CHAPTER 16 Primate Evolution What is a Primate

CHAPTER 16 Primate Evolution

What is a Primate? • A group of mammals that includes lemurs, monkeys, apes, & humans

Characteristics of Primates • Flattened nails instead of claws • Opposable thumb • Used for grasping and manipulating tools

Characteristics of Primates • Color vision • Front-facing eyes (binocular vision) • Aids in depth perception • Rounded head with flattened face

Characteristics of Primates • Flexible shoulder and hip joints • Large Brain • Leads to diverse behaviors and social interactions

Groups of primates ancestral primates STREPSIRRHINES lemurs and ayes-ayes HAPLORHINES Tarsiers and anthropoids Apes and Humans

STREPSIRRHINES: Lemurs and ayes-ayes • Large eyes and ears • Nocturnal • Habitat: tropical rain forests • Oldest found fossils: 5055 MYA

HAPLORHINES: Tarsiers and anthropoids • Larger brains • More upright posture • Anthropoids include humans, apes, and monkeys. • Humans and apes are in a group called hominoids. • Monkeys are divided into two groups: Old World and New World.

HAPLORHINES: New World monkeys • Habitat: rainforests of Central and South America • Prehensile tail: able to grasp and hold with this fifth limb Squirrel monkey

HAPLORHINES: Old World monkeys • Larger than New World monkeys • Tails that are not prehensile • Appear superficially to be like hominoid apes except that apes lack tails. • Habitat: diverse, including African savanna and Japanese mountains Mandril

HAPLORHINES: Hominoid apes: orangutans, gibbons, chimpanzees, bonobos, and gorillas • long, muscled forelimbs • climbing in trees • swinging from branches • knuckle walking Bonobo knuckle-walking

Hominoid apes • May be arboreal but mostly spends time on the ground • Defined social structure and behaviors (including grooming)

Hominoid humans • Even larger brain capacity than apes • Upright stature Note the differences in brain capacity of the skulls: left to right, ape, chimp, human

Common Ancestry? • Humans are not descended from chimpanzees or modern apes, but they likely all descended from a primitive apelike ancestor. • Evidence: structural and social similarities

Where did hominoids come from? • Scientists believed that Old World and New World monkey shared a common anthropoid ancestor.

Where did hominoids come from? • From DNA evidence, scientists believe this to be the order of ape evolution: gibbons, orangutans, African apes, gorillas, and chimpanzees.

Comparing DNA of humans and chimps • Humans and chimps share the greatest sequence of DNA nucleotides. • This implies that humans and chimps are more likely to share a recent ancestor. • This does not imply that humans descended from chimps.

Human evolution • Fossil and DNA evidence indicates that about 5 to 8 million years ago, an ancestral hominoid diverged into two pathways: chimps and humans. • Changes in food supply and climate favored those hominoids that could forage for food on land

Characteristics for non-arboreal primates �Bipedal: using two Bipedalism is a more adapted behavior than knuckle-walking apes. legs for upright walking �Upright posture: facilitates primate to see farther �Bipedal hominoid primates are called hominids and include humans.

Why was bipedalism beneficial? • Increased speed • Hands are free to feed and protect young • Able to use tools

How do scientists know that early hominids walked upright? • The opening in the skull where the spinal cord attaches (foramen magnum) shows how the head and spine are positioned. • discovered an early skull that appeared ape-like but had the spinal attachment like modern humans. Notice how the angle of the arrow changes with the human skull as compared to the ape and chimp.

How do we know what ancient hominids were like? • Paleoanthropologists study fossils of hominids to find out what they were like. • Shape and arrangement of bones gives clues about how they lived.

Who were the first hominids? • Australopithecines • Lived in Africa • Possessed both apelike & humanlike characteristics • “Lucy” was the first complete Australopithecine fossil found (3. 2 million yrs) • Small, apelike brain The skull that Dart discovered was named A. africanus. Estimated age: 2. 5 to 2. 8 MYO

1974 discovered australopithecine Lucy Australopithecus afarensis, dated about 2 -3 MYO, shows pelvis structures that would indicate bipedalism.

A new genus • Hominids with a large cranial (brain) capacity have been grouped into the genus Homo. • Examples: • Homo erectus • Homo sapiens

Comparing skulls and pelvic bones Chimps Early hominid Modern human Similar brain case size between these two Shorter and wider pelvic bones indicate bipedalism.

Homo habilis • “handy man” • Ancient stone tools found near the fossils of H. habilis • Estimated age: 1. 5 -2. 5 MYO Examples of tools that H. habilis may have used

Homo erectus may have evolved from H. habilis.

H. erectus characteristics • Larger brain than H. habilis • More human-like face

H. erectus • Stone hand axe were found near H. erectus fossils, indicating they hunted. • Hearths with charred bones found in H. erectus caves indicate that they may have used fire.

H. erectus migration • About 1 MYA, H. erectus migrated throughout Africa, Asia, and Europe.

Homo neanderthalensis • Neanderthals • Larger brains than modern humans • Shorter, stalkier • Lived in caves and used tools • Spoken language • Thick bones, large faces • Existed at the same time as Homo sapiens

Early Homo sapiens • Cro-magnons • Early Humans • Same height, skull structure, tooth structure, & brain size as modern humans • Tool-makers, artists (cave drawings) • Language

Early modern humans crossing land bridge �Originated in Africa 100, 000 -200, 000 years ago �Inhabited Africa, Asia, & Europe before crossing a land bridge into N. America � 12, 000 years ago, evidence shows that they crossed a land bridge into North America. Modern coastline Ancient coastline Ice sheets 21, 000 yrs ago Ice sheets 12, 000 yrs ago Possible migration route

CHAPTER 17 Organizing Life’s Diversity

Organization of Organisms • Why? • It helps scientists better understand organisms

Organization of Organisms • How? • Classification • The grouping of objects or information based on similarities

Taxonomy • The branch of biology that groups and names organisms based on studies of their different characteristics.

Problems with Traditional Classification • Originally, organisms were grouped according to their physical features. • now organisms are grouped based on their evolutionary history, not just physical similarities. ≠

How are evolutionary relationships determined? • Structural similarities • Geographical distribution • Biochemistry • Similar DNA and proteins • Chromosome comparison • Ex. # and structure of chromosomes • Breeding behavior • Ex. Different calls keep mates from within same group • Embryonic development

Binomial nomenclature • Carolus Linnaeus • Binomial nomenclature – each species has a scientific name with 2 parts • First part is genus • Second part is the species • Ex. Homo sapiens

Rules for scientific names • First letter of the genus is Capitalized • First letter of species is lower case • If printed it should be italicized • If handwritten it should be underlined. • Canis familiaris • Felis catus

How Living Things are Classified • A group of organisms is a taxon. • Organisms are ranked in taxa from very broad characteristics to very specific ones • Smallest taxon is species—organisms that can successfully interbreed

Taxa • Domain – Contains one or more kingdoms • Kingdom – A taxon of similar phyla • Phylum – A taxon of similar classes • Class – A taxon of similar orders • Order—A taxon of similar families • Family – Consists of a group of similar genera • Genus – A group of similar species that have similar features and are closely related • Species – organisms that look alike and can successfully interbreed

A good way to remember • Can you come up with a mnemonic device to help you remember the order? • Domain-Kingdom-Phylum-Class. Order-Family-Genus-Species • Did King Phillip Come Over For Great Spaghetti?

Human Taxonomy • Domain: Eukarya • Kingdom: Animalia • Phylum: Chordata • Class: Mammalia • Order: Primates • Family: Hominidae • Genus: Homo • Species: Homo sapiens

3 Domain System • All life is organized into 3 domains based on evolutionary history • bacteria • archaea • eukarya

The Six Kingdoms of Organisms • Archea - Archaebacteria • Bacteria - Eubacteria • Eukarya – Protista - Fungi - Plantae - Animalia

Kingdom Archaebacteria • Prokaryotic • Unicellular • No membrane-bound nuclei • Most live in harsh environments • Swamps, deep-ocean vents, etc. • Mostly no oxygen (anaerobic)

Kingdom Eubacteria • Prokaryotic • ~5000 species • Very strong cell walls • Live in most habitats, except extreme • Some causes diseases, most are harmless

Kingdom Protista • Eukaryotic • Lacks complex organ systems • Lives in moist environments • Some unicellular, some multicellular • Example: kelp

Kingdom Fungi • Eukaryotic • Heterotrophic - absorbs nutrients from organic materials in the environment • Immobile (unmoving) • Unicellular or multicellular • Over 50, 000 species

Kingdom Plantae • Eukaryotic • Multicellular • Photosynthetic • Immobile • Over 250, 000 species

Kingdom Animalia • Eukaryotic • Multicellular • Heterotrophic • Mobile (move from place to place)

Phylogeny • The evolutionary history of a species • Shown using models called phylogenetic trees

Cladistics • Scientists identify a group’s derived traits (unique inherited characteristics) and use them to construct a branching diagram called a cladogram, a model of the phylogeny of a species.

How does a cladogram work? • 2 groups on diverging branches probably share a more common ancestor than those groups farther away. • They show a probable evolution of a group of organisms from ancestral groups.

Dichotomous Key • A tool used by scientist to identify the species of an unknown organism.