Ganlea megacania and more “missing link” mania



A somewhat tamarin-like restoration of Ganlea megacania. By Mark A. Klingler of the Carnegie Museum of Natural History.

ResearchBlogging.org It seems that almost every time a new fossil primate is announced the first question everyone asks is “Is it one of our ancestors?” Nevermind that it is all but impossible to identify direct ancestors and descendants in the vertebrate fossil record (including primates). If the fossil can be construed to be a human ancestor it gets plenty of attention and if it is not the reports are left to wither. For a primate fossil to be seen, it must be promoted, and this often leads overblown reports. Such is the case with a new fossil anthropoid from Myanmar described by an international team of scientists today in the Proceedings of the Royal Society B.

When I fired up my computer this morning I was greeted by attention-grabbing headlines that proclaimed “Early Man Evolved in Burma“, “Human, Ape Ancestor Hails From Asia“, and “Rival Fossil Challenges ‘Missing Link.'” The hype was not quite as intense as that which surrounded the lemur-like “Ida“, but all this hullabaloo suggested that this new primate would tell us something significant about our own origins within the primate family tree.

After I actually read the paper I could only assume that this is yet another case of media outlets blindly swallowing press releases that overplay controversy and obscure the true significance of fossils. There is nothing in the paper to suggest that this new fossil anthropoid, named Ganlea megacania, is one of our ancestors or a common ancestor of monkeys and apes. It is only being marketed as a competitor with “Ida” to get it more attention; who would otherwise care about a 38-million-year-old seed-eating monkey?

Before I delve more deeply into the misinformation being promulgated about Ganlea, though, let me discuss what the paper actually says. During the past several decades paleontologists have been finding the fragmentary remains of a group of extinct primates called amphipithecids from Myanmar and a few other localities in Asia. There has been some debate as to how they might relate to each other and other primates in general. Some scientists have seen them as anthropoids (the group that contains monkeys and apes) or as adapiforms (an extinct group of lemur-like primates that includes “Ida”). Ganlea helps to resolve some of these relationships.



A lateral view of the right lower jaw of Ganlea. Note the size of the large canine (in green) and the presence of a single-rooted second premolar (yellow). From Beard et al. (2009).

So far Ganlea is only represented by some jaw fragments and assorted teeth, but a mammal’s teeth can tell you a lot. The teeth of Ganlea clearly group it with other amphipithecid primates from the area like Myanmarpithecus and Podaungia, and together these primates appear to belong to a monophyletic group (or they all shared a recent common ancestor and are closely related). Indeed, one key trait shared among these primates is a canine tooth that is compressed front-to-back so that it is wider than it is long. This and other minute details of the teeth appear to be unique characteristics of this group.

So how do the amphipithecids relate to other primates? The cladistic analysis undertaken by the scientists found that these primates were closely related to New World monkeys (platyrrhines) and an extinct group of anthropoid primates called propliopithecids (represented by creatures like Aegyptopithecus from the Fayum region of Egypt). Which of the two groups the amphipithecids were more closely related to is as yet uncertain, but this placement means that that the amphipithecids were anthropoid primates, not adapiforms. If were able to see Ganlena and its close relatives in life they might resemble living monkeys.



A hypothesis as to the evolutionary place of Ganlea and other amphipithecids, marked in grey. Note their proximity to New World monkeys and the propliopithecids. From Beard et al. (2009).

Indeed, the amphipithecids do not sit near the base of the anthropoid evolutionary bush, like the fossil primate Eosimias, but are more evolutionarily specialized. More fossil material will have to be discovered to further compare Ganlea and other amphipithecids to other fossil anthropoids to further test the hypotheses of the authors. (See this post for the difficulties in tracing primate evolution based upon jaws and teeth alone.)

What is particularly interesting about Ganlea, though, is that it had a huge canine tooth (hence the species name “megacania“) that looks as if it was shaved down at a steep angle. This was not a break, but a particularly intense case of tooth wear. What could have caused this? The authors proposed that Ganlea (as well as the other amphipithecids) often fed on hard seeds and nuts that abraded the canines of these primates. The large lower canines of Ganlea, in particular, might have been an adaptation to this particular feeding niche represented today by saki monkeys of Central and South America.

To sum things up, then, Ganlea was a fossil anthropoid primate that was possibly closely related to New World monkeys and often fed on seeds and tough-skinned fruit. Depending upon whether it turns out to be more closely related to New World monkeys or the extinct propliopithecids, it could help paleontologists understand the evolution and dispersal of monkeys throughout the world. Why, then, is is being touted as proof that the early evolution of our own lineage began in Asia?

The first report I saw, kindly sent to me by Karen, claimed that Ganlea represented the “ultimate ancestral group of all anthropoids,” thus making it one of our ancestors. Since humans are apes, and apes are anthropoid primates, the last common ancestor of all anthropoids would be one of our distant primate ancestors. Ganlea, though, may be more closely related to New World monkeys, a branch of the primate family tree that did not give rise to apes or humans. Perhaps some of the confusion came from this quote from Christopher Beard, one of the authors of the description of Ganlea, in which he compares Ganlea to “Ida”;

Ida is a complete fossil, and that in many ways is its calling card. We have an incomplete fossil of Ganlea but even though it is not complete, its anatomy is far more compelling for it to be the ancestor of monkeys, apes and humans than it is for Ida to be the ancestor.

Given that Ganlea is an anthropoid it is likely more closely related to us than Darwinius (“Ida”), but if the analysis of Beard et al. is correct then it is far too specialized to be considered the common ancestor of anthropoid primates. If we had to choose between Ganlea and Darwinius alone for which better represents the last common ancestor of all anthropoids Ganlea would probably win, but since this is not the case Beard’s quote all-too-easily creates confusion. Furthermore, there is a lot of irony in Beard’s remark that;

Ida is a good-looking fossil but it was the victim of incredible marketing. It is not all that it was cracked up to be. I’ve never seen such hyperbole surrounding a primate fossil as the one that came with Ida – and I’m not alone in thinking that.

The same, to a lesser degree, could be said about Ganlea. The press release about Ganlea plays up its supposed relevance to the origin of anthropoid primates in Asia, a debate which Beard has been steeped in since his involvement in the description of Eosimias in 1994, but these statements stand in stark contrast to what is actually contained in the paper. I am sorry to say so, but the press office of the Carnegie Museum of Natural History has misled the public about what the paper describing Ganlea says and its relevance to primate evolution. Despite the complaints about the hype surrounding “Ida”, they are marketing Ganlea in a similar way.

This is extremely unfortunate as the statements of the press release have been echoed without skepticism in many reports. I can only assume that almost no one has actually read the paper as each of the stories I have seen couches the actual details of the paper within the “Monkeys/Apes/Humans evolved in Asia and migrated into Africa” issue. This is a huge mess of a misunderstanding the press release played right into. Examples include the The Irrawaddy, ScientificBlogging, the Science Codex, the Pittsburgh Tribune Review, Discovery News, and MSNBC. The Pittsburgh Tribute Review is particularly confused. It starts off by saying;

An international team including a Pittsburgh researcher announced Tuesday it discovered a fossil in Myanmar that challenges the popular theory that humans evolved from a primate in Africa.

This is so vague that it can be easily misunderstood as saying that the earliest humans did not evolve in Africa, but it is contradicted further down: “This does not mean that humans evolved in Asia, Beard said.” I know what the reporter probably means, but I don’t think the average reader will have the background information to adequately parse these statements (which are the ones likely to gain the most attention). Beard has done a lot of work popularizing the idea that anthropoids first evolved in Asia, not Africa (see Hunt for the Dawn Monkey), but that is another story that Ganlea is only peripheral to. Ganlea might be important in figuring out the origins of New World Monkeys, but it does not overturn the notion that hominins originated in Africa.

Press releases and public relations announcements are skewing how Ganlea is being presented. The information being passed on to the public is being overblown to attract a wider audience, and this obscures the real scientific significance of the discovery. Indeed, the sites listed above are not engaging in journalism. They are simply parroting what they are being told because the reporters apparently do not have enough experience to read or understand the scientific research itself.

Some might argue that sensationalist headlines and hyped-up claims help bring in wider audiences, and while that is true it does not do any good if you end up confusing the people you are trying to educate. Trying to one-up other discoveries with impressive-sounding, but vague, pronouncements can be hazardous in that members of the public can be given misleading information (i.e. that humans did not evolve in Africa). People are going to remember the hook more than the details, and this is unfortunate when your hook is not accurate. If this represents standard practice in modern science communication among news outlets, we are in a helluva lot of trouble.

K. Christopher Beard, Laurent Marivaux, Yaowalak Chaimanee, Jean-Jacques Jaeger, Bernard Marandat, Paul Tafforeau, Aung Naing Soe, Soe Thura Tun and Aung Aung Kyaw (2009). A new primate from the Eocene Pondaung Formation of Myanmar and the monophyly of Burmese amphipithecids Proceedings of the Royal Society B DOI: 10.1098/rspb.2009.0836

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