Controversial footprint discovery suggests human-like creatures may have roamed Crete nearly 6m years ago

September 1, 2017 by Matthew Robert Bennett And Per Ahlberg, The Conversation
Foot for thought.

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 with remarkable, human-like characteristics at Trachilos, Crete, that are 5.7m 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 period corresponds to a interval known as the Miocene. The footprints are small tracks made by someone walking upright on two legs – there are 29 of them in total. They range in size from 94mm to 223mm, and have a shape and form very similar to human tracks. Non-human ape footprints look very different; the foot is shaped more like a human hand, with the big toe attached low on the side of the sole and sticking out sideways.

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 8.5m to 3.5m years. However, at the very end of the Miocene, about 5.6m 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 5.7m years.

Oldest known footpints.

Cradle of humanity

The "cradle of humanity" has long been thought to lie in Africa, with most researchers suggesting that Ethiopia was where the human lineage originated. The earliest known body fossils that are accepted as hominins (members of the human lineage) by most researchers are Sahelanthropus tchadensis from Chad (about 7m years old), Orrorin tugenensis from Kenya (about 6m years old) and Ardipithecus kadabba from Ethiopia (about 5.8-5.2m years old).

The oldest known footprints, however, were found at Laetoli in Tanzania and come from the next geological time interval, the Pliocene. These are some 3.66m years old and even more human-like than those of Trachilos. The second oldest tracks are those at Ileret made by Homo erectus (1.5m years old), and are little different from the tracks that we ourselves might make today.

If – and for many it is a big if – the tracks of Trachilos were indeed made by an , 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 7m-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.

The footprints.

Alternative solutions

But there are other ways to interpret the findings. Some might suggest that the distinctive anatomy of a human-like foot could have evolved more than once. The tracks could have been made by a hitherto unknown Miocene primate that had a foot anatomy and locomotive style not unlike our own.

There are examples throughout the fossil record of what is called "convergent evolution" – two unrelated animals developing similar anatomical features as adaptations to a particular lifestyle. However, there is nothing about the Trachilos footprints themselves that suggests such convergence.

Convergence rarely produces perfect duplicates; rather, you tend to get an odd mix of similarities and differences, like you see when you compare a shark and a dolphin for example. Now, imagine if the Trachilos footprints combined human-like characters with a few other characters that simply didn't "fit": for example, that the toes looked human-like but carried big claws. This would be a reason to suspect that the human-like features could be convergent. But the Trachilos footprints don't show any such discordant characters, they simply look like primitive hominin footprints as far as we can 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 at all. However, collectively, the researchers behind this study have published over 400 papers on tracks, so we are pretty confidence we know what they are.

Although the results are controversial, suggesting that the rich East African evidence for early hominids may not be telling the whole story, it's important that we take the findings seriously. The Trachilos tracksite deserves to be protected and the evidence should be debated by scientists.

It is now for the researchers in the field to embark on finding more tracks or, better still, body fossils that will help us to better understand this interesting period of primate diversity, which ultimately led to our own evolution irrespective of where this first happened. The very essence of this type of science is prospection, discovery, evidence-based inference and debate. We are sure that this paper will stimulate debate; let us hope that it also stimulates further discoveries.

Explore further: Fossil footprints challenge established theories of human evolution

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Reg Mundy
1 / 5 (2) Sep 03, 2017
"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."
Its the same in every branch of science, the establishment always fight to preserve the status quo no matter what the demonstrable facts show. I still think Physics is the worst!

jonesdave
5 / 5 (3) Sep 03, 2017
"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."
Its the same in every branch of science, the establishment always fight to preserve the status quo no matter what the demonstrable facts show. I still think Physics is the worst!



And I think that you are A) not a scientist, and B) probably haven't got a bleeding clue what you are talking about. Am I right?
jonesdave
5 / 5 (2) Sep 03, 2017
It is an interesting paper. I, personally, am not wholly convinced. However, when the title of the paper begins with the word "possibly", and ends with a "?", then one should be a little sceptical. They may be right, they may be wrong. It does not, however, give some uneducated eejit the right to question the whole of science on the basis of this paper. However, the scientific literature is open to such nutjobs, should they wish to try. Just stop doing it here, guys. Nobody is the least bit interested. Yes?
skookumQuatch
1 / 5 (2) Sep 03, 2017
This is the sasquatch ancestor on his way to the mountains and forests of the east. Not an expert but you can see similarities in the footprint with heel size and splayed toes with the footprints considered authentic .
If such a creature actually exists ..
Da Schneib
5 / 5 (2) Sep 03, 2017
Meh. "Sasquatch" is a joke on dried meat commercials. Give it up.
nrauhauser
not rated yet Sep 04, 2017
Prior to this some edgy character found a single tooth of uncertain origin in Eastern Europe and made sweeping claims against the fossil history in East Africa. The overt racist overtones from that belong eighty years ago. This paper is more weighty, but I'm curious to see how it stands up to review.
Reg Mundy
1 / 5 (1) Sep 04, 2017
"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."
Its the same in every branch of science, the establishment always fight to preserve the status quo no matter what the demonstrable facts show. I still think Physics is the worst!



And I think that you are A) not a scientist, and B) probably haven't got a bleeding clue what you are talking about. Am I right?

No, you're wrong on both counts, but I expect you are probably used to that.
And stop voting yourself up with sock puppets, you twerp!
torbjorn_b_g_larsson
not rated yet Sep 04, 2017
I like Par Ahlberg's work on tetrapods and other fossils, but this is a huge chew to swallow. For one, there were a lot of similar "homin like" evolutionary experiments going on around the Mediterranean at the time. Oreopithecus has a non-typical locomotion apparatus, and of course a similar controversial context:

"Known as the "enigmatic hominoid", Oreopithecus can dramatically rewrite the palaeontological map depending on if it is a descendant from the European ape Dryopithecus or some African anthropoid.[1] Some have suggested the unique locomotory behavior of Oreopithecus requires a revision of the current consensus on the timing of bipedality in human developmental history, but there is limited agreement on this point among paleontologists."

[ https://en.wikipe...pithecus ]

(Though notably it shows the disparate traits that the article discuss on convergent evolution.)

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