New Scientist has offered up a cool, free article, A brief history of the brain - which is brief only in comparison to a dissertation or book. For an internet post, it is quite lengthy - and very cool as a primer on the human brain, beginning in the oceans of our distant past right up to the present, when the brain seems to be shrinking.
New Scientist tracks the evolution of our brain from its origin in ancient seas to its dramatic expansion in one ape – and asks why it is now shrinking
IT IS 30,000 years ago. A man enters a narrow cave in what is now the south of France. By the flickering light of a tallow lamp, he eases his way through to the furthest chamber. On one of the stone overhangs, he sketches in charcoal a picture of the head of a bison looming above a woman's naked body.
In 1933, Pablo Picasso creates a strikingly similar image, called Minotaur Assaulting Girl.
That two artists, separated by 30 millennia, should produce such similar workseems astonishing. But perhaps we shouldn't be too surprised. Anatomically at least, our brains differ little from those of the people who painted the walls of the Chauvet cave all those years ago. Their art, part of the "creative explosion" of that time, is further evidence that they had brains just like ours.
How did we acquire our beautiful brains? How did the savage struggle for survival produce such an extraordinary object? This is a difficult question to answer, not least because brains do not fossilise. Thanks to the latest technologies, though, we can now trace the brain's evolution in unprecedented detail, from a time before the very first nerve cells right up to the age of cave art and cubism.
The story of the brain begins in the ancient oceans, long before the first animals appeared. The single-celled organisms that swam or crawled in them may not have had brains, but they did have sophisticated ways of sensing and responding to their environment. "These mechanisms are maintained right through to the evolution of mammals," says Seth Grant at the Wellcome Trust Sanger Institute in Cambridge, UK. "That's a very deep ancestry."
The evolution of multicellular animals depended on cells being able to sense and respond to other cells - to work together. Sponges, for example, filter food from the water they pump through the channels in their bodies. They can slowly inflate and constrict these channels to expel any sediment and prevent them clogging up. These movements are triggered when cells detect chemical messengers like glutamate or GABA, pumped out by other cells in the sponge. These chemicals play a similar role in our brains today (Journal of Experimental Biology, vol 213, p 2310).
Read the whole article.
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