy new niches with relatively little competition for resources

Mammalian characteristics

Mammary glands, body hair/fur, endothermic

Primate Anatomical Characteristics

Prehensile hands, nails instead of claws, opposable thumbs, hammer hold, precision hold, enhanced vision, reduced sense of smell, increased brain size, tendency towards omnivory, generalized dentition, delayed maturation, tendency to diurnality

Arboreal hypothesis

Smith and Jones early 1900’s, living in trees was the most important factor in the evolution of primates, many mammals do fine in trees without primate traits, and many non primates exhibit primate traits

Visual predation hypothesis

Matt Cartmill 1970, early primates may have first adapted to shrubby forest undergrowth and lowest tiers of the forest canopy

Angiosperm Radiation Hypothesis

Basic primate traits were developed in conjunction with the rise of flowering plants that began 140 mya, flowering plants provide numerous resources

Proprimates

Not true primates, early ancestors, no postorbital bar or convergent eyes, specialized rodent like teeth, lacked opposability of digits, claws instead of nails, small brain

Carpolestes

Grasping feet, nail on big toe, claws on most digits, non convergent eyes, possible link between Plesiadapiforms and true primates

Eocene Euprimates

First true primates, found in Western Europe, North America, Africa, and Asia, Omomyids and Adapids

Dental formula

Type of each type of tooth in each quadrant of the mouth, humans and ape have 2.1.2.3 and new world monkeys are 2.1.3.3

Knuckle walking

All apes to different degrees have arms that are longer than legs, walk on knuckle

Brachiation

Using arms to swing between trees, arms much longer than legs, very specialized anatomical structures, especially in the shoulders and fingers

Suspensory Hanging

Using hands and feet to hang from tree branches, practiced by most great apes

Great Ape Characteristics

Upright trunk posture, complex brains, Y-5 molar cusp pattern, arms longer than legs, long curved hand and foot bones, high mobility in joints of shoulders and wrists, long life stages, build nests, sexually dimorphic, canine honing complex

Canine honing complex

Space in the maxilla for mandibular canine to fit into when jaw is closed called diastema, sectorial premolar to sharpen canines

Gorillas

Confined to forested regions of central Africa, largest living primates, large degree of sexual dimorphism, primarily terrestrial knuckle walkers, sleep in nests, herbivors, groups consist of one large male, a few females and offspring

Chimpanzees

Found in equatorial Africa, knuckle walking and suspensory hanging, omnivores, fission fusion communities

Hominid

Group consisting of all modern and extinct great apes

Hominin

Group consisting of modern humans, extinct human species, and all our immediate bipedal ancestors, distinctive characteristics are bipedal locomotion, large brain size, and cultural behaviors

Primate Models for Human Behaviors

Similarities between humans and non human primates can suggest ecological and genetic factors that may have produced similarities and differences

Index of Encephalization

Relationship between body and brain size, most primates are close to predicted ratios for brain body size, modern humans are beyond that

Human traits

Large foreheads, parabolic jaws, nose projecting away from body, thick enamel on molars

Great ape skull traits

Brain towards back of skull, large temporalis muscles, clearer seperation between neurocranium and facial skeleton, roots of canines extend far into maxilla

Developmental changes in skulls

During infancy human and chimp crania are similar, later lower face and teeth of chimps become larger than humans, adult chimps the braincase is also much smaller relative to lower face

Cerebellum

Primarlily responsible for balance and movement

Cerebral cortex

Responsible for voluntary muscle movements, consiousness, and cognitive functions

Neocortex

More recently evolved portions of the cerebral cortex that are involved with higher mental functions and composed of areas that integrate incoming information from different sensory organs

Language

Humans use language by employing symbols to refer to concepts, people, objects as an open system of communication, basis is the capacity to think symbolically, located in left hemisphere, lateralized

Broca’s area

Left frontal lobe, directly involved in producing spoken language

Wernickes area

Left temporal lobe involved in perceiving spoken language

Evolution of Language

Possibly the last ancestor we shared with great apes had communication capabilities similar to those in contemporary great apes

Mosaic Evolution

Evolutionary change takes place in some body parts/system without simultaneous changes in other parts