Human brain development (Introduction)
by David Turell 
, Thursday, December 04, 2014, 20:33 (3425 days ago)
It requires a great deal of glucose energy to grow a complex human brain. Therefore babies stay small and grow slowly to allow the brain to develop as fully as possible before the body is increased to adult size. Our growth pattern is not like that of the apes or chimps for that reason:-http://blogs.discovermagazine.com/crux/2014/12/02/human-children-stay-small-long/#5465-"So human growth rate negatively shadows increased energy use in the child's brain. An interesting fact - but does it tell us more? Neanderthals and other earlier species of humans developed brains as big as ours. Why did they not survive? Bad luck? Competition from our species? Or has an overlooked advantage arisen in our evolution that puts us apart? Neanderthals grew up faster than us, and this suggests, given the link between a child brain's energy guzzling and slowed growth, a new story.- "Bigger brains may be smarter brains but they might be even smarter if their connections got to be better refined in brain development. Neuro-maturation involves an exuberance of synapses - the connectors between neurons. This initial excess lets the developing brain refine down connections, to “wire” itself in the most effective and efficient manner. Connectome research, which studies this process - both theoretically and empirically - links better efficiency of connectivity to improved cognitive ability.-"Synapses are the primary energy consumers within the brain and it is their exuberance that causes the child's brain to use so much extra energy. We cannot directly see how long this period lasted in earlier humans but we can indirectly from their pattern of growth. Since this was faster than in us we can infer that they lacked - in spite of having brains as large as ours - the extended period of connectivity refinement that we have. This means they also lacked our extraordinary capacity for complex cognitions.-"This not only resulted in us displacing them but also the creation of civilization and the complex lives we each now live."
Human brain development: Homo Erectus
by David Turell , Thursday, December 04, 2014, 21:48 (3424 days ago) @ David Turell
Very old simple engraving on a shell by H. erectus:-http://blogs.scientificamerican.com/observations/2014/12/03/worlds-oldest-engraving-upends-theory-of-homo-sapiens-uniqueness/-I'm not surprised at simple thought like this in H. Erectus:-"Now comes news that an even older, more primitive human ancestor—Homo erectus from Asia—showed signs of symbolic thought, too. Researchers have discovered a shell engraved with a geometric pattern at a H. erectus site known as Trinil, on the Indonesian island of Java, that dates to between 540,000 and 430,000 years ago. The find is at least 300,000 years older than the oldest previously known engravings, which come from South Africa.-"Detail of shell engraved by Homo erectus at Trinil GEOMETRIC DESIGN engraved on this mussel shell is 300,000 years older than engravings from South Africa that were previously thought to be the oldest. Image: Wim Lustenhouwer, VU University Amsterdam -"Analysis of the engraving, made on a freshwater mussel shell, suggests that its maker used a shark tooth or other hard, pointed object to create the zigzag design. “The engraving was probably made on a fresh shell specimen still retaining its brown [skin], which would have produced a striking pattern of white lines on a dark ‘canvas,'” Josephine C. A. Joordens of Leiden University in the Netherlands and her colleagues surmise in their report, published online December 3 by Nature. (Scientific American is part of Nature Publishing Group.)-"Other shells from the site reveal that H. erectus opened them to eat their contents. And one specimen exhibits clear signs of having been modified to create a tool for cutting or scraping. It is the earliest known example of shell used as a raw material for tool manufacture, the authors say, and it may explain the lack of stone artifacts from this time period in Java: perhaps in the absence of good sources of stone suitable for making implements, H. erectus turned to shell instead."
Human brain development: Gene for size found
by David Turell , Friday, February 27, 2015, 15:27 (3340 days ago) @ David Turell
A gene found in H. sapiens, Neanderthals and Denisovans, but not in chimps drives stem cell production and causes the size we have.:-http://medicalxpress.com/news/2015-02-gene-brain-size-humans.html-"During evolution our genome must have changed in order to trigger such brain growth. Wieland Huttner, Director and Research Group Leader a the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), and his team identified for the first time a gene that is only present in humans and contributes to the reproduction of basal brain stem cells, triggering a folding of the neocortex. The researchers isolated different subpopulations of human brain stem cells and precisely identified, which genes are active in which cell type. In doing so, they noticed the gene ARHGAP11B: it is only found in humans and in our closest relatives, the Neanderthals and Denisova-Humans, but not in chimpanzees. This gene manages to trigger brain stem cells to form a bigger pool of stem cells. In that way, during brain development more neurons can arise and the cerebrum can expand. The cerebrum is responsible for cognitive functions like speaking and thinking. "