10.4 key concept evidence of common ancestry among species comes from many sources
Post on 18-Dec-2015
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• The study of geography provides evidence of evolution.
– island species most closely resemble nearest mainland species
– populations can show variation from one island to another
• Embryology provides evidence of evolution.
– similar embryos, diverse organisms– GUESS THE HUMAN EMBRYO!
• The study of anatomy provides evidence of evolution.
– Homologous structures are similar in structure but different in function.
– Homologous structures are evidence of a common ancestor.
Human hand
Bat wing
Mole foot
Fly wing
– Analogous structures are not evidence of a common ancestor. This is called convergent evolution
• The study of anatomy provides evidence of evolution.
– Analogous structures have a similar function.
• Vestigial structures are remnants of organs or structures that had a function in an early ancestor.
• Ostrich wings are examples of vestigial structures.
Molecular and genetic evidence support fossil and anatomical evidence.
• Two closely-related organisms will have similar DNA sequences.
(Hooved animals)
Radiometric dating provides an accurate way to estimate the age of fossils.
• Relative dating estimates the time during which an organism lived.– It compares the placement
of fossils in layers of rock.– Scientists infer the order in
which species existed.
• Radiometric dating uses decay of unstable isotopes.
– Isotopes are atoms of an element that differ in their number of neutrons.
neutrons protrons
– A half-life is the amount of time it takes for half of the isotope to decay.
• Radiometric dating uses decay of unstable isotopes.
– Isotopes are atoms of an element that differ in their number of neutrons.
Fossils
• Fossils are physical remains of previous life. – This includes both impressions and physical
structural remains of once living organisms.
Examples include: Dinosaur bones, leave impressions, DNA remains in soil, and mummified animals.
Types of fossils
• Permineralized: bones hardened by sediment• Natural casts: impression in sediment• Trace fossils: footprints, leaf imprints• Amber preserved: trapped in tree sap• Preserved: ice, volcanic ash or bogs
Example of a chemically preserved fossil- Bog Man
10 ways to make a mummy
Index fossils are another tool to determine the age of rock layers.
• Index fossils can provide the relative age of a rock layer. – existed only during specific spans of time– occurred in large geographic areas
• Index fossils include fusulinids and trilobites.
The geologic time scale organizes Earth’s history.
• The history of Earth is represented in the geologic time scale.
100250
550
1000
2000
PRECAMBRIAN TIME
Cyanobacteria
This time span makes up the vast majority of Earth’s history. It includes the oldest known rocks and fossils, the origin of eukaryotes, and the oldest animal fossils.
• Eras last tens to hundreds of millions of years.
– consist of two or more periods– three eras: Cenozoic, Mesozoic, Paleozoic
• Periods last tens of millions of years.– most commonly used units of time on time scale– associated with rock systems.
• Epochs last several million years.
Formation of Earth
• Earth formed over 100 million years
• Earth melted and denser elements sank to the center
• Earth’s early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide and water (based on Alexander Oparin’s theory)
Several sets of hypotheses propose how life began on Earth.
• There are two organic molecule hypotheses.– Miller-Urey experiment
electrodes
heat source amino acids
water
“atmosphere”
“ocean”
•Set up an experiment based on Oparin’s atmosphere theory•Added electricity (lightning) and produced amino acids and organic compounds•Abiotic (nonliving) became biotic (living)
• A hypothesis proposes that RNA was the first genetic material.
– Ribozymes are RNA molecules that catalyze their own replication.
– DNA needs enzymes to replicate itself.
Microbes have changed the physical and chemical composition of Earth.
• The oldest known fossils are a group of marine cyanobacteria. – prokaryotic cells– added oxygen to
atmosphere– deposited minerals
Eukaryotic cells may have evolved through endosymbiosis.
• Endosymbiosis is a relationship in which one organism lives within the body of another.
• Mitochondria and chloroplasts may have developed through endosymbiosis.
Paleozoic Era “early life”
• Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian periods
• Early Earth was mostly marine invertebrates few plants ending with large pine trees, multicellular organisms first appeared.
• The era began 544 million years ago and ended 248 million years ago.
• The Cambrian explosion led to a huge diversity of animal species.
• Three mass extinctions occurred.
Mesozoic Era “middle life”
• Triassic, Jurassic and Cretaceous periods• It began 248 million years ago and ended 65 million
years ago.• The Mesozoic era is known as the Age of Reptiles.• Dinosaurs, birds, flowering plants, and first mammals
appeared.• Pangea breaks up
Cenozoic Era “recent life”
• Tertiary and Quaternary Periods
• The Cenozoic era began 65 million years ago and continues today.
• Lots of bird life, small mammals followed by large mammals (wooly mammoth, etc)
• Anatomically modern humans appeared late in the era.
KEY CONCEPT Humans appeared late in Earth’s history.
Lucy is estimated to have lived 3.2 million years ago.
She is the link between the prehistoric and modern human.
Humans share a common ancestor with other primates.
• Primates are mammals with flexible hands and feet, forward-looking eyes and enlarged brains.
• Primates evolved into prosimians and anthropoids.
– Prosimians are the oldest living primates.– They are mostly small and nocturnal.
– They are subdivided into the New World monkeys, Old World monkeys, and hominoids.
– Anthropoids are humanlike primates.
Old World Monkeys
• Medium to large in size, and range from arboreal (tree dwelling) forms to fully terrestrial forms.
• Most have tails (the family name means "tailed ape” which are not prehensile.
Olive baboonBlack-footed Gray Langur
New World Monkeys
• Small to mid-sized primates, almost all arboreal• The scientific name for the New World monkeys,
Platyrrhini, means "flat nosed". New World monkeys’ noses are flat and have side-facing nostrils.
• New World monkeys in the family Atelidae are the only primates with tails that are prehensile.
White headed CapuchinMantled Howler
Hominoids
– Divided into hominids, great apes, and lesser apes.– Hominids include living and extinct humans.
Genus Pan Genus Pongo
Hominids characteristics
• Walk upright, long lower limbs, opposable thumbs, large brains
• Australopithecus afarensis“southern ape”,• Homo habilis“handy human”• Homo erectus“upright human”• Homo sapiens neanderthalis• Homo sapiens sapiens “wise human”
Australopithecus afarensis“southern ape”,
• Lucy• Brain one third size of modern human• Digging tools, did not make tools• Only found in Africa
Homo erectus“upright human”
• Fully upright stance• First to control fire• Asia, Africa and Europe• Spoken language
Homo sapiens neanderthalis
• Discovered in Neander Valley in Germany• Thick heavy bones and big muscles• Knives and other tools• Rituals and cared for sick and old• Simple language
Homo sapiens sapiens “wise human”
• 150,000 years ago to present• Made 100 advanced tools• Lived in semi permanent huts• Advanced spoken language
• Bipedal means walking on two legs.
• Walking upright hasimportant adaptiveadvantages.– carrying infants and food– using tools– foraging
There are many fossils of extinct hominids. • Most hominids are either the genus Australopithecus or
Homo.• Australopithecines were a successful genus that may have
been related to Homo.• The Homo genus first evolved 2.4 million years ago.
Homo erectus
Australopithecus afarensis →
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