Laetoli

Sadiman erupts capturing the footprints at Laetoli

The next adventure was an unpremeditated trip into completely trackless country, south of Olduvai and north-west of Lake Eyasi. It was prompted by a visitor, half Masai and half Kikuyu, who announced that he knew of stone-like bones similar to those they had been finding at Olduvai at a place called Laetolil, and he volunteered to guide them there. It proved to be beside a stream which the Germans had named the Vogel River, and the deposits, in heavily eroded 'bad lands', were different from those of Olduvai. In fact they were terrestrial rather than lacustrine, and contained many land tortoises and fossil rodents, but lacked aquatic animals such as hippos which were abundant at Olduvai. Eventually it was found that they were older than Bed I at Olduvai - a lava flow covering the deposits has now been dated to more than two million years.

For several decades Laetoli had just missed as a hominid fossil site. Louis Leakey had a try there in 1935, but came up emptyhanded. He did not know that a tooth he had sent to the British Museum labeled as a baboon's was a hominid canine. Not only was it the first adult australopithecine tooth ever found, but it was the first of any kind since the discovery of the Taung Baby. Nevertheless, it lay unnoticed in the Museum collection until 1979, when it was spotted and properly identified by White.

Leakey, meanwhile, not realizing that he had had in his hand the oldest hominid fossil then known, packed up and moved to Olduvai. He was followed at Laetoli in 1938-1939 by a German named Kohl-Larsen, who recovered a bit of an upper jawbone with a couple of premolars in it, and a well-preserved alveolus - or socket - for a canine tooth.

The trouble with those early Laetoli finds was that they were far too old and far too primitive for anyone then to dream that they were not apes or monkeys; the imagination of the 1930s was simply not elastic enough to accommodate them, even though that same imagination was saying to itself, 'Look deeper into time for older ancestors.' This is an odd, schizophrenic view that still persists today.

By 1974, when Mary Leakey decided to have a go at Laetoli, her mind at least was ready to recognize and accept very old specimens of Homo. When one of the Leakey-trained Kenyan field experts, Karnoya Kimeu, took it upon himself to cut a road in to the deposits through the thicket and came out with a hominid, Mary Leakey moved in with a team of her own. In the next couple of years she or her workers found forty-two teeth, some of them associated with bits of jawbone. One in particular, LH-4 (Laetoli Hominid 4), was a fine specimen, a mandible with nine teeth in place.

But what sets Laetoli apart from every other site in the world is some footprints that have been found there, certainly one of the most extraordinary cases of preservation and discovery in all of paleoanthropology.

Laetoli has a nearby volcano, Sadiman, that is extinct today. Not quite four million years ago it was active. One day it spat out a cloud of carbonitite ash. This stuff has a consistency not unlike that of very fine beach sand, and it powdered down over the surrounding landscape in a layer that reached a thickness of about half an inch before the eruption stopped. This fall of superfine cinders must have been extremely unpleasant for the local animals and birds while it was coming down, but there is no evidence that it did more than make them uncomfortable, because they stayed in the area. That first puff of ash - probably not lasting more than a day - was followed by a rain. The ash became wet and, almost like a newly laid cement sidewalk, began taking clear impressions of everything that walked across it: elephants, giraffes, antelopes, hares, rhinos, pigs. There were also terrestrial birds like guinea fowl and ostriches, and even the small tracks of millipedes.

In the hot sun of Laetoli the wet ash layer quickly dried and hardened, preserving the footprints that crisscrossed it. Then, before it could rain again, Sadiman spoke a second time. Another cloud of ash drifted down, covering the first and sealing in the footprints. This happened a number of times over a period estimated to have been no longer than a month, producing a single volcanic tuff about eight inches thick. .But because of the periodic puffing of Sadiman and the periodic hardening of the ash that fell, the tuff is actually composed of between a dozen and two dozen distinct thin layers. Some of these layers have been exposed recently by erosion, and are visible here and there at Laetoli in the form of a gray substrate wherever the mat of coarse turf above them has been carried off.

One afternoon in 1976, some of the more boisterous members of Mary Leakey's field team were amusing themselves by throwing hunks of dried elephant dung at each other. This may seem a peculiar pastime, but recreational resources are limited on paleontological digs, and there are times when young spirits need to blow off steam. One who felt this urge was Andrew Hill, a paleontologist from the National Museum of Kenya, who, while ducking flying dung and looking for ammunition to fire back, found himself standing in a dry stream bed on some exposed ash layers. One of these had some unusual dents in it. When Hill paused to examine them, he concluded they probably were animal footprints. That diagnosis was confirmed when a larger area was surveyed and other prints found. But no serious effort was made to follow up this extraordinary discovery until the following year, 1977, when a number of large elephant tracks were found by Mary Leakey's son Philip and a co-worker, Peter Jones, and alongside them some tracks that looked suspiciously like human footprints.

The world heard about the footprints later that year when Mary Leakey came to the United States to report on them in a series of press conferences and interviews. To many it seemed almost inconceivable that anything so ephemeral as a footprint should have been preserved for so long. But Mary was positive about the hominid ones. She went on to describe the latter as having been made by a creature that was an imperfect walker; the prints indicated that it had shuffled. She also reported the probable presence at Laetoli of knuckle-walking apes and the existence of a water hole around which the animals and birds appeared to have clustered. She even saw some evidence of panic in the tracks, suggesting that the animals had been fleeing the eruption.

Those revelations by Mary Leakey electrified everybody who heard them. She resolved to devote much of the next season's effort at Laetoli to footprints, and asked the American footprint expert Louise Robbins to join her team. White went to the Laetoli site for the first time that year, and found three other young scientists there: Peter Jones, Paul Abell and Richard Hay. These men had some doubts about Mary's interpretation of the footprints. White questioned the presence of knuckle-walking apes; he had examined those prints and said that they had been made by large extinct baboons that walked flat-footed. Jones said there had been no panicky exodus from the area, because birds, which could have flown away easily and quickly, continued to walk about in the ash it was crisscrossed with their tracks. Hay could find no evidence of a water hole.

These disagreements made for a good many nights of heated argument in camp, during which the supposedly human footprints had their ups and downs. No one could agree on them. Then Paul Abell, prospecting alone one day, found a broken impression - but a much clearer one - that he said he was quite confident was a hominid print. White and Jones made some Polaroid shots of it and came back with a strong impression that Abell was right. They recommended that excavation in the area be started immediately. But Louise Robbins, the footprint expert, examined it and declared that it was the print of a bovid (a hoofed animal). She told Mary Leakey that further investigation would be a waste of time. The men objected.

By then Mary Leakey had become thoroughly exasperated by all the arguing that had been going on. She announced that there would be no excavation. Jones, now convinced that it was a hominid, continued to plead with her for permission to make an excavation. A very small one, he said, was all he asked. Mary was adamant. Louise Robbins, the authority, had spoken; there was too much incomplete excavation at the site already. If there was going to be any digging, let it be done by somebody who had nothing better to do. She pointed to Ndibo, the maintenance man, the man in camp with the least archeological training.

Ndibo, however, proved equal to the task. He returned to camp the next day and reported not one, but two footprints. One was very large. He held his hands up, about a foot apart.

'Those Africans are always exaggerating,' said Mary. But she did go out to have a look, and there they were. White was permitted to start an excavation.

The direction of the prints indicated that their maker had been walking north under some sections of turf that had not yet been eroded. Because of the dense tangle of roots at the bottom of the turf, the task of exposing a clear ash surface without destroying it - not to mention the exact ash out of a dozen or more thin layers of it turned out to be extraordinarily difficult. But Tim is an extraordinarily patient and determined man. He found another print, and then another. He proceeded to protect the prints by hardening them with a preservative, which he poured into them in very small amounts, letting the material dry and then strengthening it by adding more. Working with agonising slowness, he inched his way farther and farther into the turf and discovered that the trail consisted of the tracks of two hominids.

Now he had the riveted attention of the entire camp. Others joined the work and ultimately were able to reveal more than fifty prints covering a distance of seventy-seven feet. Louise Robbins, her interest in the footprints suddenly rekindled, issued another opinion: indeed there were two hominids; they were probably walking together; one (with slightly larger prints) was a male; the other, possibly pregnant she said, was a female; on the evidence of the prints, this type of hominid had been an erect walker for at least a million years.

These are entertaining speculations. There is no way of telling what sex the makers of the footprints were, if one was pregnant, or how long their ancestors had walked erect. The hard truth is that 3.7 million years ago erect hominids of indeterminate sex did walk through fresh-fallen ash at Laetoli and leave an imperishable record of their passing. After seventy-seven feet their trails disappeared under the overlying ash; the particular layer that marked it has been washed away. Tim's work on the footprints stopped at that point, which also marked the end of the season. But he felt strongly that the trail could be picked up again a little farther along and that it would yield more prints if proper excavation were carried out. Work in that direction was done in 1979 by Ron Clarke, and the trail picked up again.

Tim was not a party to this further work. His arguments with Louise Robbins over interpretation of the footprints have made him as unwelcome now at Laetoli as he is at Lake Turkana - a pity, because in each instance he was only trying to help the proprietors.

Tim's concern today is that as more prints are found, they be handled with the utmost care. They are supremely fragile, and the slightest mistake in excavating them can destroy them completely. Some have already been damaged. They are not like fossils, those rocklike models of durability. They are only spaces, mere shapes in a relatively soft and frangible matrix. If that matrix is nudged incorrectly, it will crumble - and the footprints will be gone.

But, by a wildly improbable linkage of random events, they are there. Sadiman had to blow out a particular kind of ash. Rain had to fall on it almost immediately. Hominids had to follow on the heels of the rain. The sun had to come out promptly and harden their footprints. Then another blast from Sadiman had to cover and preserve them before another obliterating shower came along.

All this had to happen over a period of only a few days. And the volcano had to synchronise its activity with that of the seasons. If its bursts had not come just when they did - at the beginning of the rains - the footprints would not have been preserved. A month or two earlier, during the dry season, the ash would not have had the consistency to take a sharp imprint. It would have been a hopelessly blurry one, a mere dent, like the one a passerby today makes in the dry sand on the upper margin of a beach. If it had come later, at the height of the rainy season, it is overwhelmingly likely that there would have' been too much rain; the footprints would have been washed away before they could have been baked hard by the sun. Indeed, there had to be just what the beginning of a rainy season produces: sporadic showers interspersed with intervals of hot sun.

All things considered, the preservation and recovery of the Laetoli footprints are nothing short of a miracle. They confirm without a shadow of a doubt what Lucy confirmed at Hadar: that hominids were fully erect walkers at three million B.C. and earlier. At Hadar the evidence is in the fossils, in the shape of leg and foot bones. But at Laetoli, where the fossil remains - some extremely scrappy and enigmatic postcranial bits, jaw parts, and some teeth - are of very poor quality, there is no way without the footprints of deducing how those hominids got around.

'Make no mistake about it.' says Tim. 'Thev are like modern 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 straight in line. It doesn't stick out to the side like an ape toe, or like the big toe in so many drawings you see of australopithecines in books.

I don't mean to say that there may not have been some slight differences in the foot bones; that's to be expected. But to all intents and purposes, those Laetoli hominids walked like you and me, and not in a shuffling run, as so many people have claimed for so long. Owen Lovejoy deduced all that from studying the Hadar bones. Now the footprints prove him right. I think they rank with the most wonderful and illuminating discoveries in decades. Although it didn't end too happily for me, I'm still grateful that. I was lucky enough to have participated in the work on them.'

This monograph is a lavish description of work carried out from 1974 to 1981 at one of the richest hominid sites in Africa, in northern Tanzania, at a place named after a local Maasai word for the lily. The book also contains a strong attack on the idea of a species named Australopithecus afarensis, proposed by Donald Johanson and others after the discovery of the 'Lucy' remains in Ethiopia in 1977. Mary Leakey first excavated at Laetoli in 1935 with the late Louis Leakey, but nobody realized for over forty years that this site was actually both richer and older than Olduvai and it was only in the mid-1970s that Mary Leakey returned to Laetoli to begin serious and systematic work. The Laetoli layers are in fact around 3.5 to 3.7 million years old, and include the famous footprints left, probably, by a man, a woman and a child strolling across an area of damp ash for a few moments, with a human gait. This comprehensive book covers the whole Laetoli succession in a wide range of disciplines, and brings together work from thirty-three contributors in fourteen carefully and systematically written chapters.

Unfortunately, T. D. White's descriptions of the hominid remains do not appear in this book, for reasons explained by M. Leakey in chapter 5. For White's most recent contribution on the footprints, see Tim D. White and Gen Suwa, 'Hominid footprints at Laetoli: facts and interpretations' (American Journal of Physical Anthropology, vol. 72 [April 1987], p. 485-514. bibliog.), dealing with the fossil footprints of the Australopithecines.

While building the Lodge, George Dove brought in building materials from Laetoli Gorge and noticed that they included a large number of fosils. Some of these can be seen embedded in the wall of the dining room at Ndutu. George told Mary Leakey about these, and they persuaded her to shift her attention from Oldupai to Laetoli, leading eventually to the discovery of the footprints.

Mary first visited Laetoli, an area 30 miles south of Olduvai, in 1935 but didn't establish a permanent site there until 1974. In July of 1975, the first serious excavations began. Early digs revealed an abundance of hominid materials which were dated (by finding the age of overlying lava flows) at more than 2.4-million-years-old, placing them much earlier in time than any found at Olduvai. An even more exciting find occurred in 1976 when visitors to the site accidentally stumbled upon what seemed like fossilized animal prints. "Site A," as it came to be called, ended up containing almost 18,400 individual prints.

Then, in 1978, two short parallel trails of hominid prints were found by a man named Paul Abell, again by accident. Eventually, these trails were found to extend more than 80 ft in rock that was dated at 3.6-million-years-old. The prints were made by two individuals walking side-by-side, with a third deliberately stepping in the footprints of the largest individual; Mary liked to believe that they were of the genus Homo, but other scientists, including Donald Johanson (of "Lucy" fame) think they might be of the Australopithecus line. (In fact, this was a big point of contention in a vicious feud between Leakey and Johanson.)

Despite all of the questions that the footprints raised, and that remain unanswered even today, Mary deemed their discovery as one of the most important made in her lifetime. For instance, the absence of stone tools at the site leads scientists to believe that bipedalism preceded the use of tools. Mary later explained, "The discovery of the trails was immensely exciting-something so extraordinary that I could hardly take it in or comprehend its implications for some while." After their excavation, Mary finished her stay at Laetoli, ending also the most memorable stage of her archaeological career.

This is the trail of footprints uncovered at Laetoli. They show a large and a small hominid walking in the same direction, but give no clue as to whether they walked together - or despite some assertions, as to their sex. They lie just below the present surface of the ground in some shallow layers of ash, and are extremely fragile.

Mary Leakey discovered tracks at Laetoli

For several decades Laetoli had just missed as a hominid fossil site. Louis Leakey had a try there in 1935, but came up emptyhanded. He did not know that a tooth he had sent to the British Museum labeled as a baboon's was a hominid canine. Not only was it the first adult australopithecine tooth ever found, but it was the first of any kind since the discovery of the Taung Baby. Nevertheless, it lay unnoticed in the Museum collection until 1979, when it was spotted and properly identified by White.

Leakey, meanwhile, not realizing that he had had in his hand the oldest hominid fossil then known, packed up and moved to Olduvai. He was followed at Laetoli in 1938-1939 by a German named Kohl-Larsen, who recovered a bit of an upper jawbone with a couple of premolars in it, and a well-preserved alveolus - or socket - for a canine tooth.

The trouble with those early Laetoli finds was that they were far too old and far too primitive for anyone then to dream that they were not apes or monkeys; the imagination of the 1930s was simply not elastic enough to accommodate them, even though that same imagination was saying to itself, 'Look deeper into time for older ancestors.' This is an odd, schizophrenic view that still persists today.

By 1974, when Mary Leakey decided to have a go at Laetoli, her mind at least was ready to recognize and accept very old specimens of Homo. When one of the Leakey-trained Kenyan field experts, Karnoya Kimeu, took it upon himself to cut a road in to the deposits through the thicket and came out with a hominid, Mary Leakey moved in with a team of her own. In the next couple of years she or her workers found forty-two teeth, some of them associated with bits of jawbone. One in particular, LH-4 (Laetoli Hominid 4), was a fine specimen, a mandible with nine teeth in place.

But what sets Laetoli apart from every other site in the world is some footprints that have been found there, certainly one of the most extraordinary cases of preservation and discovery in all of paleoanthropology.

Laetoli has a nearby volcano, Sadiman, that is extinct today. Not quite four million years ago it was active. One day it spat out a cloud of carbonitite ash. This stuff has a consistency not unlike that of very fine beach sand, and it powdered down over the surrounding landscape in a layer that reached a thickness of about half an inch before the eruption stopped. This fall of superfine cinders must have been extremely unpleasant for the local animals and birds while it was coming down, but there is no evidence that it did more than make them uncomfortable, because they stayed in the area. That first puff of ash - probably not lasting more than a day - was followed by a rain. The ash became wet and, almost like a newly laid cement sidewalk, began taking clear impressions of everything that walked across it: elephants, giraffes, antelopes, hares, rhinos, pigs. There were also terrestrial birds like guinea fowl and ostriches, and even the small tracks of millipedes.

In the hot sun of Laetoli the wet ash layer quickly dried and hardened, preserving the footprints that crisscrossed it. Then, before it could rain again, Sadiman spoke a second time. Another cloud of ash drifted down, covering the first and sealing in the footprints. This happened a number of times over a period estimated to have been no longer than a month, producing a single volcanic tuff about eight inches thick. .But because of the periodic puffing of Sadiman and the periodic hardening of the ash that fell, the tuff is actually composed of between a dozen and two dozen distinct thin layers. Some of these layers have been exposed recently by erosion, and are visible here and there at Laetoli in the form of a gray substrate wherever the mat of coarse turf above them has been carried off.

One afternoon in 1976, some of the more boisterous members of Mary Leakey's field team were amusing themselves by throwing hunks of dried elephant dung at each other. This may seem a peculiar pastime, but recreational resources are limited on paleontological digs, and there are times when young spirits need to blow off steam. One who felt this urge was Andrew Hill, a paleontologist from the National Museum of Kenya, who, while ducking flying dung and looking for ammunition to fire back, found himself standing in a dry stream bed on some exposed ash layers. One of these had some unusual dents in it. When Hill paused to examine them, he concluded they probably were animal footprints. That diagnosis was confirmed when a larger area was surveyed and other prints found. But no serious effort was made to follow up this extraordinary discovery until the following year, 1977, when a number of large elephant tracks were found by Mary Leakey's son Philip and a co-worker, Peter Jones, and alongside them some tracks that looked suspiciously like human footprints.

The world heard about the footprints later that year when Mary Leakey came to the United States to report on them in a series of press conferences and interviews. To many it seemed almost inconceivable that anything so ephemeral as a footprint should have been preserved for so long. But Mary was positive about the hominid ones. She went on to describe the latter as having been made by a creature that was an imperfect walker; the prints indicated that it had shuffled. She also reported the probable presence at Laetoli of knuckle-walking apes and the existence of a water hole around which the animals and birds appeared to have clustered. She even saw some evidence of panic in the tracks, suggesting that the animals had been fleeing the eruption.

Those revelations by Mary Leakey electrified everybody who heard them. She resolved to devote much of the next season's effort at Laetoli to footprints, and asked the American footprint expert Louise Robbins to join her team. White went to the Laetoli site for the first time that year, and found three other young scientists there: Peter Jones, Paul Abell and Richard Hay. These men had some doubts about Mary's interpretation of the footprints. White questioned the presence of knuckle-walking apes; he had examined those prints and said that they had been made by large extinct baboons that walked flat-footed. Jones said there had been no panicky exodus from the area, because birds, which could have flown away easily and quickly, continued to walk about in the ash it was crisscrossed with their tracks. Hay could find no evidence of a water hole.

These disagreements made for a good many nights of heated argument in camp, during which the supposedly human footprints had their ups and downs. No one could agree on them. Then Paul Abell, prospecting alone one day, found a broken impression - but a much clearer one - that he said he was quite confident was a hominid print. White and Jones made some Polaroid shots of it and came back with a strong impression that Abell was right. They recommended that excavation in the area be started immediately. But Louise Robbins, the footprint expert, examined it and declared that it was the print of a bovid (a hoofed animal). She told Mary Leakey that further investigation would be a waste of time. The men objected.

By then Mary Leakey had become thoroughly exasperated by all the arguing that had been going on. She announced that there would be no excavation. Jones, now convinced that it was a hominid, continued to plead with her for permission to make an excavation. A very small one, he said, was all he asked. Mary was adamant. Louise Robbins, the authority, had spoken; there was too much incomplete excavation at the site already. If there was going to be any digging, let it be done by somebody who had nothing better to do. She pointed to Ndibo, the maintenance man, the man in camp with the least archeological training.

Ndibo, however, proved equal to the task. He returned to camp the next day and reported not one, but two footprints. One was very large. He held his hands up, about a foot apart.

'Those Africans are always exaggerating,' said Mary. But she did go out to have a look, and there they were. White was permitted to start an excavation.

The direction of the prints indicated that their maker had been walking north under some sections of turf that had not yet been eroded. Because of the dense tangle of roots at the bottom of the turf, the task of exposing a clear ash surface without destroying it - not to mention the exact ash out of a dozen or more thin layers of it turned out to be extraordinarily difficult. But Tim is an extraordinarily patient and determined man. He found another print, and then another. He proceeded to protect the prints by hardening them with a preservative, which he poured into them in very small amounts, letting the material dry and then strengthening it by adding more. Working with agonising slowness, he inched his way farther and farther into the turf and discovered that the trail consisted of the tracks of two hominids.

Now he had the riveted attention of the entire camp. Others joined the work and ultimately were able to reveal more than fifty prints covering a distance of seventy-seven feet. Louise Robbins, her interest in the footprints suddenly rekindled, issued another opinion: indeed there were two hominids; they were probably walking together; one (with slightly larger prints) was a male; the other, possibly pregnant she said, was a female; on the evidence of the prints, this type of hominid had been an erect walker for at least a million years.

These are entertaining speculations. There is no way of telling what sex the makers of the footprints were, if one was pregnant, or how long their ancestors had walked erect. The hard truth is that 3.7 million years ago erect hominids of indeterminate sex did walk through fresh-fallen ash at Laetoli and leave an imperishable record of their passing. After seventy-seven feet their trails disappeared under the overlying ash; the particular layer that marked it has been washed away. Tim's work on the footprints stopped at that point, which also marked the end of the season. But he felt strongly that the trail could be picked up again a little farther along and that it would yield more prints if proper excavation were carried out. Work in that direction was done in 1979 by Ron Clarke, and the trail picked up again.

Tim was not a party to this further work. His arguments with Louise Robbins over interpretation of the footprints have made him as unwelcome now at Laetoli as he is at Lake Turkana - a pity, because in each instance he was only trying to help the proprietors.

Tim's concern today is that as more prints are found, they be handled with the utmost care. They are supremely fragile, and the slightest mistake in excavating them can destroy them completely. Some have already been damaged. They are not like fossils, those rocklike models of durability. They are only spaces, mere shapes in a relatively soft and frangible matrix. If that matrix is nudged incorrectly, it will crumble - and the footprints will be gone.

But, by a wildly improbable linkage of random events, they are there. Sadiman had to blow out a particular kind of ash. Rain had to fall on it almost immediately. Hominids had to follow on the heels of the rain. The sun had to come out promptly and harden their footprints. Then another blast from Sadiman had to cover and preserve them before another obliterating shower came along.

All this had to happen over a period of only a few days. And the volcano had to synchronise its activity with that of the seasons. If its bursts had not come just when they did - at the beginning of the rains - the footprints would not have been preserved. A month or two earlier, during the dry season, the ash would not have had the consistency to take a sharp imprint. It would have been a hopelessly blurry one, a mere dent, like the one a passerby today makes in the dry sand on the upper margin of a beach. If it had come later, at the height of the rainy season, it is overwhelmingly likely that there would have' been too much rain; the footprints would have been washed away before they could have been baked hard by the sun. Indeed, there had to be just what the beginning of a rainy season produces: sporadic showers interspersed with intervals of hot sun.

All things considered, the preservation and recovery of the Laetoli footprints are nothing short of a miracle. They confirm without a shadow of a doubt what Lucy confirmed at Hadar: that hominids were fully erect walkers at three million B.C. and earlier. At Hadar the evidence is in the fossils, in the shape of leg and foot bones. But at Laetoli, where the fossil remains - some extremely scrappy and enigmatic postcranial bits, jaw parts, and some teeth - are of very poor quality, there is no way without the footprints of deducing how those hominids got around.

'Make no mistake about it.' says Tim. 'Thev are like modern 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 straight in line. It doesn't stick out to the side like an ape toe, or like the big toe in so many drawings you see of australopithecines in books.

I don't mean to say that there may not have been some slight differences in the foot bones; that's to be expected. But to all intents and purposes, those Laetoli hominids walked like you and me, and not in a shuffling run, as so many people have claimed for so long. Owen Lovejoy deduced all that from studying the Hadar bones. Now the footprints prove him right. I think they rank with the most wonderful and illuminating discoveries in decades. Although it didn't end too happily for me, I'm still grateful that. I was lucky enough to have participated in the work on them.'

The upright bipedal gait of humans is a unique and highly inefficient mode of locomotion, but the anatomy of modern apes, with 60 per cent of their body weight carried on the hindlegs, indicates that the common ancestor of apes and humans was pre-adapted to bipedalism. Environmental circumstances in Africa provide an explanation of why and how the fully upright stance and bipedal gait evolved in humans.

Laetoli lies roughly 500 kilometres to the south of the Tugen Hills. Late-twentieth-century walking enthusiasts could cover the distance comfortably in twenty-five days, and the journey certainly would not have deterred their ancestors, 4 million years before. Indeed, the safari must always have been enticing: south along the Western wall of the Rift Valley; perhaps taking a slow route through the high forest, where there is fruit and honey in season, or moving more speedily through wooded grasslands borderingthe foothills below. At intervals, perennial streams gush dependably from the Rift wall. There would have been (and are still) predators to be avoided, of course, but also their prey to be scavenged. The route rises up and over the Mau escarpment, where there is an option of following the forested course of the Uaso Nyiro River to Lake Natron, or turning towards the Loita Hills and the cool grasslands above the lake basin. Volcanoes dominated the landscape to the east of Olduvai; southward, herds of antelope and zebra congregated on the plain.

Andrew Hill made the journey by road in September 1976. At Laetoli, Mary Leakey and her co-workers were bringing the season of investigations to a close. The work that year had been inspired by the discovery of hominid fossils (among them a mandible subsequently described as the type specimen of Australopithecus afarensisf during an exploratory visit made during the Christmas holiday of 1974.

A host of fossils had been found, including animals ranging in size from shrew to elephant, tortoises, a clutch of beautifully preserved eggs matching those of the modern guinea fowl, and tiny leaves identical to those on acacias in the woodlands today. The Laetoli fossil beds had been dated to between 3'59 million and-3-77 million years old - just the period during which the bipedal ancestors of humanity were consolidating their presence in the Rift Valley - but hominid finds were scarce at Laetoli: a few fragments of jaw and some isolated teeth were found in T.97S, and some pieces of a juvenile skeleton in 1.976. After a promising start, it seemed the potential of the Laetoli deposits was not to be fulfilled.

That was the state of affairs when Andrew Hill went for a stroll one evening with David Western, a wildlife ecologist also visiting the Laetoli sites. Their walk took them across a dry river bed in which an expanse of fine-grained volcanic tuff was exposed. Elephants had recently passed that way too, and had left a number of their cannonball-sized droppings scattered about the river bed. In equatorial Africa, a sun-dried ball of elephant dung appeals to the same instincts that snowballs awaken in northern latitudes. People fling them at one another and, unsurprisingly, wildlife ecologists tend to be more adept than most. Dr Hill fell as he turned to avoid a particularly well-aimed missile from Dr Western. While on his knees, pleading for a brief cessation of hostilities, he noticed a curious spattering of tiny indentations in the surface of the grey tuff. These were later identified as raindrop prints but, having attracted Hill's attention, they led him to examine the surface more closely. Amid the puzzling indentations he recognized an unmistakable series of animal tracks'

People had crossed that indented tuff surface hundreds of times during the course of the previous two seasons, but always on the way to somewhere else, with a clear picture in mind of the fossils they were looking for. By chance, an airborne ball of elephant dung introduced a fresh point of view, instantly focusing the investigators' attention on the totally different fossil information that lay at their feet - fully visible, but hidden until then by the blinkers of preconceived notion.

Dr Hill's lucky fall redirected the thrust of the Laetoli investigations. Fossil bones were relegated to a level of secondary interest and during the final weeks of the 1076 season the identification of fossil footprints became the primary endeavour.

Hundreds of prints were found, representing more than twenty different animals, ranging in size from cat and hare to elephant, rhinoceros, and giraffe. Guinea-fowl prints were numerous, so too were the prints of small antelopes, hyenas, pigs, baboons, and hipparion, the ancestral three-toed horse. During the 1977 and 1978 seasons, seven distinct sites were located and mapped. Where desirable, overlying soils were removed. Mammal and bird prints occurred everywhere, wonderfully preserved in the fine-grained volcanic ash. Most wonderful of all was the trail, nearly fifty metres long, left by three hominids walking northward from the woodlands down to the plains.

The trail records a unique moment in time and its preservation is little short of miraculous. About 3.6 million years ago, a series of light ash eruptions from a nearby volcano coincided with a series of rain showers, probably at the onset of the rainy season. The ash filled depressions in the landscape, and the rain transformed them into mud pans. Animals crossed the pans while they were still wet, and their tracks were preserved as the ash dried hard as cement. The next shower of ash laid a protective covering over the tracks. A succession of ash and rain showers created at least six distinct surfaces on which prints are preserved; in total they are fifteen centimetres thick.

Sadiman and Lemgarut, the volcanoes whose ash created the Laetoli fossil beds, are no longer active, but the Laetoli landscape is otherwise not very different today from that which its inhabitants knew over 3 million years ago. The highland foothills are covered in dense acacia thornbush, and the upper slopes are swathed in grass that turns from green to golden as the dry season advances. Westward, the plain extends to a distant horizon, the broad undulating expanse broken here and there by huge steep-sided outcrops of granite and gneiss that rise from the grassland-like islands (indeed, in geological terminology they are known as inselbergs - island mountains): Naibardad, Naabi, and Moru, where there is always water. In shallow valleys, strands of woodland mark the watercourses along which the seasonal rains drain away to Olduvai Gorge, about forty kilometres from Laetoli. Elephants come down from the highlands; giraffes cross the plain, their legs blurred in the shimmering heat haze; lions lie concealed in the dun-coloured grass,

Discovered in 1978 by Paul Abell at Laetoli in Tanzania. Estimated age is 3.7 million years. The trail consists of the fossilized footprints of two or three bipedal hominids. Their size and stride length indicate that they were about 140 cm (4'8") and 120 cm (4'0") tall. Many scientists claim that the footprints are effectively identical to those of modern humans (Tattersall 1993; Feder and Park 1989), while others claim the big toes diverged slightly (like apes) and that the toe lengths are longer than humans but shorter than in apes (Burenhult 1993). The prints are tentatively assigned to A. afarensis, because no other hominid species is known from that time, although some scientists disagree with that classification.

In 1978 Johanson and White decided to announce a new name for the discoveries. Johanson was one of many scientists scheduled to speak at a Nobel Symposium in Sweden in May. The conference would honor Mary Leakey, who would receive a medal from the King of Sweden for her scientific work.

Mary Leakey received the Golden Linnaean Medal, the first woman to do so. But she also endured one of the most embarrassing moments in her life. Johanson spoke before she did, and announced the new name for the species from Ethiopia - and in this species, he included Mary Leakey's discoveries from Laetoli. In fact, the jaw LH 4 was featured as the type specimen, or model, for the news species name Australopithecus afarensis. Australopithecus is the formal genus name for the australopithecines, and afarensis denotes the Afar Triangle of Ethiopia where they were found. But the model specimen came from Tanzania.

Johanson talked at length about the discoveries at Laetoli, which scooped Mary's own speech. She was angry and embarrassed. During the coffee break, she confided to Richard: "How am I going to give my paper now? It's all been said." Richard said later that she felt that she "was going to look as if she was a fool, repeating the material." More controversial, Johanson had named her discoveries, using a designation that was totally at odds with what she believed. Because Johanson named them first, that name stuck. When she stood up to give her talk, Mary Leakey could not say that the finds from Laetoli were Homo as she thought they were. She just expressed her deep regret that "the Laetoli fellow is now doomed to be called Australopithecus afarensis."

Some scientists suggest that White and Johanson lumped the Laetoli finds in with the others to give the new species an older date. The fossils that Mary Leakey found in Tanzania were nearly four million years old - at the time, the oldest hominids ever discovered.

The controversy continues today. In 1990 more fossils were found in Ethiopia that suggest there may have been two species, rather than one as Johanson and White claimed. But the Leakeys withdrew from this debate; they decided that their best defense was just to keep working and find more evidence.

This monograph is a lavish description of work carried out from 1974 to 1981 at one of the richest hominid sites in Africa, in northern Tanzania, at a place named after a local Maasai word for the lily. The book also contains a strong attack on the idea of a species named Australopithecus afarensis, proposed by Donald Johanson and others after the discovery of the 'Lucy' remains in Ethiopia in 1977. Mary Leakey first excavated at Laetoli in 1935 with the late Louis Leakey, but nobody realized for over forty years that this site was actually both richer and older than Olduvai and it was only in the mid-1970s that Mary Leakey returned to Laetoli to begin serious and systematic work. The Laetoli layers are in fact around 3.5 to 3.7 million years old, and include the famous footprints left, probably, by a man, a woman and a child strolling across an area of damp ash for a few moments, with a human gait. This comprehensive book covers the whole Laetoli succession in a wide range of disciplines, and brings together work from thirty-three contributors in fourteen carefully and systematically written chapters.

Unfortunately, T. D. White's descriptions of the hominid remains do not appear in this book, for reasons explained by M. Leakey in chapter 5. For White's most recent contribution on the footprints, see Tim D. White and Gen Suwa, 'Hominid footprints at Laetoli: facts and interpretations' (American Journal of Physical Anthropology, vol. 72 [April 1987], p. 485-514. bibliog.), dealing with the fossil footprints of the Australopithecines.

Nearby at Laetoli, Mary Leakey discovered in 1979 the earliest known footprints of hominids, animals and birds. They were passing that way about 3.6 million years ago through falling ash from the nearby Sadiman volcano. The raised arch and rounded heel of the footprints suggests the hominids were striding forth much like we would.

Unknown to non-Africans before the colonial period, the prehistory of the interior of Africa has since been partly pieced together. Discovered by chance in 1910 by a German entomologist who stumbled across some fossils and bones, evidence of human life was found in Tanzania's Olduvai Gorge and the place attracted the attention of Professor Leakey and his wife, whose names are forever linked to the site. Their research started in 1931 but it was not until 1959 that Mary Leakey found fragments of teeth and a skull which were part of a male hominid whom they called Zinjanthropus or Nutcracker Man, because of his huge teeth. The skull was dated to be 1.75 to 2 million years old and was proof that hominids inhabited the area; it shifted the centre of human evolution from Asia to Africa and the discovery 20 years later of footprints at Laetoli south of Olduvai pushed back the presence of hominids to 3.5 to 4 million years.

The oldest human footprints - the only proof that early man walked upright on two legs 3.6 million years ago - are being destroyed through neglect... . Mary Leakey, ... discovered the tracks at Laetoli in 1978. The prints were analysed before being covered up in 1979 with polythene, sand and rocks to protect them. ... However, scientists who recently visited the site were horrified by the neglect. Termites had eaten the polythene, torrential rain had washed away much of the sand, and acacia trees were growing over the tracks, raising fears that their roots had begun to break up the brittle volcanic ash. ...

Mary Leakey waits for my next question, watching from behind a thin curtain of cigar smoke. Leakey is as famous for her precision, her love of strong tobacco--half coronas, preferably Dutch--and her short answers as she is for some of the most significant archaeological and anthropological finds of this century. The latter would have hardly been excavated without her exactitude and toughness. And in a profession scarred by battles of interpretation and of ego, Leakey's unwillingness to speculate about theories of human evolution is unique.

These characteristics have given Leakey a formidable reputation among journalists and some of her colleagues. So have her pets. In her autobiography, "Disclosing the Past," Leakey mentions a favorite dog who tended to chomp people whom the archaeologist didn't like, "even if I have given no outward sign." So as we talk in her home outside Nairobi, I sit on the edge of a faded sofa, smiling exuberantly at her two dalmatians, Jenny and Sam, waiting for one of them to bite me. I quickly note details-- her father's paintings on the wall, the array of silver trophies from dog shows and a lampshade with cave painting figures on it--in case I have to leave suddenly. But the two dogs and soon a cat and later a puppy sleep or play, and Leakey's answers, while consistently private, seem less terse than simply thoughtful.

Leakey first came to Kenya and Tanzania in 1935 with her husband, the paleontologist Louis Leakey, and except for forays to Europe and the U.S., she has been there ever since. During those many years, she introduced modern archaeological techniques to African fieldwork, using them to unearth stone tools and fossil remains of early humans that have recast the way we view our origins. Her discoveries made the early ape Proconsul, Olduvai Gorge, the skull of Zinjanthropus and the footprints of Laetoli, if not household names, at least terms familiar to many.

Leakey was born in England, raised in large part in France and appears to have been independent, exacting and abhorrent of tradition from her very beginnings. Her father, an artist, took his daughter to see the beautiful cave paintings at such sites as Fond de Gaume and La Mouthe and to view some of the stone and bone tools being studied by French prehistorians. As she has written, these works of art predisposed Leakey toward digging, drawing and early history: "For me it was the sheer instinctive joy of collecting, or indeed one could say treasure hunting: it seemed that this whole area abounded in obje cts of beauty and great intrinsic interest that could be taken from the ground."

These leanings ultimately induced Leakey at the age of about 17 to begin working on archaeological expeditions in the U.K. She also attended lectures on archaeology, prehistory and geology at the London Museum and at University College London. Leakey says she never had the patience for formal education and never attended university; she never attended her governesses either. (At the same time, she is delighted with her many honorary degrees: "Well, I have worked for them by digging in the sun.")

A dinner party following a lecture one evening led her, in turn, to Louis Leakey. In 1934 the renowned researcher asked Mary, already recognized for her artistic talents, to do the illustrations for a book. The two were soon off to East Africa. They made an extraordinary team. "The thing about my mother is that she is very low profile and very hard working," notes Richard E. Leakey, former director of the Kenya Wildlife Service, an iconoclast known for his efforts to ban ivory trading and a distinguished paleontologist. "Her commitment to detail and perfection made my father's career. He would not have been famous without her. She was much more organized and structured and much more of a technician. He was much more excitable, a magician."

What the master and the magician found in their years of brushing away the past did not come easily. From 1935 until 1959 the two worked at various sites throughout Kenya and Tanzania, searching for the elusive remains of early humans. They encountered all kinds of obstacles, including harsh conditions in the bush and sparse funding. Success too was sparse--until 1948. In that year Mary found the first perfectly preserved skull and facial bones of a hominoid, Proconsul, which was about 16 million years old. This tiny Miocene ape, found on Rusinga Island in Lake Victoria, provided anthropologists with their first cranium from what was thought to be the missing link--a tree-dwelling monkey boasting a bigger brain than its contemporaries.

Proconsul was a stupendous find, but it did not improve the flow of funds. The Leakeys remained short of financial support until 1959. The big break came one morning in Olduvai Gorge, an area of Tanzania near the Great Rift Valley that slices East Africa from north to south. Again it was Mary who made the discovery. Louis was sick, and Mary went out to hunt around. Protruding slightly from one of the exposed sections was a roughly 1.8-million-year-old hominid skull, soon dubbed Zinjanthropus. Zinj became the first of a new group--Australopithecus boisei--and the first such skull to be found in East Africa.

"For some reason, that skull caught the imagination," Leakey recalls, pausing now and then to relight her slowly savored cigar or to chastise a dalmatian for being too forward. "But what it also did, and that was very important for our point of view, it caught the imagination of the National Geographic Society, and as a result they funded us for years. That was exciting."

How Zinj fits into the family tree is not something Leakey will speculate about. "I never felt interpretation was my job. What I came to do was to dig things up and take them out as well as I could," she describes. "There is so much we do not know, and the more we do know, the more we realize that early interpretations were completely wrong. It is good mental exercise, but people get so hot and nasty about it, which I think is ridiculous."

I try to press her on another bone of contention: Did we Homo sapiens emerge in Africa, or did we spring up all over the world from different ancestors, a theory referred to as the multiregional hypothesis? Leakey starts to laugh. "You'll get no fun out of me over these things. If I were Richard, I would talk to you for hours about it, but I just don't think it is worth it." She pauses. "I really like to feel that I am on solid ground, and that is never solid ground."

In the field, Leakey was clearly on terra firma. Her sites were carefully plotted and dated, and their stratigraphy--that is, the geologic levels needed to establish the age of finds--was rigorously maintained. In addition to the hominid remains found and catalogued at Olduvai, Leakey discovered tools as old as two million years: Oldowan stone tools. She also recorded how the artifacts changed over time, establishing a second form, Developed Oldowan, that was in use until some 500,000 years ago.

"The archaeological world should be grateful that she was in charge at Olduvai," notes Rick Potts, a physical anthropologist from the Smithsonian Institution who is studying Olorgesailie, a site about an hour south of Nairobi where the Leakeys found ancient stone axes in 1942. Now, as they did then, the tools litter the White, sandy Maasai savanna. The most beautiful ones have been stolen, and one of Leakey's current joys is that the Smithsonian is restoring the site and its small museum and plans to preserve the area.

Olduvai Gorge has not fared as well. After years of residence and work there, and after the death of Louis in 1972, Mary finally retired in 1984. Since then, she has worked to finish a final volume on the Olduvai discoveries and has also written a book on the rock paintings of Tanzania. "I got too old to live in the bush," she explains. "You really need to be youngish and healthy, so it seemed stupid to keep going." Once she left, however, the site was ignored. "I go once a year to the Serengeti to see the wildebeest migrations because that means a lot to me, but I avoid Olduvai if I can because it is a ruin. It is most depressing." In outraged voice, she snaps out a litany of losses: the abandoned site, the ruined museum, the stolen artifacts, the lost catalogues. "Fortunately, there is so much underground still. It is a vast place, and there is plenty more under the surface for future generations that are better educated."

Leakey's most dramatic discovery, made in 1978, and the one that she considers most important, has also been all but destroyed since she left the field. The footprints of Laetoli, an area near Olduvai, gave the world the first positive evidence of bipedalism. Three hominids (generally identified as Australopithecus afarensis ) had walked over volcanic ash, which fossilized, preserving their tracks. The terrain was found to be about 3.6 million years old. Although there had been suggestions in the leg bones of other hominid fossils, the footprints made the age of bipedalism incontrovertible. "It was not as exciting as some of the other discoveries, because we did not know what we had," she notes. "Of course, when we realized what they were, then it was really exciting."

Today the famous footprints may only be salvaged with the intervention of the Getty Conservation Institute. "Oh, they are in a terrible state," Leakey exclaims. "When I left, I covered them over with a mound of river sand and then some plastic sheeting and then more sand and a lot of boulders on top to keep the animals off and the Maasai off." But acacia trees took root and grew down among the tracks and broke them up.

Although Leakey steers clear of controversy in her answers and her writings, she has not entirely escaped it. She and Donald Johanson, a paleontologist at the Institute of Human Origins in Berkeley, Calif., have feuded about the relation between early humans found in Ethiopia and in Laetoli. (Johanson set up his organization as a philosophical counterweight to the L.S.B. Leakey Foundation.) And some debate erupted about how many prints there were at Laetoli. Tim White of the University of California at Berkeley claimed that there were only two and that Leakey and her crew had made the other track with a tool during excavation. Leakey's response? "It was a nonsense," she laughs, and we are on to the next subject.

A subject Leakey does not like. "'What was it like to be a woman? A mother? A wife?' I mean that is all such nonsense," she declares. Leakey--like many other female scientists of her generation, including Nobel laureates Rita Levi-Montalcini and Gertrude Belle Elion--dislikes questions about being a woman in a man's field. Her sex played no role in her work, she asserts. She just did what she wanted to do. "I was never conscious of it. I am not lying for the sake of anything. I never felt disadvantaged."

Leakey just did her work, surviving bitter professional wars in anthropolog y and political upheavals. In 1952 Louis, who had been made a member of the Kikuyu tribe during his childhood in Africa, was marked for death during the Mau Mau uprising. The four years during the height of the rebellion were terrifying for the country. The brakes on Mary's car were tampered with, and a relative of Louis's was murdered. The house that Leakey lives in today was designed during this time: a low, White square structure with a central courtyard where the dogs can run at night.

These pets are very important to Leakey--a source of companionship and safety out in the bush. She admires the traits in them that others admire in her: independence and initiative. (Any small joy that I have about emerging from her house unbitten fades sadly when I reread the section in her autobiography about her telepathic dalmatian and learn that he died years ago.)

We seem to have covered everything, and so she reviews her discoveries aloud. "But you have not mentioned the fruits," she reminds me. One of Leakey's favorite finds is an assortment of Miocene fossils: intact fruits, seeds, insects--including one entire ant nest--and a lizard with its tongue hanging out. They lay all over the sandy ground of Rusinga Island. "We only found them because we sat down to smoke a cigarette, hot and tired, and just saw all these fruits lying on the ground next to us. Before that we had been walking all over them all over the place." She stops. "You know, you only find what you are looking for, really, if the truth be known."

Laetoli, formerly Laetolil, is an archaeological site located 40 km (25 mi) south of Olduvai Gorge in Tanzania. Discovered by Louis and Mary Leakey in 1935, the site consists of numerous layers of volcanic ash in which fossil animal bones and hominid remains were found. In 1975 Mary Leakey explored the site more completely. Potassium argon dating was used to assign an age of about 3.75 million years to the fragmentary jaws and crania found at the site. These remains are nearly a million years older than the hominid fossils found by Richard Leakey in the East Turkana area of Kenya. Initially these remains were thought to be of the genus Homo, but they have since been classified as Australopithecus afarensis. Experts hypothesise that this species is the common ancestor of all later hominid species in the genera Homa and Australopithecus.

After a three year program funded by the Getty Foundation, the Director of the project, Martha Demus, announced that the footprints at Laetoli would be covered permanently so as to preserve them for posterity. The Maasai were being encourage to guard the site and a 'senior seer' had been asked to bless the site.

Mary Leakey returned to Laetoli last August with members of the California-based Getty Conservation Institute, which had contributed to a project to preserve the footprints, covering them with a synthetic protective layer.

Despite being 83, Mary Leakey was a sprightly lady with a fondness for cigars. Members of the Getty party recall that back in Laetoli she enjoyed the opportunity to be sleeping out again in the open air of the African bush.

Laetoli SITE, Tanzania (AP) - Mary Leakey and the Masai wore red - the favorite color of the Masai people who first drew the attention of the English archaeologist to the site of her most important discovery.

A short distance from the gathering of herders and scientists lay the 89-foot-long trackway of footprints. They were left by beings nearly human walking south-to-north 3.6 million years ago.

At the time, the Sandiman volcano was belching ash across what is now known as the Serengeti Plain and the prints were preserved as the volcanic sludge hardened.

By the end of September, the footprints will be covered over again to conserve them for posterity - this time with high-tech synthetic materials embedded with time-release capsules of herbicides.

The decision in 1994 by the Tanzanian Department of Antiquities and the California-based Getty Conservation Institute to bury the tracks after cleaning and restoration was difficult to take, said the project's director, Martha Demas.

It means that, for the foreseeable future, no one will be able to see the real thing - the sets of three separate hominid footprints complete with the the imprint of the skin. It is the only fossilized evidence of soft tissue of the beings who first walked upright.

Mary Leakey, the 83-year-old widow of paleoanthropologist Louis Leakey, came to the gathering from her home in Nairobi, Kenya, for a last glimpse of the footprints she first saw 18 years ago.

``They looked startlingly like our own,'' embedded in the volcanic tuff in a sloping, grassy gully that the Masai call ``Laetoli'' after the red lilies that grow in the area.

Asked what she thought about covering over her famous discovery, Leakey had a terse reply: ``You've got to bury it if you want to conserve it.''

Long covered over by dirt, the footprints became visible again when natural erosion wore away the protective layer and were discovered by Leakey in 1978. But water and wind have been eroding the prints and some have been damaged by roots of the acacia trees that abound in the region. There was also the danger that people would try to collect souvenirs.

Leakey said it would be ``very desirable'' for people to see the trackway as it was - if it were somewhere more easily protected. The site in northern Tanzania was judged too remote to justify housing it in its own museum.

Numerous casts of the footprints have been made for exhibit in the museum at Olduvai Gorge and for further study and educational purposes. The gorge, 35 miles to the north, is where Louis Leakey uncovered some of the earliest evidence of man.

Louis Leakey came to Laetoli in 1935 after a Masai herder told him about all the ``bones like stone'' lying around. His wife, who was on her first trip to Africa, remained at the Olduvai site.

She recalled that on that first trip, several Masai offered to trade her a side of beef for her tube of bright red lipstick. But she refused because ``it was the only one I had and it had to last the summer.''

It wasn't until 40 years later that the footprints were discovered.

Their discovery reinforced the theory that bipedalism - walking upright on two feet - preceded tool-making, said Neville Agnew, associate programs director for the Getty Conservation Institute.

This was established through potassium argon dating of the footprints and fossilized tools found in the same area. The footprints were much older.

After excavating the site in 1978-79, Mary Leakey and her colleagues, whose budget was tight, covered the spot as best they could with rocks and a simple structure of wooden supports and corrugated tin roof.

Acacia trees took root among the several trackways that bear hundreds of animal footprints as well as the hominid prints. Wind and rain chipped away at the cracked, slate-like layers. And the Masai, who have lived in the area for centuries, thought the building materials were more useful to live humans than to their fossilized memories.

The recent gathering at the site was arranged by the Getty institute and Tanzanian authorities to impress upon the local Masai the importance of the footprints and to seek their cooperation in preservation.

Demas, the Laetoli project director, said protecting such sites is difficult ``because people like the materials.''

The trackway will be buried under layers of synthetic netting and sheeting and topped with black volcanic rocks to deter casual diggers. When finished, the whole thing will look like a big burial mound.

Larazo Mariki, a local official, said the Masai might not initially think the footprints are very important.

``But the footprints are not only for the Masai,'' he said. ``Everybody is supposed to protect them - Americans, Tanzanians - but the nearest people who have to protect them are the Masai.''

Naanga Siaro ole Kiroway, a 27-year-old ``moran,'' or member of the Masai warrior group of men aged 15 to 25, thought for a while and then decided that, all things considered, protecting the footprints was worthwhile.

``It's better to cover them and save them,'' he said. ``Otherwise we won't have them at all.''

End Adv for Mon PMs, Sept. 23

The Getty Conservation Institute and the Tanzanian Government have decided to cover humanity�s tracks. The footprints of man�s hominoid ancestors walking from north to south through fresh volcanic ash 3.6 million years ago were discovered at Laetoli in Tanzania 18 years ago by the archaeologist Mary Leakey. After more than a decade of fretting and hand-wringing about how to preserve them, experts have opted for burial: the prints will be covered with high-tech synthetic stuff embedded with time-release herbicide capsules. The prints, the only fossilised evidence of ancient hominoid tissue, will then be concealed again - but also protected from plant damage and wind and water erosion. Said the 83-year-old Mary Leakey: 'You�ve got to bury it if you want to conserve it.'

2. Why the human feet?

During the time Johanson was discovering various bone fragments of several afarensis specimens in Ethiopia, Mary Leakey had a field party at Laetoli, Tanzania about 30 miles south of Olduvai (Figure 3). She had also discovered afarensis bone fragments within the Laetoli Beds of Pliocene age (Figures 1 & 3). On the upper surface of the Laetoli Beds, her team discovered a thin layer of volcanic ash in which they found numerous footprints of birds and animals. They found footprints of rabbits, guinea fowl, rhinos, giraffes, elephants and several kinds of animals that no longer exist in Africa. They also found human footprints showing both heel and big toe marks of an adult and a child (p.24 of Human Origins, Leakey). These were human footprints, because apes do not have a heel bone. Mary Leakey also reported the footprints of knuckle walking apes. So, the following season she brought an American footprint expert, Louise Robbins, to confirm the find. Anthropologists Tim Whyte, Peter Jones, Paul Able, and Richard Hay were also on the team. Mary's knuckle walking footprints, a water hole and evidence of a panicky exodus which she had observed the year before were questioned. The arguments regarding her interpretation became so intense, over several days, that Mary became thoroughly exasperated, to the point where she threatened the suspension of the Field Party and that there would be no more excavation that season (Johanson & Edey,p.246-247).

Do you not believe Mary Leakey, Louis Leakey's wife, knew what knuckle walking footprints looked like? She had lived in Africa for years, where modern day, knuckle walking, apes lived.

Is it possible that her peers realized that if these footprints were ape footprints they would then be faced with an unsurmountable problem of having to reconstruct their hominid with apes feet instead of human feet?

It would have destroyed their Darwinian Thesis that afarenses could have been an upright walking human ancestor.

There are two reasons for believing the human-like footprints at Laetoli are about 3 to 3.5 million years old. The first is based upon the association of these tracks with the underlying Laetoli Beds. The second is based upon potassium - argon dating of the volcanic ash.

First, geology maintains that the Laetoli sediments are of Pliocene age of between 2.5 and 7.0 million years old. These dates are estimates but are based upon fossil assemblages, magnetic reversals and the dating of a volcanic basalt intrusive. These sediments are conformable with underlying Miocene and Oligocene beds that in places attain a thickness of about 3,200 feet. When analysing the documentations that Johanson & Edey presents in their above mentioned book and by considering all of these factors together, it becomes quite clear that these beds are of Pliocene age. However, the problem is not with the age of the Laetoli Beds, but with the age of the overlying, surface layer of volcanic ash that contain all of the many footprints.

Secondly, The volcanic ash deposits are lying unconformably upon the Laetoli Beds. They were dated by potassium/argon (K/Arg) dating at about 3 to 3.5 million years old. The source of the problem is the dating method that was used. K/Arg has a half life of about 1.3 billion years with a margin of error in excess of plus or minus 5 million years. For dates less than 5 million years, this method becomes very suspect. This volcanic ash layer could be anywhere from 3.5 million to just a few thousand years in age.

Johanson & Edey's (p. 286) family tree shows A. afarensis as the ancestor of H. habilus, H. erectus and modern Man. Richard and Mary Leakey strongly opposed Johanson's interpretation. They viewed the Australopithecines as outside of the human line, evolving directly from Ramapithecus. This was in keeping with Louis Leakey's thinking that the Australopithecans were not ancestors to Man.

Is it possible that we are face to face with another hominid hoax? In light of more recent scientific information it becomes obvious that Australo- pithecus afarensis, should now be reconstructed with an apes head, an apes body and apes feet. Afarensis can now be scientifically demonstrated to be outside of the human family and within the ape (pongid) family showing an affinity to the Chimpanzee as Stern & Susman maintain.

Is this another example where evolutionists are guilty of distorting science and perpetuating scientific error? Are they guilty of allowing their followers to perpetuate the same errors under the guise of science without correcting them?

Laetoli footprints: according to most creationists, these are modern human footprints that are dated at 3.7 million years ago, long before humans were meant to exist. Creationists emphasize the close resemblance between these and modern human footprints, but often neglect to mention their extremely small size and the fact they may also be similar to the feet of the australopithecines living at the same time. Exactly how similar they are is a matter of some debate.

Tuttle (1990) thinks the footprints are too human-like to belong to A. afarensis, and suggests they may belong to another species of australopithecine, or an early species of Homo. Johanson, who has often said that Lucy was fully adapted to a modern style of bipedality, claims (Johanson and Edgar 1996) that the A. afarensis foot bones found at Hadar, when scaled down to an individual of Lucy's size, fit the prints perfectly. Stern and Susman (1983), who have argued that Lucy's foot and locomotion were bipedal but not yet fully human-like, believe that the footprints show subtle differences from human prints and could have been made by afarensis. Clarke (1999) believes that the Laetoli tracks could have been made by feet very similar to those of the new australopithecine fossil Stw 573.

In short, there is a wide range of opinions about the nature of the footprints and whether A. afarensis could have made them. Most creationists usually cite only Tuttle, whose conclusions they find most convenient. The most honest conclusion, for now, is to admit that although no-one can be entirely sure what made the Laetoli footprints, it seems quite likely that they belonged to australopithecines.

Dr Ronald Clarke used circus chimpanzees to prove his theory about the Laetoli footprints in Tanzania.

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ELISABETH LICKINDORF reports

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TWENTY years ago, Dr Ronald Clarke was invited by famed palaeoanthropologist Mary Leakey to continue an excavation begun at Laetoli in Tanzania.

An American chemistry professor from Rhode Island, Paul Abell, had discovered a hominid heel impression in 3,6-million-year-old volcanic tuff, or sediment formed out of volcanic ash. Subsequent excavation by Tim White of the University of California at Berkeley uncovered the first footprints of a trail made, apparently, by two individuals.

Clarke accepted Leakey's invitation -- and inadvertently entered an arena of fierce debate.

The prints were clearly made by individuals walking bipedally (upright on two legs) but Leakey and Clarke differed in their interpretations. Says Clarke, "I was struck by the fact that the prints did not seem fully human: there was separation of the big toe from the other toes, and, behind the end of the big toe, a smallish round impression that looked like a toe.

"Mary -- advised by other experts -- insisted it was Homo, and that the second of the two trails must have been made by one individual walking in another's footprints. I, on the other hand, thought the prints were [made by one creature:] ape-like with long toes -- not fully human."

Public outcry greeted Clarke when he stated his views in 1985 at the conference celebrating the 60th anniversary of the Taung discovery, and he didn't publish them. But he was not convinced he was wrong. Later that year he arranged an experiment with the Boswell Wilkie Circus in Johannesburg -- and a friendly trainer -- to coax a female and a male chimpanzee to walk next to each other bipedally over wet sand.

"The circus chimps produced prints that looked like the Laetoli footprints," Clarke recalls. "Not only did those of the male look similar -- big toe aligned with the others plus the 'apparent' toe within, caused by the imprint of a joint -- but also the female had a completely different footprint. She was more timid -- she dug her heels in and spread her big toe wide and kicked up a lot of sand -- whereas he was confident and tended to walk with his big toe most often close to the other toes.

"The circus prints showed that apes with toes capable of opening up to a wide degree can also bring that toe into alignment when they walk upright -- they are capable of doing both."

The conclusion -- in a scientific paper published this month -- is that "when the chimpanzee walked bipedally in a confident manner, it preferred to align its big toe with the others, presumably for more efficient locomotion".

The foot bones of the 3,33-million-year-old skeleton at Sterkfontein have inadvertently given Clarke a further -- perhaps clinching -- argument. Comparing the evidence of the foot bones, the footprints in Tanzania, and those made by the circus chimps, Clarke has announced: "The Laetoli footprints could [in fact] have been made by feet with slightly divergent big toes as represented by the Sterkfontein Australopithecus StW 573."

-- The Mail & Guardian, December 20 1999.

The Laetoli footprints were formed and preserved by a chance combination of events -- a volcanic eruption, a rainstorm, and another ashfall. When they were found in 1976, these hominid tracks, at least 3.6 million years old, were some of the oldest evidence then known for upright bipedal walking, a major milestone in human evolution. Paleoanthropologist and consultant forensic scientist Owen Lovejoy compares the ancient biped prints with those of modern humans and chimpanzees.

Backgrounder

Thank goodness for the irrepressible urge of humans (and other animals) to joke and play around in nearly any situation. Sometimes, it pays big dividends. It certainly did in 1976, when paleoanthropologist Andrew Hill and a colleague were tossing elephant dung at each other in Laetoli, a hominid archeological site in Tanzania. As Hill dived out of the way, he stumbled on what turned out to be one of the wonders of prehistoric finds: a trail of hominid footprints about 3.6 million years old.

The majority of the Laetoli footprint site was excavated in 1978. Until then, the oldest known footprints of human ancestors were tens of thousands of years old. But this trail, some 80 feet long and preserved in cementlike volcanic ash, had been made by some of the first upright-walking hominids. An almost unimaginable sequence of events preserved what paleontologist Ian Tattersall calls a fossil of human behavior -- prehistoric walking.

Initially, a nearby volcano called Sadiman erupted a cloud of fine ash, like beach sand, that left a layer on the landscape. Then a light rain fell onto the ash to create something like wet cement -- an ideal material for trapping footprints. Birds and mammals left a great number of prints, but, spectacularly, so did a pair of hominids, one large and one small, trekking across the ash. (Some analysts conclude that it is possible to detect the trail of a third, smaller individual whose tracks overlap the footprints left by one of the others.) A subsequent eruption from Sadiman dropped more ash, sealing the footprints like a laminated driver's license. Finally, erosion over millions of years unveiled the prints for Hill and other researchers in Mary Leakey's group to discover.

The prints, say experts on hominid body structure, are strikingly different from those of a chimpanzee, and in fact are hardly distinguishable from those of modern humans. The only known hominid fossils of that age in that location are those of Lucy and her kind, the small-brained but upright-walking hominids classified as Australopithecus afarensis. Some analysts have noted that the smaller of the two clearest trails bears telltale signs that suggest whoever left the prints was burdened on one side -- perhaps a female carrying an infant on her hip. While the detailed interpretation of the prints remains a matter of debate, they remain an extraordinary and fascinating fossil find, preserving a moment in prehistoric time.

I would like ask for permission to use the Laetoli-Footprints-Picture for a web documentary on the evolution of the human body. The documentary will be published on the websites of the SWR, which is the Public Broadcast for South West Germany. Copyright acknowledgements are given.

Looking forward to hearing from you

G�bor Pa�l

SWR Baden-Baden

They are the world's oldest human tracks, a set of footprints pressed into volcanic ash that have lain perfectly preserved for more than three-and-a-half million years. Made by a group of ancient apemen, the prints represent one of the most important sites in human evolutionary studies, for they show that our ancestors had already stopped walking on four legs and had become upright members of the primate world.

But now the Laetoli steps in northern Tanzania are in danger of destruction. The footprints, although reburied 10 years ago and covered by a special protective coating, are suffering storm erosion, while trees and plants begin to grow through the historic outlines.

The Laetoli steps were discovered in 1976 by scientists led by the late Mary Leakey, mother of conservationist Richard Leakey. They found a couple of prints that had been exposed by the wind and then uncovered a trail that led across an expanse of volcanic ash, like footprints left behind by holidaymakers walking on a wet beach.

The researchers could make out the arch of each foot, the big toe - even the heel. The prints had clearly been made by creatures who had long adapted to walking on two legs. Yet tests showed the prints had been made about 3.6 million years ago.

At that time, the area was populated by short, small-brained species of apeman, known as Australopithicus afarensis, an ancestor of modern human beings. Most scientists believe these were the creators of the Laetoli footprints, individuals who may have been escaping an eruption of the nearby Sadiman volcano. By studying the prints, scientists conclude that a smaller individual - presumed by Leakey to be a female - stopped in her tracks and glanced at some threat or sound to her left. 'This motion, so intensely human, transcends time,' Leakey wrote in National Geographic. 'Three million , six hundred thousand years ago, a remote ancestor - just as you or I - experienced a moment of doubt.' It is this window on human behaviour that makes Laetoli so important, say scientists.

But a study presented at an international conference last month warns that unless urgent action is taken, the Laetoli steps - 'the rarest, oldest and most important evidence' documenting humans' ability to walk on two legs - will be lost to civilisation.

'The protective blanket over the prints is already breaking up,' said Dr Charles Musiba of the University of Colorado, Denver. 'Unless something is done within the next five years, the site is going to suffer serious, irreparable damage.'

He added: 'The footprints are currently buried for their own protection - which means we can no longer study them, and that is crazy. We could use scanners and other modern tools to learn all sorts of things about the people who made these prints. We need to expose them but protect them as well. Building a museum over them is the perfect solution.'

Palaeontologists agree that action is needed, but claim that constructing a building over the steps in remote Laetoli is impossible and would only lead to further degradation. 'No matter how good the intentions, any attempt to preserve them in place is doomed to failure,' said one of the steps' discoverers, Tim White of the University of Berkeley, California. 'Laetoli is remote, inaccessible, and would require infrastructure currently not available or foreseeable to preserve these prints in place.'

Professor Terry Harrison of New York University said: 'The local people around Laetoli, the Masai, do not appreciate having structures built on their land. They tend to smash things up. These are pastoral people who do not have a sense of property and can be destructive. You would need to guard the museum constantly and carefully.'

Harrison and White believe the whole sequence of steps, about 23 metres in length, should be cut from the local hillside, transported to Dar es Salaam, Tanzania's capital, and installed in a museum. The technology for such an endeavour has precedents. In 1968, engineers relocated the Egyptian temple of Abu Simbel when it was threatened by the creation of the Aswan Dam.

the Maasai name for red lily grass