Perhaps this is being awake for 48 hours straight talking, but this story makes me sad.
It is plain as day that when new species emerge, old species breed with one another. Evolution is not a discrete function. Homo Sapiens bred with Homo Neanderthalensis and evidence to support this has existed for a while afaik.
What's truly amazing here, but sort of goes hidden in the hype around interbreding (as seen on twitter, this article etc) is that a new species of humans, previously unknown to science, has been discovered.
that's the news story, not the boring interbreeding.
Humans, for better and for worse, have a lot of mental machinery dedicated to keeping track of who is sleeping with who, whose child is whose, and whether or not Group X is part of the clan. Any meme which happens to tickle those parts of our minds thereby spreads faster.
To a Vulcan, there might be no essential difference between being related to a lizard and being related to your grandmother. To a human, however, the question of whether or not some other creature is your brother-in-law or merely a distant cousin is a very big deal.
If I translate this right, I think you are lobbying for me to become a professional writer. ;) Thanks! I do enjoy the practicing.
I'll consider it. Although it's one hell of a career, so I'll either have to think about it pretty carefully, or just accidentally find myself doing it one day without even knowing why.
It wasn't obvious to me that a population that diverged from ours a million years ago would still be able to interbreed with us less than 50,000 years ago. That's tens of thousands of generations. I'm not surprised that they tried, but mildly surprised that they produced viable offspring. After all, there was previously some doubt that we could have interbred with Neanderthals, and we diverged from them only 500,000 years ago. We're twice as many generations removed from the Denisovans.
Or maybe those dates are wrong; the diagram in the article seems to say that the Denisovans and the Neanderthals diverged from the human lineage at the same time. I got the dates I cited from this article from earlier this year: http://news.bbc.co.uk/2/hi/science/nature/8583254.stm
P.S. The other interesting aspect of interbreeding is that it tells us 1) that the humans leaving Africa had significant, repeated encounters with another kind of hominid species, and 2) not only did they interbreed with them, but the offspring were well-enough integrated into early human society that they were able to survive and reproduce further.
The second point means that either immediately or eventually, the descendants of the Denisovans were considered fully human. How did that happen? Were the Denisovans already considered fully "human" by the humans leaving Africa? Or were they considered lower, like dogs or cattle? What about vice-versa? The details of the interaction would be fascinating if we could learn them. The interbreeding was doubtlessly often a byproduct of violence, when women were stolen in raids, or when one band wiped out the men of another band in a war and appropriated their land, women, and property. But did it also happen through peaceful means? Were crossbreed children treated as fully "human" right away or were they treated as sub-human until a few more generations of cross-breeding allowed them to "pass?" Were the two kinds of humans similar enough to form families together and feel love and familiar affection, or was it just sheer horndoggery? Could they even learn each other's languages? Interbreeding shows that it makes sense to ask these kinds of questions.
If modern humans are any measure, then all your worst suppositions were probably true. Slaves, cattle, playthings, whatever, they were certainly treated differently than 'legitimate' offspring.
Imagine if today there were certifiably different, perhaps measurably inferior people around. How would we treat them? And we're educated, civilized people.
Surely if they can reliably interbreed with us then they're not another species. Isn't that how "species" is defined? You'll note that the scientists in the article aren't quoted as calling these dudes a "species", they call them a "form".
The idea of a "species" isn't terribly well defined over time anyway. Your mother is the same species as you, her mother is the same species as her, and so on. But if you keep following your family tree for far enough you'll start to find things which are clearly a different species from yourself.
Members of closely related species possess no physiological differences that would prevent them from interbreeding.
But closely related species are distinguished by subtle differences in the pulse rates of male crickets' simple courtship songs, a secondary sexual trait that plays a large role in mate attraction.
Among all species of Laupala, pulse rates of male courtship songs range from .5 to 4.2 pulses per second. Female crickets can detect these differences, says Mendelson, and they tend to hop towards the pulse rate of their own species and to reject songs sung at a different tempo.
Despite the fact that these crickets can interbreed (and produce fertile offspring, unlike when, say, a female horse and a male donkey produce an infertile mule), we consider them different species because they systematically do not breed. I recall reading about further experiments with similar crickets where scientists manipulated the pulse rates of one cricket species to be the same as the other. Mating occurred.
I think behavioral and genetic barriers are both considered factors that affect whether crickets "can" interbreed. I'm not sure if scientists would be consistent in applying that standard to humans, though.
The difficulties of defining species lead to interesting edge cases, some of which show up in nature, such as ring species: http://en.wikipedia.org/wiki/Ring_species
Formally, the issue is that interfertile "able to interbreed" is not a transitive relation – if A can breed with B, and B can breed with C, it does not follow that A can breed with C – and thus does not define an equivalence relation. A ring species is a species that exhibits a counterexample to transitivity.
Well a great dane and a chihouha are both the same species - dog. But I wouldn't see them getting it on anytime soon. And yes, you can artificially breed a dane/chihouha hybrid (presuming the resulting pup has a Dane mother?)
My understanding was that, based on DNA analysis of Neanderthal remains, humans couldn't successfully interbreed with Neanderthals because of a chromosome mismatch, in the same way a Mule can't get fancy with another mule. So while a Neanderthal/Homo Sapien baby might exist, it was essentially sterile.
But I'm happy to be told otherwise, that's just my knowledge as at the last update on the subject, which admittedly was a while ago.
Personally I think the 'we all came from Africa' story is a little too neat. I think parallell evolution of Homo Sapiens in separate continents leading to eventual interbreeding is a distinct possibility.
The tone of the article was a bit strange, as was the way it kept referring to "ancient" genes and such.
If they're genes in modern people (Melanesians), how are they any more ancient than any other genes that exist chiefly in one population subgroup?
Isn't it becoming increasingly indefensible to talk about "our own" species (or "us") when we know that all these species interbred and that their genetic material lives on in modern humans, even "anatomically modern" humans?
I think it would be correct without any punctuation. Did anyone else think "Battlestar was right"?
But we still have to deal with the issue of whether to put the question mark before or after the quote mark. Some folks insist on putting it inside, even when it obviously makes no sense, like in this case.
The question mark inside quote marks thing has annoyed me for years. I'm sure my English teacher taught me that you should always put it inside the quotation mark, but it doesn't seem logical to me...
If that's a rule it was made up by people who hadn't considered the edge cases. If you're ending a sentence with a quote, and the appropriate punctuation marks are different for the quote and the sentence, then you should do whatever makes sense, with question marks trumping fullstops. For instance:
1. Did anyone else think "Battlestar was right"?
2. I thought "Battlestar was right."
3. I thought "Was Battlestar right?"
4. Did anyone else think "Was Battlestar right?"
Oh yes, and the relevant "rules" differ between American and British English anyway.
Limiting punctuation to inside or outside of the quotation marks always struck me as exceptionally archaic as it frequently overcomplicates a sentence.
You should punctuate the quotation as if the quote were independent. If the quotation is a question it should contain the question mark, it's only logical. A question without a question mark is punctuated incorrectly - that's just plain simple logic.
If I tell you that my wife just asked me, "Can you grab a drink?" The question mark has to be inside the quotes otherwise it becomes my question. I didn't ask myself the question, so why is my punctuation asking it? Plus an unpunctuated quotation looks ugly to me.
As I understand it, the rules come from typesetting, not common practice. As for myself, I'm fine with "What's for dinner?". That strikes me as the only truly logical choice. Solves hugh3's problem cleanly, too. I mean, what, my old English teacher is going to come dock me karma points?
I'd like to see a more substantive caption on the diagram. I had no idea the French were a branch of early humans. (I take it, it's actually a name for a finding.)
If all of this is true, then it is really astonishing.
But there's something in this article that sounds very hard to accept:
DNA is extremely fragile, it is very hard to imagine it surviving 50 000 years, even in Siberian ice. It is even harder to imagine someone to be able to sequence the entire genome of such species. And also: how can they affirm there's no contamination from human DNA (e.g.: bones remaining from cannibalism)?
I'll wait to hear more confirmations of this story.
The article does not say that they sequenced the whole "ancient" genome and indeed it is quite unlikely that they did so. They probably matched lots of isolated segments, however.
As for contamination issues... Nothing beats the original article when working out the odds of such a thing.
It is plain as day that when new species emerge, old species breed with one another. Evolution is not a discrete function. Homo Sapiens bred with Homo Neanderthalensis and evidence to support this has existed for a while afaik.
What's truly amazing here, but sort of goes hidden in the hype around interbreding (as seen on twitter, this article etc) is that a new species of humans, previously unknown to science, has been discovered.
that's the news story, not the boring interbreeding.