Published May 15, 2014
The oldest complete skeleton of its kind ever found, dating to more than 12,000 years ago, is helping solve a mystery about the differences in body types between the first humans to arrive in the Americas and later Native Americans, scientists announced Thursday.
Anthropologists have long puzzled over why Native Americans don't look more like their ancient ancestors, who migrated into the Americas during the Pleistocene, the epoch that encompassed the last ice age and that ended about 12,000 years ago.
The ancient skulls are larger, their faces are narrower and more forward-projecting, and they more closely resemble native peoples of Africa, Australia, and the southern Pacific Rim than they do their supposed American descendants.
Were those differences the product of evolutionary changes in the founding populations? Or were the Paleoamericans, the first arrivals to the Americas, displaced by later migrations of people with features more like those of Native Americans?
On Thursday, a team led by archaeologist James Chatters reported in the journal Science that they'd found a big piece of the puzzle: the most complete skeleton of such antiquity ever found in the Americas, between 12,000 and 13,000 years old. The skeleton contains both the craniofacial features of ancient Paleoamericans and mitochondrial DNA possessed by latter-day Native Americans.
Tracing a DNA Trail
The skeleton, dubbed "Naia" (an ancient Greek name related to water nymphs) by her discoverers, belonged to a teenage girl who fell more than 100 feet to her death nearly a half mile inside an elaborate network of karst caves that were largely dry at the end of the Pleistocene. Divers who found Naia in the cave on Mexico's Yucatán Peninsula named her watery grave Hoyo Negro ("Black Hole" in Spanish).
Chatters described Naia's face as narrow with wide-set eyes and a low, prominent forehead; a low, flat nose; and outward-projecting teeth—"about the opposite of what Native Americans look like today." To see those features coupled with genetic markers indicating a common lineage with Native Americans is highly significant.
"This is the first time that we have genetic data from a skeleton that exhibits these distinctive skull and facial features," said Deborah Bolnick, an anthropological geneticist at the University of Texas at Austin and one of the study's co-authors.
The find from Hoyo Negro comes on the heels of the recent genomic sequencing of the 12,600-year-old remains of an infant found at the Anzick Clovis site in Montana, which also revealed a shared ancestry with Native Americans.
Genetic analyses of modern Native Americans indicate they descend from a founding population that originated in Asia. They were isolated from other population groups for several thousand years somewhere in or near the region known as Beringia, a broad swath of land that reached from Siberia to Alaska during the last glacial maximum.
It was there that this founding population developed its unique genetic markers. But until the Anzick discovery, little genetic data had been available from Paleoamerican skeletal specimens, leaving their relationship to Native Americans poorly understood.
The genetic data from the Anzick find is superior to that of Hoyo Negro's because it was derived from mitochondrial and nuclear DNA, providing a much more comprehensive lineage history than mitochondrial DNA alone, which traces only maternal lineages. But the downside of Anzick is that the specimen itself is much less complete: just four bones and the braincase portion of a cranium.
Michael Waters, director of the Center for the Study of First Americans at Texas A&M University in College Station, said the Anzick and Hoyo Negro finds complement one another.
"Now we've got two specimens, both from a common ancestor that came from Asia," he said. "Like Hoyo Negro, the Anzick genome shows that Paleoamericans are genetically related to native peoples, so the latter cannot be a replacement population. Their differences have to be a result of evolutionary change. What drove that change, we don't know."
From Hunters to Homemakers?
Chatters speculates that ancient Americans' morphology may have changed as their living conditions changed. As highly mobile hunter-gatherers became more settled, evolutionary processes may have selected for more domestic traits and temperaments, resulting in the softer, rounder features seen in the faces of Native Americans.
"You start seeing these more domestic forms when females have more control over the food supply, when they're not so dependent on aggressive men," Chatters said. He added that this process of neotenization—the retention of some juvenile traits—can be seen in populations across the Northern Hemisphere between the late Pleistocene and modern times.
Speculation about the potential drivers of evolutionary change is not part of the team's study. Even so, some scientists warn against drawing too many conclusions from the Hoyo Negro find.
"We know there's a tremendous variation in physical form, and the sample of crania we have from that time period is so tiny," said David Meltzer of Southern Methodist University, Dallas, Texas. "Imagine plucking a dozen skulls from New York City; they wouldn't look a lot alike. We've got to be really careful about drawing conclusions based on relatively small samples. That's true for the skeletal anatomy, and it's true for the genetic record as well."
Getting to Know Naia
Flooded now by higher sea levels, the Sac Actun cave system in the Mexican state of Quintana Roo is one of the two largest surveyed underwater cave systems in the world. (Read "Secrets of the Maya Underworld" in National Geographic magazine.)
In 2007, while exploring and mapping the system, divers discovered a suite of bones at the bottom of a huge chamber. The bones included those of extinct saber-toothed cats, giant ground sloths, and other Pleistocene animals—as well as Naia's skeleton.
The girl was "probably in search of water," said archaeologist Dominique Rissolo, the project's co-director. "Water would have been scarce with the water table that low. There are no lakes and rivers in the area, so people and animals would have had to venture into caves."
Naia was found with a broken pelvis, probably from the impact of the fall—a hard end to what was likely a hard life. She shows signs of tooth decay and osteoporosis, perhaps as a result of becoming pregnant at an early age, before reaching full physical maturity. "She was absolutely tiny," Chatters said.
The submergence of the cave between 10,000 and 4,000 years ago helped preserve Naia's skeleton, and the lack of sediment deposition left her bones in clear sight for the divers. "She is heavily mineralized, so there's a strong, hard quality to the bones, which is great for getting skeletal measurements," Rissolo said. "But for dating, it's a different situation altogether."
Without any bone collagen for radiocarbon dating, the team triangulated the skeleton's age by determining the age of calcite crystals known as "florets" growing on the bones, carbon-dating nearby bat guano, and carbon-dating Naia's tooth enamel.
All that, coupled with the nearby Pleistocene-era animal remains and estimates of when the cave would have flooded, led the team to conclude she was at least 12,000 years old, and perhaps closer to 13,000.
Part of her remains have been removed from Hoyo Negro for safekeeping, after unauthorized divers entered the chamber to take photographs, moving and damaging some bones in the process.
"We tried to keep everything in situ," said Mariá del Pilar Luna Erreguerena, head of underwater archaeology for Mexico's National Institute of Anthropology and History, which coordinated the Hoyo Negro project with support from the National Geographic Expeditions Council.
But leaving Naia's remains in place was deemed too big a risk. Her watery grave is an attractive target, one Chatters likens to "a mini La Brea Tar Pits, only without the tar and considerably better preservation."
First of all the non-black people in Northern Africa are not indigenous to Africa at all.
Arab occupation of the region wasn't until 650A.D.The mother of all human genes is the Haplogroup (L) which is proven to be undoubtedly black African. Now about the skull found in the Hoyo negro cave. All human skull have a particular characteristic that tells of their race origin. Notice the skull displays prognathic features.
If you are saying life began in North Africa one way or the other they would have been black or maybe albino, which I doubt. The Olmec was purely African (not North African), were here long before any European or Asian and for all practical reasoning may still be here. Remember, the Chinese (DNA Testing) are too descendants of Africa. Ask them. Even some (so called Indians) know who their ancestors are..
what about human sacrifice, throwing young women into water holes is a caracteristic ritual in this area
Are you saying that Naja's origin was Africa? Could the Olmec have been the same? I believe she was and they are.
As a matter of fact there is an artifact or maybe several artifacts associated with this skull. Look closely at photograph number four. There is a chert tool just to the right of the skull. There are also 3 or 4 other objects lying nearby that could be artifacts....
As I read it, there seems a strange situation of a young female at the bottom of what might have been a dry cavern, NO WEAPONS, NO PERSONAL ARTIFACTS, necklace or adornment that survived. Might she have been a sacrifice or a suicide?I feel deeply sad that this young girl would suffer such an injury and long painful death. My heart goes out to her.
Well that should put an end to the 5,000 year old quackery to life on earth or how long humans have been around. Well, for most people. Anyway, it is a remarkable discovery.
The article mentions she was "tiny". Was the estimated height and weight given? How young a "teen" was she? It does mention that she had at least one early pregnancy that affected her growth/bones.
Unfortunate there were no artifacts found. Seems like everybody would have carried some sort of knife at least. I guess the finds with the Iceman were unique to his circumstances and will never be duplicated.
so, what does she actually look like. science is already that far that we can recreate anything on a skull or skeleton
lets see what that girl looked like.
MOST FASCINATING if we ever get to see her.
and may all that desecrate this place
By jove, I mean it !!
A remarkable find- a good link! National Geographic is a naustalgic part of my life.
Wish National Geographic would have something to report on the submerged Dwaraka, in India! Have I missed it if you already have?
Could others from her "tribe" also be nearby in an extinct community? I hope the researchers will continue their quest to discover others and we will have a follow-up to this report in the near future.
It would be good to note as to what has been the result after DNA processing. The cave getting flooded and the fall of Naia into the cave also has to be taken into consideration. The time lapse between these two events too may have been as much as 1000 years. Who know ?
Anxious to see this petit wide eyes ancestor to the americas heritage found at this particular crossroad between todays two americas. Congratulations to all !
Why would females evolve neotenization if they were less dependent on aggressive men? Wouldn't neotenization benefit dependent women--men would treat them kinder because they were "cuter" like babies? How would neotenization benefit more independent women?
What an outstanding find. To bad so many divers destroying the site. Great photos for the readers to experience the anthropology site.
A frivolous but, I think, amusing observation derived from an episode from Britain's "Goon Show" satirical radio(?) program of years ago:
A gentleman is heard to exclaim, presumably while handling a recently discovered human skull, "I'd say this skull is three thousand years old!". There is a pause, and, then, suddenly, a chorus of male voices breaks into a spirited rendition of "Happy Birthday to You!"
Well, I said it was frivolous, didn't I?
Perhaps finds like this will better able to shed light on the human genetic origin and the commonality of the human species.
13000 years is a long eveolutionary time scale to permint such modification. Is it not possible that the migration of ancestry went in the opposiye direction from the Americas to Siberia. What evidence is there that Asia supported a population over 13000 years ago?
As we are learning in so many studies now that DNA evidence takes away a lot of speculation, the human female, requiring changes in the male for a food supply to be brought to them and their children resulting in higher survival rates with these traits, may be more of the driver of evolutionary changes in our species than the retroject of the male great white hunter and warrior. Fascinating. hopefully we can continue to take the patriarchy and Western theology out of our science and look with objective eyes rather than laying the male warrior mentality that has driven this culture for at least the past two millennia.
There are several good links for more information.
Why, for goodness sakes, would politics enter into any scientific discussion such as ths??? There is no reason for it, and those who imply such should check their own biases at the door before entering into this exchange. "Evil to him who evil thinks."
I am just curious about dating techniques. How reliable are they? Does anyone question their results or are they accepted completely by the scientific community?
@Ali B. Not likely; if your water supply was limited (as the article says it was at the time of Naia's death), then you wouldn't go tossing living things into the water to die, rot and poison the water. Our ancestors knew better than to drink water with dead bodies floating in it. In later ages when water in the area was much more plentiful, it'd be more of a possibility.
@SOLOMON HOSE There was a study of human genes a few years ago, and it revealed that all human genes originate and point to North Africa. That doesn't mean that we are all descendants of Negro's, but that human life supposedly originated there.
@SOLOMON HOSE Just a few years ago scientists studied the genes of different continents, and according to the gene study found that the origin of all human genes pointed to North Africa. The term African doesn't necessarily mean Negro. Go figure...
@george leise You are sending mixed messages; You want to see what the girl looked like using what could be interpreted as her desecrated skull? And then you want the discoverers to drown? That's a horrible thing to say. Why would you wish anyone to drown?
@Rita Woodward Maybe not; a lack of a fractured skull doesn't necessarily mean a lack of unconsciousness, and they said that she fell 100 feet. I hope she was knocked unconscious immediately so that she didn't suffer.
@Julie HawkOwl To select for less aggression, more child like tendencies seems to be the easiest evolution. Domesticated animals show more child like features.
@Julie HawkOwl Where there is less need for aggressive posing between men for dominance in a harsh environment, women would probably be more attracted to men who looked less aggressive and thus would be better co-parents and carers within the social group. Thus easier, calmer times would lead women to choose calmer men with more neotenic features as mates.
@Blaine Barrett In this case, from where did the Americans come?
@Barbara Johnston I totally agree with your prognosis.as it is more factual and closer to the truth of the real driver of evolutionary changes.
Give us multiple examples where politics and biases hasn't played a part in science in some form or another. Are you serious.
You are naive if you think that politics doesn't enter into EVERYTHING!!
@Georgia Nguepdjo Far more reliable, my friend, than genealogy lists in an ancient book.
@Georgia Nguepdjo Within limits, they are reasonably accurate. As far as I know, there is no scientific feeling that they are unreliable. I taught biology and chemistry in college and my husband is a retired physics professor who has taught with me. Grace
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