New Look at Human Origins

What We Learned About Human Origins in 2013

Charles Q. Choi, LiveScience Contributor   |   December 28, 2013
The 1.8-million-year-old skull unearthed in Dmanisi, Georgia, suggests the earliest members of the <em>Homo</em> genus belonged to the same species, say scientists in a paper published Oct. 18, 2013 in the journal Science.
 The 1.8-million-year-old skull unearthed in Dmanisi, Georgia, suggests the earliest members of the Homo genus belonged to the same species, say scientists in a paper published Oct. 18, 2013 in the journal Science.
Credit: Photo courtesy of Georgian National Museum

The existence of a mysterious ancient human lineage and the possibility that the earliest humans were actually all one species were among the human-evolution-related discoveries of 2013. Other breakthroughs include the sequencing of the oldest human DNA yet.

Here’s a look at what scientists learned about humanity and human origins this year:

Mystery lineage

Recent analyses of fossil DNA have revealed that modern humans occasionally had sex and produced offspring not only with Neanderthals but also with Denisovans, a relatively newfound lineage whose genetic signature apparently extended from Siberia to the Pacific islands of Oceania.

This year, hints began emerging that another mystery human lineage was part of this genetic mix as well. Now, the first high-quality genome sequence from a Neanderthal has confirmed those suspicions.

These findings come from Denisova Cave in southern Siberia, where the first evidence of Denisovans was discovered in 2008. To learn more about the Denisovans, scientists examined DNA from a toe bone unearthed there in 2010.

The researchers found that the fossil belonged to a Neanderthal woman. Her DNA helped refine the human family tree, as it revealed that about 1.5 to 2.1 percent of the DNA of modern people outside Africa is Neanderthal in origin, whereas about 0.2 percent of DNA of mainland Asians and Native Americans is Denisovan in origin.

The scientists also discovered that the Denisovans interbred with an unknown human lineage, getting as much as 2.7 to 5.8 percent of their genomes from it. This newfound relative apparently split from the ancestors of all modern humans, Neanderthals and Denisovans between 4 million and 900,000 years ago, before these latter groups started diverging from each other. It’s possible that this mysterious lineage could even be Homo erectus, the earliest known undisputed predecessor of modern humans. However, there are no signs that this unknown group interbred with modern humans or Neanderthals.

Genetic analysis also revealed that the parents of this Neanderthal woman were closely related — possibly half-siblings, or another close relative. (Inbreeding may have been common among early humans — it remains uncertain as to whether it was some kind of cultural practice or whether it was unavoidable due to small community populations at the time.)

Researchers have discovered a 1.42-million-year-old hand fossil that possesses the styloid process, a vital anatomical feature that allows the hand to lock into the wrist bones, giving humans the ability to make and use complex tools. Researchers have discovered a 1.42-million-year-old hand fossil that possesses the styloid process, a vital anatomical feature that allows the hand to lock into the wrist bones, giving humans the ability to make and use complex tools.
Credit: University of Missouri

Were earliest humans all one species?

Modern humans, Homo sapiens, are the only living member of the human lineage, Homo, which is thought to have arisen in Africa about 2 million years ago at the beginning of the Ice Age. Many now-extinct human species were thought to once roam the planet, such as Homo habilis, which is suspected to be among the first stone-tool makers; the relatively larger-brained Homo rudolfensis; the relatively slender Homo ergaster; and Homo erectus, the first to regularly keep the tools it made.

The level of variation seen in Homo fossils is typically used to define separate species. However, analysis of 1.8-million-year-old skulls excavated from the Republic of Georgia revealed the level of variation seen among those skulls was about the same as that seen among ancient African Homo fossils. As such, researchers suggest the earliest Homo fossils may not be multiple human species, but rather variants of a single lineage that emerged from Africa. In other words, instead of Africa once being home to multiple human species such as Homo erectus, Homo habilis, Homo ergaster and Homo rudolfensis, all of these specimens may actually simply be Homo erectus.

Oldest human DNA

The testing of the oldest known human DNA added more evidence that human evolution was complex.

The genetic material, some 400,000 years old, came from a human thighbone unearthed in the Sima de los Huesos, or “Pit of Bones,” an underground cave in northern Spain. Until now, the previous oldest known human DNA had come from a 100,000-year-old Neanderthal from a Belgian cave.

The fossils unearthed at the site resembled those of Neanderthals, so researchers expected the ancient DNA they analyzed to be Neanderthal as well. Surprisingly, the DNA revealed that this fossil’s closest known relatives were not Neanderthals but Denisovans. This finding is strange, scientists said, because studies to date currently suggest the Denisovans lived in eastern Asia, not in western Europe, where this fossil was uncovered. One possible explanation is that a currently unknown human lineage brought Denisovan-like DNA into the Pit of Bones region, and possibly also to the Denisovans in Asia.

Neanderthal burial pit
 A pit in a French cave that may have been an intentional grave dug by Neanderthals to bury one of their number.
Credit: C. Beauval, Archéosphère company

Evolution of tool use

The capability to make and use complex tools is a critical trait distinguishing modern humans from all other species alive today. Now, scientists have found an ancient hand-bone fossil that reveals that the modern human ability to make and use complex tools may have originated far earlier than previously thought.

A key anatomical feature of the modern human hand is the third metacarpal, a bone in the palm that connects the middle finger to the wrist. A little projection of bone known as a styloid process in this bone helps the thumb and fingers apply greater amounts of pressure to the wrist and palm. Researchers had thought the styloid process was a relatively recent feature, perhaps evolving close to the origin of modern humans. However, scientists have discovered a 1.4-million-year-old fossil that possesses this vital anatomical feature, meaning it existed more than 500,000 years earlier than it was previously known to have existed and was perhaps fundamental to the evolution of the whole genus Homo, not just modern humans.

This hand bone may not be the only key trait for tool use that evolved near the origin of the human lineage. Humans are the only species that can throw with great speed and precision, and scientists found this ability first evolved nearly 2 million years ago with anatomical changes to the shoulder, arm and torso. This advance likely boosted the hunting prowess of now-extinct human ancestors, helping them effectively and safely kill big game.

Neanderthal discoveries

In 2013, researchers also made important discoveries about Neanderthals, modern humans’ closest extinct relatives. For instance, analysis of a Neanderthal tomb in France suggests that, like modern humans, Neanderthals may have intentionally buried their dead. The new findings are further evidence that Neanderthals might have possessed complex forms of thought, enough for special treatment of the dead.

In addition, a cache of Neanderthal fossils discovered in a cave in Greece suggests the area may have been a key crossroad for ancient humans. The age of these fossils suggests Neanderthals and other humans may have had the opportunity to cross paths there, and even interact, the researchers added.

from:    http://www.livescience.com/42218-2013-human-origins-discoveries.html

Enduring Ancient Mysteries to Ponder

 

Top ancient mysteries of 2011

 

Peter Schmid / Lee Berger / Univ. of Wits.

The skeletal hand of an adult female Australopithecus sediba is nestled within a modern human hand. The analysis of the A. sediba bones led to what some experts called a “game-changing” view of evolution in 2011.

By Alan Boyle

Do archaeologists ever get tired of delving into ancient mysteries? One of my all-time favorite articles from The Onion is the one about the archaeologist who’s fed up with“unearthing unspeakable ancient evils,” but in real life, you can’t beat a good story about archaeology, paleontology or paleoanthropology.

I’m combining several different scientific disciplines in this end-of-year roundup of ancient mysteries. Archaeology has to do with studying the peoples of the past through an analysis of the things they’ve left behind, ranging from the bones of Ötzi the Iceman to the pigeon nests built in a cave near Jerusalem. Paleontology is the branch of geology that focuses on the fossil record left behind by bygone organisms, including dinosaur dung. And paleoanthropology focuses on our prehistoric ancestors and theirrelationships to other species.

It’s been a busy year for archaeologists coping with the tumult that swept over Egypt and Libya … for paleontologists debating where different species fit on the org chart for extinct organisms … and for anthropologists analyzing how humans swapped DNA with heaven knows what other kinds of hominids. Here’s a quick rundown, with assists from the editors of Archaeology magazine and paleo-blogger Brian Switek.

Archaeology
The top 10 discoveries of 2011, as rated by Archaeology, include revelations about these ancient mysteries:

I would add two late-breaking stories to the mix: one about the mysterious markings on the floor of an ancient complex in Jerusalem, and another about long-hidden 16-foot-wide pits in the ground near Stonehenge.

Paleontology
I asked Switek to help me sort through the year’s top stories in paleontology, and he was kind enough to send this recap:

“Last year the big news was that paleontologists had restored the colors of two feathered dinosaurs. This year, there doesn’t seem to be any major story that competes. But that’s not to say that nothing significant happened in 2011. Here’s a rundown of what I thought was interesting and important.

Dinosaur growth: Over the past few years, paleontologists have been tussling over how many dinosaur species we have collected so far. The great Triceratops-Torosaurus debate of 2010 really brought this ongoing argument into focus, and there were several 2011 papers which continued the conversation. Early in the year paleontologist Andy Farkecriticized the ‘Torosaurus as Triceratops’ hypothesis, and a reply to his reply has just appeared. Likewise, paleontologists suggested that the hadrosaur Anatotitan and the tyrannosaur Raptorex were really just growth stages of already-known dinosaurs (the latter being similar to Tarbosaurus, a juvenile of which was also described this year).” [Here’s another take on the tussle over Triceratops.]

Dinosaur senses: Two big papers – published at about the same time – probed dinosaur senses. One focused on smell, and the other vision. Studies like these represent our broadening understanding of dinosaur biology. It’s not all about naming new species.” [Learn more about thesmell and night vision research]

Archaeopteryx: This year marked the 150th anniversary of when Archaeopteryx was discovered. The year has been full of ups and downs. Even though an 11th specimen of the feathered dinosaur was announced,a ballyhooed paper proposed that the creature was not an early bird but rather a non-avian dinosaur more distantly related to the first birds.”[Here’s more ballyhoo about the claim that Archaeopteryx wasn’t a bird.]

New species: New dinosaurs are named just about every week, but there were at least two that caught my eye. One was Brontomerus – a sauropod whose name translates to “thunder thighs” – andTeratophoneus, a short-snouted tyrannosaur. (I just realized that both were found in Utah, though, so perhaps I have a bias for my adoptive state!)” [Learn more about “Thunder Thighs” as well as other ancient wonders in Utah.]

Other paleo: I usually don’t cover the really big stories – I like to root around for tales no one is telling – but a few studies from this year got my attention.”

• Plesiosaurs gave birth to live young
• Marsupial “wolf” hunted more like a cat
• Late-surviving predator was similar to those that swam the Cambrian
• Earliest saber-toothed herbivore found
• Ammonoids trapped parasites in pearls
• Cache of fossil feathers found in amber
• Woolly and Columbian mammoths may have interbred

Paleoanthropology
To round out this big list, here are a few of the tales of human ancestors that caught my eye over the past year:

That’s more than 30 tales of ancient mysteries to ponder

from:    http://cosmiclog.msnbc.msn.com/_news/2011/12/15/9478098-top-ancient-mysteries-of-2011