Fossilized human footprints that a White Sands National Park program manager first discovered.
Credit: © Dan Odess

Scientists in September 2021 announced the startling discovery of preserved ancient human footprints at Lake Otero, in White Sands National Park in New Mexico. The discovery confirms that people inhabited North America at the height of the last ice age. The archaeologists who excavated the footprints determined through Carbon 14 dating that a group of teenagers walked and ran along the shore of a shallow lake there between 21,000 and 23,000 years ago. The site is at least 5,000 years older than any other well-documented human occupation site in the Americas.

The footprints were discovered as archaeologists surveyed White Sands National Park, a region of wind-swept gypsum dunes that creep along Lake Otero, a dried-up alkaline lake. The shifting dunes sometimes reveal preserved footprints of prehistoric animals—including ground sloths and mammoths—that were laid down thousands of years ago. In 2018, the scientists discovered several sets of human footprints among the tracks of extinct ice age mammals. Many of the footprints are relatively small and likely made by teenagers as they ran and played on the ancient lakeshore. As scientists carefully excavated the fine layers of gypsum above and below the footprints, they recovered preserved seeds of an ancient grass sprinkled within various layers. Carbon 14 dates obtained from the seeds established the age of the tracks between 21,000 and 23,000 years old. This places them in a period known as the last glacial maximum, long before the North American ice sheets retreated. The astonishing dates were published in the journal Science.

For decades, archaeologists have debated when people first arrived in the Americas. Most agreed that it would have been difficult or impossible for people to migrate from Siberia to North America during the last ice age, before about 13,000 years ago. Vast ice sheets and glaciers covered much of northern North America, blocking entry. Once the ice sheets began to recede, people could migrate south into the Americas. Around this time, the Clovis culture, identified by distinctive stone spearheads found with the remains of extinct prehistoric animals, thrived in the Americas. Scientists long believed that the Clovis culture people were among the first to inhabit the Western Hemisphere.

However, a few archaeological sites have challenged this consensus view. One site is called Monte Verde, located at the southern tip of South America. There, stone tools and other remains show people occupied the site around 14,000 years ago, long before the Clovis culture thrived in North America. Archaeologists think people may have sailed in kayaks along the west coast of North and South America to reach the site, avoiding the ice sheets that covered much of the land.

Now, the Lake Otero site has been determined to be several thousand years older than Monte Verde. And, the footprints don’t just preserve a brief tourist visit. Archaeologists at Lake Otero excavated footprints from several distinct layers at the site, showing that people passed through the region frequently over a span of several thousand years. Archaeologists must now rethink their understanding of how and when people first arrived in the Americas.

April 19, 2017

A recent study has found a connection between hereditary sickle cell disease and malaria, a dangerous parasitic disease transmitted by mosquitoes. The study determined that genetic mutation responsible for sickle cell disease, a serious blood disorder, rapidly spread through human populations in Africa more than 40,000 years ago mainly because it provides protection from malaria. Genetic scientists used computer-based models to understand the conditions that spread the sickle cell mutation among certain human populations. The scientists learned that this mutation was among the most important factors affecting survival over the last 40,000 years for people living in malaria-affected regions. The study’s results were published on March 10, 2017, in the scientific journal PLOS Genetics.

A new study has shown that people carrying the sickling gene that can cause sickle cell disease have a higher natural resistance to malaria parasites, shown here in pink and blue. Credit: © CNRI/SPL from Photo Researchers

Sickle cell disease, also called sickle cell anemia, is a hereditary blood disease. In the United States, it occurs chiefly among African Americans. It also affects other groups, including people of Central African, Mediterranean, Middle Eastern, and South Asian origin. Sickle cell patients have an abnormal type of hemoglobin, the oxygen-carrying protein that gives red blood cells their color. This abnormal protein, called sickle hemoglobin, or hemoglobin S, forms crystals in red blood cells. This causes the normally round red blood cells to change into twisted, rigid sickle-shaped forms. The sickle cells can get trapped and block the normal flow of blood through blood vessels. This disruption of blood flow causes periodic crises (attacks of severe pain and fever) and related problems including strokes, lung or kidney damage, and sudden death.

This magnified blood sample shows the red blood cells of a person with sickle cell anemia. Normal red blood cells appear round in the image. But, abnormal, sickle hemoglobin causes many red blood cells to change into twisted, rigid sickle forms. Credit: © Bruce Coleman Inc./Alamy Images

Scientists know that harmful mutations, such as the one responsible for the abnormal sickle hemoglobin, should become less common in populations over time because of the process of natural selection. Natural selection sorts out these random changes according to their value in enhancing the individual’s reproduction and survival. In the past, people with sickle cell disease rarely survived long enough to have children. Today, modern medicine has improved the health and life span of people with the condition.

Scientists have lately learned that carriers of the sickling gene—that is, people who have only one copy of the mutated gene instead of two—not only have normal blood cells, but they also have a higher natural resistance than noncarriers to malaria. Sickle cell anemia is a rare disorder, but it occurs most often among populations that live in areas threatened by malaria. Thus, the sickling gene—despite its negative effects for some—represented an important advantage for other people in these tropical and subtropical regions. The new research shows that the sickle cell mutation had a rapid and dramatic effect in shaping the genetic makeup of certain human populations in the past. Such dramatic changes are also possible in the future, as human populations continue to adapt to a constantly changing global environment.

December 17, 2013

Strong evidence that Neandertals were the first humans to intentionally bury their dead has come from an analysis of fossil bones excavated at a cave in France. The findings suggest that the Neandertals, long thought of as brutish cave dwellers who lacked the cultural sophistication of physically modern humans, had funeral customs that indicate complex symbolic behavior.

The Neandertals were an early human population who lived in Ice Age Europe and central Asia from about 150,000 to 35,000 years ago. They had distinct physical features, including a large, protruding face, massive browridges, and low foreheads. Most Neandertals also lacked a chin. Today, many scientists classify Neandertals (also spelled Neanderthals) as an extinct, early subspecies of Homo sapiens, the species of modern people. Over the past century, archaeologists have interpreted several Neandertal sites as grave sites. This suggests the Neandertals were the first to practice burial as a funeral custom, a cultural practice that others consider unique to physically modern humans. Other archaeologists disputed the evidence for Neandertal burials, suggesting that excavators had misconstrued the evidence from cave sites, where concentrations of bones may result from the activity of predators.

Neandertals lived in Europe and Central Asia from about 150,000 to 35,000 years ago. (© Jay H. Matternes)

Beginning in 1999, William Rendu, a paleontologist at the Center for International Research in the Humanities and Social Sciences (CIRHUS) in New York City, led an international team of archaeologists, geologists and anthropologists to re-examine hundreds of Neandertal skeletal remains from a cave called La Chapelle-aux-Saints. This 50,000-year-old site in southwestern France was originally excavated between 1905 and 1908.  The team searched surrounding caves and discovered additional remains, including the bones of two Neandertal children and one adult. Hundreds of animals bones, including those from reindeer and bison, were also studied, as was the geology of the cave complex.

Rendu’s team reported that the Neandertal bones showed no sign of erosion or evidence they had been disturbed or chewed by animals. This suggests the bones were buried soon after death. In contrast, the animal bones at the cave site showed signs of butchery, a great deal of erosion, and other damage. Most of the Neandertal bones were found in a depression that could not have been a natural formation in the cave floor. The scientists concluded that the evidence shows the remains were intentionally buried.

Today, all human societies have various traditions, rituals, rites, and ceremonies that are performed after a person dies. Anthropologists observe that funeral customs, including burial, are deeply rooted in a people’s cultural heritage and beliefs about death. Unfortunately, Neandertal sites usually do not preserve any evidence of other funeral customs. However, archaeologists must now reassess evidence from other Neandertal sites that may show evidence of ritual or symbolic behavior that many experts originally considered beyond the capabilities of these intriguing prehistoric humans.

Additional World Book articles:

• Anthropology (2010) (A Back in Time article)
• Anthropology (2009) (A Back in Time article)
• Anthropology (1989) (A Back in Time article)
• Anthropology (1958) (A Back in Time article)
• Anthropology (1933) (A Back in Time article)

August 8, 2013

The discovery of charred remains from two Neolithic longhouses that likely served as “Halls of the Dead” for ancient Britons nearly 6,000 years ago have been reported by archaeologists in the United Kingdom. The wooden remains were uncovered within two barrows (earthen mounds) excavated at Dorstone Hill, near Hereford, by archaeologists from the University of Manchester and the Hereford Council. The longhouses were used by Neolithic people to house the bodies of high-status people. Archaeologists believe that such structures were revered because ancient Europeans believed that the household was as significant to the dead as it was to the living.

Ancient people in what is now the United Kingdom and Ireland constructed barrows from about 4000 B.C. until the start of Saxon rule, about A.D. 450 to 500. The oldest barrows date to the early Neolithic period, when the ancient Britons were starting to settle into small communities. The barrows at Dorstone Hill predate the construction of the massive complex at Stonehenge by about 1,000 years.

Upright stones surround a large barrow at West Kennet, in southern England. A barrow is a mound of earth, stone, or both built over an ancient burial place. Remains of barrows appear in many parts of the United Kingdom and Ireland. (© Alan King, Alamy Images)

Archaeologists discovered the two barrows at Dorstone Hill while surveying a field where ancient flint artifacts were found over many years. While excavating the two barrows, which are 230 feet (70 meters) and 98 feet (30 meters) in length, they discovered unusually well-preserved remains of the wooden longhouses. Much of the detail of the two longhouses could be seen from the pattern of charred timbers and stakes as well as postholes visible as patches of darkened earth. The remains revealed a pair of long buildings with aisles and internal partitions framed by upright posts that held up a wooden or thatch roof. Hard chunks of burnt clay scattered about indicated the walls of the longhouses were covered with a mud daub.

At the end of the smaller barrow, darkened earth showed a pattern of large upright posts surrounding a long trough that would have been lined with wooden planks. This structure was likely used as mortuary chamber, where the bodies of 30 to 70 people were held. The dead were usually buried in such chambers long after all the flesh had rotted away.

Archaeologists believe the longhouses were deliberately burned down after some time and the ashes were used to construct the earthen barrows. The halls were most likely burned after some critical event occurred, such as when the head of an important family died. But no human remains have been preserved in the acidic soils of Dorstone Hill. The barrow would have served as a reminder to future generations that an important person was buried at this location. The archaeologists found several fine flint blades buried in the barrows suggesting that people occasionally returned to the site to leave offerings for the dead.

Additional World Book articles:

• Arthur, King
• Celts
• Celtic art
• Druids
• England (History)

April 26, 2013

The genetic roots of modern Europeans do not stretch as deep into prehistory as most scientists had thought, reports a joint team of German and Australian scientists. A new analysis of ancient skeletons found in Germany indicates that a major population upheaval occurred in Europe around 4,000 B.C., when long-established populations were suddenly displaced by other farming people moving into the region. These more recent migrants, rather than the older populations, seem to be the direct ancestors of most living Europeans today.

Archaeologists have found fossils and stone tools that show early humans first lived in Europe more than 700,000 years ago. The Cro-Magnon people hunted throughout Europe from about 35,000 years ago to 10,000 years ago. By about 6000 B.C., farming peoples migrated into Europe from the Near East. Most scientists had believed that modern Europeans were descended from these ancient populations. The new findings, however, suggest that most living Europeans are descended from farmers who migrated into the region only about 4,500 years ago.

A megalithic monument near Carnac, France, is one of many of these stone structures made by prehistoric people. The best-known monuments are in western Europe and the Mediterranean region. These sites were built between about 4500 and 1400 B.C., during the Neolithic period and early Bronze Age. The builders made them for religious purposes or as burial places. (© Joe Cornish, Tony Stone Images)

The scientists based their conclusions on an analysis of DNA from 39 ancient skeletons excavated from the Mitelelbe Saale region, near Lepzig. The analysis was published April 23 in the online journal Nature Communications. The team focused their study on mitochondrial DNA (mtDNA)–a form of DNA found outside the chromosomes in cellular structures called mitochondria–that was preserved in the bones. In humans, mtDNA is inherited only from the mother. This makes the material useful to biologists for helping to determine relationships between groups. The scientists chose to examine a particular variety of mtDNA known as haplogroup H, the most common mtDNA variety in Europe, found in about 40 percent of Europeans today. However, haplogroup H is not common in the mtDNA from skeletons of Cro-Magnons or other early European hunter-gatherers, suggesting they made little genetic contribution to modern European populations.

The mtDNA from skeletons dated to the early Neolithic period of Europe, about 7,500 years ago, shows that farmers from the Near East migrated into Europe carrying a version of the haplogroup H with them. However, the international team found that by the Middle Neolithic, around 4,500 years ago, this early version of haplotype H was suddenly replaced by the version seen in modern Europeans.

Scientists are not certain where this newer haplotype H originated. But such a rapid replacement could only result from the migration of new populations into the region. The research shows that the movement of populations in prehistory and the genetic history of modern populations is much more complex than scientists had thought.

Additional World Book articles:

• Agriculture (History)
• Cave dwellers
• Genetics
• Prehistoric people
• Stone Age