miércoles, septiembre 28, 2005

Proponen que hubo un cerebro primigenio comun

Mother of All Brains Probed

By Jennifer Viegas, Discovery News

­ All brains originated from a single common ancestral brain that emerged
at least 700 million years ago, according to a recent analysis of brain
studies from the past decade.

The finding suggests this mother brain for all creatures with a central
nervous system ­ such as insects, birds, animals and humans ­ evolved only
once before each species underwent its own evolutionary course.

"What we see today in humans, insects and all other multicellular animals
with a central nervous system are probably just variations of one ancient
scheme," said Rudi Loesel, who conducted the analysis.

Loesel, a scientist in the Department of Developmental Biology and
Morphology of Animals at RWTH Aachen University in Germany, added, "What
this ancestral brain looked like, we do not know. Its architecture might
have been very simple, but the basic genetic mechanisms and the principal
chemical setup was already there (before 700 million years ago)."

The researchers don't know what the creature that contained the mother of
all brains looked like. Some scientists speculate that it could have been a
segmented flatworm, while others think it was a more complex creature.