Apr 25 2017

New Study of The Hobbit

HobbitI have been following the story of Homo floresiensis for the last decade, and it is fascinating. The remains of a diminutive humanoid were found on the island of Fores in Indonesia. The remains date to about 54,000 years ago. The findings immediately sparked debate, with two primary schools of thought emerging.

The first hypothesized that H. foresiensis (nicknamed the Hobbit due to their small size) was a new species of hominin, likely evolve from H. erectus and displaying an example of island dwarfism. The second argued that the remains are not a new species at all and represent a pathological H. sapiens (modern human).

The two groups have argued back and forth in the scientific literature over the years. It is, in fact, a great example of the scientific method in action. Each group brought new evidence and a new perspective to bear, and had the burden of proof to demonstrate their hypothesis. They fought it out with science and evidence.

I and many others sat of the sidelines and watched the epic battle of science. I admit I was rooting for H. floresiensis, but we would all have to listen to the evidence, whatever it showed.

It’s also a good example of the limitations of mainstream science reporting. Each time a study was published, favoring one side of the debate or the other, it was reported as if the debate were finally over and now we know the answer. Instead they should have put that one study into context – this is just another round in an ongoing debate. The fight isn’t really over until one side concedes defeat and a consensus emerges. Even then, new evidence may trump the consensus, but at least we have a consensus rather than a controversy.

The New Study

So, here we go again with a new study claiming to settle the debate. This may do it, because it is the most thorough study to date, but we will have to see how the scientific community responds. The study is by paleoanthropologist Debbie Argue and her colleagues. They examined 133 anatomical data points on the H. floresiensis remains, and compared them to modern humans, H. erectus, and older specimens.

They were essentially testing three hypotheses: H. floresiensis is a pathological human, is most closely related to H. erectus, or is most closely related to an older human lineage from Africa (such as H. habilis). What they found strongly supports the hypothesis that H. floresiensis is most closely related to H. habilis.

They argue that the data rejects the pathological human hypothesis to almost 100%. This is one way to tell which hypothesis in a true controversy has the upper hand. When the data gets more detailed and rigorous, toward which hypothesis does it move. In this case at least these researchers are saying that the more detailed analysis has all but rejected the pathological human hypothesis.

Even more interesting, however, is the fact that the data favors a closer relationship with H. habilis than H. erectus. The reason it was assumed that H. erectus was a likely immediate ancestor is because H. floresiensis was found outside of Africa. The earliest known migration of human ancestors out of Africa was of H. erectus. They were tall, they were hunters, and they used fire. It it thought that this combination of factors made them competitive enough to spread out to Europe and Asia. In fact, as large hunters they would have had to spread out.

H. floresiensis, however, shows numerous primitive features that predate H. erectus. The researchers believe that their connection to our family tree may go back 1.75 million years. This would put their common ancestor with us prior to H. habilis. Essentially they may have shared a common ancestor with H. habilis.

This would further mean that their arrival on Flores was part of an older previously unknown migration of hominins out of Africa, meaning that H. erectus was not the first.

It is fascinating that a remnant of an ancient hominin lineage survived until just 54,000 years ago, or perhaps even more recently. Imagine if a small isolated population of such hominins survived into modern times.

Conclusion

I don’t know if this study will end the controversy over H. floresiensis. We will have to wait and see the reaction of other scientists who hold different opinions. ┬áHaving followed this story, however, my impression is that the needle has been moving steadily in the direction of the conclusion that H. floresiensis is a legitimate hominin species.

This is entirely plausible. Overall, the more evidence we find of human ancestors the more complex the evolutionary bush has become. Humans were a very successful clade showing adaptive radiation, and spread throughout the world. This is generally what we see in successful groups.

We tend to have evolutionary hindsight bias, however. We look back from the perspective of the survivors as if they were inevitable and unique. We still need to purge our evolutionary thinking of this linear bias. The hippus clade was not evolving toward a modern horse, that is just one line that happened to survive. Feathered dinosaurs were not evolving toward modern birds, that is just the surviving clade.

Our human ancestors were not evolving toward us, they were just adapting to their local environment and spreading out as they became more successful and versatile. We are the survivors. However, H. floresiensis were also survivors, up until very recently. H. neanderthalensis were a very successful species. It is still not clear why sapiens ended up dominating. We did interbreed to some extent. It is possible we out-competed them. It is also possible that Neanderthals were better adapted to ice age climates.

Evolution is chaotic and complicated. H. floresiensis is now one more complicated detail in the story of hominin evolution.

 

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