The Ancient Human-Like Species with Frontal Brain Enlargement (AKA Brodmann Area 10)

Round Moni, lake in the volcanic craters of Kelimutu, Author: SerenadeGNU Free Documentation License

Modern humans (Homo Sapiens Sapiens) are not the only intelligent hominids to have existed in recent history. If we go back 30,000 years ago there were several other intelligent hominids that dominated their territories. Our ancestors had to work out how to coexist with these species. In the long run only our species survived. Thinking of these other hominids as distinct species is controversial in one special case – the so called ‘Hobbit Man’ of the Indonesian island of Flores also known as Homo Floresiensis.

The controversy centres on whether Homo Floresiensis were indeed a separate species or instead were humans with dwarfism. The debate was intense after their initial discovery although it has declined somewhat and the evidence is more in favour of them being a distinct species. The recovered specimens date back 18,000 years ago. Unfortunately early attempts at recovering DNA from the specimens were unsuccessful and the de facto gold standard of species identification through genome analysis is awaited.

Homo floresiensis, Ryan Somma , Creative Commons Attribution-Share Alike 2.0 Generic License (CC BY-SA 2.0)

However comparative anatomy helps to settle some of the questions. The authors of this Science paper produced a virtual endocast. In other words they used markings on the skull and other measurements to estimate the shape of the brain. They compared this brain to that of other species including modern humans with and without dwarfism. The researchers found that the brain shape was very different to that of modern humans. However it did fit relatively closely with that of a very distant ancestor of humans – Homo Erectus. The researchers went as far as to suggest that Homo Floresiensis and Homo Erectus shared a not too distant ancestor.

H.Floresiensis would have faced Giant Storks which towered at just under six feet compared to the 3 foot 6 height estimate for one of the recovered specimens (of a similar height to the other specimen). H.Floresiensis faced other challenges. To get to the Island of Flores it has been suggested that H.Flores was seafaring and the journey must have taken place during the initial migration. Other species in the region include Java Man (Homo Erectus) which lived around 1.8 million years ago.

The most interesting aspect of the above paper is that the researchers in this paper suggest that Brodmann Area 10 was relatively large when compared to scaled versions of the brains of other species.

Brodmann Area 10

In a previous post, I have argued that strictly speaking it is incorrect to label the Brodmann Areas on the basis of surface markings and instead Brodmann meant for them to be understood on the basis of the microscopic properties of the brain (cytoarchitecture). There is a more significant case for this in archaic species where we have little understanding of their neuroanatomy. Still we have to start somewhere. In another post I have written about the research findings in Brodmann Area 10 in humans. Thus research suggests a role for Brodmann Area 10 in memory (episodic memory and the recognition stage in spatial memory tasks) in humans as well as more complex motor activities and goal formation. There are alterations in the neurochemistry of BA10 in Schizophrenia whilst other research shows an increase in the cortical thickness in BA10 in people with Down Syndrome. Yet other studies show an increased activity in BA10 in risk-taking activities.

Clearly BA10 is a complex area with many possible functions including higher cognitive processes. Maybe H.Flores can tell us something about the brain changes that our distant intelligent ancestor H.Erectus evolved to make our species so successful in adapting to the environment.

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One thought on “The Ancient Human-Like Species with Frontal Brain Enlargement (AKA Brodmann Area 10)

  1. Pingback: Mapping of the Human Visual Cortex – News Roundup: October 2012 2nd Edition « The Amazing World of Psychiatry: A Psychiatry Blog

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