Neanderthals and other archaic humans used to be considered distant beings, with no real connection to people today. Yet discoveries in 2016 show that early humans are so close to many of us that they're in our DNA — for better or worse.

Neanderthal DNA Purged From Our Genomes

Another Neanderthal extinction is taking place, and it's happening in our genomes, according to research that found natural selection is slowly removing Neanderthal genetic variants from modern populations. The study, published in PLOS Genetics, helps to explain what happened to all of those other Neanderthal genetic signatures that were more evident right after our species — known as anatomically modern humans, or AMH — mated with Neanderthals.

"So the first generation of hybrids would have been half Neanderthal and half AMH because they had one Neanderthal parent and one AMH parent," said senior author Graham Coop, a professor at UC Davis. "Later generations of hybrids may have more or less Neanderthal ancestry depending on whether they had more Neanderthal or AMH ancestors [for example, great grandparents]."

Neanderthal-Human Sex Happened Earlier Than Thought

A child conceived 100,000 years ago from a Neanderthal and modern human mating was announced in early 2016. The woman, from Siberia, was clearly a Neanderthal, but she retained DNA from our species. It's been known that people of European and Asian ancestry today possess a small amount of Neanderthal DNA in their genomes, but the Neanderthal woman offered the first evidence that gene flow from interbreeding went from modern humans into Neanderthals as well.

The study, published in the journal Nature, "is also the first to provide genetic evidence of modern humans outside Africa as early as 100,000 years ago," said Sergi Castellano, who co-led the research and is a scientist at the Max Planck Institute for Evolutionary Anthropology.

Neanderthals Could Have Domesticated Dogs

Many of the earliest dogs resembled this modern Siberian husky. Credit: Wikimedia Commons

We learned in 2016 that dogs were domesticated not just once but twice, and in two different parts of the world. As a result, "all modern dogs are directly related to two or more wolf populations," said researcher Laurent Frantz of the Wellcome Trust Paleogenomics & Bio-Archaeology Research Network at the University of Oxford. Frantz and colleagues determined that early dogs appeared in both the East and the West more than 12,000 years ago, but in Central Asia no earlier than 8,000 years ago.

"Dogs were domesticated by hunter gatherers, prior to the advent of agriculture," Frantz said. "Dogs most likely provided multiple services to humans, such as facilitating hunting or providing protection."

The researchers can't yet rule out that Neanderthals or some other ancient human first domesticated dogs. Other research teams have found possible dog remains going back to the Neanderthal era.

Homo Erectus Walked Like a Man

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Footprints for Homo erectus, aka Upright Man, dating to 1.5 million years ago were discovered in Kenya in 2009, but analyzed in 2016. "Our analyses of these footprints provide some of the only direct evidence to support the common assumption that at least one of our fossil relatives at 1.5 million years ago walked in much the same way as we do today," said researcher Kevin Hatala of the Max Planck Institute for Evolutionary Anthropology and The George Washington University.

Right-Handed Homo habilis

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The earliest known evidence for right-handedness came to light in 2016 and from an unusual source: marks on old teeth dating to 1.8 million years ago. The teeth belonged to the early human Homo habilis, according to a paper in the Journal of Human Evolution.

Co-author David Frayer of the University of Kansas explained that, among the network of deep striations found only on the lip face of the upper front teeth, most cut marks veered from left down to the right. Analysis of the marks makes it likely they came from when the individual used a tool with his right hand to cut food he was holding in his mouth while pulling with the left hand, he said in a press release. The scratches can be seen with the naked eye, but a microscope was used to further investigate them.

Neanderthal Diet: 80 Percent Meat, 20 Percent Fruit and Veg

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Neanderthals ate a diet consisting of 80 percent red meat and 20 percent plant-based food, according to a study published in 2016. Hervé Bocherens of the Senckenberg Center for Human Evolution and Palaeoenvironment at the University of Tübingen and his colleagues analyzed skeletons of early humans from Europe and Asia. These archaic humans seemed to like large cuts of meat from the biggest animals possible.

"Previously, it was assumed that the Neanderthals utilized the same food sources as their animal neighbors," Bocherens said in a press release. "However, our results show that all predators occupy a very specific niche, preferring smaller prey as a rule, such as reindeer, wild horses or steppe bison, while the Neanderthals primarily specialized on the large plant-eaters such as mammoths and woolly rhinoceroses."

Neanderthals also ate fruits, vegetables and other plants, the researchers determined.

Clues to Hobbit Human Relatives and Disappearance

Credit: Karen Neoh, Flickr

Remains of at least three tiny humans dating to 700,000 years ago have been found on the Indonesian island of Flores, which was the homeland of Homo floresiensis, aka "Hobbit Humans," according to research findings published in the journal Nature in 2016. These diminutive people predate the Hobbits by more than half a million years.

Aida Gómez-Robles, a scientist at George Washington University specializing in human evolution, told Seeker the research demonstrates "that the origin of Homo floresiensis is very old, which confirms that this is a totally valid species with old evolutionary roots."

We also learned that humans were on Hobbit turf at around the same time that Homo floresiensis seemingly disappeared from the face of the earth. The evidence is a pair of 46,000-year-old human teeth found in Flores' Liang Bua cave. Could our appearance and the Hobbits' disappearance just be a coincidence? The discovery would seem to implicate our species in whatever happened to the Hobbits.

Many People Today Could Be Part Denisovan

Schoolchildren from Bhutan. Credit: Arian Zwegers, Flickr

Denisovans, a mysterious population of archaic humans that lived at around the same time as Neanderthals, could have interbred with Homo sapiens more than previously thought. An analysis published in 2016 proposed that modern humans interbred with Denisovans about 100 generations after their trysts with Neanderthals. As a result, many bloodlines around the world, particularly of South Asian descent, show genetic evidence of Denisovan ancestry.

"There are certain classes of genes that modern humans inherited from the archaic humans with whom they interbred, which may have helped the modern humans to adapt to the new environments in which they arrived," said senior author David Reich, a geneticist at Harvard Medical School. "On the flip side, there was negative selection to systematically remove ancestry that may have been problematic from modern humans. We can document this removal over the 40,000 years since these admixtures occurred."

In terms of helping modern humans, Denisovans are known to have given people from Tibet and nearby regions genetic adaptations for life at high altitudes.

Denisovans Gave Some People Cold Tolerance Too

Inuit family. Credit: Ansgar Walk, Wikimedia Commons

Native Americans, the Inuit and some Siberians likely can tolerate cold temperatures better than the rest of us due to their Denisovan or other archaic human ancestry, according to a paper published in 2016 in the journal Molecular Biology and Evolution. Lead author Fernando Racimo of the New York Genome Center told Seeker that he and his team identified a genetic variant in the mentioned living groups. It is thought to cause a certain type of body fat, commonly known as "brown fat," to generate heat.

He added, "The gene is also involved in a number of other traits, like body fat distribution, bone and facial morphology (structure)."

Mystery Human Species Detected in Pacific Islanders

Children outside Tuo school, Fenualoa, Reef Islands, Solomon Islands. Credit: Wikimedia Commons

Melanesians — people native to Vanuatu, the Solomon Islands, Fiji, Papua New Guinea, New Caledonia, West Papua and the Maluku Islands — could carry DNA from a now-extinct ancestor that is so far unknown in the fossil record, a genetic analysis revealed.

Their mystery relative "could have been a population relative to Denisova, or something more distantly related," Ryan Bohlender, lead author of the research, told Seeker.

Melanesians are arguably the worldliest people on the planet, given that they retain DNA from such a diverse mixture of early ancestors.