Is the Hobbit's Brain Unfeasibly Small?
2010 01 29
Homo floresiensis, a pygmy-sized small-brained hominin popularly known as 'the Hobbit' was discovered five years ago, but controversy continues over whether the small brain is actually due to a pathological condition. How can its tiny brain size be explained?
These are the skulls of Homo floresiensis (left) and Homo sapiens (right).
(Credit: Professor Peter Brown, University of New England)
The commonly held assumption that as primates evolved, their brains always tended to get bigger has been challenged by a team of scientists at Cambridge and Durham. Their work helps solve the mystery of whether Homo floresiensis -- dubbed the Hobbit due to its diminutive stature -- was a separate human species or a diseased individual.
The team combined previously published datasets of brain and body mass with measurements from fossil remains. They then used three different mathematical methods to reconstruct patterns of brain evolution across the primate family tree from these 37 existing and 23 extinct primate species.
The results show that while brains evolved to be larger in both relative and absolute terms along most branches of the primate family tree, the opposite happened along several lineages. For example brain size shrank during the evolution of Mouse Lemurs, Marmosets and Mangabeys.
In contrast, the study found no overall trend to increase body size, suggesting that brain and body mass have been subject to separate selection pressures in primates.
Gorillas, for example, have large brains but the increase in body mass during the evolution of modern gorillas greatly exceeds the increase in brain mass. Conversely, lineages leading to other primates, such as Gibbons and Colobus monkeys show an increase in brain mass but a decrease in body mass.
The findings may help solve the mystery of "the Hobbit" or Homo floresiensis. This metre-high early human species shared the planet with our species until 13,000 years ago. Its discovery on the Indonesian island of Flores in 2003 sparked a long-running debate, some scientists arguing that it was a new human species while others believed disease was more likely to be responsible for its small size.
According to co-author Stephen Montgomery of the University of Cambridge: "The discovery challenged our understanding of human evolution and created much debate about whether H. floresiensis was a distinct species or a diseased individual."
"Much of the debate about the place of H. floresiensis in the primate tree is centered around its small size, in particular the small brain size. The argument raised has been that the evolution of such a small brain does not fit with what we know about primate brain evolution.
"Our analysis, together with studies of brain size in island populations of living primates, suggests we should perhaps not be surprised by the evolution of a small brained, small bodied early human species."
The findings also deepen our understanding of how our brains and bodies have evolved and the selection pressures that may have been responsible. The results show that selection has acted in both directions, usually resulting in evolution of bigger brains but also producing smaller ones.
This is the first study to reconstruct the pattern of brain evolution across all primates. Previous studies by other researchers have looked at possible advantages and disadvantages of increased brain size in primates, but few consider how often, when, or where in the primate family tree these changes have happened.
According to lead author Dr Nick Mundy of the University of Cambridge: "A trend towards brain expansion is assumed to have occurred throughout primate evolution. This has been interpreted as an indication of selection for cognitive abilities due, for example, to 'arms races' in the ability to process social information."
"We found decreases in brain mass along several branches across the primate family tree. It is likely that reductions in brain size occurred to meet demands of the species' changing ecological needs meaning that sometimes individuals with smaller brains are favoured by natural selection."
"Periods of primate evolution which show decreases in brain size are of great interest as they may yield insights into the selective pressures and developmental constraints acting on brain size."
Primates have relatively large brains for their body size compared with other mammals. The world's smallest primate brain belongs to the grey mouse lemur (Microcebus murinus), whose brain weighs just 1.8g (half as much as a UK one penny piece). The heaviest primate brain belongs to humans, weighing in at 1330g.
Brain expansion began early in primate evolution, suggesting brain expansion had a significant role in the origin and success of modern primates. Absolute brain mass is striking in humans but large brains have evolved several times in primates -- for example Capuchins are South American monkeys which rival apes in terms of relative brain size. Indeed in the wild some populations of Capuchins are known to use tools to exploit novel food resources.
Recent studies show brain size decreased in other vertebrate lines, including birds, bats and elephants, as well as the cow and hippo families.
Article from: ScienceDaily.com
Lloyd Pye - "Everything You Know Is Wrong"
Video from: GoogleVideo.com
Lloyd Pye - The Starchild Skull Update
Lloyd Pye - The Starchild Skull & DNA Revelations (Subscription)
Lloyd Pye - Human Origins, Intervention Theory & Genetic Experimentation
Lloyd Pye - The Starchild Skull (Subscription)
Lloyd Pye - The Annunaki & Genetic Engineering
Lloyd Pye - Human Design & Properties of Annunaki Genes
Michael Cremo - Forbidden Archeology
Michael Cremo - Human Devolution (Subscription)
Freddy Silva - Ancient Sacred Sites, Invisible Temples, Giants & Our Ancestors
Bigfoot hobbit could be ancient island human
Studies say 'hobbit' previously unknown species
The Mystery of the Human Hobbit (Video)
New twist in Hobbit-human debate
Yes, it's a Hobbit. The debate that has divided science is solved at last (sort of)
Ancient 'Hobbit' not a malformed human
Hobbit cave digs set to restart
Red Ice Creations - Archeology, Architecture, Artifacts, Art & Ancient Findings
Ancient Human Ancestor 'Ida' Discovered
'Eighth wonder' Ida is not related to humans, claim scientists
Latest News from our Front Page
Pyramid of the Sun Turning to Dust
2014 03 10
All we are is dust in the wind, so the saying goes, but it’s troubling when it happens to great ancient monuments that we assume will be around forever.
Pyramid of the Sun, Pirámide del Sol, Teotihuacán, México (Wikimedia Commons)
New Scientist reports that the Pyramid of the Sun in Mexico is turning to dust and could collapse:
The Pyramid of the ...
Elephants Never Forget A Voice
2014 03 10
According to a new study, wild elephants are discerning listeners who can differentiate between various human languages, genders, ages, and more. Such surprising skills continue to marvel researchers.
Not all the intellectual surprises are on the large animal front. Research has shown that crows are extremely intelligent, some dogs recognize over a thousand words and have the intellect of a toddler, ...
RIP, psychiatry: the “chemical-imbalance” theory is dead
2014 03 10
This one is big.
Dr. Ronald Pies, the editor-in-chief emeritus of the Psychiatric Times, laid the theory to rest in the July 11, 2011, issue of the Times with this staggering admission:
“In truth, the ‘chemical imbalance’ notion was always a kind of urban legend — never a theory seriously propounded by well-informed psychiatrists.”
The point is, for decades the whole basis of ...
Space Elevator By 2035, Says International Academy of Astronautics
2014 03 10
Going up? Way up?
The space elevator - An idea which used to be pure speculative science fiction has gained renewed interest.
ExtremeTech.com lays out the technical challenges of the audacious (crazy?) plan to extend the 100,000-kilometers-long tether into space. Especially problematic to the mission is the fact that the materials and technology needed to create the space elevator don’t actually exist ...
One million Britons descended from Vikings says new study
2014 03 10
A new study is showing that approximately 930,000 people can claim to be of direct Viking descent in Great Britain today, especially in the north of Scotland. The ancient Norse peoples’ influence is still being felt in modern times.
Around one million Britons are directly related to Vikings, with people from the north of Scotland most likely to have Viking ...
|More News » |