A face only a woman could love: new research shows only the offspring of female humans and male Neanderthals contributed to the 4% of Neanderthal DNA in modern humans.
Credit: iStockPhoto
Since the discovery of the first recognised Neanderthal remains in the Neander Valley in Germany in 1856, scientists have debated the relationship between Neanderthals and humans.
At first thought to be an early human ancestor, Neanderthals lived from 370,000 to 25,000 years ago. They inhabited a vast geographical area from Portugal to western Siberia and from northern Europe to the Middle East.
Studies of the remains of Neanderthals indicate that they were not as tall as humans, had shorter limbs, thicker bones, pale skin, red hair and (surprisingly) high-pitched voices.
Despite their short stature, they were more robust than humans. Fossil Neanderthal bones exhibit the kinds of injuries sustained by American rodeo riders, suggesting that they probably hunted in close proximity to large prey.
From DNA research published in Science in 2010, we know that Neanderthals contributed to the human gene pool, with 4% of human nuclear DNA tracing back to them.
This contribution represents the equivalent of one great-great-great grandparent - an incredible finding considering how long ago Neanderthals became extinct.
While this and other recent studies of nuclear DNA reveal an infiltration of Neanderthal genetic material into the human lineage, Neanderthals and humans do not share one another's mitochondrial DNA.
Since mitochrondrial DNA is only inherited from female ancestors, this is a vital clue that only Neanderthal men contributed to the human gene pool, and key to understanding patterns of interbreeding.
Mitochondria are tiny organelles involved in the energy regulation of each cell of the body. They evolved from symbiotic bacteria vital to cellular function.
Mitochondria reproduce asexually - without mixing of genes - so in the long run, they may build up deleterious mutations that are potentially lethal to their ongoing reproduction.
Mitochondrial DNA in sperm is a candidate for mutation. Nuclear DNA is also a potential site of mutation in sperm. So the constant production of male germ cells from puberty onwards increases the likelihood of alterations in genetic sequences.
Female germ cells, however, are held in a prolonged phase of dormant suspension from the moment of formation in late foetal life until just prior to ovulation.
Nuclear and mitochondrial DNA in oocytes - female germs cells involved in reproduction - is protected from mutations. For this reason, female parents pass on their mitochondrial DNA but male parents do not.
My great-great-great-grandfather's a Neanderthal.
Recent breakthroughs have also informed us that Neanderthals shared 99.90% of our, Homo Sapiens, DNA. As we all looked fairly similar 50,000 years ago it shouldn't come as a shock that there was significant interbreeding between these separate species and that some of their offspring survived to maturity and also procreated and so on and so forth. With all of non-African humanity having around 4% of our DNA it must be said that some populations around the world should have a higher percentage and others with a lower percentage. What is the chance of a modern day couple having a child that is a genetic "throw back"? In that under the right circumstances a child could inherit the right combination of genes and therefor exhibit a physique with more Neanderthal features. In nature this phenomenon does occur albeit rarely such as with domesticated animals eg. horses, pigs etc. So would this child really stand out in crowd considering how diverse humanity already is? Probably not. In time maybe science can shed a light on how the Neanderthal DNA that we inherited makes us different in any way with Africans apart from the obvious eg. skin colour or type of hair. Recently Russian scientists discovered another relative of humanity who have been named the Denisovans, after the cave in Siberia where they were discovered, who split off our family tree some 300,000 years before our ancestors and the Neanderthals diverged which was some 500,000 years ago. Tests have shown that Papua New Guineans have inherited 5% of their genome from the Denisovans so do they also have some Neanderthal DNA as well - its gets confusing with all the possiblities.I look forward to more discoveries as more and more individuals around the world have their genomes cataloged for comparison.
Thank you!
Thank you so much for providing this much easier to digest summary!
my great-great-great grandfather's a neanderthal...
Hmm, short, pale skin, red hair and high pitched voice - Eureka! Julia Gillard is a Neanderthal! Will this discovery win me an Ignobel Prize?
Elmohu, Brisbane
teeheehee!
Thanks for the early morning giggle!
I think an unmentioned
I think an unmentioned possible explanation for our Neanderthal ancestors being male is rape.
Agreed, a likely vector.
I agree. The most likely vector for this is indeed the rape of captured human women by Neanderthal men, for example after combat between a human and neanderthal tribe.
Rape
Maybe, but you have a skewed view of the world, methinks.
Skewed towards reality...
Skewed towards reality...
Exactly what I was thinking.
Additionally, from the depictions I have seen, neanderthals seem to have a more masculine appearance than humans. Therefor the male neanderthal may have been attractive to the human female and vice-versa, while the female neanderthal would neither appear attractive, or be attracted to human males.
By analogy with the
By analogy with the relationship between Africans and Europeans, and Europeans and Asians, you may have a point. I see far more attraction between white women and black men than the reverse. I mean no editorial, just an observation. Still the differences between homo sapiens and neanderthals are greater and I doubt there was much consenting sexual activity between them.