Oldest Homo sapiens fossil? Journalistic vaporware

By Carl Zimmer | December 29, 2010 1:00 am

I’ve been baffled by the spread of a non-story over the past couple days, about the supposed discovery of the oldest fossil of our species, doubling the age of our species from 200,000 years to 400,000 years and overturning the generally-accepted idea that Homo sapiens evolved in Africa.

Here’s a typical report, from the Associated Press:

Researchers: Ancient human remains found in Israel

JERUSALEM—Israeli archaeologists said Monday they may have found the earliest evidence yet for the existence of modern man, and if so, it could upset theories of the origin of humans.

Got it?

The hook for this story is the publication of a paper in the American Journal of Physical Anthropology. Did the reporters who hyped this story actually look at the paper itself? I have to wonder.

Let me quote a few pieces from it. You tell me where the scientists actually claim they have identified 400,000 year fossil of Homo sapiens.

Here is the abstract (I’ll define a few terms and give context afterwards):

This study presents a description and comparative analysis of Middle Pleistocene permanent and deciduous teeth from the site of Qesem Cave (Israel). All of the human fossils are assigned to the Acheulo-Yabrudian Cultural Complex (AYCC) of the late Lower Paleolithic. The Middle Pleistocene age of the Qesem teeth (400–200 ka) places them chronologically earlier than the bulk of fossil hominin specimens previously known from southwest Asia. Three permanent mandibular teeth (C1-P4) were found in close proximity in the lower part of the stratigraphic sequence. The small metric dimensions of the crowns indicate a considerable degree of dental reduction although the roots are long and robust. In contrast, three isolated permanent maxillary teeth (I2, C1, and M3) and two isolated deciduous teeth that were found within the upper part of the sequence are much larger and show some plesiomorphous traits similar to those of the Skhul/Qafzeh specimens. Although none of the Qesem teeth shows a suite of Neanderthal characters, a few traits may suggest some affinities with members of the Neanderthal evolutionary lineage. However, the balance of the evidence suggests a closer similarity with the Skhul/Qafzeh dental material, although many of these resemblances likely represent plesiomorphous features.

These teeth are from a site that’s between 400,000 and 200,000 years old in Israel called the Qesem Cave. Archaeologists have been working at the site for years now, bringing forth tools that some kind of hominin was using to cut up meat. Now researchers have found a few teeth from the site, in the older layers.

Hominins–that is, species closer to us than to chimpanzees–left fossils during this period all over the Old World, from South Africa to England to Java. They all clearly belong to our own genus, Homo. They share a number of key traits, including big brains, small teeth, and many other subtler but more diagnostic traits. But which species of Homo do they belong to? Here’s where things get tricky. A lot of fossils in East Asia are similar enough to one another that they’re considered one species, called Homo erectus. But some fossils from China from this age don’t fall so neatly into this group. Are they another species? Are they just an odd subspecies of H. erectus? A firm answer is hard to find.

Over in Europe, hominins first arrived 1.2 million years ago. At 400,000 years ago, the fossil record in Europe includes a species known as Homo heidelbergensis. Among other things, it is the first species known to make wooden spears. Some fossils from Asia and Africa resemble H. heidelbergensis, too.

Now, let’s turn the clock forward on each continent…

In Europe, the H. heidelbergensis fossils start to look a lot like Neanderthals. By about 200,000 years ago, the fossil record in Europe contains full-blown Neanderthals.

In Asia, H. erectus holds on 200,000 years ago, although there are other fossils that look like they might belong to H. heidelbergensis.

In Africa, H. heidelbergensis and other hominins give way to the first full-blown Homo sapiens fossils. These are fossils that have a number of different traits that link them clearly to us, and distinguish them from other hominins. (Here are details on two important ones: Omo and Idaltu)

There were probably other lineages of hominins living at the same time as well–such as the Denisovans of East Asia.

What about the region around Israel, where the new teeth come from?

The fossil record offers a picture of hominins evolving in Africa, and pulses of new lineages rolling out through Israel and neighboring regions, and then onward to Europe and Asia. Some 1.4 million years ago, for example, a species of early Homo left fossils in Israel at a site called Ubeidiya. At several sites in and around Israel, paleoanthropologists have found fossils and tools dating back 400,000 to 200,000 years ago–the same period as the Qesem site.  Unfortunately, the fossils are mostly fragments that might belong to a number of different species. The tools are equally ambiguous.

Something really interesting happened later in Israel, between about 130,000 and 50,000 years ago. It appears that Homo sapiens, having evolved in Africa, expanded tentatively into the Near East for the first time.  Fossils of tall, slender Homo sapiens turn up at a site called Skhul/Qafzeh. But then they vanish, replaced for tens of thousands of years by Neanderthals. Only later does Homo sapiens expand again out of Africa, and this time they don’t retreat. Instead, it’s the Neanderthals that disappear from the Near East, dwindling away to refuges such as Spain before becoming extinct.

The new paper documents the struggle of the scientists to figure out who the Qesem teeth belong to. In some ways, they seem more like Neanderthal teeth. In others, they seem more like the choppers of Homo sapiens, as represented by the Skhul/Qafzeh fossils. The authors tilt towards a relationship with Homo sapiens, but mostly because the teeth are “plesiomorphous.” That term refers to a trait that was already present before the origin of a group of species. It does not refer to a trait that closely links all individuals who have it into a single lineage.

Here’s a simple example of what plesiomorphous means. Let’s say you find a fossil at a site where you had already found dogs and birds. The new fossil has four legs. In that respect, it’s more like a dog than a bird.

But it would not make sense for you to conclude that the fossil was a dog. The common ancestor of dogs and birds had four legs, and birds evolved into two-legged animals. But alligators have four legs, too, and they’re closer to birds than to dogs. All those four legs really tell you is that the fossil isn’t a bird.

The Qesem teeth–in some respects–lack distinctive Neanderthal features. Perhaps they are human. Or perhaps they belong to some other hominin, like a Denisovan.

Here’s how the scientists end their paper:

There are three scenarios that might account for the morphological details in the Qesem teeth. The first one is of a local archaic Homo population occupying southwest Asia during the Middle Pleistocene, to which the Qesem specimens would be attributed. Perhaps relevant in this regard, the Qesem lithic assemblages studied to date indicate a local origin, with no evidence of African and or European cultural affinities (Barkai et al., 2005; Gopher et al., 2005; Barkai et al., 2009). Albeit the lack of other diagnostic Middle Pleistocene SW Asian teeth, considering the evidence in its entirety, we believe that the Qesem ‘‘package’’ is more Skhul/Qafzeh like, even if some of its features are plesiomorphous.

The second scenario is one of long-term in situ evolution of Neanderthals in southwest Asia. The presence of shoveling and a lingual tubercle in the stratigraphically younger maxillary teeth may be indicating the emergence of the Neanderthal morphological pattern during the Middle Pleistocene in southwest Asia. This would parallel the situation documented in Europe, where the Neanderthal evolutionary lineage has been shown to have roots extending deep into the Middle Pleistocene (Arsuaga et al., 1997; Stringer and Hublin, 1999; Bischoff et al., 2007). Under this scenario, southwest Asia would represent one regional subpopulation within the wider geographic range of the evolving Neanderthal lineage. Nonetheless, the large and well dated samples of fossil humans from Skhul/Qafzeh that post-date the Qesem specimens but predate most of the Neanderthal specimens from the region do not show an accentuation of Neanderthal features.

The third scenario is that more than one Pleistocene human taxon is represented within the Qesem dental sample. The mandibular teeth are stratigraphically deeper (older) but are smaller and lack plesiomorphous features identified in the chronologically later specimens. The differences between these chronologically disparate samples may reflect a population or species level distinction, and may involve population replacement on a local scale.

Resolution of these alternative scenarios must await further discoveries of additional and more complete Middle Pleistocene remains from southwest Asia. Nevertheless, the Qesem specimens represent an important contribution to the growing sample of Pleistocene human fossils from this circum-Mediterranean region of the Old World.

Nowhere in this conclusion do the authors say that these teeth belong to Homo sapiens. Nowhere do they say they have just doubled the age of our species. Nowhere do they say that our species evolved in the Near East, not in Africa. There are only some vague hints that the teeth might be “Skhul/Qafzeh-like.” Or they might be something else.

While the paper itself is non-commital in its conclusions, it contains lots of good detail about the teeth, which is why it probably got accepted at the American Journal of  Physical Anthropology. Who knows how some reporter got the idea that scientists had discovered the oldest fossils of Homo sapiens? It does seem that one of the authors has played footsie with reporters, offering some tasty quote-bait:

“It’s very exciting to come to this conclusion,” said archaeologist Avi Gopher, whose team examined the teeth with X-rays and CT scans and dated them according to the layers of earth where they were found.

He stressed that further research is needed to solidify the claim. If it does, he says, “this changes the whole picture of evolution.”

The logical thing a reporter should then do is ask, “How exciting can this conclusion be, when you never actually made it in the paper?”

The illogical thing to do is to declare that these teeth could “rewrite the evolutionary history of our species.”

[Image: AP Photo/Oded Balilty]

[Update: Brian Switek scoffs at Wired.]

[Update 12/31: Nature News interviewed Ari Gopher, the lead author on the paper, about the hype (and the take-downs from me and Switek). The article is particularly useful for finally tracking down the source of all these articles: a press release from Tel Aviv University that claims that "evidence was discovered pointing to the existence of modern man (Homo sapiens) in Israel as early as 400,000 years ago." (The press release was only in Hebrew, so I'm relying on Nature's translation.) Gopher claims that he told all the reporters who called him to be very cautious, but didn't think the press release was incorrect. "We offer the most reasonable conclusion based on the statistical evidence: that they represent the same population as the Skhul and Qafzeh finds, thus pushing the date for that type of early man back to a much earlier time."

Is it me, or is he talking about some other paper I haven't seen yet?]

Comments (30)

  1. Charles Sullivan

    I like that angry tone. It suits you well on a situation such as this.

  2. Torbjörn Larsson, OM

    The logical thing a reporter should then do is ask, “How exciting can this conclusion be,

    Hear, hear!

    It would also be a reporterly thing to do, one would think, because exciting and area changing things happens on a yearly basis (say) – but how often does a reporter dig up a scientist who is trying to bloviate from non-existent data?

    [I know, I know, probably often. But how often does the public get to _see_ the footsie playing?]

  3. Torbjörn Larsson, OM

    It hits me that my proposal probably goes against the mutual trust of the situation, and reporter ethics as they may be documented.

    Then again, doesn’t the scientist betray that by bloviating from scant or non-existent data? (And betray research ethics, which definitely should be documented at least in parts, see animal testing.) It may only be fair if the reporter repays in kind…

  4. Prady Pradhyumnan

    Thanks for this timely article. I knew something was amiss when I read this last night. Coming in the heels of the Denisovans, which was much more thoroughly covered in Anthropological circles, this one seem to be out of the blue and suspect as the news was carried by regular press and not by experts. I think I will continue to rely on scientific bloggers for all scientific news.

  5. Aklıselim

    It’s funny how religious zealots will take that story on face value, after refusing all the evidence of the african origin for years, claiming “how do they know it is human with just a tooth”. Just in time for christmas, “out of jerusalem theory”, they weren’t pagans dude, they were freaking jews maaaaan :P

  6. Professor Gopher? Digging things up in the desert? Hmmmm . . .

  7. A couple of questions.
    Don’t you smell a whiff of arsenic here, Carl?
    And how many reporters you know that can let go Gopher’s “nod, nod, wink, wink”, and understand your statement “How exciting can this conclusion be, when you never actually made it in the paper?”. The right question would not be “who read the paper”, but “who can understand the paper”.

  8. Vaporware

    But you yourself use the word “vaporware” without knowing what it means. Vaporware is software that is announced, but never ships. What does that have to do with your article?

    [CZ: It's a metaphor for big announcements with nothing behind them.]

  9. whoschad

    Usually during the Christmas season we get breaking news that proves to rewrite everything we know about Jesus and or Christianity. Finding themselves without a suitable headline this year, it seems they have turned to other subjects. At what point do these media outlets deserve the name ‘tabloid’?

  10. Cochese

    @ Vaporware:

    His use of the word vaporware is contextualized once he added the modifier of “journalistic” before the word vaporware, thus applying the term. He essentially turned it into a metaphor.

  11. rwhake

    ahh, something i can sink my teeth into. the discussion of bloviation vs. elucidation and the merits of each is a sideline to the fact that we can depend on the blogger for clarification. that in itself is part of the elusive search. as for the age of my ancestors, whooeee, line up!

  12. “The Qesem teeth–in some respects–lack distinctive Neanderthal features. Perhaps they are human”

    Weren’t neandertals humans?
    Why this new trend of equating “human” = sapiens?

    [CZ: "Human" is a common name, so it lacks the precision of a species name. Here I'm using it as equal to Homo sapiens. There's a lot of debate about whether Neanderthals belong in a separate species or not.]

  13. 220mya

    Carl – your link to the paper at the beginning of the post includes the part of the URL for your specific proxy connection (NYU apparently). Here’s the naked link: http://dx.doi.org/10.1002/ajpa.21446 or this: http://onlinelibrary.wiley.com/doi/10.1002/ajpa.21446/abstract

  14. 220mya

    On another note – dear god, when will anthropologists learn modern phylogenetics? Its ‘plesiomorphic’ people! Not ‘plesiomorphous’!

  15. Carl, unless I’m rather confused this morning, I think there’s a slight mistake in your terminology. You say hominin refers to “species closer to us than to chimpanzees” but the tribe Hominini actually includes humans and the two species of Pan. The correct term for your definition, I believe, is hominan, corresponding to the subtribe Hominina.

    (Of course, usage conventions change and are somewhat variable. AFAIK, the above represents consensus, but since I’m not a physical anthropologist, I could just be confused or misinformed).

  16. Mister Mann

    I love the statements on journalistic ethics from a scientific view point. However; the two mental species while both questioning, widely vary within there reasoning. This is whereas a being speaking as a scientist is excited about knowledge gained, whereas a being speaking from a journalistic view point and therefore view of the said subject matter is looking at it from an entirely different place. This final (journalistic placing) would be one looking to find one with a “Grab” to it if you will. Whereas the scientist one is excited about the actual knowledge, and therefore spewing information in a hap-hazard fashion through excitement.

    Basically the journalist is looking for a selling point. So the article is written by a journalist from that view point. These things, and especially in the popular media format much like the huge impact of finding that male and female monkeys play with sticks in a differing manner based on there sexual biology, would happen to be nothing more than a selling point.

    So the break down in this commentary piece tells us much in one way, but still tells us nothing we did not already know in another. Yes; I can meet a cheer leader at a party, and I can meet a science major at a party. They can both have been involved in the intake of alcoholic beverage as well. However; I can tell the cheer leader my studies are to be a doctor thereby luring her to coital activities, especially if she is already inebriated. If I tell the science major this she will most likely as questions along the line of my studies, and know if I am telling the truth.

    The point is the cheer leader is looking for that which is attractive on the surface, whereas the scientist would be looking to view said issues from the base up if you will. The journalist does the same, and then tries to make you see this attraction. The fact you cannot see it from both sides, and supposedly consider your self of a higher thinking nature is disconcerting.

  17. Your indignation appears somewhat premature, given that you yourself have not interviewed professor Gopher. Once you have accomplished that obligatory journalistic task, your input will be more meaningful on this topic.

    Thanks.

    [CZ: My attention is focused on the journalists in this case. While interviewing scientists is important for an article, reading the original papers is too.]

  18. This is a great explanation of the story. When it came out it didn’t make sense to me, but I’m only a layman. This piece, and many of the comments, help clarify the odor I was getting from the initial news release. Thanks.

  19. David B. Benson

    I’m a lumper, especially now with Neanderthal genes in New Guinea.

    All one Homo sapiens as a species with varieties such as Neanderthal, Hiedelburg man, Densovoians, and of course modern humans.

    Saves a lot of contentious, scientifically silly argumentation. These people in the Israel cave were just another variety of H. sapiens, slightly different morphology since not much gene flow between the widely spread and few tribes.

    As probably the best evidence is now lost under the interglacial sea highstands, we have only the remains of some of the hill people available for study. Nonetheless, I still find Alan Templeton’s gene flow study to well represent the unity of genus Homo.

  20. By my mind dating of strata with possible error of 200 000 years is very obscure. If this strata was actually formed in time given (e.g. 200 000 years), then there would be not one, but many strata in situ, each with it’s own age. I would like to see all stratification and methods used for dating of exact strata the teeth were found in. Carl, if You have access to full text of this article, could You inform us about these questions? So far i am tended to think that it’s a political rather than scientific announcement.
    P.S. Press releases are becoming more and more yellow recently. Last week i found “news” about “discoveries” of bacterial immune system mechanisms (viral origins of those), which in fact were profoundly described already in 2009, if not even earlier.

  21. mark v

    my physical anthropology prof actually warned us about this incessant need to declare a new species by minor alterations. like H. erectus with smaller feet, to him was still a small foot erectus. teeth, by way of example, were shown to not be indicative of speciation. in a study, which i cant remember but probably can be googled with the right search, it was found that teeth are not even rudimentary consituent in evolutionary sense (save the primate formula 2/1/3) this holds true, even with subspecies of lemuridae and monkeys. there are key things in this article i do entirely appreciate . with the recent we are genetically related to H. Neadratalensis and its subsequent abuse in the media, i accolade this articles approach to a similar situation. 4 or 5 percent of (pick your favorite race really) humans genetics have neandrathalensis in them?? i would expect that, they are a species of homo, just like us. (it is like we have teeth slightly similar to neandratal so we must be related, or more to the illustration we have teeth simular to lemurs so we must be related…well yea, we are primate, i would expect nothing else)…ok my main point against this is the abuse of cladistics . we may as well say we are genetically related to fox bats, they are stereoscopically binocular vision as we are…) ; truth is, if they can extract even fossil dna and analyze the MtDNA then we would have a greater fix on which species these are. bravo on a good and sane article thanks.

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The Loom

A blog about life, past and future. Written by DISCOVER contributing editor and columnist Carl Zimmer.

About Carl Zimmer

Carl Zimmer writes about science regularly for The New York Times and magazines such as DISCOVER, which also hosts his blog, The LoomHe is the author of 12 books, the most recent of which is Science Ink: Tattoos of the Science Obsessed.

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