Transcript Chapter 17 The Evolution of Animals

Chapter 17 The Evolution of Animals
Laura Coronado
Bio 10
Chapter 17
Biology and Society:
Rise of the Hobbit People
– In 2003, anthropologists discovered bones on the
Indonesian island of Flores, dating back 12,000–
18,000 years, of people just over three feet tall and
with heads one-third the size of modern humans.
– Some scientists think that these bones represent
pygmies of a previously unknown human species,
named Homo floresiensis.
– Other scientists suggest that the bones are from
diseased Homo sapiens.
Laura Coronado
Bio 10
Chapter 17
THE ORIGINS OF ANIMAL DIVERSITY
– Animal life began in Precambrian seas with the
evolution of multicellular creatures that ate other
organisms.
– Animals are:
•
•
•
•
Eukaryotic
Multicellular
Heterotrophic organisms that obtain nutrients by ingestion
Able to digest their food within their bodies
– Animal cells lack the cell walls that provide strong
support in the bodies of plants and fungi.
Laura Coronado
Bio 10
Chapter 17
THE ORIGINS OF ANIMAL DIVERSITY
– Most animals have:
• Muscle cells
• Nerve cells that control the muscles
– Most animals:
• Are diploid
• Reproduce sexually
• Proceed through a series of typically similar
developmental stages
Laura Coronado
Bio 10
Chapter 17
Sperm
FERTILIZATION
MEIOSIS
Egg
Zygote
(fertilized egg)
MITOSIS
Eight-cell stage
Adult
METAMORPHOSIS
Blastula
(cross section)
Digestive tract
Outer cell layer
(ectoderm)
Larva
Early gastrula
(cross section)
Inner cell layer
(endoderm)
Internal sac
Later gastrula
(cross section)
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Future middle
layer of cells
(mesoderm)
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Chapter 17
Key
Haploid (n)
Diploid (2n)
Figure 17.2-8
Early Animals and the Cambrian Explosion
– Animals probably evolved from a colonial flagellated
protist that lived in Precambrian seas about 600–700
million years ago.
– At the beginning of the Cambrian period, 542 million
years ago, animals underwent a rapid diversification.
– During a span of about 15 million years:
• All major animal body plans we see today evolved
• Many of these animals seem bizarre
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Chapter 17
Digestive
cavity
Reproductive cells
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Bio 10
Chapter 17
Figure 17.3-5
Laura Coronado
Bio 10
Chapter 17
Figure 17.4
– What ignited the Cambrian explosion?
• One hypothesis emphasizes increasingly complex
predator-prey relationships that led to diverse adaptations
to feed, move, and provide protection.
• Another hypothesis, studying evolution and development,
called evo-devo, focuses on the evolution of genes that
control the development of animal forms.
Laura Coronado
Bio 10
Chapter 17
Animal Phylogeny
– Biologists categorize animals by:
• General features of body structure
• More recently, using genetic data
– One major branch point distinguishes sponges from all
other animals because, unlike more complex animals,
sponges lack true tissues.
– A second major evolutionary split is based on body
symmetry.
• Radial symmetry refers to animals that are identical all around a
central axis.
• Bilateral symmetry exists where there is only one way to split
the animal into equal halves.
Laura Coronado
Bio 10
Chapter 17
Sponges
No true tissues
Cnidarians
Radial symmetry
Ancestral
protist
Molluscs
Flatworms
Tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
Laura Coronado
Bio 10
Chapter 17
Figure 17.5
Radial symmetry. Parts radiate from the center, so any slice
through the central axis divides into mirror images.
Bilateral symmetry. Only one slice can divide left and right
sides into mirror-imageLaura
halves.
Coronado Bio 10 Chapter 17
Figure 17.6
Animal Phylogeny
– Animals also vary according to the presence and type
of body cavity, a fluid-filled space separating the
digestive tract from the outer body wall.
– There are differences in how the body cavity forms.
• If the body cavity is not completely lined by tissue derived
from mesoderm, it is a pseudocoelom.
• A true coelom is completely lined by tissue derived from
mesoderm.
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Bio 10
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Body covering
(from ectoderm)
(a) No body cavity
Tissue-filled
region (from
mesoderm)
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
(b) Pseudocoelom
Muscle
layer (from
mesoderm)
Pseudocoelom
Digestive tract
(from endoderm)
Coelom
(c) True coelom
Digestive tract
(from endoderm)
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Bio 10
Chapter 17
Body covering
(from ectoderm)
Tissue layer lining
coelom and
suspending
internal organs
(from mesoderm)
Figure 17.7
MAJOR INVERTEBRATE PHYLA
– Invertebrates:
• Are animals without backbones
• Represent 95% of the animal kingdom
Laura Coronado
Bio 10
Chapter 17
Sponges
– Sponges represent multiple phyla.
– Sponges include sessile animals that lack true
tissues and that were once believed to be plants.
– The body of a sponge resembles a sac perforated
with holes.
– Choanocyte cells draw water through the walls of
the sponge where food is collected.
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Bio 10
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Pores
Amoebocyte
Skeletal
fiber
Central
cavity
Choanocyte
(feeding cell)
Water
flow
Flagella
Choanocyte
in contact
with an
amoebocyte
Laura Coronado
Bio 10
Chapter 17
Figure 17.8
Cnidarians
– Cnidarians (phylum Cnidaria) are characterized by:
• The presence of body tissues
• Radial symmetry
• Tentacles with stinging cells
– The basic body plan of a cnidarian is a sac with a
gastrovascular cavity, a central digestive compartment
with only one opening.
– The body plan has two variations:
• The sessile polyp
• The floating medusa
– Cnidarians are carnivores that use tentacles, armed with
cnidocytes (“stinging cells”), to capture prey.
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Mouth/anus
Tentacle
Gastrovascular
cavity
Polyp form
Coral
Hydra
Sea anemone
Gastrovascular
cavity
Mouth/anus
Tentacle
Medusa form
Jelly
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Chapter 17
Figure 17.9
Tentacle
Coiled
thread
Capsule
Trigger
Discharge
of thread
Prey
Cnidocyte
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Bio 10
Chapter 17
Figure 17.10
Molluscs
– Molluscs (phylum Mollusca) are represented by softbodied animals, usually protected by a hard shell.
– Many molluscs feed by using a file-like organ called a
radula to scrape up food.
– The body of a mollusc has three main parts:
• A muscular foot used for movement
• A visceral mass housing most of the internal organs
• A mantle, which secretes the shell if present
– The three major groups of molluscs are:
• Gastropods, protected by a single, spiraled shell
• Bivalves, with a shell divided into two halves hinged together
• Cephalopods typically lacking an external shell & built for speed
and agility
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Bio 10
Chapter 17
Visceral mass
Coelom
Kidney
Heart
Reproductive
organs
Mantle
Mantle
cavity
Digestive
tract
Shell
Radula
Anus
Gill
Mouth
Foot
Digestive
tract
Radula
Nerve
cords
Laura Coronado
Mouth
Bio 10
Chapter 17
Figure 17.11
MAJOR GROUPS OF MOLLUSCS
Gastropods
Bivalves
(hinged shell)
Cephalopods
(large brain and tentacles)
Snail (spiraled shell)
Scallop
Octopus
Squid
Sea slug (no shell)
Laura Coronado
Bio 10
Chapter 17
Figure 17.12
Flatworms
– Flatworms (phylum Platyhelminthes) are the simplest
bilateral animals.
– Flatworms include forms that are:
• Parasites or
• Free-living in marine, freshwater, or damp habitats
– The gastrovascular cavity of flatworms
• Is highly branched
• Provides an extensive surface area for absorption of
nutrients
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Bio 10
Chapter 17
Digestive tract
(gastrovascular
cavity)
Nerve cords
Mouth
Eyespots
(detect light)
Planarian
Nervous tissue
clusters
(simple brain)
Blood fluke
Bilateral symmetry
Reproductive unit
with skin removed
Head
Suckers
Tapeworm
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Bio 10
Chapter 17
Figure 17.13
Hooks
Annelids
– Annelids (phylum Annelida) have:
• Body segmentation, a subdivision of the body along its
length into a series of repeated parts
• A coelom
• A complete digestive tract with
– Two openings, a mouth and anus
– One-way movement of food
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Bio 10
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Anus
Brain
Main
heart
Coelom
Digestive
tract
Segment
walls
Mouth
Accessory
hearts
Nerve cord
Laura Coronado
Waste disposal organ
Blood vessels
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Figure 17.15
Annelids
– The three main groups of annelids are:
• Earthworms, which eat their way through soil
• Polychaetes, marine worms with segmental appendages
for movement and gas exchange
• Leeches, typically free-living carnivores but with some
bloodsucking forms
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Bio 10
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MAJOR GROUPS OF ANNELIDS
Earthworms
Polychaetes
Leeches
Giant Australian earthworm
Christmas tree worm
European freshwater leech
Laura Coronado
Bio 10
Chapter 17
Figure 17.14
Roundworms
– Roundworms (phylum Nematoda) are:
• Cylindrical in shape, tapered at both ends
• The most diverse and widespread of all animals
– Roundworms (also called nematodes) are:
• Important decomposers
• Dangerous parasites in plants, humans, and other animals
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Bio 10
Chapter 17
(a) A free-living
roundworm
(b) Parasitic
roundworms in pork
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Bio 10
Chapter 17
(c) Canine heart
Infected with parasitic
roundworms
Figure 17.16
Arthropods
– Arthropods (phylum Arthropoda) are named for their jointed
appendages.
– There are about one million arthropod species identified, mostly
insects.
– Arthropods are a very diverse and successful group, occurring in
nearly all habitats in the biosphere.
– There are four main groups of arthropods.
– Arthropods are segmented animals with specialized segments and
appendages for an efficient division of labor among body regions.
– The body of arthropods is completely covered by an
exoskeleton, an external skeleton that provides:
• Protection
• Points of attachment for the muscles that move appendages
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Bio 10
Chapter 17
MAJOR GROUPS OF ARTHROPODS
Arachnids
Crustaceans
Millipedes and Centipedes
Insects
Laura Coronado
Bio 10
Chapter 17
Figure 17.17
Arachnids
– Arachnids:
• Live on land
• Usually have four pairs of walking legs and a specialized
pair of feeding appendages
• Include spiders, scorpions, ticks, and mites
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Bio 10
Chapter 17
Two feeding
appendages
Leg (four pairs)
Scorpion
Black widow spider
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Dust mite
Bio 10
Wood
tick
Chapter 17
Figure 17.19
Crustaceans
– Crustaceans:
• Are nearly all aquatic
• Have multiple pairs of specialized appendages
• Include crabs, lobsters, crayfish, shrimps, and barnacles
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Bio 10
Chapter 17
Two feeding
appendages
Leg (three or more pairs)
Antennae
Crab
Pill bug
Shrimp
Crayfish
Laura Coronado
Bio 10 Barnacles
Chapter 17
Figure 17.20
Millipedes and Centipedes
– Millipedes and centipedes have similar segments
over most of the body.
– Millipedes:
• Eat decaying plant matter
• Have two pairs of short legs per body segment
– Centipedes:
• Are terrestrial carnivores with poison claws
• Have one pair of short legs per body segment
Laura Coronado
Bio 10
Chapter 17
One pair of legs per segment
Two pairs of legs
per segment
Millipede
Centipede
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Bio 10
Chapter 17
Figure 17.21
Insect Anatomy
– Insects typically have a three-part body:
• Head
• Thorax
• Abdomen
– The insect head usually bears:
• A pair of sensory antennae
• A pair of eyes
– The mouthparts are adapted for particular kinds of
eating.
– Flight is one key to the great success of insects.
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Bio 10
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Head Thorax
Abdomen
Antenna
Eye
Mouthparts
Laura Coronado
Bio 10
Chapter 17
Figure 17.22
Insect Diversity
– Insects outnumber all other forms of life combined.
– Insects live in:
• Almost every terrestrial habitat
• Freshwater
• The air
– Many insects undergo metamorphosis in their
development.
– Young insects may:
• Appear to be smaller forms of the adult or
• Change from a larval form to something much different as an
adult
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Bio 10
Chapter 17
Leaf roller
Banded Orange
Heliconian
Giraffe weevil
Yellow jacket wasp
Praying
mantis
Peacock katydid
Leaf beetle
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Bio 10
Longhorn beetle
Chapter 17
Figure 17.23
The larva (caterpillar) spends
its time eating and growing,
molting as it grows.
Finally, the adult emerges
from the cocoon.
After several molts, the
larva becomes a pupa
encased in a cocoon.
Laura Coronado
Within the pupa, the larval organs break
down and adult organs develop from
cells that were dormant in the larva.
The butterfly flies off and reproduces, nourished mainly
by calories stored when it was a caterpillar.
Bio 10 Chapter 17
Figure 17.24-5
Echinoderms
– Echinoderms (phylum Echinodermata):
• Lack body segments
• Typically show radial symmetry as adults but bilateral
symmetry as larvae
• Have an endoskeleton
• Have a water vascular system that facilitates movement
and gas exchange
– Echinoderms are a very diverse group.
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Bio 10
Chapter 17
Sea star
Tube feet
Sea urchin
Sea cucumber
Laura Coronado
Bio 10
Chapter 17
Sand dollar
Figure 17.25
VERTEBRATE EVOLUTION AND
DIVERSITY
– Vertebrates have unique endoskeletons composed
of:
• A cranium (skull)
• A backbone made of a series of bones called vertebrae
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Chapter 17
Cranium
(protects brain)
Vertebra
Laura Coronado
Bio 10
Chapter 17
Figure 17.26
Characteristics of Chordates
– Chordates (phylum Chordata) all share four key
features that appear in the embryo and sometimes
the adult:
•
•
•
•
A dorsal, hollow nerve cord
A notochord
Pharyngeal slits
A post-anal tail
– Another chordate characteristic is body
segmentation, apparent in the:
• Backbone of vertebrates
• Segmental muscles of all chordates
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Bio 10
Chapter 17
Dorsal,
hollow
nerve cord
Notochord
Brain
Muscle segments
Mouth
Anus
Post-anal
tail
Pharyngeal
slits
Laura Coronado
Bio 10
Chapter 17
Figure 17.27
Chordates
– Chordates consists of three groups of invertebrates:
• Lancelets are bladelike animals without a cranium.
• Tunicates, or sea squirts, also lack a cranium.
• Hagfishes are eel-like forms that have a cranium.
– All other chordates are vertebrates.
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Bio 10
Chapter 17
Mouth
Tail
Lancelet
Tunicates
Laura Coronado
Bio 10
Chapter 17
Figure 17.28
Ancestral
chordate
Chordates
Tunicates
Lancelets
Hagfishes
Vertebrates
Lampreys
Cartilaginous
fishes
Bony fishes
Amniotes
Reptiles
Mammals
Laura Coronado
Bio 10
Chapter 17
Figure 17.29
Tetrapods
Amphibians
Fishes
– The first vertebrates were aquatic and probably
evolved during the early Cambrian period, about 542
million years ago. They:
• Lacked jaws
• Are represented today by hagfishes
– Fish Diversity Lampreys:
• Are vertebrates
• Have a cranium
• But lack jaws
Laura Coronado
Bio 10
Chapter 17
Fishes
– The two major groups of living fishes are the:
• Cartilaginous fishes (sharks and rays) with a flexible
skeleton made of cartilage
• Bony fishes with a skeleton reinforced by hard calcium
salts
– Ray-finned fishes
– Lungfishes
– Lobe-finned fishes
– Cartilaginous and bony fishes have a lateral line system
that detects minor vibrations in the water.
– To provide lift off the bottom:
• Cartilaginous fish must swim but
• Bony fish have swim bladders, gas-filled sacs that make them
buoyant
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Chapter 17
(a) Hagfish
(inset: slime)
(b) Lamprey
(inset: mouth)
Operculum
(c) Shark, a
cartilaginous fish
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Lateral line
Bio 10
Chapter 17
(d) Bony fish
Figure 17.30
Amphibians
– Exhibit a mixture of aquatic and terrestrial
adaptations
– Usually need water to reproduce
– Typically undergo metamorphosis from an aquatic
larva to a terrestrial adult
– Were the first vertebrates to colonize land
– Descended from fishes that had lungs and fins with
muscles
Laura Coronado
Bio 10
Chapter 17
(a) Tadpole and adult golden palm tree frog
Red-eyed tree frog
Texas barred tiger salamander
(b) Frogs and salamanders: the two major groups of amphibians
Laura Coronado
Bio 10
Chapter 17
Figure 17.31
Lobe-finned fish
Early amphibian
Laura Coronado
Bio 10
Chapter 17
Figure 17.32
Evolution of Terrestrial Vertebrates
– Terrestrial vertebrates are collectively called
tetrapods, which means “four feet.”
– Tetrapods include:
• Amphibians
• Reptiles
• Mammals
Laura Coronado
Bio 10
Chapter 17
Reptiles
– Reptiles (including birds) and mammals are amniotes,
which produce amniotic eggs that consist of a fluid-filled
shell inside of which the embryo develops.
– Reptile adaptations to living on land include:
• Amniotic eggs
• Scaled, waterproof skin
– Reptiles include:
•
•
•
•
•
•
Snakes
Lizards
Turtles
Crocodiles
Alligators
Birds
Laura Coronado
Bio 10
Chapter 17
Dinosaur
Snake
Lizard
Crocodile
Birds
Turtle
Laura Coronado
Bio 10
Chapter 17
Figure 17.33
Reptiles
– Nonbird reptiles are ectotherms, sometimes referred to
as “cold-blooded,” which means that they obtain their
body heat from the environment.
– A nonbird reptile can survive on less than 10% of the
calories required by a bird or mammal of equivalent size.
– Reptiles diversified extensively during the Mesozoic era.
– Dinosaurs were the largest animals ever to live on land.
Laura Coronado
Bio 10
Chapter 17
Birds
– Recent genetic evidence shows that birds evolved from a
lineage of small, two-legged dinosaurs during the great
reptilian radiation of the Mesozoic era.
– Birds have many adaptations that make them lighter in
flight:
• Honeycombed bones
• One instead of two ovaries
• A beak instead of teeth
– Unlike other reptiles, birds are endotherms, maintaining
a warmer and steady body temperature.
– Birds wings adapted for flight are airfoils, powered by
breast muscles anchored to a keel-like breastbone.
Laura Coronado
Bio 10
Chapter 17
Lower air pressure
Higher air pressure
Laura Coronado
Bio 10
Chapter 17
Figure 17.34
Mammals
– The first true mammals:
• Arose about 200 million years ago
• Were probably small, nocturnal insect-eaters
– Most mammals are terrestrial although dolphins,
porpoises, and whales are totally aquatic.
– Mammalian hallmarks are:
• Hair
• Mammary glands that produce milk, which nourishes the young
– There are three major groups of mammals:
• Monotremes, egg-laying mammals
• Marsupials, pouched mammals with a placenta
• Eutherians, placental mammals provide more intimate and
long-lasting association between the mother and her developing
young than do marsupial placentas.
Laura Coronado
Bio 10
Chapter 17
MAJOR GROUPS OF MAMMALS
Monotremes
(hatched from eggs)
Echidna adult
and egg
Marsupials
(embryonic at birth)
Eutherians
(fully developed at birth)
Kangaroo newborn and mother
Wildebeest newborn
and mother
Laura Coronado
Bio 10
Chapter 17
Figure 17.35
THE HUMAN ANCESTRY
– Humans are primates, the mammalian group that
also includes:
•
•
•
•
•
•
Lorises
Pottos
Lemurs
Tarsiers
Monkeys
Apes
– Primates evolved from insect-eating mammals during
the late Cretaceous period.
Laura Coronado
Bio 10
Chapter 17
Lemurs, lorises,
and pottos
Ancestral
primate
Tarsiers
Apes
Gibbons
Orangutans
Gorillas
Chimpanzees
Humans
Laura Coronado
Bio 10
Chapter 17
Figure 17.36
Anthropoids
Old World monkeys
Monkeys
New World monkeys
Primate Characteristics
– Primates are distinguished by characteristics that
were shaped by the demands of living in trees. These
characteristics include:
•
•
•
•
Limber shoulder joints
Eyes in front of the face
Excellent eye-hand coordination
Extensive parental care
– Taxonomists divide the primates into three main
groups.
Laura Coronado
Bio 10
Chapter 17
Three Groups of Primates
– The first group of primates includes:
• Lorises
• Pottos
• Lemurs
– Tarsiers form the second group.
– The third group, anthropoids, includes:
• Monkeys
• Hominoids, the ape relatives of humans
• And humans
Laura Coronado
Bio 10
Chapter 17
Ring-tailed
lemur
Tarsier
Black spider monkey
(New World monkey)
Patas monkey (Old World monkey)
Gorilla (ape)
Orangutan (ape)
Gibbon (ape)
Chimpanzee
(ape)
Laura Coronado
Bio 10 Chapter
17
Human
Figure 17.37
The Emergence of Humankind
– Humans and chimpanzees have shared a common
African ancestry for all but the last 5–7 million years.
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Bio 10
Chapter 17
Some Common Misconceptions
– Chimpanzees and humans represent two divergent
branches of the anthropoid tree that each evolved from a
common, less specialized ancestor.
– Our ancestors were not chimpanzees or any other modern
apes.
– Human evolution is not a ladder with a parade of fossil
hominids (members of the human family) leading directly
to modern humans.
– Instead, human evolution is more like a multibranched
bush than a ladder.
– At times in hominid history, several different human
species coexisted.
– Upright posture and an enlarged brain appeared at
separate times during human evolution.
– Different human features evolved at different rates.
Laura Coronado
Bio 10
Chapter 17
0
?
Paranthropus
boisei
0.5
Homo
neanderthalensis
1.0
1.5
Millions of years ago
2.0
2.5
Homo erectus
Paranthropus
robustus
3.0
3.5
Homo
habilis
Australopithecus
africanus
4.0
4.5
5.0
5.5
Australopithecus
afarensis
6.0 Ardipithecus
ramidus
Laura Coronado
Bio 10
Chapter 17
Figure 17.38
Homo
sapiens
Australopithecus and the Antiquity of
Bipedalism
– Before there was the genus Homo, several hominid
species of the genus Australopithecus walked the
African savanna.
– Fossil evidence pushes bipedalism in A. afarensis
back to at least 4 million years ago.
Laura Coronado
Bio 10
Chapter 17
(a) Australopithecus
afarensis skeleton
(b) Ancient footprints
Laura Coronado
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Chapter 17
(c) Model of an
Australopithecus
afarensis male
Figure 17.39
Homo Habilis and the Evolution of
Inventive Minds
– Homo habilis, “handy-man”:
• Had a larger brain, intermediate in size between Australopithecus
and modern humans
• Walked upright
• Made stone tools that enhanced hunting, gathering, and
scavenging on the African savanna
– Homo erectus was the first species to extend humanity’s
range from Africa to other continents.
•
•
•
•
The global dispersal began about 1.8 million years ago.
Was taller than H. habilis
Had a larger brain
Gave rise to Neanderthals
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Chapter 17
The Process of Science:
What Did Neanderthals Look Like?
– Observation: Geneticists noted that a gene mclr has a
large effect on human hair and skin pigmentation.
– Question: What form of the gene would be found in
Neanderthals?
– Experiment: The mclr pigment gene was isolated from
Neanderthal DNA.
– Results:
• The Neanderthal gene contained a mutation not found in modern
humans.
• Human cells engineered to carry the Neanderthal version of the
gene reacted in ways that suggests that Neanderthals had red
hair and pale skin.
Laura Coronado
Bio 10
Chapter 17
Laura Coronado
Bio 10
Chapter 17
Figure 17.40
The Origin and Dispersal of Homo Sapiens
– The oldest known fossils of our own species, Homo
sapiens:
• Were discovered in Ethiopia
• Date from 160,000 to 195,000 years ago
• DNA studies strongly suggest that all living humans can trace
their ancestry back to a single African Homo sapiens woman who
lived 160,000 to 200,000 years ago.
– Fossil evidence suggests that our species emerged from
Africa in one or more waves.
– The oldest fossils of H. sapiens outside of Africa are
50,000 years old.
– The oldest fossils of humans in the New World are
uncertain, but are at least 15,000 years old.
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Bio 10
Chapter 17
Cultural Evolution
– Culture is the social transmission of accumulated
knowledge, customs, beliefs, and art over generations.
– Culture is primarily transmitted by language.
– Cultural evolution has had three major stages.
• First, nomads who were hunter-gatherers:
–
–
–
–
Made tools
Organized communal activities
Divided labor
Created art
• The second main stage of cultural evolution was the
development of agriculture in Africa, Eurasia, and the
Americas, about 10,000 to 15,000 years ago.
• The third stage was the Industrial Revolution, which began
in the 1700s.
Laura Coronado
Bio 10
Chapter 17
Laura Coronado
Bio 10
Chapter 17
Figure 17.41
– The global
consequences of
human evolution
have been
enormous. Humans
can:
• Defy our physical
limitation
• Shortcut biological
evolution
• Change the
environment to meet
our needs
Laura Coronado
Bio 10
Chapter 17
Evolution Connection:
Recent Human Evolution
– Biologists have identified a number of genes that
appear to be undergoing rapid evolution.
– One such gene is the FOXP2 gene known to function
in speech.
– Studies of the FOXP2 gene indicate that:
• The human form likely arose within the last 100,000 years
• Neanderthals had the same version of FOXP2 as modern
humans
Laura Coronado
Bio 10
Chapter 17
Sponges
Cnidarians
Ancestral
protist
Molluscs
Flatworms
True tissues
Annelids
Roundworms
Arthropods
Bilateral symmetry
Echinoderms
Chordates
Laura Coronado
Bio 10
Chapter 17
Figure 17.UN15
Sponges
Cnidarians
Molluscs
Flatworms
Annelids
Roundworms
Arthropods
Echinoderms
Laura Coronado
Chordates
Bio 10 Chapter 17
Figure 17.UN01
Tunicates
Lancelets
Hagfishes
Lampreys
Cartilaginous fishes
Bony fishes
Amphibians
Reptiles
Laura Coronado
Bio 10
Mammals
Chapter 17
Figure 17.UN11
Ancestral
chordate
Chordates
Tunicates
Lancelets
Hagfishes
Vertebrates
Lampreys
Cartilaginous
fishes
Bony fishes
Mammals
Laura Coronado
Bio 10
Chapter 17
Amniotes
Reptiles
Tetrapods
Amphibians
Figure 17.UN16