They had bigger brains and muscles, but for some reason Neanderthals died out about 30,000 years ago, while we modern humans survived.
Why we, Homo sapiens, flourished and our <a href="https://blog.23andme.com/articles/neanderthal-fade-away">Homo neandertalensis cousins died out</a> after thriving for hundreds of thousands of years is an evolutionary mystery biologist are trying to unravel.
In the last few years, scientists have uncovered clues what the <a href="https://blog.23andme.com/articles/why-23andme-love-neanderthals-and-you-should-too">lives of Neanderthals may have been like</a>. And those clues also tell us more about what it means to be a modern human.
(Discover if you have Neanderthal DNA with 23andMe&#8217;s <a class="waffle-rich-text-link" href="https://www.23andme.com/dna-ancestry/">DNA Ancestry Service</a>, or sign-up for a <a class="waffle-rich-text-link" href="https://www.23andme.com/membership/">membership</a> to unlock even more ancestry insights.)
<img loading="lazy" decoding="async" class="alignright size-full wp-image-3359" title="neanderthaler_278" src="https://blog-api.23andme.com/wp-content/uploads/2009/04/neanderthaler_278.jpg" alt="" width="278" height="206" />
<h6>Ancient DNA</h6>
Most interesting of all is that, although Neanderthals disappeared long ago, their DNA lives on in all non-African people.
23andMe now offers a <a href="https://www.23andme.com/you/labs/neanderthal/">lab</a> allowing customers to connect with their prehistoric roots.
The lab, developed by one of our resident computational biologists Eric Durand, compares two modern human genomes with the Neanderthal genome. It can then determine what percentage of your own DNA is Neanderthal. Before coming to 23andMe, Eric worked on the <a href="http://www.sciencemag.org/site/special/neandertal/" target="_blank" rel="noopener noreferrer">first draft of the Neanderthal genome</a> and on analysis of <a href="https://www.nature.com/nature/journal/v468/n7327/abs/nature09710.html" target="_blank" rel="noopener noreferrer">the Denisova genome</a>, another of our early human cousins. The lab uses the same method Eric helped develop while working at the Department of Integrative Biology at the University of California, Berkeley.
See Eric’s white paper for a technical explanation of the methodology.

<h6>Modern Humans</h6>
Most people have <a href="https://www.23andme.com/dna-ancestry/">Neanderthal DNA</a>, on average about 2.5 percent. But there are outliers, who have much more.
What it means to have a higher percentage of Neanderthal DNA – whether you’re hairier, or brutish or short, for instance – isn’t known.
There are some theories, however, of how Neanderthals contributed to modern humans. One is that interbreeding gave us some sort of <a href="https://www.nature.com/news/2011/110809/full/476136a.html">“hybrid vigor,”</a> according to Peter Parham, a geneticist at Stanford University School of Medicine.
At the very least research appears to support the theory that at some point during the tens of thousands of years Neanderthals and modern humans lived side by side, a few of them may have<a href="../2010/05/06/new-evidence-suggests-interbreeding-between-humans-and-neanderthals/"> shacked up</a>.
Or as Elizabeth Kolbert deftly phrased it in the<a href="https://www.newyorker.com/reporting/2011/08/15/110815fa_fact_kolbert#ixzz1fPOs2vp2"> New Yorker</a>: 
“Before modern humans ‘replaced’ the Neanderthals, they had sex with them.”
Provocative to say the least, but it’s actually an idea that’s floated around for some time.
Anybody who ever read Jean M. Auel’s saucy prehistoric romance books beginning with<a href="http://books.google.com/books/about/The_Clan_of_the_Cave_Bear.html?id=4gOtkoiJIjEC"> “Clan of the Cave Bear”</a> could tell you that. But the notion that modern humans and Neanderthals got way past first base. They hooked up and even had children together still doesn’t tell us much about what it means now to have a smidgen of Neanderthal in your DNA.
<h6>Neanderthal Genome</h6>
Svante Paabo, the Swedish geneticist behind the sequencing of the<a href="http://www.eva.mpg.de/neandertal/index.html"> Neanderthal genome</a>, explains that from an evolutionary point of view. Comparing the modern human’s genome to that of the Neanderthal has great value, Paabo said.
Humans and Neanderthals share a common ancestor with chimpanzees – our next closest mammalian relative – that goes back between five and seven million years.
Comparing the human genome with that of chimps tells us a lot about evolution over millions of years. But by having the Neanderthal genome sequence – now 55 percent completed – and comparing that with modern humans, we can learn much more about evolutionary changes over the last 30,000 years.
It may be that the DNA of other prehistoric human groups also are intermixed in our own DNA.
<h6>Other Ancient Cousins</h6>
Much like with Neanderthals, scientists extracted ancient DNA from the skeletal remains of another ancient cousin known as the<a href="../2010/03/24/analysis-of-ancient-dna-suggests-the-existence-of-previously-unknown-type-of-extinct-human-ancestor/"> Denisovans</a>. The remains – a finger bone – were found in a cave in Siberia and showed that Denisovans were cousins of Neanderthals. They lived in Asia and disappeared about 40,000 years ago. Their DNA is found today in Melanesians.
As for the comparisons with the Neanderthals, so far, Paabo’s team has found almost 80 genetic variants that are unique to modern humans. The function of these variants could help us understand what distinguishes us from Neanderthal.
Apparently Paabo’s work has also resonated beyond the scientific community as well.
At a talk late last year, Paabo told a group of neuroscientists that for months he’s been keeping emails from people who have<a href="http://www.guardian.co.uk/science/blog/2011/nov/16/dear-professor-husband-neanderthal"> claimed that they were Neanderthal</a> and should be included in his study. Several women have written to him volunteering their husbands as subjects for study.
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Find Your Inner Neanderthal

<img loading="lazy" decoding="async" class="alignright size-full wp-image-6487" title="neanderthal_bones" src="https://blog-api.23andme.com/wp-content/uploads/2010/05/neanderthal_bones.jpg" alt="" width="309" height="371" srcset="https://blogcms.23andme.com/wp-content/uploads/2010/05/neanderthal_bones.jpg 350w, https://blogcms.23andme.com/wp-content/uploads/2010/05/neanderthal_bones-249x300.jpg 249w" sizes="auto, (max-width: 309px) 100vw, 309px" />This picture shows three bones (Vi33.16, Vi33.25, Vi33.26) from Vindija cave, Croatia. Most of the Neandertal genome sequence was retrieved from these bones./ Image courtesy of Max-Planck-Institute EVA
A new study of the Neanderthal genome, published online today in the journal <a href="https://dx.doi.org/10.1126/science.1188021" target="_blank" rel="noopener noreferrer">Science</a>, presents strong evidence that humans and Neanderthals interbred.
There&#8217;s been a lot of debate about this subject in scientific circles (see this <a href="https://blog.23andme.com/2008/10/27/did-neanderthals-and-humans-mate-absence-of-evidence-is-not-evidence-of-absence/" target="_blank" rel="noopener noreferrer">Blog post</a> and the links within it) over the last few years. &nbsp; Even some of the researchers involved in the current study previously said they thought human-Neanderthal couplings were unlikely.
ScienceNews and <a href="http://arstechnica.com/science/news/2010/05/neanderthal-genome-draft-done-indicates-interbreeding-occurred.ars?utm_source=rss&amp;utm_medium=rss&amp;utm_campaign=rss" target="_blank" rel="noopener noreferrer">Ars Technica&#8217;s Nobel Intent </a>both have good overviews of the new study and what it means. &nbsp; Ars Technica&#8217;s John Timmer gives a great summary of why scientists now think that rather than replace Neanderthals, our human ancestors instead assimilated them:
<blockquote>At the same time, the genome sequence does provide evidence that humans and Neanderthals have interbred. This became apparent when the Neanderthal genome was paired against human genomes from different parts of the globe. The Neanderthal DNA consistently matched European and Asian samples better than it did African; the difference was small, but consistent. It suggested that the Neanderthals, which were restricted to Europe and Asia at the time modern humans originated in Africa, had interbred with humans once they began migrating out of Africa.
Because African human populations are older, they tend to have more divergent genomes. But the human-Neanderthal split is older still, so the authors figured that any areas of the genome where variation was larger in populations outside of Africa may have entered the human genome through interbreeding. If they did arise through interbreeding, then the non-African segments should match Neanderthals. Researchers found at least 10 regions that fit these predictions.
Although they can&#8217;t rule out the possibility that modern humans had already started diverging from Neanderthals before leaving Africa, the research team favors the idea of interbreeding in the Mid-East as the first modern humans left Africa. This would ensure that both the Asian and European populations picked up some Neanderthal DNA.</blockquote>
Be sure to check out the Science Magazine Neanderthal Genome Special Feature (free).

New Evidence Suggests Interbreeding Between Humans and Neanderthals

Human Prehistory 101:  Out of (Eastern) Africa

<img loading="lazy" decoding="async" class="alignright size-full wp-image-4118" title="neandertaler_reconst" src="https://blog-api.23andme.com/wp-content/uploads/2009/07/neandertaler_reconst.jpg" alt="neandertaler_reconst" width="300" height="401" srcset="https://blogcms.23andme.com/wp-content/uploads/2009/07/neandertaler_reconst.jpg 300w, https://blogcms.23andme.com/wp-content/uploads/2009/07/neandertaler_reconst-224x300.jpg 224w" sizes="auto, (max-width: 300px) 100vw, 300px" />
The Neanderthals have always held a special place in the field of anthropology. &nbsp; The skeletal remains of our short, stocky evolutionary relatives have been found everywhere from Spain to Iraq.
Their physical likeness to our own species, and the possibility that humans and Neanderthals may have interacted, has long fascinated experts and enthusiastic novices alike. &nbsp; But simply studying their skeletal remains and artifacts seemed to leave more questions than answers.
More than 10 years ago an international team of scientists became the first to extract and analyze ancient DNA (aDNA) from a Neanderthal skeleton. By examining the mitochondrial DNA (mtDNA) – which is more abundant in our cells than our nuclear DNA and therefore more likely to preserve – they found that there were enough genetic differences between this Neanderthal and modern humans to classify the two as separate species.
Since this initial foray into Neanderthal genetics there have been attempts to improve aDNA analysis, with the goal of filling in the gaps that traditional anthropological techniques had been unable to. &nbsp; Earlier this year, scientists at the Max Planck Institute for Evolutionary Anthropology became the first to sequence the entire Neanderthal mitochondrial genome &#8211; no easy feat. &nbsp;Now scientists have taken aDNA analysis to the next level by developing a novel technique to extract it more easily, yielding the most comprehensive and accurate results to date. &nbsp; Along the way, they have uncovered some intriguing clues to the possible fate of the Neanderthals. &nbsp;Their results are reported in the July 17 issue of <a id="rvka" title="Science" href="http://www.sciencemag.org/cgi/content/abstract/325/5938/318" target="_blank" rel="noopener noreferrer">Science</a>.

This new study, also led by Max Planck Institute scientists, centers around a novel method for finding and extracting that elusive aDNA from Neanderthal remains. The study took advantage of a new kind of aDNA extraction process, called Primer Extension Capture (PEC). This technique has many advantages over the others, primarily because it allows the aDNA to be completely isolated from all the other molecular junk &nbsp; that can accumulate over time. This yields highly accurate results with much less effort. So instead of simply using this technique on one Neanderthal individual, they analyzed five.
The remains they chose had been excavated from a variety of locations, from Croatia to Germany to Spain and Russia. &nbsp; Most of the remains were between 35,000 and 40,000 years old, which is very close to when Neanderthals were believed to have disappeared from most of their range. &nbsp; They also examined Neanderthal remains from Russia that dated to between 60,000 and 70,000 years old.
After successfully extracting and analyzing the DNA of these remains, the researchers came to a few startling conclusions. &nbsp; First, the level of genetic diversity among the samples was exceedingly low. &nbsp; In fact, the amount of genetic diversity of the Neanderthal samples was less than one-third the diversity we see in modern humans today. For example, two of the samples &#8212; one from Croatia and the other from Germany &#8212; had identical mtDNA genomes. For two individuals living nearly 1,000 miles apart, this is quite unusual; unless there wasn&#8217;t much variation in mtDNA in the first place.
The authors of this report think this genetic homogeneity means that there were far fewer Neanderthals living in Europe and western Asia than they&#8217;d previously thought. Based on their analysis of the five individuals, the they estimated that the total population size of Neanderthals in Europe 35,000 years ago may have had as few as 3,500 females (because mtDNA is passed down maternally, it cannot be used to estimate male population size).
The authors believe there are two possible explanations for this small population size. &nbsp; The first is that, over the 400,000 year history of Neanderthals, their population may have always been small. &nbsp; After all, for much of their existence they survived harsh ice age conditions, so low population size may have been necessary for survival.
But the authors offer an alternate explanation as well. They think this small population size is the result of long-term population decline, perhaps beginning about 40,000 years ago and continuing until Neanderthals were wiped out. To test their hypothesis, the researchers re-analyzed the Neanderthal mtDNA genomes and found that their protein-encoding genes had evolved much more quickly than those of humans or chimpanzees since the three species split, millions of years ago.
This high rate of evolution, the authors argue, was not present in the older Russian Neanderthal sample. &nbsp; This fact implies a pattern of decline in population size, not a population that had been small from the start. These results support their idea that the Neanderthal numbers were on the decline. &nbsp; Without direct evidence, they can only speculate as to the cause of of their decline, but the scientists believe it may be tied to the arrival of humans in Europe and western Asia about 40,000 years ago.
Today most experts believe the Neanderthals were being out-competed by the incoming humans, who had superior technology and language skills. &nbsp; Over time, the Neanderthals were forced to move to more isolated regions in the mountains of France and Spain. &nbsp; By 30,000 years ago, only a few traces remained. &nbsp; Soon after, they were gone. &nbsp; This study reveals some compelling evidence that humans were in fact responsible &#8211; whether directly or indirectly &#8211; for the demise of the Neanderthals.

Novel Techniques Suggest Neanderthal Populations Dwindled in the Face of Expanding Humans

It is estimated that there are up to 8,000 distinct languages spoken around the world today.   At birth, the human mind is capable of learning and understanding any of these languages; an impressive feat given how uniquely complex they are.   The fact that humans are able to understand and communicate with one another in such a way that even our closest primate relatives cannot has long been supposed to be the result of some sort of genetic distinction separating us from the rest of the animal kingdom.  
In 2002, scientists believed they had found this genetic distinction in the form of a gene called FOXP2.   Their early studies suggested that FOXP2 was linked to the development of language in humans, and in humans&#8217; ability to manipulate the brain, lungs, and vocal chords to make the complicated suite of sounds and movements resulting in speech.
<h6>Origins of Langauge</h6>
However, the expression of FOXP2 in humans &#8211; and its presence in other species &#8211; is anything but simple.  
Research has revealed that FOXP2 isn&#8217;t expressed just in the brain, but in a host of other tissues and organs throughout the body.   Moreover, FOXP2 isn&#8217;t unique to humans, but is found in many species, from chimpanzees to field mice.   It&#8217;s the version of FOXP2 we humans carry that is distinct from those of other species.   So it is the differences in FOXP2 across species that has been at the heart of scientific research into the origins of complex language.
A few years after the FOXP2 gene&#8217;s possible role in promoting complex language skills was announced in 2002, scientists analyzing ancient DNA extracted from Neanderthals, our closest fossil ancestors, found that they had the same version of FOXP2 as humans.   This discovery was revolutionary, as it meant that humans may not have been the first species capable of complex speech and language. It also pushed back the appearance of this version of FOXP2 to at least 350,000 years ago.
<h6>The Role of FOXP2</h6>
Recently, the focus of genetic research into FOXP2 has focused on the specific role FOXP2 plays in our language ability.   Was it involved in enhancing our cognitive abilities?   Our motor skills? Our breathing patterns?   The results of scientists&#8217; most recent effort to uncover the answers to these questions are in the May 29th issue of <a href="http://www.cell.com/fulltext/S0092-8674%2809%2900378-X" target="_blank" rel="noopener noreferrer">Cell</a>, in a paper published by researchers from the Max-Planck Institute of Evolutionary Anthropology.
In order to advance our understanding of FOXP2, the scientists chose to examine its expression in mice, a surprisingly strong model for many human biological systems.   The chief difference in FOXP2 between humans and many other species such as mice boils down to two changes in the gene.   At some point in human prehistory, these changes arose and quickly became universal in the FOXP2 of humans.
To see what effect those changes might have had, the Max Planck scientists altered the copies of FOXP2 in mice to be identical to the copies of FOXP2 in humans.   They then examined any changes that took place surrounding the cognition and vocal skills of the genetically altered mice, to see how they might be affected by the supposedly advanced copy of FOXP2.   And, while the linguistic skills of the mice failed to rival our own, the scientists did see some surprising changes.  
<h6>Squeaking</h6>
First, they found that the altered mice showed changes in their brain circuitry that bore some similarity to that of humans.   And perhaps most intriguing, the altered mice had distinct ultrasonic vocalizations that differed from their unmodified brethren.   Ultrasonic vocalizations, sometimes referred to as chirps or squeaks, are used by mice to communicate to each other, such as to warn of a predator.  
When the young altered mice were separated from their mothers, something that usually elicits many such squeaks, they emitted ultrasonic vocalizations that were distinctly different in intensity and frequency than their counterparts.   The authors argue that the altered FOXP2 in the mice was influencing the type of squeaks that they were making when separated from their mothers.   And the scientists therefore believe there is some kind of connection to language development.
<h6>Being Human</h6>
But what does all this mean to humans?  
The past several years of research into FOXP2 has revealed that human patients who carry at least one non-functional version of the gene (i.e., the version of the gene found in species other than humans) have problems producing the facial movements necessary to form words.   It had been thought that part of the function of FOXP2 in humans was to develop motor control needed to articulate our mouths, vocal chords, and esophagus to produce complex language.   Many experts have also proposed that FOXP2 in humans plays a role in the development of both the lungs and the esophagus &#8211; both of which are vital to speech.   This most recent study shows that by simply tweaking FOXP2 in mice, we see a noticeable change in how they communicate.
Clearly, there is much more work to be done and many more questions to be answered.   In the future, these researchers envision going even further to understand exactly how FOXP2 influences our ability to communicate with each other.  
Their next goal? 
To understand the exact mechanics behind the version of FOXP2 found in humans, so that they can finally piece together its importance in giving us the power of speech.

New Research on FOXP2 Gene in Mice Reveals Insights to Origins of Language in Humans

<img loading="lazy" decoding="async" class="alignright size-full wp-image-3359" title="neanderthaler_278" src="https://blog-api.23andme.com/wp-content/uploads/2009/04/neanderthaler_278.jpg" alt="" width="278" height="206">
Over the past decade, there has been no shortage of studies focused on the relationship between Neanderthals and our own species, Homo sapiens. Researchers have dug deep into the fossil record and our genomes to uncover how closely related we are to the Neanderthals, whether we interacted with them, and even whether our two species shared offspring.
But what about the Neanderthals themselves? We know that beginning around 400,000 years ago, they occupied over 3 million square miles of Europe and Western Asia, from Spain to Iraq. &nbsp; We know that they developed a unique tool technology and that they buried their dead. &nbsp; But what we really don&#8217;t know is how they compared to each other: &nbsp; were there in fact distinct Neanderthal sub-groups, shaped by the vastly different environments in which they lived? &nbsp; Or can they all be considered a single, genetically similar population? These questions are addressed in the most recent issue of <a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005151" target="_blank" rel="noopener">PLoS One</a> by anthropologists from the UniversitÃ© de la MÃ©diterranÃ©e in France, using a method that is both unique and comprehensive. 
 
This study is of interest not only because it attempts to understand Neanderthal diversity, but also because it utilized data from a various sources. &nbsp; First, the researchers collected data from the mitochondrial DNA sequences of 12 separate Neanderthal skeletons. These skeletons ranged in age from 29,000 to 100,000 years and were uncovered in various parts of the Neanderthal homeland, from Siberia to Spain. &nbsp; The researchers then took physical measurements of the skeletons themselves. Finally, they developed and ran complex computer simulations based on the genetic and skeletal data, in an attempt to discover the most likely scenario for how Neanderthals evolved and spread across much of Eurasia.
The authors concluded that the most likely scenario for how the Neanderthals populated Europe and Western Asia involves three Neanderthal sub-groups: one centered in Western Europe, another in Southern Europe, and the final group in the Levant/Western Asia. &nbsp; They propose that the Neanderthals within each of these sub-groups were more genetically – and perhaps physically – similar to each other than they were to members of another sub-group. &nbsp; This is contrary to the idea that the Neanderthals were a single, uniform population.
This result begs the question of cultural distinctions between the sub-groups. &nbsp; After all, if they were genetically and physically different from one another, it is entirely plausible that cultural differences, such as tool technologies, between the sub-groups also existed. &nbsp; The authors hope to understand cultural differences between Neanderthal sub-groups in the same way as they&#8217;ve understood genetic and physical differences. &nbsp; And, as more fossils are found and more DNA extracted, we will hopefully develop – with even more confidence – a clear picture on the origins and movements of Neanderthals.

There’s More to Neanderthals than Meets the Eye

<img loading="lazy" decoding="async" class="alignright size-full wp-image-421" title="Neanderthal" src="https://blog-api.23andme.com/wp-content/uploads/2008/07/neanderthaler2.jpg" alt="" width="400" height="266" srcset="https://blogcms.23andme.com/wp-content/uploads/2008/07/neanderthaler2.jpg 400w, https://blogcms.23andme.com/wp-content/uploads/2008/07/neanderthaler2-300x200.jpg 300w" sizes="auto, (max-width: 400px) 100vw, 400px" />
First came the Human Genome Project when, in the year 2000, an international team of scientists began mapping all 23 pairs of our chromosomes.   Then in 2005, the Chimpanzee Genome Project took off, attempting to do the same for the 24 chromosomes of our species&#8217; closest living relative.   With intimate knowledge of the genetic make-up of both species, scientists could decipher the evolutionary changes that took place in the 7 million years since the time of our last shared ancestor.
Now, a joint research team led by Svante PÃ¤Ã¤bo of the Max Planck Institute for Evolutionary Anthropology has gone one step further by mapping the complete genome of our nearest extinct relative. PÃ¤Ã¤bo and his colleagues announced the completion of a draft Neanderthal genome sequence today in Chicago at the annual meeting of the <a href="http://www.aaas.org" target="_blank" rel="noopener noreferrer">American Association for the Advancement of Science</a>.

Neanderthals &#8211; our short, stocky, evolutionary cousins &#8211; lived in Europe during the harshest conditions of the Ice Age.   They survived in regions where few other animals could.   Neanderthals first came on the scene over 350,000 years ago, but seemed to dwindle in numbers with the arrival of humans about 40,000 years ago.   By 25,000 years ago they had disappeared completely.
But there are still many questions surrounding the fate of the Neanderthals.   While most scientists argue that Neanderthals were simply out-competed by the arriving humans, some believe that Neanderthals and early humans may have interbred, and that many modern Europeans have Neanderthal DNA interspersed throughout their genome.   Others believe that Neanderthals and early humans were in fact members of the same species, and should therefore have very similar DNA.
Solving the mystery has been no easy task. Because the archaeological samples available to PÃ¤Ã¤bo and his colleagues – three bone fragments from a cave in Croatia – are 30,000 years old, what little DNA they contain has been broken down into short fragments of just a few hundred base pairs each – a fraction of the billions that make up a complete genome.
Initially, the researchers focused on the mitochondrial DNA, because it is so prevalent in each cell.   When comparing the mitochondrial DNA of Neanderthals to that of modern humans, they found substantial differences between the two &#8211; indicating that humans and Neanderthals could not have been members of the same species.
However, the mitochondrial DNA represents only a fraction of the entire Neanderthal genome.   If we want to know the real genetic differences between humans and Neanderthals, then we&#8217;ll have to examine not just a small fraction, but the whole genome – all 46 chromosomes of it.
Working with 454 Life Sciences Corp of Branford, Conn., PÃ¤Ã¤bo and his team have devised a way to extract large amounts of nuclear DNA &#8211; DNA from the 23 pairs of chromosomes inside each cell &#8211; from prehistoric mammals, including Neanderthals.   All told, the two research teams have so far sequenced over 3 billion bases of Neanderthal nuclear DNA, constructing a &#8216;rough draft&#8217; of the entire Neanderthal genome.
The sheer difficulty in completing such a task cannot be underestimated.   As soon as these Neanderthals died, tens of thousands of years ago, the DNA inside each cell began breaking down.   Up until recently, extracting the few remaining bits of DNA from fossils like these was virtually impossible.   Now, as PÃ¤Ã¤bo and others comb through the Neanderthal genome, we can embark on new chapter in the continuing saga surrounding the relationship between humans and Neanderthals.

Researchers Announce Draft Version of Complete Neanderthal Genome

The Blog has pointed out several times in the last few months that when researchers look for evidence of interbreeding between early humans and Neanderthals, they often fail to find any.
But there are still several geneticists who would like us to heed the words of former defense secretary Donald Rumsfeld, who once pointed out that &#8220;the absence of evidence is not evidence of absence.&#8221;
During a briefing for science writers this morning at Stanford University, geneticist Bruce Lahn argued that interbreeding with Neanderthals may have introduced a mutation that appears to confer an evolutionary advantage about brain development into the human gene pool.
&#8220;We argue that in modern humans, there may actually be some Neanderthal genes,&#8221; Lahn said at the Council for the Advancement of Science Writing&#8217;s New Horizons in Science briefings.

Lahn based his argument on a gene known as microcephalin. Because certain gene mutations can cause brain underdevelopment, microcephalin is assumed to be involved in that organ&#8217;s development.
Lahn described research he and several colleagues first described two years ago in the <a href="https://www.pnas.org/content/103/48/18178.full?sid=a8247834-aa24-4260-b390-4213ac428291" target="_blank" rel="noopener noreferrer">Proceedings of the National Academy of Sciences</a>. The researchers sequenced microcephalin in 89 people from populations around the world. They found that the sequences fell into two very different groups – so different, in fact, that they apparently traced back to a common ancestor older than the human species itself.
Moreover, each of the two groups appeared to have a very distinct history. One appeared to have arisen about a million years ago and diversified at a steady pace since then. The other group appeared to have arisen just 37,000 years ago and spread rapidly throughout 70% of the human population. That kind of pattern suggests what evolutionary biologists call a &#8220;selective sweep,&#8221; the introduction of an advantageous genetic variant that quickly wipes out older versions of the gene.
Usually, when geneticists see a selective sweep in action, the new variant appears to arise out of the pre-existing one. But in this case, Lahn argues, the new genetic variation traces back to a common ancestor that precedes both populations. He believes Neanderthals could have been that population and that they could have transferred the &#8220;new&#8221; variation into the human gene pool through interbreeding about 40,000 years ago.
It&#8217;s just a hypothesis at this point – and one that many geneticists consider challenging to <a href="https://www.nature.com/hdy/journal/v98/n4/full/6800953a.html" target="_blank" rel="noopener noreferrer">confirm</a>. But suppose ongoing efforts to sequence the Neanderthal genome find a version of the microcephalin gene identical to the one currently sweeping through the human population. In that case, Lahn will have strong evidence for his claim.

Neanderthal — Page 5

Find Your Inner Neanderthal

New Evidence Suggests Interbreeding Between Humans and Neanderthals

Human Prehistory 101: Out of (Eastern) Africa

Novel Techniques Suggest Neanderthal Populations Dwindled in the Face of Expanding Humans

New Research on FOXP2 Gene in Mice Reveals Insights to Origins of Language in Humans

There’s More to Neanderthals than Meets the Eye

Researchers Announce Draft Version of Complete Neanderthal Genome

Did Neanderthals and Humans Mate?

Stay in the know.