Turkana boy a ***.

It seems our primitive forebears were all
living together in a sort of African
incestuous commune, freely intermarrying, and
screwing it all up for the
paleoarchaelogists.
No more the simple family tree....
A.ramidus
A.afarensis
A.africanus
P.aethiopicus
P.boisei
P.robustus
H.rudolfensis
H.habilis
H.ergaster
H.erectus (censored)
H.heidelbergensis
H.neanderthalensis
H.sapiens

but rather now the whole lot mixed in
together in the one African cage.

Of course, simple observation and the
following tract implies they all still live
among us; just glance at any newspaper.

Read on...

*********
African skulls find throws story of human
evolution into disarray
IAN JOHNSTON ENVIRONMENT CORRESPONDENT (
ijohnston@xxxxxxxxxxxx)
IT IS the iconic image of human evolution:
the gradual transformation over millions of
years of an ape-like creature into a tall,
modern-day human.

But the startling discovery of two fossils in
Africa has cast serious doubt on this
traditional picture, as they prove an early
form of human called Homo habilis did not
evolve into Homo erectus, as previously
believed.

Instead the two species lived side by side
for hundreds of thousands of years in what is
now Kenya.

The finding has effectively created a new
missing link as researchers said it was no
longer clear which animal evolved into Homo
erectus, the stage before modern humans, or
Homo sapiens.

The first fossil, found east of Lake Turkana,
is a habilis jaw bone dated to 1.44 million
years ago, much later than was previously
recorded for the species.

The second, discovered in the same area, was
a beautifully preserved erectus skull dating
back 1.55 million years ago. It is remarkable
in its own right as it is much smaller than
previous specimens and close to the average
size of the supposedly more primitive
habilis.

Dr Meave Leakey, one of the authors of a
paper published by the leading journal Nature
yesterday, said: "Their coexistence makes it
unlikely that Homo erectus evolved from Homo
habilis.

"The fact that they stayed separate as
individual species for a long time suggests
they had their own ecological niche, thus
avoiding direct competition."

Both species must, therefore, have had their
origins between two and three million years
ago, a time from which few human fossils are
known, and the hunt is on to find Homo
erectus's real ancestor.

Professor Fred Spoor, an anatomist from
University College, London and lead author of
the paper, said human evolution was much more
complex than once thought. The classic single
line from ape to human is something we
already knew is not the case," he said.
"But we know a bit more about the process of
human evolution [as a result of this
research]. It is very much like the
evolutionary path of any other animal, with
lots of side branches and not a single
straight line that you see in cartoons."
Prof Spoor said that habilis, largely
vegetarian, and erectus, which ate a more
meat-based diet, would probably have had
little contact, much like chimps and gorillas
today.

Asked if erectus might have hunted and eaten
habilis, he said: "I'm not sure, but I doubt
it. I suspect they largely avoided each
other.

"These were not enormous populations, they
were in relatively small groups over a large
area.

"The same discussion is going on with modern
humans and Neanderthals. There's no good
evidence whether they actually interacted
much."

Both habilis and erectus were skilled
tool-makers, able to shape stones into large,
"impressive" axe-heads. This ability emerged
about two to three million years ago, the
same time as Homo erectus's unknown ancestor
is believed to have lived.

But despite having similar skills, for some
reason it appears only Homo erectus was able
to survive and eventually turn into Homo
sapiens.

"Homo habilis probably died out and is just
one of those side branches, but it was pretty
successful; it lived for at least half a
million years and we, as modern humans, have
been here for only 100,000 to 200,000 years,"
Prof Spoor said.

The small size of the erectus skull is a sign
of "sexual dimorphism", where males are much
larger than females. This trait is related to
social groupings of one dominant male with
several females.

The variation in size of erectus fossils from
east Africa - from the small new skull to a
large specimen discovered previously at
Olduvai Gorge in neighbouring Tanzania -
almost rivals that shown by modern gorillas.
Sexual dimorphism is believed to be a
primitive, or ancestral, feature during human
evolution, so the new fossil skull implies
that erectus was less human-like than once
thought.

"In gorillas, males are much larger than
females, related to their strategy of having
multiple mates," said co-author Susan Antón.
"The new Kenyan fossil suggests that,
contrary to common belief, this may have been
true of Homo erectus as well."

Q & A: LINKS
If the linear theory that Homo habilis
evolved into Homo erectus and on into Homo
sapiens is debunked, then from what did Homo
sapiens evolve?
All available evidence suggests Homo sapiens
did evolve from Homo erectus, possibly via an
intermediate form. This process happened in
Africa, some time after a million years ago.
What are possible candidates for ancestors of
Homo habilis and Homo erectus?
Difficult to tell. The two species will
likely have had a common ancestor living in
Africa between two and three million years
ago.
What were the different ecological niches the
two species were inhabiting?
It is not known for sure, but there are clues
from the teeth and jaws - which are smaller
in Homo erectus - that the diet of Homo
habilis was tougher, possibly including more
vegetation, than that of erectus. And erectus
may have included greater quantities of
animal meat and fat in their diets than
habilis. Both seem to have favoured areas
with a ready source of water, but may have
focused on different primary food items.
Why is a notable body size difference between
males and females, sexual dimorphism,
considered a primitive condition and why is
this important to the study of human
evolution?
Early human ancestors, such as species of
Australopithecus, are known to show high
levels of sexual dimorphism, whereas modern
humans and closer relatives such as
Neanderthals have much less of a size
difference.
Size differences between males and females of
a species arise for a variety of reasons,
many relating to reproductive strategies and
sexual selection.
That Homo erectus may still have been highly
dimorphic suggests the possibility of a
reproductive strategy that mostly was not
monogamous and this may have implications for
understanding behavioural evolution, the size
of groups that Homo erectus may have lived in
and so on.
.. Information supplied by University College
London.



.