Weenosday. Apel 13, 1904

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an’s ancestry

Skull discovery i in Ethiopia proves a Single species as the missing link

SOME 100 years after Charles
- Darwin first published his the-_
ory of evolution, his “missing -

. tink” i is no longer missing. |

By Kevin Gillies

Contributing Writer

The concept that man descend-
ed from trees is one that has kept
paleontologists and anthropologists
at odds since Darwin proposed his
theory in the 19th century.

One of those battles pitted ‘the
,. dernationally revered Sir Richard

“Leakey and father Louis Leakey,
“amongst others, against Dr. Donald
* Johanson and Tim White.

The ‘debate centred ‘around

- whether Australopithicus afarensis, -

“the predecessor to ail homonids,
including the modern-day Homo
Sapiens, was a single species or a

- group of loosely related lineages.”

.» The few hundred bones that had

“> been unearthed since the early

1970s indicated a wide variety of

sizes in afarensis which supported

‘the theory that the bones were in

fact from more than one ‘species.

But they all differ from the more

modern lincages in that they were
believed to have small brain cases.

* Homo has a large brain case.
Johanson’s 1974 discovery of

Lucy, the three million-year-old A.
afarensis skeleton, did not include
a skull

None of the discoveries includ-

eda full skull — necessary to-

determine whether fossil samples
cane from the same species.
: _ Reconstructions using various

THIS 86%-complete skull! of
A. afarensis ts the oldest,
moat complete cranium ever
found.

skull fragments from different A

afarensis samples indicated that,

Australopithecus had small brain
cases.

,. Johanson’s hypothesis, that A.
afarensis was the single predeces-
sor to the Homo lines, was refuted
using ihe argument that his skull
reconstruction included skull
pieces from a variety of Species
and genders.

But on March 3}, Johanson’s s
Institute of Human Origins (IHQ),
out of Berkeley, California,
announced that they had discov-
ered an 80%-complete A. afarensis

skull which —barring discoveries —

of a new, older species (which is
always possible) — is the discov-
ery to end the debate.

“It'is, at the moment, the best
evidence we have for the view that,
as Darwin had of course suggested
way back in the last century, that
there must be some intermediate

, forms,” Johanson told the News.

The largest criticism evolution-
ary biologists faced was that no

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intermediate “finks” existed to
prove the theory,

Until now.

“The skull is very primitive,”
Johanson said. “it still has at pros
jecting-like, ape-like face and
small brain case, and is very con-

istent with our idea that A, afaren-
sis is a generalized, primitive
species.”

“And what is so significant
about the skull is that in the 1980s
there was an outery for ‘What does
a skull look like of this species?" ”

“Skulls tend to be very altrac-
live to amilomists and anthrapolo-
gists in the sense that they pre-
serve, usually, the most diagnostic
a. the most easily read characteris-
tics of a particular species.

“Without a skull there was a
question as to whether or not A,
afarensis was really a bonefide,
different species from some of the
South African Australopithecus
types.”

His discovery supports the theo-
ry, projected by an earlier skull
reconstruction, that A. afarensis
was a single species that lasted
from 3.9 to three million years ago.

The fossil findings show that A.
afarensis was a durable, adaptable
species that managed to exist for
almost a million years without
major evolutionary changes.

That it was, in fact, the trunk of
man's family tree.

“It could operate many different
sorts of habitats, probably had. a
fairly wide-range of foodstuffs that
it ate,” he said.

Johanson said that a dramatic
cooling and drying off of Eastern

Africa, combined with dramatic

facth movement, wis prohahty
responsible fur ending A. afuren-
sin’ survival ers,

Johanson will describe his eape-
ticnees and hypotheses ae t30
pio, Sunday, April 17 at the
Orpheum Theatre,

WILLIAM KIMBAZL, lett, and Dr. Don Johanson, right, examine
recent A. afarensis fossils with Yoel Rak of Tal Aviv University.
‘The three paleo-anthropologists teamed up to find and recon:
struct the fossils found at Hadar in Ethiopia. Their findings,
discovered two years ago, were announced last month,

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