primates & hominin evolution

taxonomy

A scientific method for classifying and categorizing organisms to understand their origins.

Derived trait

A newly evolved trait unqiue to a certain group of organisms.

Ancestral trait

A trait inheritied from a distant ancestor shared with different species.

•Hominoid

Humans, our direct ancestors, great apes, and lesser apes.

•Hominid

Humans, our direct ancestors, and great apes.

•Hominin

Humans and our direct ancestors

~6 million years ago.

The human evolutionary lineage diverged from the chimpanzee lineage

•Prognathism

forward projecting jaw

•Dental arcade

the shape of the teeth in the upper jaw (U-shape vs.

parabolic)

•Chin

a feature of a flat face

•Foramen magnum

opening at the bottom of the skull which connects to the spine (posterior vs. anterior)

•Postorbital constriction

narrowing of the skull behind the eye sockets

primates

Humans belong to a group of mammals known as .

vision

primates tend to have large

brains, interact in social groups, and use ___ as a primary sense (many other animals use smell).

cytochrome-c

-- an enzyme required for the release of energy from food

Neutral Drift:

most of the changes in DNA inside individuals are the result of genetic drift -- random changes that go on all the time and aren’t steered by natural selection in one direction or another.

that natural selection favoring beneficial variations in an organism's genes is the primary mechanism.

gene

Each ____ is a chemical recipe for a protein that the cell

manufactures.

molecular evolution

The changes

and variations in genetic code that occur over time are referred to as

Motoo Kimura

proposed neutral drift hypothesis

minor

variations of a few letters in the code

major

mutations in which a whole

piece of a gene is replaced.

negative changes

-- they cause a normal protein not to be made by the

cell, or to have harmful properties.

positive changes

help the organism adapt to a changing environment

Detrimental mutations

tend to be lost because they are selected against.

98%

About ____ of all the organisms that have ever existed on our planet our now extinct.

mass extinction

when species vanish much faster than they are replaced, this is known as

2.8 million years.

mass extinction is usually defined as about 75% of the world’s species being lost in a “short” amount of geological time which is less than

five

At least __ mass extinctions have been recorded throughout Earth’s history.

Ordovician

Devonian

Permian

Triassic

Cretaceous

cladogram

a diagram that shows the evolutionary relationship between organisms. It does this with reference to specific traits that the organisms have in common.

main line

represents the passage of time. The start of the line is the furthest back in the past, typically millions of years ago.

The nodes of a cladogram

represent common ancestors that evolved a particular physical trait or characteristic. All of the animals that branch off at or after a node share that trait or characteristic (and that common ancestor).

The branches of a cladogram

show when each animal split off from the main line. The node where an animal branches off is the last characteristic that animal has in common with the animals that branch off further up the line.

hypothetical

in cladogram, the relationships are ____; you can easily make your own

molecular evidence

in phylogenetic tree, relationships are backed by

genetics

A cladogram is based on characteristics while a phylogenetic tree is based on .

genetic difference.

A cladogram shows the passage of time while a phylogenetic tree shows

earliest point

That starting point you identified is the ____ in time represented on the cladogram you’re looking at. The opposite end of the cladogram is the most recent point in time.

relative point in time

The position of a node on the line indicates the ____ when that particular characteristic or trait evolved.

cladogram?

a diagram that depicts evolutionary relationships among groups.

PHYLOGENY,

the study of evolutionary relationships.

EVOLUTIONARY CLASSIFICATION

In the past, biologists would group organisms based solely on their physical appearance. Today, with the advances in genetics and biochemistry, biologists can look more closely at individuals to discover their pattern of evolution, and group them accordingly - this strategy is called

CLADISTICS

form of analysis that looks at features of organisms that are considered "innovations", or newer features

that serve some kind of purpose.

DERIVED CHARACTERS.

characteristics that appear in later organisms but not earlier ones and are called

Cytochrome c

is a protein located in the mitochondria of cells involved with cellular respiration.