Neanderthals are considered our closest extinct relatives. There have been a number of debates as to whether they may have been a subspecies of Homo sapiens, or a distinct species of the Homo genus- Homo neanderthalensis. This well known, but often misunderstood fossil lived in the Pleistocene Epoch in the Eurasia, as far back as 200,000-300,000 years ago, and was still there between 41,000 and 39,000 years ago.
In 1856, workers at a quarry in western Germany on the Rhine, unearthed bones that were initially thought to belong to a deformed human. The skull had thick bones, with distinct brow ridges, a receding forehead, and was oval shaped. Additional studies showed that the skull belonged to a previously unknown human ancestor or species of hominid that was very similar to our own species, and in 1864, the specimen was named Homo neanderthalensis, after the Neander Valley, where the bones were discovered.
The First Cave Men
Neanderthals lived during the Ice Age, and took shelter from the cold in limestone caves found throughout Eurasia. Subsequent discovery of fossils almost always occurred in caves, leading to the popular attribution of them as “cave men”.
Like Homo sapiens, Neanderthals originated in Africa but later migrated to Eurasia before humans did. They lived all across Eurasia from as far north as Britain, through the Middle East, and west central Asia, in Uzbekistan. It is estimated that the peak of Neanderthal population was around 70,000, but more conservative estimates put the number at a modest 3,500.
Their short, stocky stature was an ideal evolutionary adaptation for extremely cold weather, since it helped consolidate heat. According to the American Museum of Natural History, other notable differences between the Neanderthal and Humans are a flaring pelvis and funnel-shaped chest, robust fingers and toes.
Their brains grew- more or less- at a similar rate to ours and were about the same size. 1% of Neanderthals had pale skin, red hair, and possibly freckles.
Scientists for a long time theorized that Neanderthals grew up faster than humans; reaching maturity faster and dying relatively young (like chimps). However in 2008, the National Academy of Sciences disproved this theory after publication of evidence showing that Neanderthals and humans grew at the same rate.
The Social Structure
Scientific discoveries suggest that Neanderthals lived in nuclear families and took care of the sick and the elderly, and also buried their dead. Majority lived to be about 30, but some lived longer. The tools they used were no more sophisticated than those used by early humans, but over time they began to create more complex tools by using stone flakes, bones and antlers. There has been speculation that Neanderthals perhaps used some type of glue and/or pitch, to attach stone tips to one end of wooden shafts, making formidable weapons for hunting.
Neanderthals were mainly carnivorous, and had control of fire, but occasionally the harsh climate may have forced them to resort to cannibalism. In December 2013, researchers reported evidence that Neanderthals practiced burial behavior and intentionally buried their dead.
Interbreeding With Humans
One of the most debated aspects of Neanderthals in recent years has been the question of interbreeding. The answer may remain ambiguous, as scholarly opinions tend to range from belief that they certainly interbred to belief that the two species didn’t exist on earth at the same time. The interbreeding theory caught fire in 2010 when Science magazine published a study that stressed that Neanderthal DNA is 99.7 identical to human DNA (a chimp’s DNA has been found to be 99.8 identical to that of humans).
Erik Trinhaus, a Neanderthal expert, has long supported the hypothesis, and researchers at the Neanderthal Genome Project found that the average non-African human genome is at least 2.5% Neanderthal. What’s interesting is that modern Africans who never left the continent share no Neanderthal DNA, and it suggests that the two species only bred once humans had migrated from Africa, into Eurasia.
In a conflicting study led by Dr. Rachael Wood in 2012, researchers used advanced technology to date early Neanderthal bones and found they were a lot older than presumed- at least 50,000 years old. Humans hadn’t began to settle in Eurasia until about 42,000 years ago, which would mean that Homo sapiens and Neanderthals never co-existed.
If there wasn’t any interbreeding between humans and Neanderthals, similarities in genomes of humans can be attributed to fact that both groups have a common ancestor in Africa.
Gene Association in Recent Studies
By lining up genes from the Neanderthal with DNA from humans and chimps, geneticist Svante Paabo and a team of researchers at the Max Planck Institute for Evolutionary Anthropology found small defects that are unique to humans- including some that are associated with skeletal development, metabolism and conditions such as schizophrenia, autism, and Down syndrome.
The researchers had pieced together gene fragments from bones discovered in a cave in Croatia, and they employed exhaustive processes to retrieve as much of the original DNA structure (the original DNA was degraded, and much of the existing DNA came from microbes that colonized the bones after the Neanderthal died).
It took four years to create a reasonable sequence– 60% complete- and the researchers looked for gene flow among individuals from West Africa, Southern Africa, Papua Guinea, China, and France. Because they assumed Neanderthal genes hadn’t passed to humans, the researchers expected to find the same degree of difference between human and Neanderthal genomes in all the subjects.
Surprisingly, they discovered that Neanderthal DNA was a bit more similar to the individuals living outside Africa, and the similarities were much more pronounced for the individual from France (the Neanderthals’ old stumping grounds).
A 2014 study from Harvard Medical School suggests that our likelihood for having type 2 diabetes, lupus, Crohn’s disease and a number of other conditions can be linked to genetic variants gotten from Neanderthals. Both human and Neanderthal offspring came with genetic mutations in the X chromosome- and some have said that a considerable number of East Asians may have reduced fertility as a result.
Nobody really knows why Neanderthals got wiped out and humans survived. A number of scholars suggest climate change may have had something to do with it, but dietary deficiencies have also been mentioned. A few researchers theorize that humans may have killed Neanderthals, but the hypothesis that they simply interbred with humans and got absorbed into our species is also a popular belief.
These theories are pushing researchers to study human ancestors in ways they hadn’t before. As John Hawkins, evolutionary geneticist with the University of Wisconsin, said in a recent interview, “They’re not ‘them’ anymore; they’re ‘us.'”
Bring back the caveman
Isaac Asimov explored some of the ethical questions involving Neanderthals brought to the present in his excellent 1958 science fiction short story, “The Ugly Little Boy“. A romantic notion would be to bring back the caveman since Humans were most likely the cause for their extinction. However there are a lot of ethical questions we need to consider before doing so.
- If we bring a Neanderthal into our world, it will undoubtedly be tested extensively – psychologically and physically.
- Would everyone be so hunky-dorey if the next baby born today was selected to be painfully tested on, watched and examined for the rest of its life.
Further debate on this topic can be read here.