Human Evolution
Misconceptions
Avoid common misconceptions when thinking about
human evolution.
http://factsanddetails.com/media/2/20120201Charles_Darwin_as_an_ape_(1871).jpg
Misconceptions
First, chimpanzees didn’t
‘become’ humans or give birth
to them. As with many of the
other lineages of primates,
many of these branches lived
alongside one another for at
least some of their respective
histories.
The various lineages acquired
a variety of derived
characters during their
divergence from the common
ancestor.
Misconceptions
Human evolution is NOT a direct ladder that leads from
Homo sapiens directly back to the ancestral ape.
http://2.bp.blogspot.com/-CfC3oepWZjk/UFln-UgyPdI/AAAAAAAACTo/G2PTqLFvkwg/s1600/IMG_001.jpg
Misconceptions
Homo sapiens ARE the
end result of a highly
branched evolutionary
tree, and NOT a straight
line path.
Misconceptions
The fossil record of human
ancestry is incomplete and
presents challenges. We
cannot, with absolute
certainty, determine the exact
time when a certain species
originated and when it
became extinct.
http://commons.wikimedia.org/wiki/File:Lucy_blackbg.jpg
Misconceptions
Early fossil record is fragmented and
scarce because often times the
organisms were not buried, rather
they were killed by predators so the
bones were spread about, and very
few of them died in a location where
they would be preserved.
There are numerous ‘missing links’ so
it cannot be ensured that the
hypothesized evolution of hominids is
completely accurate.
http://commons.wikimedia.org/wiki/File:Lucy_blackbg.jpg
Modern Primates
A primate is a member of the
mammalian order Primates.
Modern primates evolved more
than 50 million years ago, and
most have gone extinct.
http://thedispersalofdarwin.wordpress.com/category/natural-history/
Fossil evidence indicates small,
insect-eating mammals with large
eyes and small sharp teeth gave
rise to the first primates-Algeripithecus is pictured to right.
http://cdn.physorg.com/newman/gfx/news/hires/2009/theafricanor.jpg
Baby Pygmy Marmosets
http://www.factzoo.com/sites/all/img/mammals/monkeys/baby-pygmy-marmosets.jpg
Modern Primates
There are many groups of primates including humans, apes,
monkeys, lemurs, tarsiers and they can be divided into either
the New World monkeys or the Old World monkeys.
http://www.sheppardsoftware.com/content/animals/animals/mammals/apevsmonkey.htm
Modern Primates
Old World Monkeys and Apes are native to Africa and Asia.
They have non-grasping tails.
They are catarrhines meaning they have noses with nostrils that
face downward.
http://ars.els-cdn.com/content/image/1-s2.0-S0960982212008068gr1.jpg
http://www.sheppardsoftware.com/content/animals/animals/mammals/apevsmonkey.htm
Modern Primates
New World Monkeys are native to central and South America.
Have prehensile tails.
They are platyrrhines meaning they have flat noses with nostrils
that face outward.
http://ars.els-cdn.com/content/image/1-s2.0-S0960982212008068gr1.jpg
http://www.sheppardsoftware.com/content/animals/animals/mammals/apevsmonkey.htm
Major anatomical features defining humans as
primates
Old World monkeys include baboons, apes, orangutans,
bonobos, chimpanzees, gorillas, and gibbons.
http://animals.nationalgeographic.com/animals/mammals/chimpanzee/
http://en.wikipedia.org/wiki/File:Olive_baboon_Ngorongoro.jpg
https://secure3.convio.net/sdzoo/images/adopt/adopt_bonobo.jpg
http://news.discovery.com/animals/zooms/ape-skull-20-million-found-uganda.html
http://4.bp.blogspot.com/_W90V87w3sr8/TMf7rliXGSI/AAAAAAAAAEk/keKwAtKZfoE/s1600/Orangutan2_468x619.jpg
http://www.esa.org/esablog/research/those-gibbons-sure-can-wail/
http://www.huffingtonpost.com/elizabethgordon/guide-to-gorilla-trekking_b_1803602.html
Major anatomical features defining humans as
primates
Monkeys, apes, and humans
are known as Simian (and
sometimes Anthropoiea) and
differ from other primates in a
number of ways.
All Old World monkeys are
catarrhines meaning they have
‘hooked’ noses with nostrils
that face downward.
http://crujonessociety.com/wordpress/wp-content/uploads/2009/02/monkeypa2_450x300.jpg
Major anatomical features defining humans as
primates
All have grasping hands (opposable thumbs) and most
have grasping feet.
They have flattened nails instead of claws which enable
the manipulation of tools.
Primate eyes are located at the front of the face giving
binocular vision and enabling depth perception.
Major anatomical features defining humans as
primates
A primate’s shoulder joints allow for movement in 3
dimensions and are modified for upright posture.
Parental care and long nurturing of offspring.
Usually give birth to a single offspring.
Major anatomical features defining humans as
primates
Other defining characteristics that are
unique to humans:
Humans have a larger brain and are capable
of language, symbolic thought, artistic
expression, and the manufacture and use of
complex tools.
http://upload.wikimedia.org/wikipedia/commons/d/db/Primate_skull_series_with_legend_cropped.png
Humans also have reduced jawbones and
jaw muscles, and a shorter digestive tract.
Gorilla
We have reduced canine teeth and flat
faces.
Neanderthal
Australopithecus
H. steinheimensis
Homo erectus
H. sapien
http://upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Craniums_of_Homo.svg/300px-Craniums_of_Homo.svg.png
Hominid and hominin
All early primates walked on four limbs.
There are two terms that need to be distinguished: Hominid and
Hominin.
Hominid is a general term that describes all living and extinct
Great Apes--humans, chimps, gorillas, etc. This group may have
evolved about 7 million years ago.
Hominin is the group of primates consisting of modern humans,
extinct human species, and all immediate ancestors-including
members of the genera Homo, Australopithecus, Paranthropus,
and Ardipithecus.
Hominid and hominin
Hominins differ from other primates in many ways.
1. They are bipedal
2. They have S-shaped spines (as opposed to C-shaped).
3. Our arms are relatively short.
http://www.fallingpixel.com/chimpanzee-skeleton-3d-model/39802
http://www.cedars-sinai.edu/Patients/Programs-and-Services/Spine-Center/Anatomy-of-the-Spine/Curves-of-the-Spine.aspx
Hominid and hominin
Hominins differ from other primates in many ways.
4. We have a bowl-shaped pelvis.
5. Our thighs angle under our bodies.
http://www.healingourchildren.net/safe_natural_birth.htm
http://en.wikipedia.org/wiki/File:Human_skeleton_front_en.svg
Hominid and hominin
Hominins differ from other
primates in many ways.
6. Our spinal cord exits at the
base of our skull.
7. We have smaller canine
teeth than those of other
primates.
http://johnhawks.net/taxonomy/term/998
Hominin
The majority of the information
we’ve got about early hominins
comes from fossils.
Unfortunately, fossils of
hominins are usually
incomplete.
However, scientists can use
the fossils to identify and
classify the species enabling
various inferences such as
where and when the species in
question lived.
http://commons.wikimedia.org/wiki/File:Lucy_blackbg.jpg
http://www.dailymail.co.uk/sciencetech/article-1217400/Ardi-skeleton-Ethiopia-closestthing-missing-link-humans-apes.html
Trends in the human lineage
There are some major trends
that define the many different
species of the human
lineage.
For instance: Ardipithecus
ramidus, or “Ardi” was small
(about 50kg) and was at
least partially bipedal. Ardi
also had a protruding jaw.
http://www.dailymail.co.uk/sciencetech/article-1217400/Ardi-skeleton-Ethiopia-closest-thing-missing-link-humans-apes.html
Trends in the human lineage
Australopithecus species
lived between 4 and 2
million years ago and likely
comprised a paraphyletic
group.
The earliest member of this
group lived along side Ardi.
Trends in the human lineage--australopithecus
Australopithecus africanus was
discovered in 1924 and lived
between 3 and 2.4 million years
ago.
This species walked fully upright
and had human-like hands and
teeth.
Its brain was about ⅓ the size of
modern humans.
They had a flatter face and large
molars for a plant based diet.
http://australianmuseum.net.au/image/Australopithecus-africanus-skull-side-view/
Trends in the human lineage--australopithecus
In 1974, a 3.2 million year old fossil
belonging to the species
Australopithecus afarensis was found.
It has since been termed “Lucy” and
was about 1m tall.
Trends in the human lineage--australopithecus
Lucy was bipedal and
had a brain about the
size of a softball (about
the size of a modern
chimp’s brain), they
have a long lower jaw,
and had relatively long
arm that enabled
arboreal locomotion.
http://www.prehistoricstore.com/item.php?item=1387
Trends in the human lineage--genus homo
The earliest fossils
belonging to the genus
Homo include Homo habilis,
Homo erectus, and Homo
neanderthalensis.
The Homo genus is
currently dated to about 2.4
million years ago.
http://www.theosophy-nw.org/theosnw/evol/ev-ibel2.htm
Trends in the human lineage--genus homo
In comparison to
australopiths, Homo
habilis had a short jaw and
a larger brain volume, and
they were the first to have
the ability to use sharp,
stone tools.
http://www.prehistoricstore.com/item.php?item=1387
The smaller teeth were an
adaptation for a meatier
diet.
http://hoopermuseum.earthsci.carleton.ca/emily/eighth.html
QuickTime™ and a
H.264 decompressor
are needed to see this picture.
Trends in the human lineage--genus homo
Homo erectus is believed to have originated in Africa and
is thought to be the first hominin to have migrated out of
Africa.
http://stryder.com/staid/migration_of_anatomically_modern_humans_bldg_blog_2008.jpg
Trends in the human lineage--genus homo
Homo erectus used more
complex tools than H. habilis,
meat was a significant part of
the diet, and there were
further changes in their teeth.
http://web.mesacc.edu/dept/d10/asb/origins/hominid_journey/pictures/afar_hs.teth.gif
A. afarensis H. erectus
http://web.mesacc.edu/dept/d10/asb/origins/hominid_journey/pictures/afar_hs.teth.gif
H. habilis
http://www.macroevolution.net/homo-habilis-maxilla-oh-65.html
H. erectus H. sapien
Trends in the human lineage--genus homo
The oldest fossils of
hominins found outside of
Africa are about 1.8 million
years old and were found in
Southern Russia (former
Soviet Georgia), referred to
as Dmanisi.
The fossil may be that of
Homo erectus.
http://www.freerepublic.com/focus/f-news/1012772/posts
Trends in the human lineage--genus homo
Homo erectus may have
migrated as far as
Indonesia and is believed
to have become extinct
sometime between
200,000 and 50,000
years ago.
http://www.freerepublic.com/focus/f-news/1012772/posts
QuickTime™ and a
decompressor
are needed to see this picture.
Trends in the human lineage--genus homo
Homo neanderthalensis
was discovered in 1856.
Neanderthals comprise a
fossil lineage that lived
between 350,000 and
40,000 years ago. These
hominins had unusually
thick bones and a
prominent brow.
http://essayweb.net/history/ancient/prehistory_03.shtml
Trends in the human lineage--genus homo
They lived in Europe, the Near
East, central Asia, and
Southern Siberia.
Their brain was as large as
present-day humans, they
buried their dead, and made
hunting tools from stone and
wood.
http://www.dailymail.co.uk/sciencetech/article-1273904/Neanderthal-DNA-reveals-ancestors-DID-interbreed-extinct-species.html
Trends in the human lineage--genus homo
Homo sapiens are believed to have originated in Africa.
Older species gave rise to later ones, and the oldest
known fossils of our lineage have been found at two
different sites in Ethiopia and were dated to 195,000 and
160,000.
The early humans had less pronounced brow ridges than H.
neanderthalensis and H. erectus.
They have pelvic changes that support organs in walking.
The legs are stronger and longer and the arms become shorter and weaker.
The opposable toe is lost and the foot is more rigidly shaped and platform
like.
Trends in the human lineage--genus homo
1. Australopithecus afarensis
2. Australopithecus africanus
3. Homo habilis
4. Homo erectus
5. Neanderthal
http://www.sculpturegallery.com/sculpture/hominid_series_of_five_skulls.html
Trends in the human lineage--genus homo
The oldest H. sapien fossils found outside of Africa are
from the Middle East and date to about 115,000 years
old.
Humans are believed to have spread out of Africa in
waves, and this evidence is supported by a variety of
DNA studies.
Humans are believe to have arrived in the New World
about 15,000 years ago.
Cultural evolution
As time progressed, humans evolved further and so too
did their various cultures.
Cultural evolution refers to changes in the behavior of a
species. For instance, as the Homo lineage progressed
through time, the tools became more advanced, they
branched further out from their ancestral land, and their
diets changed.
Cultural evolution
Cultural evolution has spanned a long period of time.
It began with primates being nomadic (hunter-gatherers).
They progressed to an agricultural society whereby they
settled in one spot and grew crops that could support a
large population of people.
Currently, we are in the industrial/post-industrial age with
a society that has the ability to manufacture much of what
it needs to survive.
Cultural evolution
It could be argued that our intelligence hasn’t changed
much since nomadic times. What have changed are our
technologies and experiences we have available to us.
So, what led to these advances in human societies?
Cultural evolution
Largely, our advancements are due to the expansion of
the human brain.
Cultural evolution has changed far more quickly than
genetic evolution of humans have.
Our behaviors have changed greatly as have our abilities
to change the environment around us (as opposed to
changing to suit our environment).