Human Footprints Discovered Dating From 5 Million Years Ago

Original Article

By Jamie Seidel

These footprints, found at Trachilos in western Crete, have been attributed to an ancient human ancestor that walked upright some 5.7 million years ago. Credit: Andrzej Boczarowski

HUMAN-like footprints have been found stamped into an ancient sea shore fossilised beneath the Mediterranean island of Crete.

They shouldn’t be there.

Testing puts the rock’s age at 5.7 million years.

That’s a time when palaeontologists believe our human ancestors had only apelike feet.

And they lived in Africa.

But a study into the Trachilos, western Crete, prints determines them to feature prominent human features and an upright stance.

And that’s significant as the human foot has a unique shape. It combines a long sole, five short toes, no claws — and a big toe.

In comparison, the foot of a Great Ape look much more like a human hand.

And that step in evolution wasn’t believed to have taken place until some 4 million years ago.

Comparison of Trachilos footprint with bears (top), non-hominin primates (middle), and hominins (bottom). (a) Brown bear (b) Grizzly bear (c) Vervet monkey (d) Lowland gorilla (e) chimpanzee. (f) modern human (g) Trachilos footprint (h) modern human foot (i) Archaic Homo footprint. Pictures: Gerard D. Gierliński et al / Elsevier

Comparison of Trachilos footprint with bears (top), non-hominin primates (middle), and hominins (bottom). (a) Brown bear (b) Grizzly bear (c) Vervet monkey (d) Lowland gorilla (e) chimpanzee. (f) modern human (g) Trachilos footprint (h) modern human foot (i) Archaic Homo footprint. Pictures: Gerard D. Gierliński et al / Elsevier

Published in the latest edition of Proceedings of the Geologists’ Association, the study’s conclusions are bound to raise eyebrows in the human evolution community.

“The interpretation of these footprints is potentially controversial,” the study’s abstract admits.

“The print morphology suggests that the trackmaker was a basal member of the clade Hominini (human ancestral tree), but as Crete is some distance outside the known geographical range of pre-Pleistocene (2.5 million to 11,700 years ago) hominins we must also entertain the possibility that they represent a hitherto unknown late Miocene primate that convergently evolved human-like foot anatomy.”

Put simply, the study argues there was another — previously unidentified — human-like creature walking the Earth long before we believed it was possible.

A reconstruction of the skeleton of Australopithecus sediba, centre, next to a small-bodied modern human female, left, and a male chimpanzee. Picture: AP

A reconstruction of the skeleton of Australopithecus sediba, centre, next to a small-bodied modern human female, left, and a male chimpanzee. Picture: AP

The existing pool of evidence into humanity’s origins is built around Australopithecus fossils found in south and East Africa, along with a 3.7 million-year-old set of upright hominin (human ancestor) footprints found in Tanzania.

RELATED: Mystery of the Kimberley dinosaur prints solved

Called the Laetoli footprints, these are believed to have been made by Australopithecus with a narrow heel and poorly defined arch.

In contrast, a set of 4.4 million-year-old prints found in Ethiopia are believed from the hominin Ardipithecus ramidus. These prints are much closer to that of an ape than a modern human.

But the Trachilos footprints, at 5.7 million years, appear to be more human than Ardipithecus.

Maps and photos detailing the location and shape of the track-bearing stone in Crete. Pictures: Gerard D. Gierliński et al / Elsevier

Maps and photos detailing the location and shape of the track-bearing stone in Crete. Pictures: Gerard D. Gierliński et al / Elsevier

They were found by the study’s lead author, Gerard Gierlinski, while he was holidaying on the island of Crete in 2002. The palaeontologist at the Polish Geological Institute has taken more than a decade to analyse his find.

The Trachilos prints have a big toe very similar to our own in size, shape and position. It has a distinct ball on its sole. It has the human-like sole. It doesn’t have claws.

They were pressed into the firm but wet sands of a small river delta at a time when the Sahara was lush and green, and savanna extended from North Africa around the Eastern Mediterranean. Crete itself was still part of the Greek mainland then.

The three most well-preserved footprints, each shown as a photo (left), laser surface scan (middle) and scan with interpretation (right). a was made by a left foot, b and c by right feet. Scale bars, 5cm. 1—5 denote digit number; ba, ball imprint; he, heel imprint. Pictures: Gerard D. Gierliński et al / Elsevier

The three most well-preserved footprints, each shown as a photo (left), laser surface scan (middle) and scan with interpretation (right). a was made by a left foot, b and c by right feet. Scale bars, 5cm. 1—5 denote digit number; ba, ball imprint; he, heel imprint. Pictures: Gerard D. Gierliński et al / Elsevier

They have been dated using foraminifera (analysis of marine microfossils) as well as their position beneath a distinctive sedimentary rock layer created when the Mediterranean Sea dried up about 5.6 million years ago.

The footprints’ discovery also comes shortly after the fragmentary fossils of a 7.2 million-year-old primate Graecopithecus, discovered in Greece and Bulgaria, were reclassified as belonging to the human ancestral tree.

Scientist Crack The Code On “Neandertar”

By George Dvorsky
Image courtesy James Ives.

Over a hundred thousand years ago, Neanderthals used tar to bind objects together, yet scientists have struggled to understand how these ancient humans, with their limited knowledge and resources, were able to produce this sticky substance. A new experiment reveals the likely technique used by Neanderthals, and how they converted tree bark into an ancient form of glue.

Neanderthals were manufacturing their own adhesives as far back as 200,000 years ago, which is kind of mind blowing when you think about it. We typically think of fire, stone tools, and language as the “killer apps” of early human development, but the ability to glue stuff together was as much of a transformative technology as any of these.

Tar produced from the experiment seen dripping from a flint flake. (Image: Paul Kozowyk)

New research published in Scientific Reports reveals the startling ingenuity and intellectual capacities of Neanderthals, and the likely method used to cook up this ancient adhesive.

Based on the archaeological evidence, we know that Neanderthals were manufacturing tar during the Middle Pleistocene Era. The oldest traces of this practice date back to a site in Italy during a time when only Neanderthals were present in Europe. Similar tar lumps and adhesive residues have also been found in Germany, the oldest of which dates back some 120,000 years ago. The Neanderthals used tar for hafting—the practice of attaching bones or stone to a wooden handle to create tools or weapons. It was a force multiplier in engineering, allowing these ancient humans to think outside the box and build completely new sets of tools.

What makes the presence of tar at this early stage in history such a mystery, however, is that Neanderthals had figured out a way to make the useful goo thousands of years before the invention of ceramics, which by the time of the ancient Mesopotamians was being used to produce tar in vast quantities. For years, archaeologists have suspected that Neanderthals performed dry distillation of birch bark to synthesize tar, but the exact method remained a mystery—particularly owing to the absence of durable containers that could be used to cook the stuff up from base materials. Attempts by scientists to replicate the suspected Neanderthal process produced tar in miniscule amounts and far short of what would be required for hafting.

To finally figure out how the Neanderthals did it, a research team led by Paul Kozowyk from Leiden University carried out a set of experiments. Tar is derived from the dry distillation of organic materials, typically birch bark or pine wood, so Kozowyk’s team sought to reproduce tar with these substances and the cooking methods likely at the disposal of the Neanderthals. It’s very likely that the Neanderthals stumbled upon the idea while sitting around the campfire.

Tar collected in a birch bark “container.” (Image: Paul Kozowyk)

“A tightly rolled piece of birch bark simply left in a fire and removed when partially burned, once opened, will sometimes contain small traces of tar inside the roll along the burned edge,” explained the authors in the study. “Not enough to haft a tool, but enough to recognize a sticky substance.”

With this in mind, the researchers applied three different methods, ranging from simple to complex, while recording the amount of fuel, materials, temperatures, and tar yield for each technique. Their results were compared to known archaeological relics to see if they were on the right (or wrong) track. By the end of the experiments, the researchers found that it was entirely possible to create tar in the required quantities using even the simplest method, which required minimal temperature control, an ash mound, and birch bark.

The maximum amount of tar obtained from a single experimental attempt was 15,7 grams—far more than any tar remains from the Middle Paleolithic Era. (Image: Paul Kozowyk)

“A simple bark roll in hot ashes can produce enough tar to haft a small tool, and repeating this process several times (simultaneously) can produce the quantities known from the archaeological record,” write the researchers. “Our experiments allowed us to develop a tentative framework on how the dry distillation of birch bark may have evolved, beginning with the recognition of small traces of birch bark tar in partially burned bark rolls.” They added: “Our results indicate that it is possible to obtain useful amounts of tar by combining materials and technology already in use by Neandertals.”

Indeed, by repeating even the simplest process, the researchers were able to obtain 15.9 grams of useable tar in a single experiment, which is far more than any tar remains found in Middle Paleolithic sites. What’s more, temperature control doesn’t need to be as precise as previously thought, and a durable container, such as a ceramic container, is not required. That said, the process did require a certain amount of acumen; for this process to come about, Neanderthals needed to recognize certain material properties, such as the degree of adhesiveness and viscosity. We’ll never be certain this is exactly what Neanderthals were doing, but it’s a possibility with important implications for early humans in general.

“What this paper reinforces is that all of the humans that were around 50,000 to 150,000 years ago roughly, were culturally similar and equally capable of these levels of imagination, invention and technology,” explained Washington University anthropologist Erik Trinkaus, who wasn’t involved in the study, in an interview with Gizmodo. “Anthropologists have been confusing anatomy and behavior, making the inference that archaic anatomy equals archaic behavior, and ‘modern’ behavior [is equivalent to] modern human anatomy. What is emerging from the human fossil and Paleolithic archeological records across the Eurasia and Africa is that, at any one slice in time during this period, they were all doing—and capable of doing—basically the same things, whatever they looked like.”

Sabrina Sholts, an anthropologist at the Smithsonian Institute’s National Museum of Natural History, says this study is a nice example of how experimental archaeology can be used to supplement the material record and address questions about past hominid behavior.

“I think it’s certainly worthwhile to test methods of tar production that could have been used by Neanderthals and early modern humans, if only to challenge our assumptions about the kind of technologies—and ideas—within their reach,” she told Gizmodo.

The Theoretical Origin of Complex Life and “Snowball” Earth

Original Article

Life on Earth goes back at least two billion years, but it was only in the last half-billion that it would have been visible to the naked eye. One of the enduring questions among biologists is how life made the jump from microbes to the multicellular plants and animals who rule the planet today. Now, scientists have analyzed chemical traces of life in rocks that are up to a billion years old, and they discovered how a dramatic ice age may have led to the multicellular tipping point.

Writing in Nature, the researchers carefully reconstruct a timeline of life before and after one of the planet’s most all-encompassing ice ages. About 700 million years ago, the Sturtian glaciation created what’s called a “snowball Earth,” completely covering the planet in ice from the poles to the equator. About 659 million years ago, the Sturtian ended with an intense greenhouse period when the planet heated rapidly. Then, just as things were burning up, the Marinoan glaciation started and covered the planet in ice again. In the roughly 15 million years between the two snowballs, a new world began to emerge.

Just before the rise of plankton that provided food for multicellular animals, the Earth's continents had merged and broken apart and merged again.
Just before the rise of plankton that provided food for multicellular animals, the Earth’s continents had merged and broken apart and merged again.

Jochen J. Brocks, a geologist from the Australian National University, Canberra, joined with his colleagues to track the emergence of multicellular life by identifying traces left by cell membranes in ancient rocks. Made from lipids and their byproducts, cell membrane “biomarkers” are like fossils for early microorganisms. By measuring chemical changes in these membranes, Brocks and his team discovered a “rapid rise” of new, larger forms of sea-going plankton algae in the warming waters after the Sturtian snowball. Some of these lifeforms were eukaryotes, meaning they had developed a nucleus—that’s another necessary step on the road to multicellular life.

But multicellular life couldn’t evolve without a major shift in the planet’s geochemistry after the Sturtian. From the upper atmosphere to the deepest oceans, the planet’s molecular composition had to change.

The great oxygen rush

The researchers suggest this transformation started when melting glaciers at the end of the snowball caused rapid erosion of landmasses, sending huge amounts of nutrients into the oceans. Slurries of icy minerals cascaded into the sea, sinking to the bottom and sequestering carbon.

That’s when things got real. “Such massive burial of reduced carbon must have been balanced by a net release of oxygen into the atmosphere, initiating the protracted oxygenation of Neoproterozoic deep oceans,” write the scientists. A world with very little oxygen in it was suddenly inundated with the stuff, both in and out of the water.

The rise of oxygen set off a cascade of linked events. It very likely led to the rise of phosphorous in the water, which is a key building block in DNA, and the energy-rich molecule ATP that provides fuel for our bodies. This meant more complex lifeforms like algae, which release oxygen during their digestive process. As algae diversified, lifeforms evolved to feed on the algae. Over time, new predators evolved to feed on those creatures, and so on. The more creatures who died and sank to the ocean floor, the more carbon was sequestered. As the researchers put it, the planet developed “a more efficient biological pump.”

A timeline showing the relationship between Earth's changing geochemistry and the rise of eukaryotic life like algae.
A timeline showing the relationship between Earth’s changing geochemistry and the rise of eukaryotic life like algae.
Brocks, et. al.

This oxygen- and phosphorus-driven change was unstoppable. Even after the Minoan glaciation’s snowball, when the surface of the ocean heated up to as much as 60 degrees Celsius in the tropics, algae found its way to the poles and continued to diversify. Life as we know it appears to have emerged in the warm waters of a planet vacillating wildly between snowball and greenhouse. The climate became more stable about 550 million years ago, and we see the emergence of animals with heads, tails, and internal organs.

Harvard geobiologist Andrew Knoll, who was not involved in the study, wrote that this discovery“will change the conversation” about the emergence of complex life on Earth. Fundamentally, Brocks and his colleagues’ work shows that environmental changes are key to the evolution of life. Without an oxygenated ocean, there would be no animals on this world.

That’s why scientists are deeply concerned about the de-oxygenation of the seas today as a result of climate change and nutrient runoff from land. De-oxygenated areas called “dead zones” will slow or even halt the planet’s biological pump. Earth is a glorious geochemical machine, running processes that take millions of years. Perturbations in those processes can completely transform the world. Sometimes that means the planet blooms with life, as it did during the rise of oxygen and phosphorous in the ocean. But sometimes it brings death.

Nature, 2017. DOI: 10.1038/nature23457