viernes, 2 de septiembre de 2016

Un nuevo estudio sugiere que la cantidad de sangre que llega al cerebro fue la clave en la evolución de la inteligencia humana

1/3. Índice de suministro de sangre al cerebro en relación a la edad geológica de los homínidos

Que el aumento de tamaño del cerebro humano en algún punto remoto de nuestra evolución tiene que ver con el desarrollo de la inteligencia es algo comunmente aceptado. Pero ahora un equipo de investigadores de Sudáfrica y Australia lo cuestionan. Según explican, la auténtica clave para la evolución de la inteligencia fue el aumento del suministro de sangre al cerebro.

Según explican en el artículo publicado en Royal Society Open Science, para demostrar su hipótesis calcularon como había ido variando la cantidad de sangre suministrada al cerebro de nuestros ancestros a lo largo del tiempo. Encontraron que el cerebro humano no solo evolucionó en tamaño, sino que también pasó a consumir mayores cantidades de sangre. [...]

Blood-Guzzling Brain Key To Evolution Of Human Intelligence | Popular Science
The human brain is a fuel hog, and that, it turns out, is key to how our intelligence evolved. It has long been believed that the evolution of human intelligence was simply related to increasing brain size, but a team of researchers from South Africa and Australia have overturned that assumption.
By calculating how blood supply to the brains of human ancestors changed over time, the researchers were able to show that the human brain not only evolved to become larger, but also more blood-thirsty. And the need for blood outpaced the volume increase of the brain itself.
"Brain size has increased about 350% over human evolution, but we found that blood flow to the brain increased an amazing 600%," project leader Roger Seymour, from the University of Adelaide, said in a statement. "We believe this is possibly related to the brain's need to satisfy increasingly energetic connections between nerve cells that allowed the evolution of complex thinking and learning."...

Actualización: How our species got smarter: through a rush of blood to the head
Anthropologists have been curious about the evolution of human intelligence for many decades. The main lines of research have involved archaeological finds concerning the use of fire, tools and so on.

But what about looking for evidence in fossil skulls, the place where the brain resided?

The volume of the human brain increased to be about three and a half times larger than our Australopithecus ancestors 3 million years ago.

It is generally assumed that intelligence is correlated with brain size, and the reason for this is that the number of nerve cells in mammalian brains seems to be directly related to brain size.

Our research focused on the rate of blood flow to the brain, which relates closely to metabolic rate because the blood supplies the essential oxygen. If blood flow to your brain is stopped, you will pass out within seconds.

Normally you have about 7 millilitres of blood flowing to your brain each second. Remarkably, this rate changes little, regardless of whether you are awake, asleep or solving mathematical problems...

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Actualización: How our species got smarter: through a rush of blood to the head