O - r - i - g - i - n - s / E - v - o - l - u - t - i - o - n
(Top Posts - Science - 081703; updated 081609)

Humans?

A blip in time.

- - -

Links to a comprehensive view (the standard
origins links which I've been maintaining for the
last few years) and links expanding on -and-
complementing that view are included in this
post.

- - -

Meanwhile ...

Where did we come from? What are our origins?
How did we evolve?

. . . . . . . .

Intelligent Designer / 'Irreducible Complexity' /
God / 'First Cause' (041001)
http://prohuman.net/science/intelligent_designer.htm
"The evidence is clear that Intelligent Designer
and so-called 'irreducible complexity' are little
more than code-words for God and that, in fact,
within the area of remaining unknowns regarding
the origins of the universe and life, science is
humankind's only legitimate hope as the myths
from the caves of human ignorance just don't
cut it anymore. ..."

- - -

Origins of Energy, Matter, Space
Time, and Life (040701)
http://prohuman.net/science/origins.htm
"No god(s) required or desired. ..."

- - -

Everything From Everlasting
Not-Quite Nothing ... (040401)
http://prohuman.net/science/everything_nothing.htm
"... well, not really from not-quite nothing,
more like from a world that's theoretically
everywhere and every'when' while at the same
time nowhere in our substantive experience,
a world that has always been and will always
be, the sub-atomic quantum world ..."

- - -

DRAMATIC Discoveries About
What Humans Really Are (021801)
http://prohuman.net/science/what_humans_are.htm
"One comment - This post includes details
on one of the most exciting and dramatic
advances in human understanding of our
true place in the grand scheme of life and
matter ..."

- - -

Discovery Implies Life Could Be
Everywhere In the Universe (013001)
http://prohuman.net/science/life_everywhere.htm
"... Scientists have managed to create
'primitive cells' in an experiment which
may indicate that life began in space
and was delivered to Earth. ..."

- - -

Search for Human Origins (070100)
http://prohuman.net/science/search_human_origins.htm
"Fascinating web resource (September, 1999)
from the Discovery Channel, with details on
the whys and wherefores of the search for
human origins ... great for kids and adults
alike, puts TRUE science by TRUE scientists
into perspective! ..."

- - -

History/Origins/Future of Energy,
Matter, Space, Time, and Life (Index)
Reprise/Intro
http://prohuman.net/origins_august2009intro.htm

1 of 7: From Past Infinity to ~3.5 Billion Years Ago
  
http://prohuman.net/origins_1_of_7.htm

2 of 7: From ~3.5 Billion to ~359 Million Years Ago
  
http://prohuman.net/origins_2_of_7.htm

3 of 7: From ~359 Million to ~145 Million Years Ago
  
http://prohuman.net/origins_3_of_7.htm

4 of 7: From ~145 Million to ~23 Million Years Ago
  
http://prohuman.net/origins_4_of_7.htm

5 of 7: From ~23 Million to ~2 Million Years Ago
  
http://prohuman.net/origins_5_of_7.htm

6 of 7: From ~2 Million to ~32,000 Years Ago
  
http://prohuman.net/origins_6_of_7.htm

7 of 7: From ~30,000 Years Ago to the Future & Infinity
  
http://prohuman.net/origins_7_of_7.htm

* Bonus *

For thorough understanding of fundamental processes
and perspectives on biology:

On-line Biology Book: Table of Contents
  
http://www.estrellamountain.edu/faculty/farabee/biobk/biobooktoc.html

- - -

Science and Creationism - A View From the National
Academy of Sciences
http://books.nap.edu/html/creationism/
"Scientists have considered the hypotheses proposed
by creation science and have rejected them because
of a lack of evidence.

Furthermore, the claims of creation science do not
refer to natural causes and cannot be subject to
meaningful tests, so they do not qualify as scientific
hypotheses.

In 1987 the U.S. Supreme Court ruled that creationism
is religion, not science, and cannot be advocated in
public school classrooms.

And most major religious groups have concluded
that the concept of evolution is not at odds with their
descriptions of creation and human."

---

Teaching About Evolution and the Nature of Science
Chapter 1 - Why Teach Evolution
http://www.nap.edu/readingroom/books/evolution98/evol1.html
"Why is it so important to teach evolution?"

---

Teaching About Evolution and the Nature of Science
Chapter 2 - Major Themes in Evolution
http://www.nap.edu/readingroom/books/evolution98/evol2.html
"The world around us changes. This simple fact is
obvious everywhere we look. Streams wash dirt and
stones from higher places to lower places. Untended
gardens fill with weeds. Other changes are more gradual
but much more dramatic when viewed over long time
scales."

---

Teaching About Evolution and the Nature of Science
Chapter 3 - Evolution and the Nature of the Universe
http://www.nap.edu/readingroom/books/evolution98/evol3.html
"Science is a particular way of knowing about the world.
In science, explanations are restricted to those that can
be inferred from confirmable data-the results obtained
through observations and experiments that can be sub-
stantiated by other scientists.

Anything that can be observed or measured is amenable
to scientific investigation. Explanations that cannot be
based on empirical evidence are not a part of science.

The history of life on earth is a fascinating subject that
can be studied through observations made today, and
these observations have led to compelling accounts of
how organisms have changed over time."

---

Teaching About Evolution and the Nature of Science
Chapter 4 - Evolution and National Science Education Standards
http://www.nap.edu/readingroom/books/evolution98/evol4.html
"Over the last six years, several major documents have
been released that describe what students from kinder-
garten through twelfth grade should know and be able
to do as a result of their instruction in the sciences. ...

These documents agree that all students should leave
biology class with an understanding of the basic
concepts of biological evolution and of the limits,
possibilities, and dynamics of science as a way of
knowing."

---

Teaching About Evolution and the Nature of Science
Chapter 5 - Frequently Asked Questions About Evolution
and the Nature of Science
http://www.nap.edu/readingroom/books/evolution98/evol5.html
"Teachers often face difficult questions about evolution,
many from parents and others who object to evolution
being taught.

Science has good answers to these questions, answers
that draw on the evidence supporting evolution and
on the nature of science. This chapter presents short
answers to some of the most commonly asked questions."

---

Teaching About Evolution and the Nature of Science
Chapter 6 - Activities for Teaching About Evolution
and the Nature of Science
http://www.nap.edu/readingroom/books/evolution98/evol6.html
"Prior chapters in this volume answer the what and why
questions of teaching about evolution and the nature of
science. As every educator knows, such discussions only
set a stage. The actual play occurs when science teachers
act on the basic content and well-reasoned arguments for
inclusion of evolution and the nature of science in school
science programs."

---

Teaching About Evolution and the Nature of Science
Chapter 7 - Selecting Instructional Materials
http://www.nap.edu/readingroom/books/evolution98/evol7.html
"Quality instructional materials are essential in teaching
about evolution and the nature of science. It also is
important to consider the context within which specific
materials will be used."

---

Teaching About Evolution and the Nature of Science
Appendix A - Six Significant Court Decisions Regarding
Evolution and Creationism Issues
http://www.nap.edu/readingroom/books/evolution98/app-a.html
"The following are excerpts from important court decisions
regarding evolution and creationism issues. The reader is
encouraged to read the full statements as need and time
allows."

---

Teaching About Evolution and the Nature of Science
Appendix B - Excerpt from "Religion in the Public
Schools: A Joint Statement of Current Law"
http://www.nap.edu/readingroom/books/evolution98/app-b.html
"Schools may teach about explanations of life on earth,
including religious ones (such as 'creationism'), in com-
parative religion or social studies classes. In science
class, however, they may present only genuinely scientific
critiques of, or evidence for, any explanation of life on
earth, but not religious critiques (beliefs unverifiable by
scientific methodology)."

---

Teaching About Evolution and the Nature of Science
Appendix C - Three Statements in Support of Teaching
Evolution from Science and Science Education Organizations
http://www.nap.edu/readingroom/books/evolution98/app-c.html

---

Teaching About Evolution and the Nature of Science
Appendix D - References for Further Reading and
Other Resources
http://www.nap.edu/readingroom/books/evolution98/app-d.html

---

Teaching About Evolution and the Nature of Science
Appendix E - Reviewers
http://www.nap.edu/readingroom/books/evolution98/app-e.html

- - -

From The Simon & Schuster Encyclopedia of
Dinosaurs & Prehistoric Creatures : A Visual
Who's Who of Prehistoric Life, by Douglas Palmer,
Barry Cox (Editor), R. J. G. Savage, Brian Gardiner,
Douglas Dixon
http://www.amazon.com/exec/obidos/ASIN/0684864118

The first large fossil bones to be discovered were
generally construed as belonging to mythical beasts.
However, within the Judeo-Christian tradition, the Bible
provided another explanation for such remains - The
Flood.

The power of this explanation was so strong - even
among many eminent geologists - that it was not
dislodged until the early 19th century. ...

By the early 1800s great thicknesses of rocks filled
with fossil remains had been discovered, and it became
clear that they could not all have been produced by
a single flood, however catastrophic.

At the same time, scholarship had shown that the
Bible was not a simple document of fact, but
a complex accumulation of historical narratives
that required interpretation. ...

By the middle of the 19th century, geological time
as represented by great thicknesses of rock strata,
was well-enough understood to allow for formal
subdivision. ...

Fossil discoveries have changed our understanding
of the history of life. The origin of life has been
pushed back to at least 3.6 billion years ago, and
our view of the first 3 billion years of life has been
transformed.

The evolution of many-celled organisms is thought
to have been at least 1 billion years ago, and diverse
soft-bodied organisms called Ediacarans (the
biological relationships of which are unclear) were
present in marine waters 600 million years ago.
By Cambrian times, 550 million years ago, clearly
identifiable groups of invertebrate animals, such as
mollusks, annelid worms, and arthropods had evolved. ...

Vertebrate beginnings - The first known fossil animal to
show the beginnings of vertebrate characteristics is Pikaia,
which dates from mid-Cambrian times, around 535 million
years ago. ...

The body of this small eellike creature was stiffened and
elongated by the presence of a stiff but flexible rod called
a notochord.

It is thought that from such unpromising chordate
beginnings all vertebrate organisms evolved - the
notochord developing into a backbone from which
a skeleton of shoulder and hip girdles could be hung.

Eventually, paired limbs were slung from the girdles for
improved steering and locomotion. The development of
the front-back body axis led to the concentration of the
sense organs at the front, where they encountered the
environment "head-on."

Intriguingly the fossil record reveals another group of
primitive chordates, the extinct conodont animals, which
had the ability to use bonelike material in their bodies. The
mineral bonelike tissue is found in their tiny arrays of teeth
which intermesh as a very effective prey-catching apparatus.

The fossil record also reveals a great diversity of bizarre-
looking marine fish-like animals that had neither teeth nor
jaws. The jawless fishes (agnathans), who had bony scales
and plates embedded in their skin, fed by sucking and
filtering organic debris and microorganisms from seawater
and seabed deposits. Agnathans, the stratigraphic rock
record shows, were soon joined by jawed fishes with teeth.

One of the most important developments in the history
of life occurred when animals were first equipped for life
on land. ...

To facilitate the move from sea to land a number of
modifications were needed to be in place before the move
was made. The earliest tetrapods - the first four-limbed
fossil vertebrates - were neither amphibians in the modern
sense, nor were they land-going animals. ...

It is now known that the first tetrapods had limbs with
fingers and toes, although they retained fishlike gills and
powerful "fishy" tails. These pre-adaptations would have
equipped their descendants for life on land. ...

Recently a 334-million-year-old tetrapod called Eucritta has
been described. This salamander-sized fossil incorporates
features associated with the amphibians and reptiles.

By later Carboniferous times true amphibians and reptiles
had diverged from the ancestral tetrapods. ...

The diversification of these land-living tetrapods went
a step further in Permian times when the first of the
so-called mammallike reptiles evolved. They show the
first differentiation of teeth for separate functions of
capturing, holding, killing, and cutting up prey as
a means of predigestion.

In addition, there are indications of early mechanisms
for controlling body temperature. ...

Teeth are some of the most commonly preserved skeletal
remains and allow the separation of true mammal fossils
from the remains of the mammal-like reptiles, from which
they evolved some 225 million years ago. ...

It was not until Tertiary times that mammals were able to
diversify into the new environmental niches provided by
the rapid evolution of the flowering plants and grasses.
Within a few tens of millions of years, several thousand
species of mammals had evolved.

In later Permian times, some 230 million years ago, a group
of scaly-skinned, egg-laying reptiles evolved and gradually
came to dominate the planet for over 155 million years. ...

In the history of life, no other group of large animals have
been so successful for so long. There are over 6,500
species of reptiles alive today, most of which are lizards.
By comparison, there are only 4,000 mammals, most of
which are rodents. ...

Geological Time Chart
(
http://www.dinosauria.com/dml/history.htm)
Focus on the events in the last 600 million
years impacting the evolution of vertebrates
and leading to the evolution of humans:

----- 600 million years ago -----

Precambrian mass extinction; 70 percent of flora
and fauna perish - causality suspect:
http://www.wf.carleton.ca/Museum/
extinction/vencause.html


----- Cambrian: 570 to 495 million years ago -----

Continued evolution of jawless fishes (agnathans)

At least 4 mass extinctions occurred during the
Cambrian period - causality suspects:
http://www.wf.carleton.ca/Museum/extinction/camcause.html

----- Ordovician: 495 to 443 million years ago -----

Evolution of some jawless fishes into jawed fishes
(gnathostomes), consisting of sharks and their relatives
(chondrichthyes), flat-plated heavily armored jawed
fishes (placodermi), spiny jawed fishes (acanthodii),
and bony fishes (osteichtheyes)

Ordovician mass extinction, ~50% of species
decline & vanish, including over 100 families
of marine invertebrates - causality suspect:
http://www.wf.carleton.ca/Museum/extinction/ordcause.html

----- Silurian: 443 to 417 million years ago -----

Continued evolution of jawless and jawed fishes

----- Devonian: 417 to 354 million years ago -----


Evolution of some bony fishes into early tetrapods

Devonian mass extinction, ~70% of species vanish
with major losses of ocean life - causality suspects:
http://www.wf.carleton.ca/Museum/extinction/devcause.html

----- Carboniferous: 354 to 290 million years ago -----

Begins with extinction of flat-plated heavily armored
jawed fishes (placodermi) and ends with extinction
of spiny jawed fishes (acanthodii);

Evolution of early tetrapods into a varied assortment
of amphibia (extends beyond the Carboniferous but
included here in one lump for purposes of brevity),
including strange creatures looking like fish with tiny
legs / lizards with fish-like tails / lizards with snake-like
tails / gator-like creatures / lizards with armored plate
back, gator-like creatures with fish-like tails, snakes,
lizards with very small arms and hands, frogs with
large webbed feet;

Evolution of some tetrapods into reptiles (reptilia),
the earliest known of which is the Hylonomus, the
earliest-known, fully adapted terrestrial vertebrate,
from which many different types of reptiles evolved

----- Permian: 290 to 248 million years ago -----

Evolution of some reptiles, the cynodonts (dog teeth)
into the mammals (mammalia)

Permian extinction, the *largest extinction event*
in history, ~96% of marine species and ~75% of
vertebrate families disappear - causality suspects:
http://www.wf.carleton.ca/Museum/extinction/permcause.html

----- Triassic: 248 to 205 million years ago -----

Dinosaurs evolving during this period include the winged
Pterosaur, Dicynodants, Herrerasaurus, Plateosaurus,
Ornithosuchus, Coelophysis, Melenosaurus, Eoraptor,
Staurikosaurus

Later Triassic extinction; up to ~25% of all
families became extinct:
http://www.bbc.co.uk/education/darwin/exfiles/triassic.htm

----- Jurassic: 205 to 142 million years ago -----

Dinosaurs evolving during this period include Stegosaurus,
Allosaurus, Dryosaurus, Ornitholestes, Compsagnathus,
Megalosaurus, Brachiosaurus, Diplodocus, Apatosaurus,
Dicraeosaurus, Mamenchisaurus, Leptoceratops;

Evolution of Icthyosaurus, a marine reptile;

Some reptiles evolve into birds (aves)

----- Cretaceous: 142 to 65 million years ago -----

Plants with flowers evolve; dinosaurs evolving in
this period include Iguanodon, Tyrannosaurus rex,
Diplodocus, Triceratops, Protoceratops, Hypsilo-
phodon, Polocanthus, Baryonyx, Styracosaurus,
Brachyceratops, Centrosaurus, Chasmosaurus,
Gallimimus, Saltasaurus, Alamosaurus, Corytho-
saurus, Ankylosaurus;

Marsupials (including kangaroos, koalas, and
opossums) evolve; insectivores (placental mammals)
evolve - almost all are small and nocturnal or crepus-
cular (active at dusk or dawn)

End Cretaceous mass extinction, the 2nd largest
extinction in history with over 85% of all families
disappearing, including most dinosaurs - causality
suspects:
http://www.bbc.co.uk/education/darwin/exfiles/asteroid1.htm
http://www.bbc.co.uk/education/darwin/exfiles/asteroid2.htm
http://www.bbc.co.uk/education/darwin/exfiles/volcano.htm

----- Tertiary: 65 to 2 million years ago -----

Early in this period, rodents evolve - resembling small
squirrels, rodents are the largest order of mammals
in the present day, by far, with about 2,000 species
in 35 families;

Mammals begin to thrive;

Towards the end of this period, events being to unfold
which catch the interest of modern-day humans in a
profound way ...

... ~6 million years ago ...

Orrorin tugenensis
(6 million years ago)*

*Because fossil evidence for Orrorin tugenensis is scant,
a range of dates for when this species lived is not available.

Orrorin tugenensis - If Orrorin tugenensis is truly a hom-
inid as its discoverers describe it, the species is by far
the oldest-known member of the family to which humans
belong. In fact, at 6 million years old, O. tugenensis lived
near the time when genetic analyses suggest our oldest
hominid ancestor split from the oldest ancestor of the
great apes. This means that there's a chance O. tugen-
ensis could be the proverbial "missing link" -- or at least
one of them.

Certain features, like the teeth of O. tugenensis, suggest
this species could even be more closely related to Homo
sapiens than the many Australopithecus species it pre-
dates. Like our molars, the molars of O. tugenensis were
small compared to any of the australopithecine teeth. Their
teeth also had very thick enamel like ours.

Grooves in the femurs of O. tugenensis, presumably points
where muscles and ligaments attached, suggest that the
species was bipedal. Unfortunately, much about this
species, including the suggested close relationship between
it and Homo sapiens, is extremely speculative and hotly
contested:
http://www.pbs.org/wgbh/evolution/humans/humankind/a.html

New early human fossils, Fossils fuel controversy
about humanity's earliest days (July 12, 2001):
http://www.nature.com/nsu/010712/010712-14.html


BBC resource on human evolution:
http://www.bbc.co.uk/science/apeman

Map of Some of the Pivotal Human Evolution Discoveries
http://a740.g.akamai.net/f/740/606/1d/image.pathfinder.com/time/
covers/1101010723/images/africamap.jpg

A Walk Through Human Evolution
http://a740.g.akamai.net/f/740/606/1d/image.pathfinder.com/time/
covers/1101010723/images/apes_timeline1.gif

Walk Like a Man
http://www.time.com/time/covers/1101010723/graphic.html

... ~5.8 million years ago ...

Between five and six million years ago, the great
desiccation touched off what scientists call the
Messinian Salinity Crisis--a global chemical
imbalance that triggered a wrenching series of
extinctions and plunged the Earth into an ice age:
http://www.newscientist.com/hottopics/disaster/vanished.jsp

... ~5 million years ago ...

Continents are essentially modern in form; Iceland
volcanic island appears; Atlantic Ocean rises enough
to flood back into the Mediterranean.

... ~4.4 million years ago ...

Ardipithecus ramidus
(4.4 million years ago)*

*Because fossil evidence for Ardipithecus ramidus is scant,
a range of dates for when this species lived is not available.

Ardipithecus ramidus was discovered in December 1992.
Although not nearly as old as Orrorin tugenensis, Ar. ramidus
is much more widely accepted by the scientific community
as a hominid than is O. tugenensis, and thus is considered
by some to be the oldest-known hominid.

A partial skeleton and indirect evidence from skeletal frag-
ments indicate that Ar. ramidus may have walked upright.
Although considered to be one of the most primitive hom-
inids, Ar. ramidus shares some novel characteristics with
much later hominids, namely aspects of its teeth. The molars
of Ar. ramidus are smaller than are those of any of the
Australopithecus species.

Other fossils found with Ar. ramidus suggest that it may
have been a woodland forest dweller. This may modify
current theories about why hominids became bipedal in
the first place. Walking upright has typically been linked
to movement onto the savanna:

http://www.pbs.org/wgbh/evolution/humans/humankind/b.html

Human Family Tree:
http://www.bbc.co.uk/science/cavemen/familytree/familytree.shtml

... ~4.2 million years ago ...

Australopithecus anamensis
(4.2 to 3.9 million years ago)

Australopithecus amenesis possesses a mix of advanced
and primitive traits. A partial tibia (the larger of the two
lower leg bones) suggests that A. anamensis probably
walked upright. The teeth of A. anamensis were covered
with a layer of enamel much thicker than that of Ar. ramidus,
suggesting a diet of hard-to-chew foods. The thickened
enamel is also a trait characteristic of all later hominids. In
size and shape, however, the teeth of A. anamensis were
primitive relative to later hominids. A. anamensis probably
lived in open woodland habitats in what is now northern
Kenya and southern Ethiopia.:
http://www.pbs.org/wgbh/evolution/humans/humankind/c.html

... ~4 million years ago ...

A. anamensis was walking 4 million years ago
(May 7, 1998):
http://abcnews.go.com/sections/science/DailyNews/hominid980506.html

... ~3.9 million years ago ...

Australopithecus afarensis is known to have walked
upright and may have appeared as early as 3.9 million
years ago (May 7, 1998):
http://more.abcnews.go.com/sections/science/DailyNews/hominid980506.html

Australopithecus afarensis
(3.6 to 2.9 million years ago)

Australopithecus afarensis had a very low forehead,
a face that projected far forward (as viewed in profile),
and a very prominent brow ridge. A. afarensis is the
earliest species for which we have reliable brain and
body size estimates, thanks to a rich fossil record for
the species.

The brain of A. afarensis was about one-third the size
of the average modern human brain, or about the same
size as a modern ape's brain. Males and females varied
significantly in body size, with males standing approxi-
mately 4 feet 11 inches tall and weighing 100 pounds
and females standing about 3 feet 5 inches tall and
weighing about 62 pounds. Males also typically had
large crests on top of their skulls; females did not.

The knee and pelvic bone structure of A. afarensis were
very humanlike, leaving no doubt that A. afarensis walked
upright. A. afarensis probably inhabited the savannas and
open woodlands where they likely found fruits, seeds,
and roots
:
http://www.pbs.org/wgbh/evolution/humans/humankind/d.html

... ~3.5 million years ago ...

Kenyanthropus platyops
(3.5 to 3.3 million years ago)

Kenyanthropus platyops - although it occupied parts of
Africa at the same time as A. afarensis, K. platyops is
quite distinctive physically and, thus, has been classified
not only as a different species, but belonging to a different
genus.

The features that distinguish K. platyops from A. afarensis
include primitive traits like small ear holes and advanced
traits like a relatively flat face and small molars. K. platyops
has been compared most closely with Homo rudolfensis or
Homo habilis, species that lived as many as 1 million years
later.

Similarities between these species might be explained in
terms of convergent evolution, in which two distinct groups
adapt to similar environmental conditions in similar ways,
or by the possibility of a direct ancestral line between
K. platyops and H. rudolfensis or H. habilis.

Indeed, some scientists have placed H. rudolfensis speci-
mens in the genus Kenyanthropus. Others ignore Kenyan-
thropus as a genus altogether, placing K. platyops speci-
mens into the genus Australopithecus, saying that the
species is not different enough to warrant its own genus.
Until the species can be substantiated by more fossil
evidence, many anthropologists will continue to withhold
judgement on its validity and significance:
http://www.pbs.org/wgbh/evolution/humans/humankind/e.html

... ~3 million years ago ...

Australopithecus africanus
(3 to 2 million years ago)

Australopithecus africanus was nearly identical in body
and brain size to A. afarensis. Like A. afarensis, A. africanus
also showed marked differences in size between males and
females. Although the teeth and jaws of A. africanus were
much larger than modern human teeth, they are still more
similar to ours than to the teeth of apes. The upper and
lower jaws of A. africanus were also fully rounded in front,
like those of modern humans, and their canine teeth were
smaller on average than those of A. afarensis. Australo-
pithecus africanus individuals probably inhabited open
woodlands, where they would have foraged for fruits,
seeds, and roots:
http://www.pbs.org/wgbh/evolution/humans/humankind/f.html

Recent discovery of a 1.22-meter-tall (four feet)
hominid (ape-man) north of Johannesburg, South
Africa (December 10, 1998):
http://news.bbc.co.uk/hi/english/sci/tech/newsid_231000/231442.stm

... ~2.7 million years ago ...

Australopithecus aethiopicus
(2.7 to 2.3 million years ago)

Australopithecus aethiopicus may be an ancestor of
two later species, Australopithecus robustus and
Australopithecus boisei. The species has a peculiar
mixture of primitive and highly derived traits relative
to earlier species.

Brain size of A. aethiopicus is comparable to that of
modern apes and the much-earlier A. afarensis. Other
skull traits appear to be novel adaptations, some of
which probably allowed A. aethiopicus to exploit
tougher food sources. The massive face was flat or
concave with no forehead.

A very large sagittal crest (a ridge of bone running
along the top of the skull) and other heavily reinforced
areas of the skull would have provided strong points
of attachment for chewing muscles. Powerful chewing
muscles, paired with the species' extremely large and
thickly enameled molars and premolars, suggest that
A. aethiopicus ate very tough, grainy foods that re-
quired a great deal of processing
:
http://www.pbs.org/wgbh/evolution/humans/humankind/g.html

... ~2.6 million years ago ...

The earliest stone tools, thought to be 2.6 million years
old, were found nearby in Gona, Ethiopia:
http://www.pbs.org/wgbh/evolution/humans/humankind/h.html

... ~2.5 million years ago ...

Australopithecus garhi
(2.5 million years ago)

Australopithecus garhi may represent an evolutionary link
between the genera of Australopithecus and Homo. Circum-
stantial evidence suggests that A. garhi may have been the
earliest tool user. Antelope fossils excavated from the same
site as A. garhi show cut marks made by a stone tool; both
the hominid and antelope fossils are dated at 2.5 million
years old:
http://www.pbs.org/wgbh/evolution/humans/humankind/h.html

Technology being used to eat meat and scrape marrow out
of bones; fossil find, in Addis Ababa, Ethiopia, was of skull
and tooth fragments that may be those of a completely new
hominid - a "missing link" or human-like species with long
arms and long legs.

The scientists have called their new hominid Australopithecus
garhi, after the local word for "surprise". From anatomical
analyses and measurements they argue A. garhi is quite dis-
tinct from A. africanus and from the other hominid species
known to be alive around the same time and may be a crea-
ture that immediately preceded humans (April 23, 1999):
http://news.bbc.co.uk/hi/english/sci/tech/newsid_326000/326037.stm

... ~2.4 million years ago ...

Oldowan tools are the oldest known, appearing first in the
Gona and Omo Basins in Ethiopia about 2.4 million years
ago. They likely came at the end of a long period of oppor-
tunistic tool usage: even chimpanzees use rocks, branches,
leaves and twigs as tools:
http://www.handprint.com/LS/ANC/stones.html

... ~2.3 million years ago ...

Australopithecus boisei
(2.3 to 1.4 million years ago)

Australopithecus boisei is similar in body and brain size to
A. robustus. Like members of many other Australopithecus
species, males and females of A. boisei showed marked
differences in size. Some features of A. boisei's skull, includ-
ing the large grinding teeth, are even larger than are those of
A. robustus. Certain molars measure up to two centimeters
in length from front to back. A. boisei probably inhabited
mixed woodland and savanna habitats, where individuals
would most likely have eaten foods like nuts and roots:
http://www.pbs.org/wgbh/evolution/humans/humankind/i.html

Homo habilis
(2.3 to 1.6 million years ago)

Homo habilis has been a controversial species since it was
first described in the mid-1960s. Originally, many scientists
did not accept its validity, believing that all specimens should
be assigned either to the genus Australopithecus or to Homo
erectus. Today, H. habilis is widely accepted as a species.

Some scientists, however, still believe that many of the ear-
liest fossils assigned to H. habilis are too fragmented and
separated in time for conclusions about their relationships
or species compositions to be possible. H. habilis speci-
mens with particularly large features -- brains or teeth, for
instance -- are sometimes assigned as Homo rudolfensis.

Homo habilis, "handy man," is so called because of the
wealth of tools that have been found with its fossils. The
average H. habilis brain was considerably larger than the
average Australopithecus brain. The brain shape is also
more humanlike. The bulge of Broca's area, essential for
speech, is visible in one H. habilis brain cast, indicating
that the species may have been capable of rudimentary
speech. The average H. habilis individual is thought to have
been about five feet tall and 100 pounds, although females
may have been smaller:
http://www.pbs.org/wgbh/evolution/humans/humankind/j.html

... ~1.8 million years ago ...

Homo erectus
(1.8 million to 300,000 years ago)

Homo erectus, unlike H. habilis and all of the Australo-
pithecus species, ranged far beyond Africa. Some scientists
have split H. erectus into three separate species, based on
the geographic region in which specimens have been found:
H. ergaster (Africa), H. erectus (Asia), and H. heidelber-
gensis (Europe). Homo heidelbergensis specimens are also
sometimes classified as archaic H. sapiens.

Generally, H. erectus (inclusive) is characterized by large
molars, an unpronounced chin, heavy brow ridges, and a
long, low skull, relative to modern Homo sapiens. The skel-
eton of H. erectus was heavier, or "more robust," than the
average modern human skeleton. Body proportions vary
greatly from individual to individual. "Turkana Boy" was
tall and slender, like modern humans from the same area,
while the few limb bones found of "Peking Man" indicate
a shorter, sturdier build:
http://www.pbs.org/wgbh/evolution/humans/humankind/k.html

Australopithecus robustus
(1.8 to 1.5 million years ago)

Australopithecus robustus possesses a combination of
primitive and derived physical traits. While its brain size
is much like that of A. afarensis, other characteristics are
quite different.

Specimens of this species have massive flat or concave
faces. The front teeth of A. robustus are small relative to
the species' massive grinding teeth and thickly enameled
molars and premolars. Most A. robustus specimens also
have sagittal crests (large ridges of bone running along
the top of their skulls), which indicate powerful chewing
muscles used for grinding tough foods.

Skeletal remains identified as belonging to A. robustus
indicate that males and females differed markedly in body
size, with males standing on average 4 feet 4 inches tall
and weighing about 92 pounds and females standing 3 feet
7 inches tall and weighing 71 pounds.

Modified bones found alongside A. robustus skeletons
suggest members of the species may have used tools to
help them access buried food. A. robustus probably
inhabited woodland and savanna habitats where they
foraged for foods like roots, nuts, and possibly insects:
http://www.pbs.org/wgbh/evolution/humans/humankind/l.html

... ~1.7 million years ago ...

Hominids in Europe - Skulls probably represent
first populations to migrate from Africa - Homo
ergaster - falls between H. habilis and H. erectus.
These partial human-like skulls were found in
the former Soviet Republic of Georgia, dated at
1.7 million years, making them the oldest human
ancestral fossils ever found outside of Africa
(May 12, 2000):
http://abcnews.go.com/sections/science/DailyNews/
hominid_caucasus000512.html

http://news.bbc.co.uk/hi/english/sci/tech/newsid%5F745000/745080.stm

... ~1.6 million years ago ...

Earliest evidence of the use of fire, at Chesowanja,
Kenya and Swartkrans (South Africa).

... ~1.5 million years ago ...

The Acheulean tool industry first appeared around
1.5 million years ago in East-Central Africa, associated
with Homo ergaster and western Homo erectus:
http://www.handprint.com/LS/ANC/stones.html#2

... ~1 million years ago ...

Proliferation of Homo erectus, including the spread
into many areas of Asia and Europe; beginning of
the modern (Pleistocene) Ice Age.

The Koolau volcano, in Hawaii, split right down the
middle, and the mountain's northeast face began
cascading into the sea. Slabs of rock tumbled into
the water by the thousands and hundreds of blocks
the size of small towns followed. One--the size of
New York City--finally came to rest 100 kilometres
from shore. When the dust settled, a tenth of the
island was gone. But worse was to come:
http://www.newscientist.com/hottopics/disaster/landslide.jsp

... ~800,000 years ago ...

Earliest evidence thus far of sea-faring, in Bali, by
Homo erectus (May 12, 1998):
http://news.bbc.co.uk/hi/english/world/asia-pacific/newsid_64000/64943.stm

... ~640,000 years ago ...

The last eruption in the Yellowstone Park area of
America occurred at this time, resulting in massive
volcanic flood basalt flows, covering a large area
of the present-day northwest United States . This
is one of the largest supervolcanoes in the world.
Scientists have revealed that it has been on a regular
eruption cycle of 600,000 years, so it is long overdue
(February 3, 2000):
http://www.bbc.co.uk/science/horizon/1999/supervolcanoes.shtml

... ~600,000 years ago ...

Homo heidelbergensis
(600,000 to 100,000 years ago)

The skulls of this species share features with both Homo
erectus and anatomically modern Homo sapiens. The
archaic H. heidelbergensis brain was larger than H. erectus
and smaller than most modern humans, and the skull is
more rounded than in H. erectus. The skeleton and teeth
are usually smaller than in H. erectus, but larger than in
modern humans. Many still have large brow ridges and
receding foreheads and chins. There is no clear dividing
line between late H. erectus and H. heidelbergensis, so
many fossils between 500,000 and 200,000 years ago
are difficult to classify as one or the other:
http://www.pbs.org/wgbh/evolution/humans/humankind/m.html

... ~400,000 years ago ...

Recent findings indicate mitochondrial DNA research
might place the common ancestor of modern humans
approximate to this time period (March 11, 1999):
http://news.bbc.co.uk/hi/english/sci/tech/newsid%5F294000/294808.stm

Theories for the evolution of language and speech
are presented, with evidence indicating modern
speech may have occurred 300,000 to 500,000
years ago (April 10, 2000):
http://ampere.scale.uiuc.edu/anth102/lec2000/041000.html

When were the first words? Duke University
researchers present evidence the physical
capability for human speech may have been
present 400,000 years ago (April 27, 1998):
http://more.abcnews.go.com/sections/science/dailynews/speech980427.html

... ~300,000 years ago ...

Possibly the oldest known human structure, a hut,
is found at Terra Amata, France.

... ~250,000 years ago ...

Homo neanderthalensis
(250,000 to 30,000 years ago)

Like H. erectus, H. neanderthalensis had a protruding jaw,
receding forehead, and weak chin. The average Neanderthal
brain was slightly larger than that of modern humans, but this
is probably correlated with larger body size in general. The
mid-facial area of Neanderthals protruded much more than
the same area in H. erectus or H. sapiens and may have
been an adaptation to cold. Indeed, Neanderthals lived
mostly in cold climates.

Their short, stocky bodies are similar in proportion to those
of modern cold-adapted peoples; men averaged about
5 feet 6 inches tall. Neanderthal bones are thick and heavy
and show signs of powerful muscle attachments. Neander-
thals most likely would have been extraordinarily strong
by modern standards, and their skeletons show that they
endured brutally hard lives. They are found throughout
Europe and the Middle East. Western European Neander-
thals usually have a more robust form, and are considered
"classic Neanderthals."

Some scientists consider Homo neanderthalensis to be
a subspecies of Homo sapiens, rather than a species unto
itself:
http://www.pbs.org/wgbh/evolution/humans/humankind/n.html

... ~200,000 years ago ...

The Mousterian industry appeared around 200,000
years ago and persisted until about 40,000 years ago,
in much the same areas of Europe, the Near East and
Africa where Acheulean tools appear:
http://www.handprint.com/LS/ANC/stones.html#3


... ~160,000 years ago ...

Three fossilised skulls unearthed in Ethiopia are said by
scientists to be among the most important discoveries
ever made in the search for the origin of humans. ... The
crania of two adults and a child, all dated to be around
160,000 years old, were pulled out of sediments near
a village called Herto in the Afar region in the east of the
country. They are described as the oldest known fossils
of modern humans, or Homo sapiens (June 11, 2003):
http://news.bbc.co.uk/2/hi/science/nature/2978800.stm

Herto skulls discovery: Their mortuary practices may
represent the earliest evidence of modern human sophisti-
cation (cover image by Nature):
http://news.bbc.co.uk/1/shared/spl/hi/pop_ups/03/
sci_nat_enl_1059401523/html/1.stm

The afore-mentioned discovery occurred recently, prior
to the following reference which uses a more recent date
for Homo sapiens:

Homo sapiens
(100,000 years ago to present)

The modern form of Homo sapiens first appeared about
100,000 years ago. This species is distinguished by large
brain size, a forehead that rises sharply, eyebrow ridges
that are very small, a prominent chin, and lighter bone
structure than H. heidelbergensis.

Even in those 100,000 years, anatomical trends toward
smaller molars and decreased bone mass can be seen in
the Homo sapiens fossil record. For example, contem-
porary humans in Europe and Asia have bones that are
20 to 30 percent thinner and lighter than those of upper
Paleolithic humans dating from about 30,000 years ago.

About 40,000 years ago, with the appearance of the Cro-
Magnon culture, tools became markedly more sophisti-
cated, incorporating a wider variety of raw materials such
as bone and antler. They also included new implements
for making clothing, engravings, and sculptures. Fine art-
work, in the form of decorated tools, beads, ivory carv-
ings of humans and animals, clay figurines, musical instru-
ments, and cave paintings, appeared over the next 20,000
years:
http://www.pbs.org/wgbh/evolution/humans/humankind/o.html

... ~125,000 years ago ...

Oyster Cult - coastal way of life existed 125,000
years ago for ancient humans (May 3, 2000):
http://abcnews.go.com/sections/science/DailyNews/
ancienthuman_route000503.html

... ~100,000 years ago ...

Early migration of Homo sapiens out of Africa, to
the eastern Mediterranean and Greece, per mitochondrial
DNA evidence (November 30, 1999):
http://more.abcnews.go.com/sections/science/dailynews/ancienthuman
_route991130.html

... ~90,000 years ago ...

The Hominid Brain - technological, abstract and
computational thinking seems to arise in the parietal
lobe, and this is the area of greatest relative difference
between the two outlines (Homo sapiens compared
to Homo erectus). We might associate this parietal
expansion with the appearance of remarkably
diverse and refined tool cultures about 90,000
years ago:
http://www.handprint.com/LS/ANC/brain.html

... ~74,000 years ago ...

The last supervolcano to erupt was Toba 74,000 years
ago in Sumatra. Ten thousands times bigger than Mt St
Helens, it created a global catastrophe dramatically affecting
life on Earth. Scientists know that another one is due - they
just don't know when or where (February 3, 2000).
http://www.bbc.co.uk/science/horizon/1999/supervolcanoes.shtml

The evidence suggests that humans came within a cigarette
paper's thickness of becoming extinct along about this
time (May 26, 1999):
http://abcnews.go.com/sections/science/DyeHard/dye990526.html

A hypothesis about recent human evolution suggests
that humans came close to extinction because of
a 'volcanic winter' that occurred 71,000 years ago.
Some scientists estimate that there may have been as
few as 15,000 humans alive at one time. The 'volcanic
winter' lasted about six years.

It was followed by 1,000 years of the coldest Ice Age
on record. It brought widespread famine and death to
human populations around the world. It also affected
subsequent human evolution (September 8, 1998):
http://news.bbc.co.uk/hi/english/sci/tech/newsid_166000/166869.stm

... ~70,000 years ago ...

When humans faced extinction - humans may have come
close to extinction about 70,000 years ago, according to
the latest genetic research - the research also suggests that
humans (Homo sapiens sapiens) made their first journey
out of Africa as recently as 70,000 years ago. (June 9, 2003):
http://news.bbc.co.uk/2/hi/science/nature/2975862.stm

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