Hello? Darwinians ? Why is everything so surprising?
from a mainstream paper:
Recent delineation of the serine protease cascade controlling dorsal–ventral patterning during Drosophila embryogenesis allows this cascade to be compared with those controlling clotting and complement in vertebrates and invertebrates.
Extensive similarities suggest that these cascades were built by adding enzymes from the bottom of the cascade up and from similar macromolecular building blocks.
There is a surprising degree of convergent (repeated) evolution uniting the enzyme cascades for blood and hemolymph clotting, and the innate immune response against microorganisms. The use of homologous macromolecules to conduct these activities in both protostomes and deuterostomes points strongly to the possibility that the basic elements responsible for these functions existed before the divergence of the protostomes and deuterostomes.
The author also thinks that:
We must consider the possibility that some of our most ‘primitive’ ancestors were much more physiologically complex than was anticipated.