In a cave in Siberia, scientists have found a 40,000-year old pinky bone that could belong to an entirely new species of hominid. Or it may be yet another example of how hard it is to figure where one species stops and another begins–even when one of those species is our own. Big news, perhaps, or ambiguous news.
In Nature today, Svante Paabo and his colleagues published a paper describing their work in a place known as the Denisova Cave in the Altai Mountains of Siberia. There are lots of hominid bones and tools indicating people lived in the cave, off and on, for 125,000 years. There’s good evidence of Homo sapiens in the region for at least 40,000 years, and Paabo and his colleagues have also isolated 30,000-year old DNA from Siberian sites that is similar to the DNA from Neanderthals in Europe.
The scientists succeeded in fishing out human-like DNA from a pinky bone found in Denisova, and so far they’ve sequenced its mitochondrial DNA–that is, the DNA that is housed in mitochondria, sausage-shaped, fuel-producing structures in our cells. The majority of our DNA, which sits in the nucleus of cells, comes from both our mother and father. But mitochondrial DNA all comes from Mom. When the scientists compared the pinky DNA to DNA of humans and Neanderthals, they got something of a shock. If you line up the mitochondrial DNA from any given living human to any other living human, you might expect to find a few dozen points at which they are different. Compare human mtDNA to Neanderthal DNA, and you’ll find about 200 differences. But when the scientists compared the Denisova DNA to a group of human mitochondrial genomes, they found nearly 400 differences. In other words, their DNA was about twice as different from ours than Neanderthal DNA.
The scientists then used the DNA to draw a family tree. Here’s the figure from the paper, which you can also see here for full-size viewing.
The Denisova mitochondrial DNA has been passed down, mother to child, on a lineage of hominids that’s separate from the one that produced mitochondria in Neanderthals and in living humans. Paabo and his colleagues estimated the age of common ancestor from which all the mitochondria evolved, based on the mutations in each branch. They concluded that common ancestor lived 1 million years ago. Below is a simple tree that shows the timing more clearly, from an accompanying commentary in Nature.
No matter how you slice it, this is very exciting. All the mitochondrial DNA from living humans is believed to date back just 150,ooo years. That doesn’t mean that we all descend from a single “Eve.” There were other woman around at the time, and they passed down their own mitochondria. But those lineages eventually hit dead ends. In some cases, women only had sons. In others, they never had children. Eventually, all the mitochondrial DNA in the human population could be traced to only one of the women alive at the time.
All the Neanderthal mitochondrial DNA also shares a relatively recent common ancestor of its own–probably thanks to the same process. And now, for the first time, scientists have found hominid mitochondrial DNA that comes from a far more ancient split.
So–how to explain this? A couple possibilities present themselves.
1. The DNA belongs to a species of hominid that’s neither human nor Neanderthal.
This is the most interesting, most science-fictionish possibility.
Our hominid ancestors evolved into upright apes in Africa some six million years ago. By about 1.9 million years ago, some of those hominids had made their way out of Africa and strolled all the way to Indonesia. They go by the name of Homo erectus, and they stuck around Asia for quite a long time–some would argue they were still around 40,000 years ago. Neanderthals appear to have evolved from another wave out of Africa, which spread to Europe and Siberia several hundred thousand years ago. Meanwhile, our own ancestors appear to have stayed put in Africa. The oldest fossils of anatomically modern humans come from Africa 200,000 years ago, for example, and studies on human DNA find that African lineages are the oldest.
The Denisova DNA split too recently from our own to have been carried by H. erectus, the first globe-trotting hominids. But paleoanthropologists have found a fair number of other hominid fossils in Europe and Asia that might belong to more recent waves out of Africa. (Here, for example, is a report on hominids in Europe 1.2 million years ago.) So perhaps there was at least one other wave aside from H. erectus, the expansion of Neanderthals, and the spread of modern humans. If that’s true, this new discovery also means that this wave produced a long lineage of hominids that survived long enough to live alongside humans. We coexisted with yet another species of hominid–along with Neanderthals, H. erectus, and those lovable hobbits, Homo floresiensis–for thousands of years. Our current solitude is a recent fluke.
If #1 turns out to be true, then this DNA deserves a species name of its own. But for now, Paabo and his colleagues have refrained from giving it one. Instead, they’ve nicknamed the source of the DNA “X-woman.” Why the reticence? Probably because of possibility #2…
2. The DNA comes from the finger of a Neanderthal or a human–thanks to a love that dare not speak its name. Imagine, if you will, that an early Neanderthal male takes a morning constitutional in search of woolly rhinos when, gadzooks, he meets up with a fetching X-woman hominid. For whatever reason, the two of them decide to have an interspecies tryst, and X-woman gets pregnant. She gives birth to a girl carrying Neanderthal and X-woman DNA in her nucleus–and nothing but X-woman DNA in her mitochondria. Somehow this girl becomes a part of Neanderthal society; she has Neanderthal children of her own, and they continue to carry the X-woman mitochondrial DNA.
Remember that in every generation, nuclear DNA gets mixed up. Half of the DNA a child carries in the nucleus comes from its father, half from its mother. And with the generation of new eggs and sperm, chromosomes from each parent get chopped up and shuffled back into new combinations. So over generations, the X-woman DNA might gradually dwindle away from the Neanderthal gene pool–but some Neanderthals might still carry X-woman mitochondria, handed down from mother to daughter to grand-daughter.
(It’s also possible that the interbreeding male in this scenario was a human–although just in terms of timing, that’s less likely, since Neanderthals were out of Africa sooner than we were.)
One reason to take this possibility seriously is the fact that other primate species regularly mix up their DNA in just this way. Mongoose lemurs expanded into the range of brown lemurs, for example, and mitochondrial DNA ended up jumping the species barrier. In many cases, the species were separated by a million years or so, just like the Denisov DNA and human/Neanderthal DNA. (This is why it’s hard to use DNA-barcoding to tell closely related primates apart.) Another reason to take this possibility serious is lies in our own genomes. Some scientists have made a forceful case for the presence of ancient non-human DNA in the gene pool of living humans.
Still, even if this scenario turned out to be right, it would mean that a previously unknown X-woman hominid line expanded out of Africa and lived in Asia until relatively recently. Whether that lineage could be rightly considered a separate species of its own is tricky. (For more on that trickiness, see my article, “What is a Species?” from Scientific American.)
I can imagine other possible interpretations, but I’m not sure how plausible they really are. I’ve sent out some queries to some experts, and will add anything interesting I get back [Update: See the end of the post]. Fortunately, it may be possible to rule some possibilities out in just a few months. Paabo and company are busily churning out the sequence of the nuclear DNA from the Denisova pinky. It’s conceivable that the nuclear DNA will be a lot more like human DNA, or a lot more like Neanderthal DNA–making it likely that the fossil belongs to a hybrid. But if the nuclear DNA is just as exotic as the mitochondria, then perhaps the finger bone really does belong to a distinct species that lived 40,000 years ago–a species, it’s worth pointing out, that left its bones behind in the same layer of sediment where Russian scientists have dug up tools and ornaments made of stone and antler.
The possibility of a highly intelligent Siberian Other will have to dance in our heads until more studies come out.
Update: After I posted this, the paleoanthropologist John Hawks offers an alternative explanation on his blog. I followed up with a few questions via email, and based on his post and his reply, here’s my quick distillation:
Maybe the X-woman was not a separate species at all.
Wind back the clock to a million years ago. In Africa, there’s a population of hominids that will eventually give rise to Neanderthals and humans. The Neanderthal lineage expands out across Europe and Asia. They take with them a wide diversity of mitochondria. Most of the studies on Neanderthal DNA have focused on European Neanderthals–and have thus only captured a limited sample of that diversity. Now, in Siberia, Paabo and his colleagues have moved so far from the areas they had studied before that they’re finally getting to other branches of Neanderthal mitochondria.
In this scenario, Neanderthals play a role similar to that of Africans in the diversity of living humans. In Africa, you can find people with genes belonging to very old lineages. The Khoisan bushmen of southern Africa, for example, have genes that branched off from all other human lineages long ago. In other words, the genes of other Africans share a closer ancestor with genes from people out of Africa. Likewise, some Neanderthal mitochondrial DNA is more like human DNA than it is to the Neanderthal DNA found in the Denisova pinky.
[3/27/10: Time to go Borges: an update within an update! The Atavism (which has already displayed great skills in visualization by illustrating my recent reader survey) whipped together a diagram that gets this concept across nicely:
I’ll post more replies as they come in.
Update, 3/25/10 10:15 am: I also got in touch with Laurent Excoffier, a biologist at the University of Bern in Switzerland, who has published models of human evolution indicating that there has been little, if any interbreeding between our own lineage and Neanderthals or other hominids.
Excoffier has argued that some genes that have been claimed to have entered our lineage through interbreeding were actually already present in ancient African human populations. I wondered if the mitochondrial DNA in the Denisova pinky might just be from an old human, not a separate species. Excoffier was skeptical:
This seems relatively unlikely, since it is difficult to understand why this mtDNA lineage would not have been preserved in Africa. Of course some otherwise rare mutations (or DNA sequences) can surf to higher frequencies during range expansions, and this could potentially explain why it could be seen outside Africa and not within Africa. But if that was the case, then it would be difficult to understand why this once frequent sequence would then have disappeared. So, I would thus consider this hypothesis as very unlikely.
I then asked if he thought the best explanation for this DNA was that it came from a separate species, or that it spread from a separate species into Neanderthals or humans through interbreeding.
If this sequence is really true (not an artefact from next-gen sequencing) and if there was no contamination, then a more plausible explanation would be that this sequence comes from a divergent Homo species, as claimed by the authors of the paper.
It is indeed plausible that some non-modern homo or non-Neanderthals roamed in Asia before modern humans spread there, and this sequence could well belong to one of them.
The interesting point for me is that if this sequence is representative of, say, erectus mtDNA diversity in Asia 40-60,000 years ago, then it means that some divergent erectus were there when modern humans expanded into that region, and that did NOT hybridize with them, or at least not enough to be introgressed by them during their expansion (which is the expectation when hybridization can occur between a local and an invading species).
So there’s a vote for possibility #1.
Reference: Krause et al., “The complete mitochondrial DNA genome of an unknown hominin from southern Siberia” Nature, doi:10.1038/nature08976
March 24th, 2010 at 2:40 pm
[...] tree gets bushier? Just see John Hawks and Carl Zimmer. Tags: Paleoanthropology Leave a comment No comments [...]
March 24th, 2010 at 3:42 pm
The x group DNA has been around several years now. There are many of these, usually natives that can’t be figured where they go to the Americas. Most agree that this is interesting, but theories about time and adaptive native x group DNA(faster) are wrong because they appear to been of planet. X woman is a female, so the DNA’s are looking for the same female that found Africa and Europe. This may be difficult if the specific DNA isn’t found in any other human/animal.
March 24th, 2010 at 4:28 pm
This is the best article I have read so far on this topic, namely FOX news, NY Times, Scientific American etc. Thanks!!
March 24th, 2010 at 7:20 pm
[...] updated my X-woman post with an interpretation from John Hawks: there was no X-woman [...]
March 24th, 2010 at 9:36 pm
You say:
- “Our hominid ancestors evolved into upright apes in Africa some six million years ago.” This is an assumption without good evidence: 1) The Moroto lumbar vertebra 19 Ma was remarkably human and suggests an upright posture (google “Filler Moroto”). 2) Gibbon locomotion is mostly upright, and gibbons & great apes split c 17 Ma. 3) Sahelanthropus c 7 Ma is called bipedal, but probably predates the H/P split c 5 Ma. IOW, uprightness is probably much older than 6 Ma and is not uniquely human: apparently knucke-walking (in parallel in chimps & gorillas) derived from some earlier sort of bipedalism.
- “By about 1.9 million years ago, some of those hominids had made their way out of Africa and strolled all the way to Indonesia.” Retroviral data suggest that human ancestors might have been absent from Africa between 4 & 3 Ma (google ” Yohn PLoS”): it is well possible that the Mojokerto Homo fossils in marine sediments at Java were not newcomers there, but had lived there for a few millions of years (eg, at coasts now submerged), and that Homo c 1.8 Ma in Africa was a newcomer from S.Asia.
March 24th, 2010 at 10:41 pm
A wonderful article about a truly awesome subject.
March 25th, 2010 at 12:16 am
Why is it always assumed that all hominids originated in Africa?
Why can’t it have been that the X group (if they really are a separate species) and/or the Hobbits and/or even some other group(s) split off from other hominids outside of Africa? Surely this is what happened with, for instance, the other primates (e.g. did the orangutan ancestor originate in Africa and from there spread out to SE Asia or did they evolve into a separate species in SE Asia?).
Just asking.
March 25th, 2010 at 5:08 am
Thank you for this article!
You have no idea how many terrible versions of this there are out there. A few “articles” didn’t even want to use the word mitochondrial DNA. Too complex. So they just call it plain DNA till 3/4 of the way through the article, and then have to explain the difference. And of course the sensationalist headlines.
Why can’t we make good use of hyperlinks to explain concepts you need an understanding of to even grasp the basics of the story?
Science journalism is just getting worse out there.
March 25th, 2010 at 6:10 am
[...] The X-Woman’s Fingerbone – possible undiscovered species by Carl Zimmer [...]
March 25th, 2010 at 8:58 am
You say:
- “Our hominid ancestors evolved into upright apes in Africa some six million years ago.”
This is an assumption without good evidence.
Uprightness was probably much older, and not confined to human ancestors.
1) The Moroto lumbar vertebra 19 Ma was remarkably humanlike and suggests an upright posture already some 20 Ma in early hominoids (google “Filler Moroto”).
2) Gibbon as well as human locomotion is mostly upright, and gibbons & humans split c 17 Ma. It’s well possible that the different locomotions of the great apes (suspensory orangs & knuckle-walking chimps & gorillas) derived from more upright ancestors (upright for whatever reason: hanging from branches, wading in shallow water &/or walking on land).
3) Sahelanthropus c 7 Ma is called bipedal, but probably predates the H/P split c 5 Ma.
IOW, uprightness is probably much older than 6 Ma and is not uniquely human: apparently knucke-walking (in parallel in chimps & gorillas) derived from some earlier sort of bipedalism.
IMO, paleoanthropologists should stop believing that every upright fossil hominoid (including australopithecines) is a closer relative of humans than of other hominoids.
Google “aquarboreal”.
You also say:
- “By about 1.9 million years ago, some of those hominids had made their way out of Africa and strolled all the way to Indonesia.”
Retroviral data suggest that human ancestors might have been absent from Africa between 4 & 3 Ma (google ” Yohn PLoS”): it is well possible that the Mojokerto Homo fossils 1.9 or 1.8 Ma (found in marine sediments at Java) were not newcomers there, but had lived along South Asian coasts & rivers for a few millions of years (eg, at coasts now submerged), and that instead Homo in Africa was a newcomer from S.Asia.
Google “econiche Homo”.
March 25th, 2010 at 9:29 am
[...] added comments from biologist Laurent Excoffier to my X-woman post. His verdict: probably another species of [...]
March 25th, 2010 at 10:02 am
[...] an in-depth look at the science and the implications of this discovery, check out Carl Zimmer’s post on the DISCOVER blog, The [...]
March 25th, 2010 at 12:16 pm
[...] Zimmer has about the best explanation I’ve found (no surprise – his writing on science in general, and evolution in [...]
March 25th, 2010 at 1:44 pm
I don’t really understand how possibility 2 is different from possibility 1. Both posit the existence of a non-human, non-Neanderthal lineage.
[CZ: Karen, you're right that both post the *existence* of a non-h/n lineage. However, the question also remains as to which species the possessor of the pinky itself belonged. It's conceivable that 20,000 years earlier, the pinky's possessor's great-great-great-etc. grandfather had a tryst with a non-h/n female, but otherwise, all his or her other ancestors are Neanderthals. One way to think about this is to consider recent arguments in favor of admixture of Neanderthal genes into the human gene pool. If these arguments are right, then there are some Neanderthal genes in circulation right now. But the people who carry those genes wouldn't be considered Neanderthals.]
March 25th, 2010 at 3:15 pm
“The Denisova DNA split too recently from our own to have been carried by H. erectus, the first globe-trotting hominids.”
That depends on how you define “Homo erectus”. The type specimen is late-occurring and from Java, so a restricted usage of that name could refer only to late Asian/Malayan populations (Java Man, Peking Man, etc.), and not to earlier African/European populations (Nariokotome Boy, Dmanisi Man, etc. — “Homo ergaster” or “Homo erectus ergaster”).
One morphological analysis found Homo erectus sensu stricto to share more ancestry with the human-Neandertal clade than with Homo ergaster. (Or, if you prefer, found that Homo erectus sensu lato is an ancestral species.) Under this hypothesis, it is possible for the specimen in question to be Homo erectus.
(Also, if, as some studies suggest, Homo floresiensis branched off before Homo ergaster, even Homo erectus sensu lato might not include the first globe-trotting hominins.)
March 25th, 2010 at 4:15 pm
Dear Mr. Zimmer: Thank you so much for this clear and elegant exploration of the possible “meaning” of this new discovery. I think we should no longer be amazed to find that “our” history is more ancient, complex, and diversified than we have previously understood or believed. We humans (of all kinds) are a strange and mysterious lot!
In my upcoming book, I call us The Sacred Ape because spiritual inquiry and expression seems to be our most compelling and distinctive feature. It’s found in Neanderthal burials and prehistoric Homo sapiens’ use of symbols, and I’m not surprised to hear that bracelets and other “decorations” were discovered in the surrounding layers around the Demisova child. A closer look at the map you provided (thank you) reveals that these people lived at the very heart of the “Old World” and the epicenter of a shamanic tradition and culture that still lives powerfully today.
I, like you, look very much forward to the further (and hopefully conclusive) results of genetic testing. The “proof” of either of the two main hypotheses you outlined would provide fascinating insight into our place in the world. One thing we know for certain is that as special as we are to be the only (we believe) human species alive today, we must balance our self-appreciation (and perhaps at times overly zealous self-congratulation) with humility and wonder.
In kindness,
Aaron Zerah
P.S. What do you think about the possibility (as offered by geneticists at MIT and others) that hominins and chimpanzees interbred and that we are descendants of that hybrid
March 25th, 2010 at 9:39 pm
[...] X-Woman: Species or not? [...]
March 25th, 2010 at 11:40 pm
[...] a really cool find whether it turns out to be a separate species or not. As usual Zimmer has an awesome write up on the Nature paper and anthropologist John Hawks has an interesting perspective as well. Svante [...]
March 26th, 2010 at 1:41 am
[...] DNA strain begs question of where man begins and caveman [...]
March 26th, 2010 at 11:54 am
[...] one that may have branched off from modern humans 1 million years ago. There are other theories – Carl Zimmer proposes one alternate theory built on the rather salacious premise of interspecies lovin’ – but [...]
March 27th, 2010 at 8:59 am
[...] Allerdings sind die Forscher noch nicht bereit tatsächlich von einer neuen Menschenart zu sprechen, denn es gibt noch weitere mögliche Erklärungen. [...]
March 27th, 2010 at 9:01 am
[...] just got a little larger and a lot more mysterious thanks to the mitochondrial DNA recovered from a single hominid bone found in a cave overlooking the windy steppes of [...]
March 27th, 2010 at 11:25 am
[...] http://blogs.discovermagazine.com/loom/2010/03/24/the-x-womans-fingerbone/ [...]
March 27th, 2010 at 6:04 pm
[...] just got a little larger and a lot more mysterious thanks to the mitochondrial DNA recovered from a single hominid bone found in a cave overlooking the windy steppes of [...]
March 27th, 2010 at 8:22 pm
[...] The Atavism put together a nice picture showing how the X-woman’s DNA could just be plain old Neanderthal genes. I’ve shamelessly stolen it for my own post. [...]
March 27th, 2010 at 9:52 pm
[...] 28, 2010 · Leave a Comment Carl Zimmer has a continually updated blog post on the mtDNA of “X-Woman”, which is being informed by his readers and experts. It’s a useful antidote to hasty and [...]
March 28th, 2010 at 2:41 am
[...] bush which may have been coexistent which modern humans and Neandertals. I recommend The Atavism, Carl and John Hawks on this story. Interesting [...]
March 29th, 2010 at 3:04 pm
[...] is a distinct species. A good place to learn more about the debate is Carl Zimmer’s blog The Loom. The Atavism also has a post about this [...]
March 31st, 2010 at 11:59 pm
I know Paabo is very good with ancient DNA, but any chance the highly divergent sequence is due to degradation/contamination?
April 1st, 2010 at 1:49 am
Excellent coverage, still too early to define though. Keep on it, Carl!
April 1st, 2010 at 4:06 am
[...] Outlasting the competition is one way to win. Our mitochondrial Eve is the ultimate example of outlasting the competition. Well, her mitochondria are! Thanks to Mr Burden for the link to this article which talks about a possible new human species discovered in Siberia and in so doing discusses mitochondrial Eve: article. [...]
April 1st, 2010 at 9:07 am
You wrote:
“There’s good evidence of Homo sapiens in the region for at least 40,000 years, and Paabo and his colleagues have also isolated 30,000-year old DNA from Siberian sites that is similar to the DNA from Neanderthals in Europe.”….”The scientists then used the DNA to draw a family tree. Here’s the figure from the paper, which you can also see…”
Just wondering why they don’t include this ‘similar’ Neanderthals mtDNA from Siberia in their family-tree?
April 2nd, 2010 at 7:03 am
What’s surprising about the Caucasian finger is that people were surprised. If we accept that Heidelbergensis, if the term pleases you, was present under suitable conditions from western Europe to western Asia at say half mya give or take, and was simultaneously spawning the lines to Neanderthals and moderns, but in Africa, then the European Heidelbergers would not have been ancestral to either Neanderthals or moderns, except through interbreeding with the African arrivals. A million year old mitochondrial split between the African and European Heidelberg branches is not surprising, and could appear between say Neanderthals and any surviving descendant of the likes of Boxgrove.
Actually I wasn’t surprised that people were surprised, seeing as how shocked they were by Ardi’s revelation last October that the human-chimp ancestor was upright when the lineages split, even though this theory had not just been on the cards for years but explained the evidence best, and should have been compulsorily considered in journal articles instead of being invisibled along with its early proponents. I predict people will be even more surprised when they finally twig that chimps are from Lucy but we aren’t (but are instead from the Kenyanthropus lineage) and that gorillas are from a line of robust “australopithecines” that weren’t actually australopithecines. The lesson is simple. Don’t choose your theory until you’ve laid out the entire space of potential theories, in your mind or even on paper, and then select the theory that explains the evidence best, not necessarily the theory which you think, even subconsciously, will avoid criticism.
On the Caucasian finger though, John Hawks’ comment this week (http://johnhawks.net/weblog) that a million year split can appear between mammoths of the same species, and even in the gene trees of chimps, may be a slightly different way from mine of referring to the same evolutionary events.
April 2nd, 2010 at 7:13 am
Quoting Laurent Excoffier:
“It is indeed plausible that some non-modern homo or non-Neanderthals roamed in Asia before modern humans spread there,…”
There’s no point referring to view as well-established as that, as if it’s something we might like to start considering.
“…if this sequence is representative of, say, erectus mtDNA diversity in Asia 40-60,000 years ago, then it means that some divergent erectus were there when modern humans expanded into that region, and that did NOT hybridize with them…”
Other evidence may suggest we did not hybridise with Asian erectus (though I believe there’s evidence that suggests we did), but how you can use non-combining mitochondrial evidence against hybridisation is beyond me.
April 2nd, 2010 at 7:14 am
Quoting Laurent Excoffier:
“It is indeed plausible that some non-modern homo or non-Neanderthals roamed in Asia before modern humans spread there,…”
There’s no point referring to view as well-established as that, as if it’s something we might like to start considering.
“…if this sequence is representative of, say, erectus mtDNA diversity in Asia 40-60,000 years ago, then it means that some divergent erectus were there when modern humans expanded into that region, and that did NOT hybridize with them…”
Other evidence may suggest we did not hybridise with Asian erectus (though I believe there’s evidence that suggests we did), but how you can use non-combining mitochondrial evidence against hybridisation is beyond me.
April 2nd, 2010 at 7:24 am
What’s surprising about the Caucasian finger is that people were surprised. If we accept that Heidelbergensis, if the term pleases you, was present under suitable conditions from western Europe to western Asia at say half mya give or take, and was simultaneously spawning the lines to Neanderthals and moderns, but in Africa, then the European Heidelbergers would not have been ancestral to either Neanderthals or moderns, except through interbreeding with the African arrivals. A million year old mitochondrial split between the African and European Heidelberg branches is not surprising, and could appear between say Neanderthals and any surviving descendant of the likes of Boxgrove.
Actually I wasn’t surprised that people were surprised, seeing as how shocked they were by Ardi’s revelation last October that the human-chimp ancestor was upright when the lineages split, even though this theory had not just been on the cards for years but explained the evidence best, and should have been compulsorily considered in journal articles instead of being invisibled along with its early proponents. I predict people will be even more surprised when they finally twig that chimps are from Lucy but we aren’t (but are instead from the Kenyanthropus lineage) and that gorillas are from a line of robust “australopithecines” that weren’t actually australopithecines. The lesson is simple. Don’t choose your theory until you’ve laid out the entire space of potential theories, in your mind or even on paper, and then select the theory that explains the evidence best, not necessarily the theory which you think, even subconsciously, will avoid criticism.
On the Caucasian finger though, John Hawks’ comment this week (http://johnhawks.net/weblog) that a million year split can appear between mammoths of the same species, and even in the gene trees of chimps, may be a slightly different way from mine of referring to the same evolutionary events.
April 2nd, 2010 at 7:46 am
Congratulations Zimmer! By pointlessly blocking my main comment here, you’ve demonstrated yet again that you disapprove of any scientific insight that doesn’t show abject servility to those you want to stay on the good side of.
You’re not “doing good science” by this, you’re not propagating an understanding of what good science is, and above all, you won’t be blocking my message, which will now of course give you the featuring role you so richly deserve.
[CZ: Spare me the theatrics. Your comments were automatically held for moderation. Their time stamps show they came in an hour ago. I just sat down this morning and started approving comments that came through overnight. Then I came across this one. Frankly, I was too busy sleeping to play the part of the censor you imagine for me.]
April 2nd, 2010 at 9:39 am
Since there was a misunderstanding, sorry. However your blogging software sometimes told me posts were being held for approval, sometimes removed them after initially displaying them and sometimes just printed them as though they had been accepted. I know you’re not fully responsible for every detail of operation of the system you use, but I have to say it doesn’t do me any favours either. And I still claim your record of interpreting and portraying the scientific theoretical landscape in all the areas I know anything about, is unbalanced.
April 6th, 2010 at 2:21 pm
[...] Which is sort of how science works. And so I’d like to talk about it. Fortunately for me, Carl Zimmer has already encapsulated the controversy in one post. He’s good like that, what with the writing and all. It’s pretty dense for [...]
April 7th, 2010 at 10:33 am
[...] course, not everyone thinks this means its a new species. As Carl Zimmer points out, while that’s one possibility, the mtDNA patterns might have also [...]
April 9th, 2010 at 3:33 pm
[...] from more than 40,000 years ago, a modern pygmy chimpanzee and a modern common chimp. The results indicated that there are about 400 differences between us and the DNA in the pinky. This is twice as many [...]
April 10th, 2010 at 2:01 pm
search “Almas” + “Altai” for an anomalous hominid in modern times.
April 25th, 2010 at 8:09 pm
an update favoring option #2
http://www.nature.com/news/2010/100420/full/news.2010.194.html
May 12th, 2010 at 5:57 pm
[...] A full sequence may help to resolve this.” I think we’ll know a lot more about X-woman and how she relates to us in the near [...]
May 12th, 2010 at 7:02 pm
[...] A full sequence may help to resolve this.” I think we’ll know a lot more about X-woman and how she relates to us in the near [...]
August 18th, 2010 at 4:58 pm
[...] years ago. This population is a sister lineage to the various Eurasian hominins, Neandertals, X-woman, [...]
August 18th, 2010 at 8:32 pm
[...] years ago. This population is a sister lineage to the various Eurasian hominins, Neandertals, X-woman, [...]
August 19th, 2010 at 11:34 am
[...] years ago. This population is a sister lineage to the various Eurasian hominins, Neandertals, X-woman, [...]
August 27th, 2010 at 11:49 am
[...] years ago. This population is a sister lineage to the various Eurasian hominins, Neandertals, X-woman, [...]
August 31st, 2010 at 1:29 pm
[...] data seem to indicate that modern humans made it no further than previous hominin groups for several tens of thousands of years. But something happened within the last 20,000 years, and [...]
December 22nd, 2010 at 8:24 pm
In science we tend to favor the simplest explanation, which is of course not necessarily correct. Regardless, the simplest explanation is that this X woman was a member of Homo erectus. It is slightly younger than the oldest H. erectus in Asia, but not by much. There is no reason to believe that human migration is a series of all or nothing square waves. Africans first left Africa, say, 60,000 years ago, but the migration has ever stopped since the first wave. And it continues to this date.
February 7th, 2011 at 1:43 am
[...] Carl Zimmer – Mar 24, 2010 – The X-Woman’s Fingerbone [...]
September 7th, 2011 at 5:06 pm
“1. The DNA belongs to a species of hominid that’s neither human nor Neanderthal.”
Neanderthals are human. You mean neither Homo sapiens nor Homo neanderthalensis.