Transcript Human biogeo and inv..

Hominidae is family containing
great apes and humans
Species that had many similarities to
humans, and that were in the genera
Australopithecus and Homo have gone
extinct. Homo sapiens is the only species
that survives today of these two genera.
Oldest fossil species of these two genera is
Australopithecus afarensis, from about 3.7
mya in the Africa
For the next 1-2 million years, our relatives
lived in eastern and southern Africa in
savannas
• The first fossil species of the genus
Homo is Homo habilis. This species
made simple stone tools which may
have been used in butchering animals
and to cut vegetation.
2.0 mya Homo erectus evolved
H. erectus was taller (5-6') than H. habilis,
had a larger brain, and developed more
advanced tools.
Did H. erectus use fire?
Fire could be used to hunt game, for
protection against predators and to cook
toxic chemicals out of plant foods.
Possibly the use of fire allowed H. erectus to
move into other habitat types in Africa.
Check out movie, Quest for Fire
Over the next 1.4 my, H. erectus
engaged in migrations within and out
of Africa
Populations that evolved in subSaharan Africa would have to cross
the Sahara, perhaps during
interglacial periods
After interglacial periods a landbridge
connecting Africa and Eurasia, the Arabian
peninsula, allowed H. erectus to move into
Europe and Asia, about 800,000 years
ago
H. erectus populations were well-distributed
in Asia and Europe by 500,000 years ago
Many anthropologists believe H. sapiens evolved
from H. erectus in Africa about 300,000 years ago,
again in savannas
These early men and women had heavier
bones than today, thicker skulls, and brow
ridges, i.e. they are archaic H. sapiens but
still H. sapiens, with brains as big as
modern humans.
Then, H. sapiens replaced H. erectus
populations throughout world.
Neanderthals (H. sapiens)—lived in Europe,
Middle East, and Asia, 130,000 to 35,000 years
ago
Neanderthals used tools and had burial
rituals
Both Neanderthals and modern humans
evolved from archaic H. sapiens
Hypotheses as to where modern
Homo sapiens came from
Modern H.s. evolved several times from
groups of archaic H.s. in Europe, Asia,
and Africa.
H.s. evolved one time in Africa. Archaic
H.s., Neanderthals included, were
evolutionary dead ends.
Biochemists today try to recover DNA
samples from fossilized skulls of
Neanderthals to compare with DNA of
living humans, to see whether
Neanderthals contributed genes to modern
pops
Work published Nov. 2006
DNA came from leg bone of male
Neanderthal
Suggests Neanderthals and modern
humans diverged from a common
ancestor between 370,000 and 500,000
years ago
Suggests Neanderthals and modern
humans did not interbreed (much?)
H. sapiens then followed the path of H.
erectus into the Sahara and across the
Arabian peninsula into Europe and Asia.
By 100,000 years ago H. sapiens moved
out of Africa and started replacing H.
erectus across its range.
How was H. erectus replaced?
Interbreeding?
Losing in competition for resources to H.
sapiens?
From 75,000 to 50,000, glaciers were at a
maximum around the world.
50,000 years ago there was a brief
interglacial and it is at this time that first
fossils of H. sapiens are found in Europe.
It is hypothesized that H. sapiens'
development of projectile weapons and
group hunting techniques allowed them to
take relatively large game, like mammoths,
whose bones could be used for tools and
to construct shelters.
Theory of “creative explosion”
Modern human behavior didn’t really take off
until Homo sapiens was in Europe 40,000
years ago
Modern human behavior
Refined tool-making from bones, art,
symbols on tools.
Creative explosion hypothesis may be a
result of a biased sampling of
archaeological sites, i.e., many sites in
Europe were explored while few in Africa
received the same level of attention.
Recent finds from Blombos Cave in
South Africa
Bone tools, some with etching on them that
suggest the use of symbols, a behavior thought
to be linked to abstract thought and speech.
Bone tools were likely awls for working leather,
others were weapons, probably spear points.
The finds are about 70,000 years old and show
that the inhabitants of the cave ate antelope and
fish
40,000 to 50,000 years ago humans were
up to the limits of the ice sheets in Europe
and Asia.
25,000-18,000 years ago, much of northern
regions was glaciated and sea level was
relatively low so that Beringia formed
Shortly before 25,000 ya humans first invaded
Alaska, perhaps following the species they
hunted.
Even though colonists made it into Alaska, they
may have been prevented from moving further
south by glaciers that would have lasted until
about 16,000 years ago.
When glaciers receded, colonists moved south
and eventually spread throughout North and
South America.
It's possible that some earlier movements
occurred, if, for example, ice-free areas
existed along the Pacific coast, or in the
interior.
However, colonization of North and South
America before about 15,000 years ago is
debatable.
The range expansion of humans throughout
North and South America in 15,000 years
is one of the most rapid and extensive
range expansions of which we have
evidence.
What allowed the Homo species to expand
their range so quickly?
Their ability to live in and modify their
environment, e.g.
The use of tools and fire.
For example, they started building shelters.
Colonization by humans of oceanic islands
was taking place concurrently with some
of the events of above
Some of the islands were not islands at
points in the past.
For example, colonization of the Sunda
region of Asia was a result of landbridges
available 75,000 years ago at a time of
glaciation.
Wallacea (Sunda) was probably relatively
easily colonized because the many islands
were close to each over--i.e. less than 40
miles apart.
New Guinea may have been reached
70,000 years ago and then colonization of
Australia and Tasmania could have
occurred, again partly when landbridges
were present.
Islands relatively close to Sahul like the
Bismarcks were colonized by about
32,000 but more distant islands were not
colonized till fairly recently (last 4000
years), when Polynesians had developed
navigational abilities.
I
Important features in the evolution of population
leading to H. sapiens
Evolution of erect stance--hands are free for
other activities
Enlargement of brain
Evolution of long period or parental care,,
providing us with the basis of culture—
accumulated knowledge, customs
transmitted over generations.
Complex language
Culture is what makes human unique
species, allows us to pass on knowledge
which allows us to manipulate
environments to meet our needs
3 stages of human culture
Scavenging/gathering/hunting Scavenging
from other animals was probably important
part of getting food for early humans.
Only in the last 50,000 (maybe 70,000?)
years has toolmaking become
sophisticated enough that hunting could
make significant contribution to diet.
3 stages of human culture
Agriculture-developed in Eurasia and
Americas 10-15,000 years ago
Earliest was slash and burn
As people settled down, populations
became bigger.
As agriculture became more efficient, some
people could specialize in other activities
(technology, industry, and the arts)
3 stages of human culture
Machine age—Industrial revolution, means
we have a greater need for fuel, death
rates have declined, so that our population
is growing.
In terms of organic evolution, we probably
haven’t changed that much from our
ancestors of 10,000 years ago.
Culturally, we have changed, much faster
than organically
For example, 100 years ago, no one drove
cars--today everyone does. This is a
change in behavior caused by cultural,
rather than organic evolution.
One consequence of our cultural evolution is
our impact on species invasions
Species invasions and biotic
homogenization
Introductions of non-native species have
become more and more prevalent over
time with the increasing ease with which
humans traverse the globe
In historical times, many of the invasions
have been a result of settlers in a new
area wanting to bring familiar plants and
animals with them
Most commonly introduced
mammals include
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rabbits
domestic cats
several species of rats
house mice
domestic pigs
domestic cattle
domestic goats
domestic dogs
Most commonly introduced birds
include
• waterfowl species
• gallinaceous birds (chickens, pheasants,
etc.)
• pigeons
• parrots
Geographic patterns of
introductions
Palearctic region has largest number of bird
and mammal introductions and has the
largest area
Australia has a large number of
introductions as well, despite its relatively
small size
Oceanic islands have been the hardest hit
with 60% of all bird and mammal
introductions
Patterns with non-native plant
introductions are similar
Islands often have a substantial part of their
biotas composed of non-native species.
New Zealand has approximately 1790 native
plant species and 1570 exotics.
Hawaii has 1150 native plant species and
850 exotics.
Aquatic systems also affected—In Arizona,
67 of 95 breeding fish species, 71%, are
non-native
Much of the biota of isolated oceanic islands
is endemic, found nowhere else, making
their displacement by exotics particularly
harmful to global biodiversity.
The species of islands and Australia, in
particular, are more vulnerable to being
negatively impacted by exotics than
mainland species. For example, over half
of the terrestrial vertebrate species of
Australia are negatively affected by exotics
whereas for the other continents the value
is 0-10% negatively affected.
Hawaiian birds
40% of avifauna is non-native
38 bird species introduced since 1800 as
game birds or because the species were
ornate
14 native species have gone extinct since
1800
New Zealand mammals
2 native species—bats
26 non-native species
Introduced species’ effects on
native species
Prey on native animals and plants (reduce
resource base for natives)
Carry introduced diseases
Hybridize with native species
Four subspecies of Galapagos
tortoises went extinct
Introduced rats ate eggs
Introduced cats and dogs ate hatchlings
Introduced goats ate tortoises food plants
Why are island communities
susceptible to exotics?
They tend to be depauperate
They tend to have small population sizes of
species leading to more extinction
They tend to be isolated, with fewer chances
for populations to be “rescued”
They tend to have large amounts of
converted habitat
Biotic homogenization— the replacement of local
biotas by non-indigenous species that can coexist
with humans
Homogecene coming?
Reduced habitat heterogeneity
Increased ease of movement between
habitats
Both of the above increase homogenization
NPS and mountain goats
“conserve the scenery and the natural and
historic objects and wildlife therein and to
provide for the enjoyment of the same in
such manner and by such means as will
leave them unimpaired for the enjoyment
of future generations".
Late 1920s 12 mountain goats (Oreamnos
americanus) from Canada and Alaska
were released on the northern edge of the
Olympic peninsula.
By the 1980s the population had reached
approximately 1200 and goats were found
in groups throughout the mountain range.
Park biologists noted trampling, wallowing,
and grazing of much of the vegetation,
including some species that are endemic
to the peninsula.
Removal efforts were initiated in the 1980s
and included sterilization of individuals and
live removal of some of the goats.
1990 the removal program ended, after 407
individuals had been removed from the
park. Program stopped because of its
expense and questions about
effectiveness.
Report that came out in 2000 by independent
group, Conservation Biology Institute, contracted
by the Park Service
The goats were not native
Previous studies, because of their design,
had not definitively demonstrated that
goats caused serious problems to
populations and communities in the park
Removal was feasible
Previous reviews of potential control
methods concluded that shooting is the
most feasible removal method
Other techniques tried:
– various types of snares and nets to catch the
goats and birth control techniques including
chemical sterilization, iuds, tubal ligations and
ovariectomies
Costs of techniques
Financial
Risk of injury/infection to workers/goats
Report concluded that decision had to made
as to the importance of the three criteria
regarding whether removal should be
implemented.
As of 12-6-04 the park was continuing to
monitor and census the goats but there
were no removal programs planned
2005—some goats fitted with GPS radio
collars to help biologists estimate numbers
of goats and to look at habitat selection
2006—survey being conducted to refine
census techniques