16 SEP 2011 by ideonexus
Ontogeny Recapitulates Phylogeny
Now, we’re not absolutely sure why some species retain much of their
evolutionary history during development. The “adding new stuff onto
old” principle is just a hypothesis—an explanation for the facts of embryology.
It’s hard to prove that it was easier for a developmental program
to evolve one way rather than another. But the facts of embryology
remain, and make sense only in light of evolution. All vertebrates begin
development looking like embryonic fish because we all descended...Embryos go through the stages of the evolution of their ancestors as they develop.
20 MAY 2011 by ideonexus
An Origami Metaphor for Fetal Development
The sheets of tissue that
fold, invaginate and turn inside out in a developing embryo do indeed grow, and it is that very growth that provides part of the motive force which, in origami, is supplied by the human hand. If
you wanted to make an origami model with a sheet of living tissue instead of dead paper, there is at
least a sporting chance that, if the sheet were to grow in just the right way, not uniformly but faster
in some parts of the sheet than in others, this might automatically cau...Cells divide and fold into new forms, just as origami structures become other structures through new folds.