12 - ALWAYS SOMETHING
NEW OUT OF AFRICA
-
Reek's Skeleton
-
The Kanjera Skulls and Kanam
Jaw
-
The Birth of
Australopithecus
-
Zinjanthropus
-
Homo Habilis
-
ATale of Two Humeri
-
Discoveries of Richard
Leakey
-
The ER 813 Talus
-
OH 62: Will the Real Homo Habilis
Please Stand Up?
-
Oxnard's Critique of
Australopithecus
-
Lucy in the Sand with
Diatribes
-
A. Afarensis: Overly
Humanized?
-
The Laetoli Footprints
-
Black Skull, Black Thoughts
-
Summary of Anomalous
Evidence Related to Human Antiquity
The controversies surrounding Java man and Beijing man, what to
speak of Castenedolo man and the European eoliths, have long since
subsided. As for the disputing scientists, most of them are in their
graves, their bones on the way to disintegration or fossilization.
But today Africa, the land of Australopithecus and Homo habilis,
remains an active battlefield, with scientists skirmishing to
establish their views on human origins.
RECK'S SKELETON
The first significant African discovery took place early in this
century. In 1913, Professor Hans Reck, of Berlin University,
conducted investigations at Olduvai Gorge in Tanzania, then German
East Africa. While one of Reck's African collectors was searching
for fossils, he saw a piece of bone sticking up from the earth.
After removing the surface rubble, the collector saw parts of a
complete and fully human skeleton embedded in the rock. He called
Reck, who then had the skeleton taken out in a solid block of hard
sediment. The human skeletal remains, including a complete skull,
had to be chipped out with hammers and chisels. The skeleton was
then transported to Berlin.
Reck identified a sequence of five beds at Olduvai Gorge. The
skeleton was from the upper part of Bed II, which is now considered
to be 1.15 million years old. At Reck's site, the overlying layers
(Beds III, IV, and V) had been worn away by erosion.
But Bed II was still covered by rubble from bright-red Bed III and
from Bed V. Perhaps as little as 50 years ago, the site would have
been covered by Beds III and V, including a hard limestone-like
layer of calcrete. Bed IV was apparently removed by erosion before
the deposition of Bed V.
Reck, understanding the significance of his find, carefully
considered the possibility that the human skeleton had arrived in
Bed II through burial.
Reck observed:
"The wall of the grave would
have a definite border, an edge that would show in profile a
division from the undisturbed stone. The grave filling would show an
abnormal structure and heterogeneous mixture of excavated materials,
including easily recognizable pieces of calcrete. Neither of these
signs were to be found despite the most attentive inspection. Rather
the stone directly around the skeleton was not distinguishable from
the neighboring stone in terms of color, hardness, thickness of
layers, structure, or order."
Louis Leakey examined Reck's skeleton in Berlin, but he judged it
more recent than Reck had claimed. In 1931, Leakey and Reck visited
the site where the skeleton had been found. Leakey was won over to
Reck's view that the anatomically modern human skeleton was the same
age as Bed II.
In February of 1932, zoologists C. Forster Cooper of Cambridge and
D. M. S. Watson of the University of London said the completeness of
the skeleton found by Reck clearly indicated it was a recent burial.
Leakey agreed with Cooper and Watson that Reck's skeleton had
arrived in its position in Bed II by burial, but he thought the
burial had taken place during Bed II times.
In a letter to Nature, Leakey argued that no more than 50 years ago
the reddish-yellow upper part of Bed II would have been covered by
an intact layer of bright-red Bed III. If the skeleton had been
buried after the deposition of Bed II, there should have been a
mixture of bright-red and reddish-yellow sediments in the grave
filling.
"I was lucky enough personally to examine the skeleton at
Munich while it was still intact in its original matrix," wrote
Leakey, "and could detect no trace whatever of such admixture or
disturbance."
Cooper and Watson were still not satisfied. In June 1932, they said
in a letter to Nature that red pebbles from Bed III may have lost
their color. This would explain why Reck and Leakey did not see the
Bed III pebbles in the matrix surrounding the skeleton. A. T.
Hopwood, however, disagreed that Bed III pebbles would have lost
their bright-red color. He pointed out that the top of Bed II, in
which the skeleton was found, was also reddish and stated:
"The
reddish color of the matrix is against the theory that any
inclusions of Bed III would have been decolorized."
Despite the broadsides from Cooper and Watson, Reck and Leakey
seemed to be holding their own. But in August 1932, P. G. H.
Boswell, a geologist from the Imperial College in England, gave a
perplexing report in the pages of Nature.
Professor T. Mollison had sent to Boswell from Munich a sample of
what Mollison said was the matrix surrounding Reck's skeleton.
Mollison, it may be noted, was not a completely neutral party. As
early as 1929, he had expressed his belief that the skeleton was
that of a Masai tribesman, buried in the not too distant past.
Boswell stated that the sample supplied by Mollison contained
"(a)
pea-sized bright red pebbles like those of Bed 3, and
(b) chips of
concretionary limestone indistinguishable from that of Bed 5."
Boswell took all this to mean that the skeleton had been buried
after the deposition of Bed V, which contains hard layers of
steppe-lime, or calcrete.
The presence of the bright-red Bed III pebbles and Bed V limestone
chips in the sample sent by Mollison certainly calls for some
explanation. Reck and Leakey had both carefully examined the matrix
at different times over a period of 20 years. They did not report
any mixture of Bed III materials or chips of limestone like calcrete,
even though they were specifically looking for such evidence. So it
is remarkable that the presence of red pebbles and limestone chips
should suddenly become apparent. It would appear that at least one
of the participants in the discovery and the subsequent polemics was
guilty of extremely careless observation—or cheating.
The debate about the age of Reck's skeleton became more complicated
when Leakey brought new soil samples from Olduvai. Boswell and
J. D.
Solomon studied them at the Imperial College of Science and
Technology. They reported their findings in the March 18, 1933 issue
of Nature, in a letter signed also by Leakey, Reck, and Hopwood.
The letter contained this very intriguing statement:
"Samples of Bed
II, actually collected at the 'man site,' at the same level and in
the immediate vicinity of the place where the skeleton was found
consist of pure and wholly typical Bed II material, and differ very
markedly from the samples of matrix of the skeleton which were
supplied by Prof. Mollison from Munich."
This suggests that the
matrix sample originally supplied by Mollison to Boswell may not
have been representative of the material closely surrounding Reck's
skeleton.
But Reck and Leakey apparently concluded from the new observations
that the matrix sample from Reck's skeleton was in fact some kind of
grave filling, different from pure Bed II material. As far as we can
tell, they offered no satisfactory explanation for their previous
opinion that the skeleton had been found in pure, unmistakable Bed
II materials.
Instead, both Reck and Leakey joined Boswell, Hopwood, and Solomon
in concluding that "it seems highly probable that the skeleton was
intrusive into Bed II and that the date of the intrusion is not
earlier than the great unconformity which separates Bed V from the
lower series."
It remains somewhat of a mystery why both Reck and Leakey changed
their minds about a Bed II date for Reck's skeleton. Perhaps Reck
was simply tired of fighting an old battle against odds that seemed
more and more overwhelming. With the discovery of Beijing man and
additional specimens of Java man, the scientific community had
become more uniformly committed to the idea that a transitional
ape-man was the only proper inhabitant of the Middle Pleistocene. An
anatomically modern Homo sapiens skeleton in Bed II of Olduvai Gorge
did not make sense except as a fairly recent burial.
Leakey, almost alone, remained very much opposed to the idea that
Java man (Pithecanthropus) and Beijing man (Sinanthropus) were human
ancestors. Furthermore, he had made additional discoveries in Kenya,
at Kanam and Kanjera. The fossils he found there, in his opinion,
provided indisputable evidence for Homo sapiens in the same period
as Pithecanthropus and Sinanthropus (and Reck's skeleton). So
perhaps he abandoned the fight over Reck's highly controversial
skeleton in order to strengthen support for his own recent finds at
Kanam and Kanjera.
There is substantial circumstantial evidence in support of this
hypothesis. Leakey's statement abandoning his previous position on
the antiquity of Reck's skeleton appeared in Nature on the same day
that a committee met to pass judgment on the Kanam and Kanjera
finds. Some of the most vocal opponents of Reck's skeleton, such as
Boswell, Solomon, Cooper, Watson, and Mollison, would be sitting on
that committee.
Although Reck and Leakey gave up their earlier opinion that Reck's
skeleton was as old as Bed II, their revised opinion that the
skeleton was buried into Bed II during Bed V times still gives a
potentially anomalous age for the fully human skeleton. The base of
Bed V is about 400,000 years old, according to current estimates.
Today, however, most scientists believe that humans like ourselves
first appeared about 100,000 years ago, as shown by the Border Cave
discoveries in South Africa.
Stone tools characterized as "Aurignacian" were found in the lower
levels of Bed V.
Archeologists first used the term Aurignacian in
connection with the finely made artifacts of Cro-Magnon man (Homo
sapiens sapiens) found at Aurignac, France. According to standard
opinion, tools of the Aurignacian type did not appear before 30,000
years ago. The tools lend support to the idea that anatomically
modern humans, as represented by Reck's skeleton, were present in
this part of Africa at least 400,000 years ago. Alternatively, one
could attribute the tools to Homo erectus. But this would mean
granting to Homo erectus tool-making abilities substantially greater
than scientists currently accept.
In 1935, in his book The Stone Age Races of Kenya, Leakey repeated
his view that Reck's skeleton had been buried into Bed II from a
land surface that existed during the formation of Bed V. But now he
favored a time much later in that period. He thought that Reck's
skeleton resembled skeletons found at Gamble's Cave, a site with an
age of about 10,000 years. But from the standpoint of geology, all
that could truthfully be said (granting the Bed V burial hypothesis)
was that the skeleton could be anywhere from 400,000 to perhaps a
few thousand years old.
Reiner Protsch later attempted to remedy this situation by dating
Reck's skeleton itself, using the radiocarbon method. In 1974, he
reported an age of 16,920 years. But there are several problems with
this age determination.
First of all, it is not clear that the bone sample actually came
from Reck's skeleton. The skull was considered too valuable to use
for testing. And the rest of the skeleton had disappeared from a
Munich museum during the Second World War. The museum director
provided some small fragments of bone, which Protsch said were "most
likely" part of the original skeleton.
From these fragments, Protsch was able to gather a sample of only
224 grams, about one third the normal size of a test sample.
Although he obtained an age of 16,920 years for the human bone, he
got very much different dates from other materials from the same
site, some older and some younger.
Even if the sample actually belonged to Reck's skeleton, it could
have been contaminated with recent carbon. This would have caused
the sample to yield a falsely young age. By 1974, the remaining bone
fragments from Reck's skeleton, if they in fact belonged to Reck's
skeleton, had been lying around in a museum for over 60 years.
During this time, bacteria and other microorganisms, all containing
recent carbon, could have thoroughly contaminated the bone
fragments. The bones also could have been contaminated with recent
carbon when they were still in the ground. Furthermore, the bones
had been soaked in an organic preservative (Sapon), which contained
recent carbon.
Protsch did not describe what chemical treatment he used to
eliminate recent carbon 14 contributed by the Sapon and other
contaminants. Thus we have no way of knowing to what degree the
contamination from these sources was eliminated.
The radiocarbon method is applied only to collagen, the protein
found in bones. This protein must be extracted from the rest of the
bone by an extremely rigorous purification process. Scientists then
determine whether a sample's amino acids (the building blocks of
proteins) correspond to those found in collagen. If they do not,
this suggests that amino acids may have entered the bone from
outside. These amino acids, being of a different age than the bone,
could yield a falsely young radiocarbon date.
Ideally, one should date each amino acid separately. If any of the
amino acids yield dates different from any of the others, this
suggests the bone is contaminated and not suitable for carbon 14
dating.
Concerning the radiocarbon tests on Reck's skeleton reported by
Protsch, the laboratories that performed them could not have dated
each amino acid separately. This requires a dating technique
(accelerator mass spectrometry) that was not in use in the early
1970s. Neither could these labs have been aware of the stringent
protein purification techniques now deemed necessary. We can only
conclude that the radiocarbon date Protsch gave for Reck's skeleton
is unreliable. In particular, the date could very well be falsely
young.
There are documented cases of bones from Olduvai Gorge giving
falsely young radiocarbon dates. For example, a bone from the Upper
Ndutu beds yielded an age of 3,340 years. The Upper Ndutu beds, part
of Bed V, are from 32,000 to 60,000 years old. A date of 3,340 years
would thus be too young by at least a factor of ten.
In his report, Protsch said about Reck's skeleton:
"Theoretically,
several facts speak against an early age of the hominid, such as its
morphology."
This suggests that the skeleton's modern morphology was
one of the main reasons Protsch doubted it was as old as Bed II or
even the base of Bed V.
In our discussion of China, we introduced the concept of a probable
date range as the fairest age indicator for controversial
discoveries. The available evidence suggests that Reck's skeleton
should be assigned a probable date range extending from the late
Late Pleistocene (10,000 years) to the late Early Pleistocene (1.15
million years). There is much evidence that argues in favor of the
original Bed II date proposed by Reck. Particularly strong is Reck's
observation that the thin layers of Bed II sediment directly around
the skeleton were undisturbed.
Also arguing against later burial is
the rocklike hardness of Bed II. Reports favoring a Bed V date seem
to be founded upon purely theoretical objections, dubious testimony,
inconclusive test results, and highly speculative geological
reasoning. But, setting aside the questionable radiocarbon date,
even these reports yield dates of up to 400,000 years for Reck's
skeleton.
THE KANJERA SKULLS AND KANAM JAW
In 1932, Louis Leakey announced discoveries at Kanam and Kanjera,
near Lake Victoria in western Kenya. The Kanam jaw and Kanjera
skulls, he believed, provided good evidence of Homo sapiens in the
Early and Middle Pleistocene.
When Leaky visited Kanjera in 1932 with Donald MacInnes, they found
stone hand axes, a human femur, and fragments of five human skulls,
designated Kanjera 1-5. The fossil-bearing beds at Kanjera are
equivalent to Bed IV at Olduvai Gorge, which is from 400,000 to
700,000 years old. But the morphology of the Kanjera skull pieces is
quite modern.
At Kanam, Leakey initially found teeth of Mastodon and a single
tooth of Deinotherium (an extinct elephant-like mammal), as well as
some crude stone implements. On March 29, 1932, Leakey's collector,
Juma Gitau, brought him a second Deinotherium tooth. Leakey told
Gitau to keep digging in the same spot. Working a few yards from
Leakey, Gitau hacked out a block of travertine (a hard calcium
carbonate deposit) and broke it open with a pick. He saw a tooth
protruding from a piece of travertine and showed it to MacInnes, who
identified the tooth as human. MacInnes summoned Leakey.
Upon chipping away the travertine surrounding Gitau's find, they saw
the front part of a human lower jaw with two premolars. Leakey
thought the jaw from the Early Pleistocene Kanam formation was much
like that of Homo sapiens, and he announced its discovery in a
letter to Nature. The Kanam beds are at least 2.0 million years old.
For Leakey, the Kanam and Kanjera fossils showed that a hominid
close to the modern human type had existed at the time of Java man
and Beijing man, or even earlier. If he was correct, Java man and
Beijing man (now Homo erectus) could not be direct human ancestors,
nor could Piltdown man with his apelike jaw.
In March of 1933, the human biology section of the Royal
Anthropological Institute met to consider Leakey's discoveries at
Kanam and Kanjera. Chaired by Sir Arthur Smith Woodward, 28
scientists issued reports on four categories of evidence:
geological, paleontological, anatomical, and archeological. The
geology committee concluded that the Kanjera and Kanam human fossils
were as old as the beds in which they were found. The paleontology
committee said the Kanam beds were Early Pleistocene, whereas the
Kanjera beds were no more recent than Middle Pleistocene.
The
archeology committee noted the presence at both Kanam and Kanjera of
stone tools in the same beds where the human fossils had been found.
The anatomical committee said the Kanjera skulls exhibited "no
characteristics inconsistent with the reference to the type Homo
sapiens." The same was true of the Kanjera femur. About the Kanam
jaw, the anatomy experts said it was unusual in some respects. Yet
they were "not able to point to any detail of the specimen that is
incompatible with its inclusion in the type of the Homo sapiens."
Shortly after the 1933 conference gave Leakey its vote of
confidence, geologist Percy Boswell began to question the age of the Kanam and Kanjera fossils. Leakey, who had experienced Boswell's
attacks on the age of Reck's skeleton, decided to bring Boswell to
Africa, hoping this would resolve his doubts. But all did not go
well.
Upon returning to England, Boswell submitted to Nature a negative
report on Kanam and Kanjera:
"Unfortunately, it has not proved
possible to find the exact site of either discovery."
Boswell found
the geological conditions at the sites confused. He said that
"the
clayey beds found there had frequently suffered much disturbance by
slumping." Boswell concluded that the "uncertain conditions of
discovery . . . force me to place Kanam and Kanjera man in a
'suspense account.'"
Replying to Boswell's charges, Leakey said he had been able to show
Boswell the locations where he had found his fossils. Leakey wrote:
"At Kanjera I showed him the exact spot where the residual mound of
deposits had stood which yielded the Kanjera No. 3 skull in situ. .
. . the fact that I did show Prof. Boswell the site is proved by a
small fragment of bone picked up there in 1935 which fits one of the
1932 pieces."
Regarding the location of the Kanam jaw, Leakey said:
"We had
originally taken a level section right across the Kanam West
gullies, using a Zeiss-Watts level, and could therefore locate the
position to within a very few feet—and, in fact, we did so."
Boswell suggested that even if the jaw was found in the Early
Pleistocene formation at Kanam, it had entered somehow from above—by
"slumping" of the strata or through a fissure. To this Leakey later
replied:
"I cannot accept this interpretation, for which there is no
evidence. The state of preservation of the fossil is in every
respect identical to that of the Lower [Early] Pleistocene fossils
found with it."
Leakey said that Boswell told him he would have been
inclined to accept the Kanam jaw as genuine had it not possessed a
humanlike chin structure.
Nevertheless, Boswell's views prevailed. But in 1968 Philip V.
Tobias of South Africa said,
"There is a good prima facie case to
re-open the question of Kanjera."
And the Kanjera case was in fact
reopened. Leakey's biographer Sonia Cole wrote:
"In September 1969
Louis attended a conference in Paris sponsored by UNESCO on the
theme of the origins of Homo sapiens. . . . the 300 or so delegates
unanimously accepted that the Kanjera skulls were Middle
Pleistocene."
Tobias said about the Kanam jaw:
"Nothing that Boswell said really
discredited or even weakened the claim of Leakey that the mandible
belonged to the stratum in question."
Scientists have described the Kanam jaw, with its modern chin
structure, in a multiplicity of ways. In 1932, a committee of
English anatomists proclaimed that there was no reason the jaw
should not be considered Homo sapiens. Sir Arthur Keith, a leading
British anthropologist, also considered the Kanam jaw Homo sapiens.
But in the 1940s Keith decided the jaw was most likely from an
australopithecine. In 1962, Philip Tobias said the Kanam jaw most
closely resembled a late Middle Pleistocene jaw from Rabat in
Morocco, and Late Pleistocene jaws such as those from the Cave of
Hearths in South Africa and Dire-Dawa in Ethiopia. According to
Tobias, these jaws display neanderthaloid features.
In 1960, Louis Leakey, retreating from his earlier view that the
Kanam jaw was sapiens-like, said it represented a female
Zinjanthropus. Leakey had found Zinjanthropus in 1959, at Olduvai
Gorge. He briefly promoted this apelike creature as the first
toolmaker, and thus the first truly humanlike being. Shortly
thereafter, fossils of Homo habilis were found at Olduvai. Leakey
quickly demoted Zinjanthropus from his status as toolmaker, placing
him among the robust australopithecines (A. boisei).
In the early 1970s, Leakey's son Richard, working at Lake Turkana,
Kenya, discovered fossil jaws of Homo habilis that resembled the
Kanam jaw. Since the Lake Turkana Homo habilis jaws were discovered
with a fauna similar to that at Kanam, the elder Leakey changed his
mind once more, suggesting that the Kanam jaw could be assigned to
Homo habilis.
That over the years scientists have attributed the Kanam jaw to
almost every known hominid (Australopithecus, Australopithecus
boisei, Homo habilis, Neanderthal man, early Homo sapiens, and
anatomically modern Homo sapiens) shows the difficulties involved in
properly classifying hominid fossil remains.
Tobias's suggestion that the Kanam jaw came from a variety of early
Homo sapiens, with neanderthaloid features, has won wide acceptance.
Yet as can be seen outlines of the Kanam mandible and other hominid
mandibles, the contour of the Kanam mandible's chin region (h) is
similar to that of the Border Cave specimen (f), recognized as Homo
sapiens sapiens, and to that of a modern South African native (g).
All three share two key features of the modern human chin, namely,
an incurvation toward the top and a swelling outward at the base.
But even if one were to accept Tobias's view that the Kanam jaw was
neanderthaloid, one would still not expect to discover Neanderthals
in the Early Pleistocene, over 1.9 million years ago. Neanderthaloid
hominids came into existence at most 400,000 years ago and persisted
until about 30,000 or 40,000 years ago, according to most accounts.
To ascertain the age of the Kanam jaw and Kanjera skulls, K. P.
Oakley of the British Museum performed fluorine-, nitrogen-, and
uranium-content tests. Bones buried in the ground absorb fluorine.
The Kanam jaw and the Kanjera skulls had about the same fluorine
content as other bones from the Early and Middle Pleistocene
formations where they were found. These results are consistent with
the hypothesis that the human bones at Kanam and Kanjera are as old
as the faunal remains at those sites.
Nitrogen is a component of bone protein. Bones normally tend to lose
nitrogen over time. Oakley found that a Kanjera 4 skull fragment
showed just a trace of nitrogen (0.01 percent), while a Kanjera 3
skull fragment showed none. Neither of the two animal fossils tested
showed any nitrogen. The presence of "measurable traces" of nitrogen
in the Kanjera 4 skull fragment meant, said Oakley, that all the
human fossils were "considerably younger" than the Kanjeran fauna.
But certain deposits, such as clay, preserve nitrogen, sometimes for
millions of years. So perhaps the Kanjera 4 fragment was protected
from complete nitrogen loss by clay. In any case, the Kanjera 3
fragment, like the animal samples, had no nitrogen. So it is
possible that all the bones were of the same age.
As shown in Table 12.1, the uranium content values for the Kanjera
human fossils (8-47 parts per million) overlapped the values for the
Kanjeran fauna (26-216 parts per million). This could mean they were
of the same age.
But the human bones averaged 22 parts per million while the
mammalian fauna averaged 136 parts per million. To Oakley, the
substantial difference between the averages meant that the human
bones were "considerably younger" than the animal bones. Similar
uranium-content results were obtained at Kanam.
But Oakley himself pointed out that the uranium content of ground
water can vary considerably from place to place. For example, Late
Pleistocene animal bones from Kugata, near Kanam, have more uranium
than the Early Pleistocene bones at Kanam.
Significantly, the uranium-content values that Oakley reported in
1974 were apparently not the first he had obtained. In a paper
published in 1958, Oakley said, immediately after discussing the
uranium-content testing of the Kanam jaw:
"Applied to the Kanjera
bones our tests did not show any discrepancy between the human
skulls and the associated fauna."
It would appear that Oakley was
not satisfied with these early tests and later performed additional
tests on the Kanjera bones, obtaining results that were more to his
liking.
Our review of the chemical testing of the Kanam and Kanjera fossils
leads us to the following conclusions. The fluorine - and
nitrogen - content tests gave results consistent with the human bones
being as old as their accompanying faunas. This interpretation can
nevertheless be challenged. The uranium-content test gave results
consistent with the human bones being younger than their
accompanying faunas. But here again, if one chooses to challenge
this interpretation, one will find ample grounds to do so.
All in all, the results of chemical and radiometric tests do not
eliminate the possibility that the Kanam and Kanjera human fossils
are contemporary with their accompanying faunas. The Kanjera skulls,
said to be anatomically modern, would thus be equivalent in age to
Olduvai Bed IV, which is 400,000 to 700,000 years old. The taxonomic
status of the Kanam jaw is uncertain. Recent workers hesitate to
call it anatomically modern, although this designation cannot be
ruled out completely. If it is as old as the Kanam fauna, which is
older than Olduvai Gorge Bed I, then the Kanam mandible would be
over 1.9 million years old.
THE BIRTH OF AUSTRALOPITHECUS
In 1924, Josephine Salmons noticed a fossil baboon skull sitting
above the fireplace in a friend's home. Salmons, a student of
anatomy at the University of the Witwatersrand in Johannesburg,
South Africa, took the specimen to her professor, Dr. Raymond A.
Dart.
The baboon skull given to Dart by Salmons was from a limestone
quarry at Buxton, near a town called Taung, about 200 miles
southwest of Johannesburg. Dart asked his friend Dr. R. B. Young, a
geologist, to visit the quarry and see what else might be found.
Young collected some fossil-bearing chunks and sent them to Dart.
Two crates of fossils arrived at Dart's home on the very day a
friend's wedding was to be held there. Dart's wife pleaded with him
to leave the fossils alone until after the wedding, but Dart opened
the crates. In the second crate, Dart saw something that astonished
him: "I found the virtually complete cast of the interior of a skull
among them. This brain cast was as big as that of a large gorilla."
Dart then found another piece of rock that appeared to contain the
facial bones.
After the wedding guests departed, Dart began the arduous task of
detaching the bones from their stony matrix. Without proper
instruments, he used his wife's knitting needles to carefully chip
away the stone.
"What emerged," wrote Dart, "was a baby's face, an
infant with a full set of milk teeth and its permanent molars just
in the process of erupting. I doubt if there was any parent prouder
of his offspring than I was of my Taung baby on that Christmas."
After freeing the bones, Dart reconstructed the skull. He
characterized the Taung baby's brain as unexpectedly large, about
500 cubic centimeters. The average brain capacity of a large male
adult gorilla is only about 600 cubic centimeters. Dart noted the
absence of a brow ridge and thought that the teeth displayed some
humanlike features.
Dart also noted that the foramen magnum, the opening for the spinal
cord, was set toward the center of the base of the skull, as in
human beings, rather than toward the rear, as in adult apes. Dart
took this to indicate the creature had walked upright, which meant
the Taung specimen was, in his eyes, clearly a human ancestor.
Dart sent a report to Nature, the prestigious British science
journal.
"The specimen," said Dart, "is of importance because it
exhibits an extinct race of apes intermediate between living
anthropoids and man."
From the accompanying animal fossils, he
estimated his find's age at 1 million years. He named his Taung baby
Australopithecus africanus—the southern ape of Africa.
Australopithecus, he believed, was ancestral to all other hominid
forms.
In England, Sir Arthur Keith and Sir Arthur Smith Woodward received
the report from Dart with utmost caution. Keith thought
Australopithecus belonged with the chimpanzees and gorillas.
Grafton Elliot Smith was even more critical. In May 1925, in a
lecture delivered at University College, Smith stated:
"It is
unfortunate that Dart had no access to skulls of infant chimpanzees,
gorillas, or orangs of an age corresponding to that of the Taung
skull, for had such material been available he would have realized
that the posture and poise of the head, the shape of the jaws, and
many details of the nose, face, and cranium upon which he relied for
proof of his contention that Australopithecus was nearly akin to
man, were essentially identical with the conditions met in the
infant gorilla and chimpanzee."
Grafton Elliot Smith's critique
remains valid even today. As we shall see, despite the enshrinement
of Australopithecus as an ancestor of human beings, several
scientists remain doubtful.
Dart was dismayed by the cool reception he received from the British
scientific establishment. For many years, he remained silent and
stopped hunting for fossils. British scientists, led by Sir Arthur
Keith, maintained their opposition to Dart's Australopithecus
throughout the 1930s. Piltdown man, believed to be similar in
geological age to the Taung specimen, entered Keith's calculations.
The skull of Piltdown man was like that of Homo sapiens. This fact
argued against Australopithecus, with its apelike skull, being in
the line of human ancestry.
When Dart retired from the world stage, his friend Dr. Robert Broom
took up the battle to establish Australopithecus as a human
ancestor. From the beginning, Broom displayed keen interest in
Dart's discovery. Soon after the Taung baby made his appearance,
Broom rushed to Dart's laboratory. Dart said,
"he strode over to the
bench on which the skull reposed and dropped on his knees 'in
adoration of our ancestor,' as he put it."
British science, however,
demanded an adult specimen of Australopithecus before it would kneel
in adoration. Early in 1936, Broom vowed to find one.
On August 17, 1936, G. W. Barlow, the supervisor of the Sterkfontein
limestone quarry, gave Broom a brain cast of an adult
australopithecine. Broom later went to the spot where the brain cast
had turned up and recovered several skull fragments. From these he
reconstructed the skull, naming its owner Plesianthropus
transvaalensis. The deposits in which the fossil was discovered are
thought to be between 2.2 and 3.0 million years old.
More discoveries followed, including the lower part of a femur (TM
1513). In 1946, Broom and G. W. H. Schepers described this femur as
essentially human. W. E. Le Gros Clark, initially skeptical of this
description, later admitted that the femur "shows a resemblance to
the femur of Homo which is so close as to amount to practical
identity."
This estimation was reconfirmed in 1981 by
Christine Tardieu, who said the key diagnostic features of the Sterkfontein
femur are "characteristic of modern Man." Since the TM 1513 femur
was found by itself, it is not clear that it belongs to an
australopithecine. It is possible, therefore, that it could belong
to a more advanced hominid, perhaps one resembling anatomically
modern humans.
On June 8, 1938, Barlow gave Broom a fragment of a palate with a
single molar attached. When Broom asked from where it had come,
Barlow was evasive. Some days later, Broom again visited Barlow and
insisted that he reveal the source of the fossil.
Barlow told Broom that Gert Terblanche, a local schoolboy, had given
the bone fragment to him. Broom obtained some teeth from Gert, and
together they went to the nearby Kromdraai farm, where the boy had
gotten the teeth. There Broom collected some skull fragments. After
reconstructing the partial skull, Broom saw it was different from
the Sterkfontein australopithecine. It had a larger jaw and bigger
teeth. He called the new australopithecine creature Paranthropus
robustus. The Kromdraai site is now considered to be approximately
1.0 to 1.2 million years old.
Broom also found at Kromdraai a fragment of humerus (the bone of the
upper arm) and a fragment of ulna (one of the bones of the lower
arm). Although he attributed them to the robust australopithecine
called Paranthropus, he said:
"Had they been found isolated probably
every anatomist in the world would say that they were undoubtedly
human."
An analysis done by H. M. McHenry in 1972 puts the TM 1517 humerus from Kromdraai "within the human range."
In McHenry's study,
a robust australopithecine humerus from Koobi Fora, Kenya, fell
outside the human range. So perhaps the TM 1517 humerus belonged to
something other than a robust australopithecine. It is not
impossible that the Kromdraai humerus and ulna, like the
Sterkfontein femur, belonged to more advanced hominids, perhaps
resembling anatomically modern humans.
World War II interrupted Broom's excavation work in South Africa.
After the war, at Swartkrans, Robert Broom and J. T. Robinson found
fossils of a robust australopithecine called Paranthropus crassidens
(large-toothed near-man). This creature had large strong teeth and a
bony crest on top of the skull. The crest served as the point of
attachment for big jaw muscles.
Broom and Robinson also found the jaw of another kind of hominid in
the Swartkrans cave.
They attributed the jaw (SK15), smaller and
more humanlike than that of Paranthropus crassidens, to a new
hominid called Telanthropus capensis. Member 1 at Swartkrans, where
all of the Paranthropus bones were found, is now said to be 1.2 to
1.4 million years old. Member 2, where the SK 15 Telanthropus
mandible was found, is said to be 300,000 to 500,000 years old. In
1961, Robinson reclassified the Swartkrans jaw as Homo erectus.
Broom and Robinson found another humanlike lower jaw at Swartkrans.
This fragmentary mandible (SK 45) came from the main deposit
containing the Paranthropus fossils.
Broom and Robinson said in
1952:
"In shape it is more easily matched or approached by many
modern Homo jaws than by that of Telanthropus."
Robinson later
referred the SK 45 jaw to Telanthropus and then to Homo erectus. But
there are reasons, admittedly not unclouded, to consider other
possibilities.
In the postwar years, Broom also found another australopithecine
skull (St 5) at Sterkfontein. Later he discovered further remains of
an adult female australopithecine (St 14)—including parts of the
pelvis, vertebral column, and legs. Their morphology, along with
certain features of the Sterkfontein skulls, demonstrated, in
Broom's opinion, that the australopithecines had walked erect.
In 1925, Raymond A. Dart investigated a tunnel at Makapansgat, South
Africa. Noting the presence of blackened bones, Dart concluded
hominids had used fire there. In 1945, Philip V. Tobias, then Dart's
graduate student at the University of the Witwatersrand, found the
skull of an extinct baboon in the cave deposits of Makapansgat and
called it to Dart's attention. In 1947, Dart himself went back out
into the field, after a lapse of two decades, to hunt for
Australopithecus bones at Makapansgat.
At Makapansgat, Dart found australopithecine skull fragments and
other bones, along with more signs of fire. Dart therefore called
the creature who lived there Australopithecus prometheus, after the
Titan who stole fire from the gods. Today Australopithecus
prometheus is classified, along with the Taung and Sterkfontein
specimens, as Australopithecus africanus, distinct from the robust
australopithecines of Kromdraai and Swartkrans.
Dart discovered 42 baboon skulls at Makapansgat, 27 of which had
smashed fronts. Seven more showed blows on the left front side. From
this evidence, Dart created a lurid portrait of Australopithecus
prometheus as a killer ape-man, bashing in the heads of baboons with
primitive bone tools and cooking their flesh over fires in the
Makapansgat cave.
"Man's predecessors," said Dart, "differed from living apes in being
confirmed killers; carnivorous creatures, that seized living
quarries by violence, battered them to death, tore apart their
broken bodies, dismembered them limb from limb, slaking their
ravenous thirst with the hot blood of victims and greedily devouring
their writhing flesh."
Today, however, paleoanthropologists characterize Australopithecus
as merely a scavenger, not a hunter and maker of fire. Nevertheless,
the new discoveries by Broom and Dart convinced influential
scientists, especially in Great Britain, that Australopithecus was
not just a variety of fossil ape but was a genuine human ancestor.
ZINJANTHROPUS
The next important discoveries were made by Louis Leakey and his
second wife Mary. On July 17, 1959, Mary Leakey came across the
shattered skull of a young male hominid in Bed I of Olduvai Gorge at
site FLK. When the skull was pieced together, Louis and Mary Leakey
saw that the creature had a saggital crest, a bony ridge running
lengthwise along the top of the skull. In this respect, it was very
much like Australopithecus robustus.
Leakey nevertheless created a
new species for this hominid, partly because its teeth were bigger
than those of the South African robustus specimens. Leakey called
the new find Zinjanthropus boisei. Zinj is a name for East Africa
and boisei refers to Mr. Charles Boise, one of the Leakeys' early
financial backers. Along with the skull, Leakey found stone tools,
causing him to call Zinjanthropus the first stone toolmaker, and
hence the first "true man."
Leakey became the first superstar that paleoanthropology had seen in
a while. The National Geographic Society honored Leakey with funds,
publication of lavishly illustrated articles, television specials,
and worldwide speaking tours.
But despite an outpouring of publicity, the reign of Zinjanthropus
was all too brief. Leakey's biographer, Sonia Cole, wrote:
"Granted
that Louis had to persuade the National Geographic Society that in Zinj he had a likely candidate for 'the first man' in order to
ensure their continued support—but need he have stuck out his neck
quite so far? Even a layman looking at the skull could not be
fooled: Zinj, with his gorilla-like crest on the top of the cranium
and his low brow, was quite obviously far more like the robust
australopithecines of South Africa than he was like modern man—to
whom, quite frankly, he bears no resemblance at all."
HOMO HABILIS
In 1960, about a year after the discovery of Zinjanthropus, Leakey's
son Jonathan found the skull of another hominid (OH 7) nearby. In
addition to the skull, the OH 7 individual included the bones of a
hand. Also in 1960, the bones of a hominid foot (OH 8) were found.
In succeeding years, more discoveries followed, mostly teeth and
fragments of jaw and skull. The fossil individuals were given
colorful nicknames: Johnny's Child, George, Cindy, and Twiggy. Some
of the bones were found in the lower part of Bed II of Olduvai
Gorge.
Philip Tobias, the South African anatomist, gave the OH 7 skull a
capacity of 680 cc, far larger than Zinjanthropus at 530 cc, and
larger even than the biggest australopithecine skull, at roughly 600
cc. It was, however, around 100 cc less than the smallest Homo
erectus.
Louis Leakey decided he had now come upon the real toolmaker of the
lower levels of Olduvai, the real first true human. His bigger brain
confirmed his status. Leakey called the creature Homo habilis, which
means "handy man."
After the discovery of Homo habilis, Zinjanthropus was demoted to
Australopithecus boisei, a somewhat more robust variety of
Australopithecus robustus. Both of these robust australopithecines
had saggital crests, and are regarded not as human ancestors but as
evolutionary offshoots that eventually became extinct.
The whole business of saggital crests complicates matters somewhat.
Male gorillas and some male chimpanzees also have saggital crests,
whereas the females of these species do not. Mary Leakey therefore
said in 1971:
"The possibility that A. robustus and A. africanus
represent the male and female of a single species deserves serious
consideration."
If the possibility raised by Mary Leakey were found
to be correct, this would mean that generations of experts have been
wildly mistaken about the australopithecines.
With the discovery at Olduvai Gorge of Homo habilis, a creature
contemporary with the early australopithecines but with a bigger
brain, Louis Leakey believed he had excellent evidence supporting
his view that Australopithecus was not in the direct line of human
ancestry. The australopithecines would be merely a side branch. And
because Homo erectus was thought to be a descendant of
Australopithecus, Homo erectus would also be removed from the line
of human ancestry.
But what about the Neanderthals? These, say some authorities, show
clearly an evolutionary transition between Homo erectus and Homo
sapiens. But Leakey had another explanation:
"Is it not possible
that they are all variants of the result of crossbreeding between
Homo sapiens and Homo erectus. One might object that such
crossbreeding would have yielded hybrids that were unable to
reproduce."
But Leakey pointed out that American bison cross
fertilely with ordinary cattle.
A TALE OF TWO HUMERI
In 1965, Bryan Patterson and W. W. Howells found a surprisingly
modern-looking hominid humerus (upper arm bone) at Kanapoi, Kenya.
In 1977, French workers found a similar humerus at Gombore,
Ethiopia.
The Kanapoi humerus fragment, consisting of the intact lower (or
distal) part of the bone, was found on the surface. But the deposit
from which the bone apparently came was about 4.5 million years old.
Patterson and Howells found that the Kanapoi humerus was different
from the humeri of gorillas, chimpanzees, and australopithecines but
similar to those of humans. They noted that "there are individuals
in our sample of man on whom measurements . . . of Kanapoi Hominoid
I can be duplicated almost exactly."
Patterson and Howells would not have dreamed of suggesting that the
Kanapoi humerus belonged to an anatomically modern human.
Nevertheless, if an anatomically modern human had died at Kanapoi
4.0-4.5 million years ago, he or she might have left a humerus
exactly like the one they found.
Further confirmation of the humanlike morphology of the Kanapoi
humerus came from anthropologists Henry M. McHenry and Robert S.
Corruccini of the University of California. They concluded that "the
Kanapoi humerus is barely distinguishable from modern Homo" and
"shows the early emergence of a Homo-like elbow in every subtle
detail."
In a 1975 study, physical anthropologist C. E. Oxnard agreed with
this analysis. He stated: "we can confirm clearly that the fossil
from Kanapoi is very humanlike." This led Oxnard to suggest, as did
Louis Leakey, that the australopithecines were not in the main line
of human evolution. Keeping Australopithecus as a human ancestor
would result in a very unlikely progression from the humanlike
Kanapoi humerus, to the markedly less humanlike humerus of
Australopithecus, and then to one more humanlike again.
The Gombore humerus, given an age of about 1.5 million years, was
found along with crude stone tools. In 1981, Brigitte Senut said
that the Gombore humerus "cannot be differentiated from a typical
modern human." So now we seem to have two very ancient and humanlike
humeri to add to our list of evidence challenging the currently
accepted scenario of human evolution.
These are the Kanapoi humerus
at 4.0-4.5 million years in Kenya and the Gombore humerus at more
than 1.5 million years in Ethiopia. They support the view that human
beings of modern type have coexisted with other humanlike and
apelike creatures for a very long time.
DISCOVERIES OF RICHARD LEAKEY
In 1972 Louis Leakey's son Richard found at Lake Turkana, Kenya, a
shattered hominid skull. Richard's wife Meave, a zoologist,
reconstructed the skull, which was designated ER 1470. Its cranial
capacity was over 810 cc, bigger than the robust australopithecines.
Richard Leakey initially hesitated to designate a species for the ER
1470 skull but eventually decided to call it Homo habilis.
The stratum yielding the skull lay below the KBS Tuff, a volcanic
deposit with a potassium-argon age of 2.6 million years. The skull
itself was given an age of 2.9 million years, as old as the oldest
australopithecines. The KBS Tuff's age was later challenged, with
critics favoring an age of less than 2 million years.
Some distance from where the ER 1470 skull had been found, but at
the same level, John Harris, a paleontologist from the Kenya
National Museum, discovered two quite humanlike femurs. Harris
summoned Richard Leakey, who later reported that "these femurs are
unlike those of Australopithecus, and astonishingly similar to those
of modern man." Other workers found the femurs different from those
of Homo erectus.
The first femur, with associated fragments of tibia and fibula, was
designated ER 1481 and the other ER 1472. An additional fragment of
femur was designated ER 1475. They were all attributed to Homo
habilis.
But Leakey stated in a scientific journal that these leg bones
"cannot be readily distinguished from H. sapiens if one considers
the range of variation known for this species." In a National
Geographic article, Leakey repeated this view, saying the leg bones
were "almost indistinguishable from those of Homo sapiens." Other
scientists agreed with Leakey's analysis. B. A. Wood, anatomist at
the Charing Cross Hospital Medical School in London, stated that the
femurs "belong to the 'modern human walking' locomotor group."
Although most scientists would never dream of it, one could consider
attributing the Koobi Fora femurs to a hominid very much like modern
Homo sapiens, living in Africa about 2 million years ago.
The ER 1472 and ER 1481 femurs show that distinctly anomalous
discoveries are not confined to the nineteenth century. They have
continued to occur with astonishing regularity up to the present
day, right under our very noses, so to speak, although hardly anyone
recognizes them for what they are. In Africa alone, we are building
up quite a catalog: Reck's skeleton, the Kanam jaw, the Kanjera
skulls, the Kanapoi humerus, the Gombore humerus, and now the Lake
Turkana femurs.
All have been either attributed to Homo sapiens or
described as being very humanlike. Except for the Middle Pleistocene Kanjera skulls, all were discovered in Early Pleistocene or Pliocene
contexts.
THE ER 813 TALUS
In 1974, B. A. Wood described a talus (ankle bone) found at Lake Turkana. It lay between the KBS Tuff and the overlying Koobi Fora
Tuff. Wood compared the fossil talus, designated ER 813, with those
of modern humans, gorillas, chimpanzees, and other arboreal
primates. "The fossil aligned with the modern human tali," said
Wood.
The humanlike ER 813 talus is 1.5 to 2.0 million years old, roughly
contemporary with creatures designated as Australopithecus robustus,
Homo erectus, and Homo habilis.
In a subsequent report, Wood said his tests confirmed "the
similarity of KNM-ER 813 with modern human bones," showing it to be
"not significantly different from the tali of modern bushmen." One
could therefore consider the possibility that the KNM-ER 813 talus
belonged to an anatomically modern human in the Early Pleistocene or
Late Pliocene.
If the KNM-ER 813 talus really did belong to a creature very much
like modern human beings, it fits, like the ER 1481 and ER 1472
femurs, into a continuum of such finds reaching back millions of
years. This would eliminate Australopithecus, Homo habilis, and Homo
erectus as human ancestors.
OH 62: WILL THE REAL HOMO HABILIS PLEASE STAND UP?
Artists, working from fossils and reports supplied by
paleoanthropologists, have typically depicted Homo habilis as having
an essentially humanlike body except for its apelike head.
This highly speculative portrait of Homo habilis persisted until
1987. In that year, Tim White and Don Johanson reported they had
found at Olduvai Gorge the first Homo habilis individual (OH 62)
with the bones of the body clearly associated with the skull. The
skeletal remains showed the creature was only 3.5 feet tall and had
relatively long arms. Drawings of the new Homo habilis were
decidedly more apelike than those of the past.
Johanson and his coworkers concluded it was likely that scientists
had incorrectly attributed to Homo habilis many limb bones
discovered prior to 1987.
The OH 62 find supports our suggestion that the ER 1481 and ER 1472
femurs from Koobi Fora, described as very much like those of modern
Homo sapiens, might have belonged to anatomically modern humans
living in Africa during the Late Pliocene. Some scientists
attributed them to Homo habilis. But the new view of Homo habilis
rules this out. Could the femurs perhaps belong to Homo erectus? G.
E. Kennedy, for example, assigned the ER 1481 femur to Homo erectus.
But E. Trinkhaus noted that key measurements of this bone, with one
exception, are within the range of anatomically modern human femurs.
The discoverers of OH 62 had to grapple with the evolutionary link
between the new, more apelike Homo habilis and Homo erectus. The two
species are separated by only 200,000 or so years. But the H.
habilis-H. erectus transition involves some rather extreme
morphological changes, including a big change in size. Richard
Leakey, applying normal human growth patterns, calculated that an
adolescent Homo erectus discovered in 1984 (KNM-WT 15000) would have
grown to over 6 feet tall as an adult.
The adult OH 62, on the other
hand, was only about 3.25 feet tall. Altogether, an evolutionary
leap from small, apelike OH 62 to big, more humanlike KNM-WT 15000
in less than 200,000 years seems implausible.
Advocates of the much-debated punctuational model of evolution,
however, can easily accept the transition. Unlike the traditional
gradualists, punctuationalists assert that evolution proceeds by
rapid episodes of change interrupted by long periods of stasis.
Punctuationalism can, therefore, accommodate a variety of
troublesome evolutionary anomalies, such as the habilis-to-erectus
transition.
"The very small body size of the OH 62 individual," said its
discoverers, "suggests that views of human evolution positing
incremental body size increase through time may be rooted in
gradualistic preconceptions rather than fact."
But punctuational
views may also be rooted in preconception rather than fact. The
paleontological facts, considered in their entirety, suggest that
various ape-man-like and humanlike beings, including some resembling
modern humans, coexisted throughout the Pleistocene, and earlier.
It was not only new evidence such as OH 62 that challenged the
long-accepted picture of Homo habilis. Previously discovered fossil
evidence relating to Homo habilis, originally interpreted by some
authorities as very humanlike, was later characterized by others as
quite apelike.
As mentioned earlier, a fairly complete foot skeleton, designated OH
8, was found in Bed I at Olduvai Gorge. Dated at 1.7 million years,
the OH 8 foot was attributed to Homo habilis. In 1964, M. H. Day and
J. R. Napier said the OH 8 foot very much resembled that of Homo
sapiens, thus contributing to the overall humanlike picture of Homo habilis.
But O. J. Lewis, anatomist at St. Bartholomew's Hospital Medical
College in London, demonstrated that the OH 8 foot was more like
that of chimpanzees and gorillas. He considered the foot to be
arboreal, adapted to life in trees. This poses a problem. It
certainly does not serve the propaganda purposes of evolutionists to
have the public visualizing a supposed human ancestor like Homo habilis climbing trees with an aboreally adapted foot rather than
walking tall and brave across the African savannahs.
From Lewis's study of the OH 8 foot, one could conclude that Homo
habilis was much more apelike than most scientists have tended to
believe. The OH 62 discovery supports this view. Another possible
conclusion: the OH 8 foot did not belong to Homo habilis but to an
australopithecine. This view was favored by Lewis.
Over the years, different scientists have described the OH 8 foot
skeleton as humanlike, apelike, intermediate between human and ape,
distinct from both human and ape, and orangutan-like. This
demonstrates once more an important characteristic of
paleoanthropological evidence—it is often subject to multiple,
contradictory interpretations. Partisan considerations often
determine which view prevails at any given point in time.
The OH 7 hand was also found at Olduvai Gorge, as part of the type
specimen of Homo habilis. In 1962, J. R. Napier described the hand
as quite human in some of its features, especially the fingertips.
As in the case of the OH 8 foot, subsequent studies showed the OH 7
hand to be very apelike, calling into question either its
attribution to Homo habilis or the generally accepted humanlike
picture of Homo habilis, which the original interpretation of the OH
7 hand helped create. The apelike character of the hand suggested to
Randall L. Susman and Jack T. Stern that it was used in "in suspensory climbing behavior."
In others words, Homo habilis, or whatever creature owned the OH 7
hand, may have spent much of its time hanging by its arms from tree
limbs. This apelike image differs from the very humanlike portrait
of Homo habilis and other supposed human ancestors one usually
encounters in Time-Life picture books and National Geographic
Society television specials.
In light of the contradictory evidence connected with Homo habilis,
some researchers have proposed that there was no justification for
"creating" this species in the first place.
If the bones attributed to Homo habilis did not really belong to
this species, then what did they represent? T. J. Robinson argued
that Homo habilis had been mistakenly derived from a mixture of
skeletal elements belonging to Australopithecus africanus and Homo
erectus. Others have suggested that the Homo habilis bones are all
australopithecine.
So in the end, we find that Homo habilis is about as substantial as
a desert mirage, appearing now humanlike, now apelike, now real, now
unreal, according to the tendency of the viewer.
Taking the many
conflicting views into consideration, we find it most likely that
the Homo habilis material belongs to more than one species,
including a small, apelike, arboreal australopithecine (OH 62 and
some of the Olduvai specimens), a primitive species of Homo (ER 1470
skull), and anatomically modern humans (ER1481 and ER 1472 femurs).
OXNARD'S CRITIQUE OF AUSTRALOPITHECUS
Homo habilis is not the only human ancestor to come under sustained
criticism. According to most paleoanthropologists, Australopithecus
was a direct human ancestor, with a very humanlike body. Advocates
of this view have also asserted that Australopithecus walked erect,
in a manner practically identical to modern human beings. But right
from the very start, some researchers objected to this depiction of
Australopithecus. Influential English scientists, including Sir
Arthur Keith, said that the Australopithecus was not a hominid but a
variety of ape.
This negative view persisted until the early 1950s, when the
combined effect of further Australopithecus finds and the fall of
Piltdown man created a niche in mainstream paleoanthropological
thought for a humanlike Australopithecus.
But even after Australopithecus won mainstream acceptance as a
hominid and direct human ancestor, opposition continued. Louis
Leakey held that Australopithecus was an early and very apelike
offshoot from the main line of human evolution. Later, his son
Richard Leakey took much the same stance.
In the early 1950s, Sir Solly Zuckerman published extensive
biometric studies showing Australopithecus was not as humanlike as
imagined by those who favored putting this creature in the lineage
of Homo sapiens. From the late 1960s through the 1990s, Charles E.
Oxnard, employing multivariate statistical analysis, renewed and
amplified the line of attack begun by Zuckerman. According to
Oxnard,
"it is rather unlikely that any of the Australopithecines... can have any direct phylogenetic link with the genus Homo."
Oxnard found the brain, teeth, and skull of Australopithecus to be
quite like those of apes. The shoulder bone appeared to be adapted
for suspending the body from the limbs of trees. The hand bones were
curved like those of the orangutan. The pelvis appeared to be
adapted for quadrupedal walking and acrobatic behavior.
The same was
true of the femur and ankle structure.
"Pending further evidence,"
wrote Oxnard in 1975, "we are left with the vision of intermediately
sized animals, at home in the trees, capable of climbing, performing
degrees of acrobatics and perhaps arm suspension."
In 1973, Zuckerman and Oxnard presented a paper at a symposium of
the Zoological Society of London in 1973. At the conclusion of the
symposium, Zuckerman made some important remarks. He said:
"Over the
years I have been almost alone in challenging the conventional
wisdom about the australopithecines alone, that is to say, in
conjunction with my colleagues in the school I built up in
Birmingham—but I fear to little effect. The voice of higher
authority had spoken, and its message in due course became
incorporated in text books all over the world."
The situation has not changed since Zuckerman spoke in 1973. The
voices of authority in paleoanthropology and the scientific
community in general have managed to keep the humanlike view of
Australopithecus intact. The extensive and well-documented evidence
contradicting this favored view remains confined to the pages of
professional journals, where it has little or no influence on the
public in general, even the educated public.
Reviewing the decades-long controversy about the nature of
Australopithecus, Oxnard wrote in 1984:
"In the uproar, at the time,
as to whether or not these creatures were near-ape or human, the
opinion that they were human won the day. This may well have
resulted not only in the defeat of the contrary opinion but also in
the burying of that part of the evidence upon which the contrary
opinion was based. If this is so, it should be possible to unearth
this other part of the evidence. This evidence may actually be more
compatible with the new view; it may help open the possibility that
these particular australopithecines are neither like African apes
nor humans, and certainly not intermediate, but something markedly
different from either."
Of course, this is exactly the point we have been making throughout
this book. Evidence has been buried. We ourselves have uncovered
considerable amounts of such buried evidence relating to the
antiquity of the modern human type.
Summarizing his findings, Oxnard stated:
"The various
australopithecine fossils are usually quite different from both man
and the African apes . . . Viewed as a genus, they are a mosaic of
features unique to themselves and features bearing some resemblance
to those of the orangutan."
Considering the anatomical uniqueness of
the australopithecines, Oxnard said:
"If these estimates are true,
then the possibility that any of the australopithecines is a direct
part of human ancestry recedes."
Like Louis and Richard Leakey, Oxnard believed that the Homo line
was far more ancient than the standard evolutionary scenario allows.
In this connection, Oxnard called attention to some of the fossils
we have previously discussed, such as the humanlike ER 813 talus,
over 1.5 million years old, and the Kanapoi humerus, perhaps 4 or
more million years old.
From such evidence, Oxnard concluded that
the genus Homo was 5 or more million years old.
"The conventional
notion of human evolution," said Oxnard, "must now be heavily
modified or even rejected . . . new concepts must be explored."
LUCY IN THE SAND WITH DIATRIBES
Despite Oxnard's work, most scientists still adhere to the doctrine
that Australopithecus is a direct human ancestor. One such scientist
is Donald Johanson. Donald Johanson studied anthropology at the
University of Chicago, under F. Clark Howell. As a young graduate
student, eager to learn the romantic business of hominid fossil
hunting, Johanson accompanied Howell to Africa, working at the Omo
site in Ethiopia.
Johanson later returned to Africa, this time heading his own
expedition to Hadar, in the Afar region of Ethiopia. One afternoon,
he found the upper portion of a tibia, a long bone between the knee
and the ankle. The bone was obviously from some kind of primate.
Nearby, Johanson found a distal femur, the lower end of a thighbone.
From the way the femur and tibia fit together, Johanson believed he
had found the complete knee joint not of some ancient monkey but of
a hominid, an ancestor of modern humans. The deposits yielding the
fossils were over 3 million years old, making this one of the oldest
hominid finds ever made.
In scientific publications that followed, Johanson reported that the
Hadar knee (AL 129) was 4 million years old and belonged to a
primitive australopithecine with a fully human bipedal gait.
During the next year's work, Alemayehu Asfaw, an Ethiopian working
at the Hadar site with Johanson, found some fossil jaws. Classifying
them proved difficult. Johanson asked Richard Leakey to come and
have a look at them. Leakey took up the invitation and arrived
accompanied by his mother Mary Leakey and wife Meave. Together with
Johanson, they examined the jaws and judged them to be Homo, making
them the oldest Homo fossils yet found.
On November 30, 1974, Donald Johanson and Tom Gray were searching
Locality 162 at the Hadar site, collecting bits of mammalian bone.
After some time, Gray was ready to call it quits and go back to the
camp. Johanson, however, suggested they check out a nearby gully.
Gray and Johanson did not find much.
But as they were about to leave, Johanson spotted a piece of arm
bone lying exposed on the surface. As they looked around, they could
see scattered on the surface other bones—apparently from the same
hominid individual. Johanson and Gray started jumping and howling in
the 110-degree heat, celebrating what was obviously an extremely
significant find. That evening Johanson and his coworkers partied
while a Beatles song, "Lucy in the Sky with Diamonds," blared
repeatedly from the camp sound system. From the lyrics of that song,
the female hominid received her name, Lucy.
By a combination of potassium-argon, fission track, and
paleomagnetic dating methods, Johanson determined that Lucy was 3.5
million years old.
In 1975, Johanson was back at Hadar, this time with a National
Geographic photographer, who recorded another important discovery.
On the side of a hill, Johanson and his team found the fossil
remains of 13 hominids, including males, females, and children. The
group was called the First Family. They were the same geological age
as Lucy, about 3.5 million years old.
With the First Family, the major discoveries at Hadar, which also
included the Hadar knee, Alemayehu's jaws, and Lucy, were completed.
We shall now examine how these fossils were interpreted and
reinterpreted by various parties.
In classifying his finds, Johanson initially relied heavily upon the
judgment of Richard and Mary Leakey that the Alemayehu jaws and
First Family specimens were Homo. If Lucy and the AL 129 femur and
tibia were australopithecine, as Johanson believed, then there were
two kinds of hominids at Hadar.
Johanson was later influenced to change his mind about the number of
species at Hadar. The person who convinced him to do so was Timothy
D. White, a paleontologist who had worked at Lake Turkana with
Richard Leakey. White also convinced Johanson that the Hadar hominid
represented a new species. Johanson and White called it
Australopithecus afarensis, after the Afar region of Ethiopia.
According to Johanson and White, Australopithecus afarensis, the
oldest australopithecine ever discovered, gave rise to two lineages.
The first led by way of Australopithecus africanus to the robust
australopithecines. The second lineage led by way of Homo habilis to
Homo erectus and thence to Homo sapiens.
A. AFARENSIS: OVERLY HUMANIZED?
Johanson said that Australopithecus afarensis individuals had
"smallish, essentially human bodies." But several scientists have
strongly disagreed with Johanson's picture of Australopithecus
afarensis. These dissenters have painted a far more apelike portrait
of Lucy and her relatives. In most cases, their views on Lucy
parallel the earlier work of Oxnard, Zuckerman, and others on
Australopithecus.
The Hadar fossils did not include a complete skull of an A.
afarensis individual, but Tim White managed to pull together a
partial reconstruction, using cranial fragments, pieces of upper and
lower jaw, and some facial bones from several First Family
individuals. According to Johanson, the reconstructed skull "looked
very much like a small female gorilla." Here there was no dispute
between Johanson and his critics. Both agreed that the afarensis
head was apelike.
As for the body of A. afarensis, Randall L. Susman, Jack T. Stern,
Charles E. Oxnard, and others have found it very apelike, thus
challenging Johanson's view that Lucy walked upright on the ground
in human fashion. Lucy's shoulder-blade was almost identical to that
of an ape. The shoulder joint was turned upward, indicating that
Lucy's arms were probably used for climbing in trees and perhaps
suspending the body.
The bones of the arm were like those of
tree-climbing primates, and the spinal column featured points of
attachment for very powerful shoulder and back muscles. The bones of
the wrist and palm region of the hand were adapted for powerful
grasping, as were the long, curved finger bones. The hip and leg
bones were also adapted for climbing, and the foot had curved toes
that would be useful in grasping branches of trees.
One can just imagine the effects of a painting or model of Lucy
engaged in suspensory or other arboreal behavior. This would surely
detract from her image as a creature well on the way to human
status. Even if one believes Lucy could have evolved into a human
being, one still has to admit that her anatomical features appear to
have been misrepresented for propaganda purposes.
Before leaving the topic of Australopithecus afarensis, we note that
Richard Leakey, Christine Tardieu, and many others have argued that
the fossil material for this species actually included two or even
three species.
Within the scientific community there is as yet no unanimous picture
of what the australopithecines, including A. afarensis, were really
like, both in terms of their morphology and their evolutionary
relation with modern humans. Some see them as ancestors, while
others, such as C. E. Oxnard, do not.
THE LAETOLI FOOTPRINTS
The Laetoli site is located in northern Tanzania, about 30 miles
south of Olduvai Gorge. Laetoli is the Masai word for red lily. In
1979, members of an expedition led by Mary Leakey noticed some marks
on the ground. They proved to be fossil footprints of animals. Among
them were some that appeared to have been made by hominids. The
prints had been impressed in layers of volcanic ash, which yielded a
potassium-argon age of 3.6 to 3.8 million years.
National Geographic magazine featured an article by Mary Leakey
titled "Footprints in the Ashes of Time." In her analysis of the
prints, Leakey cited Louise Robbins, a footprint expert from the
University of North Carolina, who said "they looked so human, so
modern, to be found in tuffs so old."
Readers who have accompanied us this far in our intellectual journey
will have little difficulty in recognizing the Laetoli footprints as
potential evidence for the presence of anatomically modern human
beings over 3.6 million years ago in Africa. We were, however,
somewhat astonished to encounter such a striking anomaly in the
unexpected setting of the more recent annals of standard
paleoanthropological research. What amazed us most was that
scientists of worldwide reputation, the best in their profession,
could look at these footprints, describe their humanlike features,
and remain completely oblivious to the possibility that the
creatures that made them might have been as humanlike as ourselves.
Their mental currents were running in the usual fixed channels.
Mary
Leakey wrote:
"At least 3,600,000 years ago, in Pliocene times, what
I believe to be man's direct ancestor walked fully upright with a
bipedal, free-striding gait. . . . the form of his foot was exactly
the same as ours."
Who was the ancestor? Taking Leakey's point of view, the Laetoli
footprints would have been made by a non-australopithecine ancestor
of Homo habilis. Taking the Johanson-White point of view, the
Laetoli footprints would have been made by Australopithecus
afarensis. In either case, the creature who made the prints would
have had an apelike head and other primitive features.
But why not a creature with fully modern feet and fully modern body?
There is nothing in the footprints that rules this out. Furthermore,
we have compiled in this book quite a bit of fossil evidence, some
of it from Africa, that is consistent with the presence of
anatomically modern human beings in the Early Pleistocene and the
Late Pliocene.
Are we perhaps exaggerating the humanlike features of the Laetoli
footprints? Let us see what various researchers have said. Louise M.
Robbins, who provided an initial evaluation of the Laetoli prints to
Mary Leakey in 1979, later published a more detailed report. Several
sets of tracks, identified by letters, were found at Laetoli. In
examining the "G" trails, representing three individuals described
by Mary Leakey as a possible family group, Robbins found that the
prints "share many features that are characteristic of the human
foot structure."
She especially noted that the big toe pointed
straight forward, as in humans, and not out to the side as in the
apes. In apes, the big toe can be moved much like the human thumb.
Robbins concluded that "the four functional regions—heel, arch,
ball, and toes—of the hominids' feet imprinted the ash in a
typically human manner" and that "the hominids walked across the ash
surface in characteristic human bipedal fashion."
M. H. Day studied the prints using photogrammetric methods.
Photogrammetry is the science of obtaining exact measurements
through the use of photography. His study showed the prints had
"close similarities with the anatomy of the feet of the modern human
habitually unshod; arguably the normal human condition."
Typically,
Day concluded:
"There is now no serious dispute as to the upright
stance and bipedal gait of the australopithecines."
But what proof did he have that an australopithecine made the
Laetoli footprints? There is no reason to rule out the possibility
that some unknown creature, perhaps very much like modern Homo
sapiens, was the cause of them.
R. H. Tuttle, a physical anthropologist, stated:
"The shapes of the
prints are indistinguishable from those of striding, habitually
barefoot humans."
Tuttle concluded:
"Strictly on the basis of the morphology of the G
prints, their makers could be classified as Homo . . . because they
are so similar to those of Homo sapiens, but their early date would
probably deter many palaeoanthropologists from accepting this
assignment. I suspect that if the prints were undated, or if they
had been given younger dates, most experts would probably accept
them as having been made by Homo." Tuttle also stated: "They are
like small barefoot Homo sapiens."
Furthermore, Tuttle held that the A. afarensis foot could not have
made the prints. As we have seen, the A. afarensis foot had long,
curved toes, and Tuttle said it was hard to imagine them "fitting
neatly into the footprints at Laetoli." The same would be true of
any australopithecine foot.
Stern and Susman objected to this. Convinced that the apelike A.
afarensis foot had made the Laetoli footprints, they proposed that
the ancient hominids had walked across the volcanic ash with their
long toes curled under their feet, as chimpanzees have sometimes
been observed to do. Curled-under toes would explain why the A.
afarensis footprints at Laetoli so much resembled those made by the
relatively short-toed human foot.
Could an australopithecine walking with curled toes have made the
humanlike prints? Tuttle found this extremely unlikely. If the
Laetoli hominid had long toes, then, said Tuttle, one would expect
to find two patterns of toe impressions—long extended toes and short
curled toes, with extra-deep knuckle marks. This was not the case,
which meant the long-toed afarensis foot could not have made the
prints.
Even Tim White, who believed Australopithecus afarensis made the
footprints, stated:
"The Stern and Susman (1983) model of toe
curling 'as in the chimpanzee' predicts substantial variation in
lateral toe lengths seen on the Laetoli prints. This prediction is
not borne out by the fossil prints."
Directly challenging Johanson, White, Latimer, and Lovjoy, who
asserted Australopithecus afarensis made the Laetoli prints, Tuttle
said:
"Because of digital curvature and elongation and other
skeletal features that evidence arboreal habits . . . it is unlikely
that Australopithecus afarensis from Hadar, Ethiopia, could make
footprints like those at Laetoli."
Such statements have provoked
elaborate counterattacks from Johanson and his followers, who have
continued to promote the idea that A. afarensis could have made the
tracks.
Tim White, for example, published in 1987 a study of the Laetoli
prints in which he disputed Tuttle's contention that their maker was
a hominid more advanced than A. afarensis.
White asserted:
"There is not a single shred of evidence among the
26 hominid individuals in the collection of over 5,000 vertebrate
remains from Laetoli that would suggest the presence of a more
advanced Pliocene hominid at this site."
But, as we have seen in our
review of African hominid fossils, there are in fact a few "shreds"
of evidence for the presence of sapiens-like creatures in the
Pliocene, some not far from Laetoli. Also, it is well known that
human skeletal remains are quite rare, even at sites where there are
other unmistakable signs of a human presence.
White predicted that,
"the Laetoli prints will eventually be shown to
be subtly distinct from those left under analogous conditions by
anatomically modern humans."
But as far as anyone can see now, they
are indistinguishable from those of modern humans. Even White
himself once said:
"Make no mistake about it. They are like modern
human footprints. If one were left in the sand of a California beach
today, and a four-year-old were asked what it was, he would
instantly say that somebody had walked there. He wouldn't be able to
tell it from a hundred other prints on the beach, nor would you. The
external morphology is the same. There is a well-shaped modern heel
with a strong arch and a good ball of the foot in front of it. The
big toe is in a straight line. It doesn't stick out to the side like
an ape toe."
And Tuttle noted:
"in all discernible morphological features, the
feet of the individuals that made the G trails are indistinguishable
from those of modern humans."
BLACK SKULL, BLACK THOUGHTS
In 1985, Alan Walker of Johns Hopkins University discovered west of
Lake Turkana a fossil hominid skull stained dark by minerals. Called
the Black Skull, it raised questions about Donald Johanson's view of
hominid evolution.
According to Johanson's original idea, Australopithecus afarensis
gave rise to two lines of hominids. This arrangement can be
visualized as a tree with two branches. The trunk is
Australopithecus afarensis. On one branch is the Homo line,
proceeding from Homo habilis to Homo erectus to Homo sapiens. On the
second branch are the australopithecines arising from
Australopithecus afarensis.
Johanson and White claimed that Australopithecus afarensis gave rise
to Australopithecus africanus, which in turn gave rise to
Australopithecus robustus. The trend was toward larger teeth and
jaws, and a larger skull with a ridge of bone, the saggital crest,
running lengthwise along the top. The saggital crest served as a
point of attachment for the powerful jaw muscles of robust
australopithecines. Australopithecus robustus then supposedly gave
rise to the super-robust Australopithecus boisei, which manifested
all the abovementioned features in an extreme form. The Black Skull,
designated KNM-WT 17000, was similar to Australopithecus boisei, but
was 2.5 million years old—older than the oldest robust
australopithecines.
How did Johanson respond to the discovery of the boisei-like Black
Skull? He admitted that the Black Skull complicated things, making
it impossible to arrange Australopithecus africanus,
Australopithecus robustus, and Australopithecus boisei in a single
line of succession coming from Australopithecus afarensis. Johanson
proposed four possible arrangements of these species, without
suggesting which one was correct. There was, he said, not yet enough
evidence to decide among them.
The uncertainty about the number of species at Hadar, combined with
the confused relationships among the successor species
(Australopithecus africanus, Australopithecus robustus,
Australopithecus boisei, and Homo habilis), create problems for
evolutionists. Pat Shipman said in 1986:
"The best answer we can
give right now is that we no longer have a very clear idea of who
gave rise to whom."
In the midst of the new complexity, one question is especially
important—the origin of the Homo line. Shipman told of seeing Bill Kimbel, an associate of Johanson, attempt to deal with the
phylogenetic implications of the Black Skull.
"At the end of a
lecture on Australopithecine evolution, he erased all the tidy,
alternative diagrams and stared at the blackboard for a moment. Then
he turned to the class and threw up his hands," wrote Shipman.
Kimbel eventually decided the Homo line came from Australopithecus
africanus. Johanson and White continued to maintain that Homo came
directly from Australopithecus afarensis.
After she considered various phylogenetic alternatives and found the
evidence for all of them inconclusive, Shipman stated:
"We could
assert that we have no evidence whatsoever of where Homo arises from
and remove all members of the genus Australopithecus from the
hominid family. . . . I've such a visceral negative reaction to this
idea that I suspect I am unable to evaluate it rationally. I was
brought up on the notion that Australopithecus is a hominid."
This
is one of the more honest statements we have heard from a mainstream
scientist involved in paleoanthropological research.
In the foregoing discussion, we have considered only the evidence
that is generally accepted today by most scientists. Needless, to
say, if we were to also consider the evidence for anatomically
modern humans in very ancient times that would complicate the matter
even further.
Summary of Anomalous Evidence Related to Human
Antiquity
Having reviewed the history of African discoveries related to human
evolution, we can make the following summary observations.
(1) There
is a significant amount of evidence from Africa suggesting that
beings resembling anatomically modern humans were present in the
Early Pleistocene and Pliocene.
(2) The conventional image of
Australopithecus as a very humanlike terrestrial biped appears to be
false.
(3) The status of Australopithecus and Homo erectus as human
ancestors is questionable.
(4) The status of Homo habilis as a
distinct species is questionable.
(5) Even confining ourselves to
conventionally accepted evidence, the multiplicity of proposed
evolutionary linkages among the hominids in Africa presents a very
confusing picture.
Combining these findings with those from the
preceding chapters, we conclude that the total evidence, including
fossil bones and artifacts, is most consistent with the view that
anatomically modern humans have coexisted with other primates for
tens of millions of years.
Back
to Contents
|