Scientists discover organism that hasn't evolved in more than 2 billion years

This is a section of a 1.8 billion-year-old fossil-bearing rock.

An international team of scientists has discovered the greatest absence of evolution ever reported -- a type of deep-sea microorganism that appears not to have evolved over more than 2 billion years. But the researchers say that the organisms' lack of evolution actually supports Charles Darwin's theory of evolution.

The findings are published online by the Proceedings of the National Academy of Sciences.

The scientists examined sulfur bacteria, microorganisms that are too small to see with the unaided eye, that are 1.8 billion years old and were preserved in rocks from Western Australia's coastal waters. Using cutting-edge technology, they found that the bacteria look the same as bacteria of the same region from 2.3 billion years ago -- and that both sets of ancient bacteria are indistinguishable from modern sulfur bacteria found in mud off of the coast of Chile.

"It seems astounding that life has not evolved for more than 2 billion years -- nearly half the history of Earth," said J. William Schopf, a UCLA professor of earth, planetary and space sciences in the UCLA College who was the study's lead author. "Given that evolution is a fact, this lack of evolution needs to be explained."

Charles Darwin's writings on evolution focused much more on species that had changed over time than on those that hadn't. So how do scientists explain a species living for so long without evolving?

"The rule of biology is not to evolve unless the physical or biological environment changes, which is consistent with Darwin," said Schopf, who also is director of UCLA's Center for the Study of Evolution and the Origin of Life. The environment in which these microorganisms live has remained essentially unchanged for 3 billion years, he said.

"These microorganisms are well-adapted to their simple, very stable physical and biological environment," he said. "If they were in an environment that did not change but they nevertheless evolved, that would have shown that our understanding of Darwinian evolution was seriously flawed."

Schopf said the findings therefore provide further scientific proof for Darwin's work. "It fits perfectly with his ideas," he said.

The fossils Schopf analyzed date back to a substantial rise in Earth's oxygen levels known as the Great Oxidation Event, which scientists believe occurred between 2.2 billion and 2.4 billion years ago. The event also produced a dramatic increase in sulfate and nitrate -- the only nutrients the microorganisms would have needed to survive in their seawater mud environment -- which the scientists say enabled the bacteria to thrive and multiply.

Schopf used several techniques to analyze the fossils, including Raman spectroscopy -- which enables scientists to look inside rocks to determine their composition and chemistry -- and confocal laser scanning microscopy -- which renders fossils in 3-D. He pioneered the use of both techniques for analyzing microscopic fossils preserved inside ancient rocks.

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Ancient skull shows modern humans colonized Eurasia 60-70,000 years ago

This image shows a skull found in the Manot Cave, Israel.

 While it is widely accepted that the origins of modern humans date back some 200,000 years to Africa, there has been furious debate as to which model of early Homo sapiens migration most plausibly led to the population of the planet -- and the eventual extinction of Neanderthals. While fossil records prove that some anatomically modern human groups reached the Levantine corridor (the modern Middle East) as early as 100,000 years ago, genetic testing indicates that human populations inhabiting the globe today descended from a single group that migrated from Africa only 70,000 years ago -- an unexplained gap of 30,000 years. Little evidence has emerged to bridge the contradictory theories.

Until now. The discovery in the Manot Cave of Israel's Western Galilee of an almost complete skull dating back 55,000 years provides direct anatomical evidence that fills the historic time gap of modern human migration into Europe. It is also the first proof that anatomically modern humans existed at the same time as Neanderthals in the same geographical area.

The finding, by Prof. Israel Hershkovitz, the Tassia and Dr. Joseph Meychan Chair for the History and Philosophy of Medicine at the Department of Anatomy and Anthropology at TAU's Sackler Faculty of Medicine and Head of The Dan David Laboratory for the Search and Study of Modern Humans at the Steinhardt Museum of Natural History and National Research Center, was published in Nature this week.

A new light on our ancestors

"The morphology of the skull indicates that it is that of a modern human of African origin, bearing characteristics of early European Upper Palaeolithic populations. This suggests that the Levantine populations were ancestral to earlier European populations," said Prof. Hershkovitz. "This study also provides important clues regarding the likely inbreeding between anatomically modern humans and Neanderthals."

The Manot Cave, where the skull was unearthed, was discovered accidentally in 2008 when a bulldozer struck the cave roof, revealing a time capsule tens of thousands of years old. "This is a goldmine," said Prof. Hershkovitz. "Most other caves are 'disturbed caves,' but this is untouched, frozen in time -- truly an amazing find. Among other artefacts found there, the skull, which we dated to 55,000 years ago using uranium thorium methods, was astonishing. It provides insight into the beginnings of the dispersal of modern humans all over the world."

According to Prof. Hershkovitz, the skull disproves two major narratives: that all modern human populations are linked to migrations out of Africa 100,000 years ago, and that early European Upper Paleolithic populations interbred with local European Neanderthals. Instead the skull indicates that modern humans met and interbred with Neanderthals in Israel, only to later pass on their genes to the rest of the world. Considering Europe was in the last Ice Age period, its harsh climate rendered it generally inhospitable, so humans from the Levant moved first to Asia, and only later (45,000 ago) to Europe.
 
Sorting out the contradictions

"This was a wonderful scenario, but there was one problem," said Prof. Hershkovitz. "Geneticists discovered that present-day human populations were linked to a group of African modern humans who started migrating 70,000 years ago. Accordingly, all previous migrations of modern humans out of Africa were presumed to have reached a dead end, contributing nothing to present-day human life. But this was a prediction based on genetic studies only. No fossils to be found anywhere to back it up."

The first physical evidence that modern man left Africa 70,000 years ago, stopped in Israel, then moved afterward to Europe came in the form of the newly discovered Manot skull. "This skull dates back 55,000 years, a critical time period," said Prof. Hershkovitz. "If modern humans indeed moved from Africa 70,000 years ago to Israel, this skull means they settled in the Levant for a long period of time, before moving to Europe (45,000 years ago).

"When we analysed the morphology of Manot skull, we made two important discoveries. First, we found African affinities, confirming that the Manot population originated in Africa. Second, we noted many morphological peculiarities akin to early Upper Paleolitic populations in Europe, which suggest ancestral connections to earlier European populations. All of this confirms that people in Manot came from Africa, stayed in Israel for several thousand years, and later, when weather conditions improved, moved to Europe. The Manot people are indeed the ancestors of European populations."

A further critical finding was the apparent communication and interbreeding between the local Neanderthals and the Manot Homo sapiens in the Levant -- not in Europe, as some anthropologists previously hypothesized. "When the Manot people came to Israel, they encountered a flourishing population of Neanderthals, with whom they must have communicated, shared tools and interbred with," said Prof. Hershkovitz. "According to our analysis of the skull, which bears a complex mix of archaic and modern characteristics, this was probably the only place on earth where Neanderthals and anatomically modern humans lived side by side for a long period of time."

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Oldest stone tool ever found in Turkey discovered

Stone tool approximately 1.2 million years old.

Scientists have discovered the oldest recorded stone tool ever to be found in Turkey, revealing that humans passed through the gateway from Asia to Europe much earlier than previously thought, approximately 1.2 million years ago.

According to research published in the journal Quaternary Science Reviews, the chance find of a humanly-worked quartzite flake, in ancient deposits of the river Gediz, in western Turkey, provides a major new insight into when and how early humans dispersed out of Africa and Asia.

Researchers from Royal Holloway, University of London, together with an international team from the UK, Turkey and the Netherlands, used high-precision equipment to date the deposits of the ancient river meander, giving the first accurate timeframe for when humans occupied the area.

Professor Danielle Schreve, from the Department of Geography at Royal Holloway, said: "This discovery is critical for establishing the timing and route of early human dispersal into Europe. Our research suggests that the flake is the earliest securely-dated artefact from Turkey ever recorded and was dropped on the floodplain by an early hominin well over a million years ago."

The researchers used high-precision radioisotopic dating and palaeomagnetic measurements from lava flows, which both pre-date and post-date the meander, to establish that early humans were present in the area between approximately 1.24 million and 1.17 million years ago. Previously, the oldest hominin fossils in western Turkey were recovered in 2007 at Koçabas, but the dating of these and other stone tool finds were uncertain.

"The flake was an incredibly exciting find," Professor Schreve said. "I had been studying the sediments in the meander bend and my eye was drawn to a pinkish stone on the surface. When I turned it over for a better look, the features of a humanly-struck artefact were immediately apparent.

"By working together with geologists and dating specialists, we have been able to put a secure chronology to this find and shed new light on the behaviour of our most distant ancestors."

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