In this article we present a summary on the discovery of the oldest (5.7 millions of years ago) hominin footprint found on Earth so far.
A trail of 5.7 million-year-old fossil footprints discovered in Crete could upend the widely accepted theories on early human evolution.
The new prints have a distinctly human-like form, with a similar big toe to our own and a ‘ball’ in the sole that’s not found in apes.
But, the researchers say the prints found on the Greek island were created during a time when it’s thought early human ancestors were still in Africa – and, when they still had ape-like feet.
Studies in recent decades have led to the conclusion that all fossil human-ancestors older than 1.8 million years lived and evolved in Africa.
The new fossil footprints are not the oldest hominin evidence to be found, but they could drive a wedge in the timeline of evolution.
‘The interpretation of these footprints is potentially controversial,’ the authors wrote in the study, published to the journal Proceedings of the Geologists’ Association.
‘The print morphology suggests that the trackmaker was a basal member of the clade Hominini, but as Crete is some distance outside the known geographical range of pre-Pleistocene hominins we must also entertain the possibility that they represent a hitherto unknown late Miocene primate that convergently evolved human-like foot anatomy.’
The prints were found in a type of sedimentary rock that formed when the Mediterranean Sea briefly dried out, 5.6 million years ago.
This knowledge, coupled with dating methods based on marine microfossils, indicates that the prints are about 5.7 million years old.
The researchers now say that during this time, before modern day Crete detached from the Greek mainland or the Sahara Desert even existed, early hominins could have lived across southeast Europe as well as Africa.
“The story of human evolution begun already 5.5 million years ago, and, interestingly, it was not in East Africa, but the Greek island of Crete” – said Dr. Gerard Gierliński from the Polish Geological Institute – State Research Institute during the press conference.
The earliest previously known footprints of ancient human relatives have been identified in Africa (Laetoli, Tanzania). Scientists determined that they had been left about 3.6 million ago by the Australopithecus species.
In the light of the latest research by Polish palaeontologists, it can not be ruled out that the first hominins appeared in Europe.
Dr. Gierliński discovered the oldest known footprints of human relatives in 2002, while on vacation in Crete. Wide-ranging international research was launched in 2010 and continued for 6 years. The age of the sediments from Trachilos, in which footprints had been preserved, was estimated by Dr. Zofia Dubicka from the University of Wroclaw. Her research shows that they are about 5.7 million years old.
“The footprints, left one after the other, indicate that this creature was perfectly adapted to moving swiftly across the land in a two-footed position. From this point of view, we are dealing with our family, our relatives” – the researcher explained.
Dr. Gierliński explained that it was possible to determine that the footprints belonged to ancient human relatives because of the location of the toes. Asked about the “shoe size”, the scientist stated that it was “very small – ladies or children”. The researchers found a total about 50 prints of several individuals.
“The front of the foot – where the toes are, is basically the same as the 2 million years younger younger footprints from Laetoli – of australopithecus, as Homo erectus from Kenya, as contemporary footprints of Homo sapiens” – he said. “In general, in the front we have a human foot” – he added.
The back of the foot, however, was different – the heel of the Cretan prints is not as elongated and rounded as that of later humans. It was also shorter, as the researcher pointed out. On this basis, he stated that it was an “evolutionarily very distant” being.
The human foot is distinctive. Our five toes lack claws, we normally present the sole of our foot flat to the ground, and our first and second toes are longer than the smaller ones. In comparison to our fellow primates, our big toes are in line with the long axis of the foot—they don’t stick out to one side.
In fact, some would argue that one of the defining characteristics of being part of the human clade is the shape of our foot. So imagine our surprise when we discovered fossil footprints with remarkable, human-like characteristics at Trachilos, Crete, that are 5.7 million years old. This research, published in the Proceedings of the Geologist Association, is controversial as it suggests that the earliest human ancestors may have wandered around southern Europe as well as East Africa.
The footprints were dated using a combination of fossilised marine microorganisms called foraminifera and the character of the local sedimentary rocks. Foraminifera evolve very rapidly and marine sedimentary rocks can be dated quite precisely on the basis of the foraminifera they contain. These indicated an age somewhere in the span 8.5 million to 3.5 million years. However, at the very end of the Miocene, about 5.6 million years ago, an extraordinary thing happened: the entire Mediterranean sea dried out for some time. This event left a clear signature in the sediments of the surrounding areas. The sediments that contain the footprints suggest they probably date to the period immediately before this, at about 5.7 million years.
If—and for many it is a big if—the tracks of Trachilos were indeed made by an early human ancestor, then the biogeographical range of our early ancestors would increase to encompass the eastern Mediterranean. Crete was not an island at this time but attached to the Greek mainland, and the environment of the Mediterranean region was very different from now.
The discovery comes just months after another study reported the discovery of seven million-year-old Greek and Bulgarian fossil teeth from a hominin ape dubbed “El Graeco.” This is the oldest fossil of a human-like ape, which has led some to suggest that humans started to evolve in Europe hundreds of thousands of years before they started to evolve in Africa. But many scientists have remained sceptical about this claim—as are we. The presence of Miocene hominids in Europe and Africa simply shows that both continents are possible “homelands” for the group. In theory, El Graeco could be responsible for the Trachilos foorprints but without any limb or foot bones it is impossible to tell.
For those unable to see beyond Africa as the “human cradle,” these tracks present a considerable challenge, and it has not been easy to get the discovery published. Some have even questioned whether the observed features are footprints at all. However, collectively, the researchers behind this study have published over 400 papers on tracks, so we are pretty confident we know what they are.
A set of ancient footprints has been found on a Greek island. They are extremely old – 5.7 million years – yet they seem to have been made by one of our hominin ancestors.
At that time, hominins are thought to have been confined to Africa. The discovery supports the controversial suggestion that they may also have been living in eastern Europe.
The ancient footprints discovered by Gerard Gierliński of the Polish Research Institute in Warsaw are a further 2500 kilometres away from Chad – this time to the north-east, on the tiny island of Trachilos near Crete. Gierliński teamed up with colleagues, including Per Ahlberg at Uppsala University, Sweden, to analyse the tracks.
The team found they could recognise two distinct sets of footprints, both apparently left by an animal that walked upright on two legs.
The shape of the prints suggests similarities with hominin feet. Most obviously, they were clearly left by an animal that walked on the soles of its feet, as hominins do, rather than just on its toes. The prints show the track-maker had five toes, with the big toe particularly well developed – another hominin feature. And there is no evidence of claw marks, consistent with the fact that hominins have toenails rather than claws.
But surprisingly, fossil and geological evidence indicates that the footprints are 5.7 million years old. That means they predate the period during which hominins are conventionally believed to have left Africa by about 4 million years.
“They are almost without doubt actual footprints of a bipedally-walking animal,” says Robin Crompton at the University of Liverpool, UK, who was not involved in the study but who has analysed other hominin footprints.
Some prominent researchers savaged the idea that early hominins could have lived outside Africa. “There are people who simply dismiss the idea because they think it’s just not possible,” says Begun. “But it’s widely accepted that what became the African savannah fauna – giraffes, antelopes, rhinos – those species lived in the southern Balkans and migrated from there into Africa.”
In principle, Begun says hominins might also have originated in eastern Europe and migrated south with these other species. “It doesn’t mean it’s true – but it’s certainly plausible,” he says.
But even discussing this idea in formal academic papers is difficult, he says. It took months for Begun to find a journal prepared to publish the Graecopithecus research – even though the papers were written by well-regarded researchers. Ahlberg says the paper on the Trachilos footprints proved similarly difficult to publish.
The footprints have suffered a number of indignities since the discovery — from being sprayed with graffiti to being chiselled from the rock and stolen. But the bigger scandal may be the reception Gierlinski and his colleagues faced after they first reported their find.
No pre-human fossils that old have ever been found in Europe, and Gierlinski’s claim generated vicious criticism and disbelief from other scientists in a field where most influential researchers are committed “Africanists.”
Per Ahlberg, a researcher at Uppsala University in Sweden, was the member of Gierlinski’s team who took responsibility for getting the research published, and described the process as “six and a half years of sort of living hell.”
Gierlinski’s find casts a light not only on the often chance nature of scientific discovery, but the sometimes fierce conflict among the humans in the scientific community, who often bristle when their beliefs are challenged by new ideas — especially ones that may be ahead of their time.
Gierlinski is no stranger to astonishing discoveries. In the past, he found the feather imprints from a dinosaur’s belly that had rested on the mud millions of years ago in Massachusetts. He was also one of the co-authors of a study of footprints that suggested dinosaurs “danced” to attract mates, in much the same way some modern birds do. Those discoveries piqued people’s interest, but didn’t cause much controversy.
But when Gierlinski saw the Trachilos footprints for the second time and recognized their human-like shape, he realized that he had found something extraordinary.
After returning to Poland, he looked up the age of the sediments in Trachilos and was amazed to learn they were from the Miocene era. In layers of rock and sediments, the start of the Miocene is marked by a deposit left when the Mediterranean Sea temporarily dried up about 5.6 million years ago.
That was before a group of human-like footprints were left in volcanic ash at Laetoli, Tanzania. The 3.66-million-year-old Laetoli footprints have long been regarded as the oldest human-like footprints in the world.
The Miocene also predates Ardipithecus, a fossil hominin with an ape-like foot that lived in modern-day Ethiopia 4.4 million years ago and is thought to be part of the human lineage.
The prints clearly belonged to creatures that normally walked on two feet. They kept their feet close together, like humans, rather than waddling, as chimpanzees do.
“What’s also very telling is we have no palm prints … nor are there any knuckle prints,” Ahlberg said.
The researchers think the creatures that made the prints could potentially be part of the human family tree. Or, they could potentially have been from another branch of upright-walking ape that happened to have developed similar feet — something they think is less likely.
Gierlinski said it was the most extraordinary find of his career. These are “the oldest human-like tracks in the world, unexpectedly found in Europe, not in Africa,” he said. “Obviously, it’s very important.”
The team started submitting the research to peer-reviewed journals. Since this appeared to be something extraordinary — the oldest human-like footprints in the world — they started with high-profile publications such as Nature.
Since the editors of scientific journals aren’t experts on every topic, they typically send submitted manuscripts to expert peer reviewers to evaluate the quality of the research.
Many of the reactions to the Trachilos discovery were negative, to say the least. Ahlberg has been publishing papers since 1989 — including in Nature and Science — and had never experienced anything like this before.
“We got ferociously aggressive responses saying this couldn’t possibly be true and these can’t be footprints at all,” said Ahlberg. “In every round [of reviews], there would be at least one, and sometimes several, reviewers who were in the first instance savagely hostile. They would just flatly deny that these would be human or hominin footprints. They would say almost anything — they’re bear or monkey [tracks] or whatever.”
The researchers addressed any criticism they could with further measurements, but the rejection letters continued to pile up as the researchers moved from one journal to the next.
Ahlberg alleged many of the reviews accused the authors, who were mostly experts in ancient footprints, of incompetence in interpreting tracks. But the reviewers provided no evidence to support their criticisms.
“Basically, it wasn’t a true peer review process at all,” he said. “They were just trying to shut us down.” One editor rejected the paper even though two out of three reviews were positive, which is unusual.
The team submitted a “scaled-down” version to a journal you probably haven’t heard of, the Proceedings of the Geologists’ Association — not the type of place that scientists normally try to publish a story they consider this potentially groundbreaking. While it doesn’t have a huge profile, the journal does command respect — and Bennett knew the editor.
After six and a half years of responding to critical reviews, taking more measurements, doing more analysis, rewriting the manuscript and resubmitting it to different editors and reviewers, the research was made public. The paper finally made it through peer review and was published on Aug. 31, 2017, with the cautious title, “Possible hominin footprints from the late Miocene (c. 5.7 Ma) of Crete?”.
Ahlberg said that since the paper was published, very few scientists have disputed that the marks are footprints, and “most have been cautiously positive about our interpretation.”
Ahlberg said the study only appears extraordinary “if you have already decided that humans originated in Africa, and that humans were restricted to Africa for millions of years.”
David Begun, a paleoanthropologist at the University of Toronto, said the people with the most influence on the major journals are committed Africanists.
“They simply cannot see the possibility that any important event in ape and human evolution could have occurred outside Africa until the first Homo left that continent about 2 million years ago,” he wrote in an email. He said there’s “no earthly reason why there could not have been (pre)humans on Crete 6 million years ago.”
Many other mammals made the trek back and forth between the eastern Mediterranean and Africa numerous times, he said.
Begun was the co-author of a paper that analyzed the jawbone and molar of an ape called Graecopithecus freybergi that lived 7.2 million years ago in Europe, including in southern Greece.
Ahlberg said his experience has shaken his confidence in the process of science.
“The thing that really troubles me is the sense that we won here only through extreme persistence,” he said. “It really does rather make you wonder what other sort of stories have been buried and have never come out.”
Gierlinski said it was important to him to have the scientific community check over his work to ensure he hadn’t made a mistake. But now that his research has been validated by peer review and official publication, he said, “I will be fighting to prove that I am right… because I am sure 100 per cent.”
Abstract We describe late Miocene tetrapod footprints (tracks) from the Trachilos locality in western Crete (Greece), which show hominin-like characteristics. They occur in an emergent horizon within an otherwise marginal marine succession of Messinian age (latest Miocene), dated to approximately 5.7 Ma (million years), just prior to the Messinian Salinity Crisis. The tracks indicate that the trackmaker lacked claws, and was bipedal, plantigrade, pentadactyl and strongly entaxonic. The impression of the large and non-divergent first digit (hallux) has a narrow neck and bulbous asymmetrical distal pad. The lateral digit impressions become progressively smaller so that the digital region as a whole is strongly asymmetrical. A large, rounded ball impression is associated with the hallux. Morphometric analysis shows the footprints to have outlines that are distinct from modern non-hominin primates and resemble those of hominins. The interpretation of these footprints is potentially controversial. The print morphology suggests that the trackmaker was a basal member of the clade Hominini, but as Crete is some distance outside the known geographical range of pre-Pleistocene hominins we must also entertain the possibility that they represent a hitherto unknown late Miocene primate that convergently evolved human-like foot anatomy.
(Source: “Possible hominin footprints from the late Miocene (c. 5.7 Ma) of Crete?”, by Gerard D.Gierliński, Grzegorz Niedźwiedzki, Martin G.Lockley, Athanassios Athanassiou, Charalampos Fassoulas, Zofia Dubicka, Andrzej Boczarowski, Matthew R.Bennett, Per Erik Ahlberg – The interested reader may read the full paper in the following link: https://www.sciencedirect.com/science/article/pii/S001678781730113X)
NovoScriptorium: Paleontology, Paleoanthropology, Archaeology are based on Discovering and Dating Finds, which simply means that at any moment a new, single find may overturn an existing theory – whatever that may be. Development of ‘absolute theories’ in the above fields of Science is simply unacceptable.
Research-Selection-Comments for NovoScriptorium: Philaretus Homerides